Disertación/Tesis

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2024
Disertaciones
1
  • EDUARDO JORGE DA CUNHA LINS
  • Development of sustainable blends for application in geothermal wells

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • JÚLIO CÉZAR DE OLIVEIRA FREITAS
  • RODRIGO CESAR SANTIAGO
  • BRUNO LEONARDO DE SENA COSTA
  • Data: 15-ene-2024
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The cementing process is a fundamental stage in the construction of a geothermal well. Its importance ranges from factors such as mechanical stability, such as the support of liners and rock formations, to the hydraulic isolation of the different drilled intervals, restricting the movement of fluids between the formations. Among the materials most commonly used in geothermal wells are blends containing Portland cement and silica flour. This mixture is used to control retrogression, a process which consists of reducing the compressive strength of cement pastes when subjected to high temperatures, common in geothermal wells, which can easily reach 300 °C. Rice husk ash (RHA) is a sustainable source of silica that has been widely applied as a partial replacement for cement as an alternative to crystalline silica. The aim of this work was to develop cement blends with varying proportions of silica flour and RHA for use in geothermal wells. The pastes were subjected to 300 °C and 2000 psi for 7, 14 and 28 days. After this period, compressive strength tests and physical-chemical characterizations were carried out using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. Increasing the concentration of RHA in the blends increased the mechanical strength by up to 4X when compared to the reference paste (water and cement only), as well as proving to be mechanically superior when compared to blends containing only silica flour, showing that the interaction between silica flour and CCA produces promising results in the geothermal well scenario. It was also noted that this interaction formed a denser microstructure in addition to maintaining the microstructures characteristic of cementitious materials subjected to high temperatures, which may explain why there was an increase in compressive strength in the blends containing CCA in their composition. Based on the above, blends containing CCA and Silica Flour are a sustainable alternative for application in geothermal well scenarios.

2
  • BRUNA LUZ CARRERAS LAMAS
  • Obtaining hybrid composite HDPE/mALGAS/MMT-Ag/PE-g-MAH

  • Líder : EDSON NORIYUKI ITO
  • MIEMBROS DE LA BANCA :
  • EDSON NORIYUKI ITO
  • FELIPE PEDRO DA COSTA GOMES
  • GRACO AURELIO CAMARA DE MELO VIANA
  • Data: 08-mar-2024
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Polymeric hybrid composites are formed by several phases of different compositions, in which the interfacial interaction between these materials is one of the factors that determine the final properties. The study of interfacial modifications is extremely important for the development of a material with technical quality for use. The objective of this work was to obtain hybrid composites with a high-density polyethylene (HDPE) matrix, varying the compositions and types of fillers, that is, microalgae (mALGAS), organophilic montmorillonite clay (MMT), montmorillonite clay treated with nanoparticles silver (MMT-Ag) and the use of polyethylene grafted with maleic anhydride (PE-g-MAH), as an interfacial compatibilization agent, aiming to study interfacial interactions correlated with the mechanical and rheological properties of polymer hybrid composites. Bulk formulations were varied from 2 and 4 wt% mALGAS, 2 and 4 wt% MMT, 3 wt% MMT-Ag and 3 wt% PE-g-MAH. The mixtures were made in a twin-screw extruder and test specimens were produced by injection molding. Material characterizations were carried out by measurements of fluidity index (MFI), X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), uniaxial tensile and Shore D hardness. The results showed that mALGAS contribute to an increase in fluidity, while MMT decreases fluidity during processing in the melt state. Hybrid composites using PE-g-MAH showed lower fluidity, whereas HDPE/MMT/PE-g-MAH composites showed lower fluidity, that is, the results showed the reactive interaction of maleic anhydride with mALGAS and MMT. The mechanical characterizations evaluated the influence of the shape, types of fillers and interfacial reaction on the properties of the HDPE/mALGAS/MMT-Ag/PE-g-MAH hybrid composites, resulting in a good synergism of properties of the studied polymeric hybrid composite.

Tesis
1
  • ANDRESSA GALVÃO DE ARAÚJO
  • Synergistic effect of vermiculite-lignosulfonate mixtures on the thermomechanical properties of coating mortars
  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • ERICA NATASCHE DE MEDEIROS GURGEL PINTO
  • JÚLIO CÉZAR DE OLIVEIRA FREITAS
  • KLEBER CAVALCANTI CABRAL
  • RÍSIA AMARAL ARAÚJO
  • Data: 29-ene-2024
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Currently, the search for construction materials that promote energy efficiency in buildings is increasingly growing. These materials not only contribute to the reduction of greenhouse gas emissions but also enhance thermal comfort and reduce energy consumption. The partial substitution of sand with porous aggregates, such as expanded vermiculite, holds great potential for modifying the thermal properties of mortars, thereby improving the thermal insulation of buildings. However, porous aggregates also decrease the mechanical strength of mortars. To overcome this challenge, plasticizing additives, such as lignosulfonates, can be employed in combination with porous aggregates to reduce the mixing water in the mixtures, resulting in higher mechanical strength and durability of the mortars. Therefore, the objective of this study was to evaluate the synergistic effect of combined addition of expanded vermiculite and a lignosulfonate-based plasticizer in rendering mortars. Mortars with a volume ratio of 1:3 were prepared, with replacement levels of sand by expanded vermiculite at 0%, 25%, and 50%, and an addition of 0% and 2% of lignosulfonate. The resulting mortars were characterized in the fresh state by measuring the consistency index and fresh bulk density. In the hardened state, apparent bulk density, water absorption, voids index, modulus of elasticity, compressive strength, and flexural tensile strength and and tensile adhesion strength were evaluated. The thermal insulation of the mortars was assessed by measuring the temperature gradient between opposite faces of mortar specimens measuring 26.5 x 20.0 x 1.5 cm. It was observed that as the concentration of vermiculite increased, the density and mechanical strength of the mortars decreased. The addition of 2% of plasticizer in the mortar containing 50% of vermiculite reduced the amount of mixing water, improving compressive strength by 15% and flexural tensile strength by 9%. The combined use of 50% vermiculite and 2% lignosulfonate resulted in an increased temperature gradient between opposite faces of the mortars from 6.7°C (reference mortar) to 9.2°C. This result confirms the synergistic effect of the vermiculite-lignosulfonate mixture in formulating mortars with enhanced thermal insulation effects.
2
  • ELLA RAQUEL DO VALE SOUZA DE LIMA
  • Selflubricating Ni-composites sintered using DC plasma

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • GUILHERME OLIVEIRA NEVES
  • ANTONIO EDUARDO MARTINELLI
  • CRISTIANO BINDER
  • RUBENS MARIBONDO DO NASCIMENTO
  • UILAME UMBELINO GOMES
  • Data: 28-feb-2024


  • Resumen Espectáculo
  • The present work aimed to evaluate the respective effects of different solid lubricants dispersed throughout the volume in the nickel matrix, produced via powder metallurgy. Graphite was used as a solid lubricant, which was introduced into the matrix by the conventional route in the simple mixing step, and the lubricant generated In-situ by the dissociation of silicon carbide (SiC) during sintering. In the mixtures, the graphite and SiC content was fixed at 10 vol.%, the conformation of the samples was carried out by uniaxial compaction at a pressure of 600MPa, the sintering took place in a hybrid plasma DC reactor and conventional oven, different sintering temperatures were applied (800 ºC, 900 ºC and 1000 ºC). The study of the microstructure and hardness of these materials was carried out using the analysis of green and sintered densities, XRD, Raman spectroscopy, MO, SEM/FEG-EDS and Vickers microhardness, which showed the influence of different solid lubricants, temperature and sintering medium on the formation of composites, on the continuity of the nickel matrix and on the dissociation kinetics of SiC. The silicon resulting from the dissociation of silicon carbide enriches the nickel matrix, in which the solubility of carbon varies with temperature, however the retained carbon precipitates and remains in the form of graphite. The addition of solid lubricant in the matrix promoted a reduction in the density of the sintered. Increasing the sintering temperature increased densification and reduced porosity. Sintering at 1000 ºC promoted higher hardness values. Graphite deposits increased in SiC containing samples with increasing temperature. Based on this information, the tribological behavior of materials sintered at 1000 ºC was analyzed. Composites containing solid lubricant obtained by the conventional route showed the lowest values of friction coefficient, the wear rate was close to that of the pure nickel matrix. The microstructural and hardness aspects indicate a similarity between plasma sintering processes under abnormal (DC) conditions and in a tubular furnace.

3
  • VIVIANE DA SILVA PINHEIRO
  • STUDY OF THE PROPERTIES OF PHOTOCATALYSIS AND PHOTOLUMINESCENCE OF BaMoO4/g-C3N4 SYNTHESIZED BY THE MICROWAVE-ASSISTED SOLVOTHERMAL METHOD

  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • ELSON LONGO DA SILVA
  • FABIANA VILLELA DA MOTTA
  • JUAN MANUEL ANDRÉS BORT
  • MAURICIO ROBERTO BOMIO DELMONTE
  • RICARDO LUÍS TRANQUILIN
  • Data: 29-feb-2024
    Ata de defesa assinada:


  • Resumen Espectáculo
  •  

    The need for environmental preservation has been the subject of study in several areas of application. Heterogeneous photocatalysis has been used for some years for the degradation of effluents. In this approach, the electronic band structure makes semiconductor type materials used as catalysts. However, degradation of organic dyes is damaged by the rapid recombination of charge carriers in semiconductors. One way to solve it is to promote the formation of heterostructures to improve particle properties. Among the various materials, barium molybdate has been highlighted due to its excellent properties and possibility of application in several areas. BaMoO4/xg-C3N4 heterostructures (x= 0.3 and 0.5 grams) were synthesized by the coprecipitation method followed by microwave-assisted solvothermal at 140 °C for 30 minutes. To employ the solvothermal method, 1,4 - butanediol alcohol was used as solvent. Then, analyzes were carried out to characterize the structure by X-ray diffraction (DRX), Raman scattering spectroscopy, morphological analysis by scanning electron microscopy by field emission (FEG-MEV), optical properties by means of the UV-Vis spectrophotometer, and investigation of the photocatalysis activity under UV radiation in the decontamination of simulated organic pollutants with Methylene Blue/AM (cationic) and Crystal Violet/VC (cationic). XRD diffractograms show that the microwave assisted solvothermal method is efficient for obtaining BaMoO4 particles and heterostructures with well defined peaks, showing high crystallinity without a secondary phase. The micrographs showed irregularly shaped BaMoO4 particles with a mean diameter between 168.84 and 240.86 nanometers. g-C3N4 exhibited nanosheet morphology with a porous surface. The gap energy measured by the direct method ranged from 4.63 – 4.70 eV for pure BaMoO4 samples and from 3.33 – 3.50 eV for BaMoO4/xg-C3N4. The heterostructures showed improved efficiency, achieving degradation rates of 95,17% for crystal violet and 95,16% for methylene blue, in contrast to the 25% and 19%, respectively, observed in pure BaMoO4 samples. In reuse tests with 4 consecutive cycles, the samples showed good photocatalytic capacity. Photoluminescence spectra were obtained at room temperature and revealed a blue emission peak for all samples when excited at 355 nm.

4
  • TOMAZ RODRIGUES DE ARAÚJO
  • SYNTHESIS OF ZnFe2O4-Fe2O3-ZnO NANOCOMPOSITE VIA MICROWAVE-ASSISTED SELF-COMBUSTION AND GREEN SYNTHESIS USING JATOBA WASTE (Hymenaea Courbaril L.)

     
     
  • Líder : DULCE MARIA DE ARAUJO MELO
  • MIEMBROS DE LA BANCA :
  • DENER DA SILVA ALBUQUERQUE
  • DULCE MARIA DE ARAUJO MELO
  • GILVAN PEREIRA DE FIGUEREDO
  • MARCO ANTONIO MORALES TORRES
  • MARCUS ANTONIO DE FREITAS MELO
  • RENATA MARTINS BRAGA
  • Data: 07-mar-2024


  • Resumen Espectáculo
  • The goal of this work was to enhance the textural, morphological, physical, structural, and crystalline properties of the ZnFe2O4-Fe2O3-ZnO nanocomposite using residues (phytochemicals from the liquid phase and lignocellulosic materials from the solid phase) originating from the processing of jatobá wood, which exhibits high production, low added value, and few technological applications. For this purpose, the following syntheses were used: microwave-assisted self-combustion and adapted green synthesis. The residues (liquid and solid phases) used were extracted through a hot process at various temperatures, and the liquid part was used in microwave-assisted self-combustion by replacing water with 50% and 100%; meanwhile, the solid part was used in adapted green synthesis as a structure and pore director.The characterization techniques used were X-ray diffraction, scanning electron microscopy (SEM-EDS and SEM-FEG), thermogravimetric and proximate analysis, calorific value, and thermal capacity; density by helium gas; contents of cellulose, hemicellulose, lignin, and phenolics; infrared, Raman, and ultraviolet-visible spectrophotometry; diffuse reflectance; Mossbauer; magnetic properties; in addition to particle size by dynamic light scattering (DLS) and specific surface area and pore size volume (BJH).Furthermore, analyses of the extraction process yield and syntheses were conducted. Regarding the results: The extraction yields were approximately 2% (by mass) for the aqueous extract and over 70% (by volume) for the solubles. The immediate analysis shows moisture content below 20%, high percentages of volatiles, low ash content, and fixed carbon. The raw and post-extraction residues exhibit specific heat ranging from 950.13 to 9091.98 cal/g°C and thermal capacity ranging from 2,433.10 to 2,504.03 cal/°C. The formation of ZnFe2O4-Fe2O3-ZnO occurred via the green synthesis route, while ZnFe2O4-Fe2O3 was formed through microwave-assisted self-combustion, along with the ZnFe2O4 phase. The crystallite size was from 14.2 to 26.39 nm, crystallinity from 40.39 to 57.45 % and band-gap from 1.48 to 2.46 eV. The microscopies show diverse morphologies with signs of cavities and channels oriented in accordance with the fiber orientations. The liquid part of the waste (used in the self-combustion synthesis) provided a specific area between 80.41 and 99.74 cm².g⁻¹ (approximately 100% increase), while the solid waste provided a maximum increase of 49%. The solid residues from jatobá in the green synthesis of nanocomposites yielded stable structures with low ferromagnetic properties and high magnetization, consistent for applications in devices subjected to alternating magnetic fields.In summary, the results showed the formation of the ternary nanocomposite (ZnFe2O4-Fe2O3-ZnO), demonstrating a technological application capable of adding value to this class of lignocellulosic waste.

     
5
  • MÁRIO ANDREAN MACÊDO CASTRO
  • Synthesis of CaMoO4/g-C3N4 Heterojunctions and Evaluation of their Photocatalytic Properties for Dye Degradation

  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • ANTÔNIO ERNANDES MACEDO PAIVA
  • FABIANA VILLELA DA MOTTA
  • MARCIO ASSOLIN CORREA
  • MAURICIO ROBERTO BOMIO DELMONTE
  • RICARDO LUÍS TRANQUILIN
  • Data: 08-mar-2024
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The development of efficient photocatalysts for environmental depollution caused by textile dyes remains a challenge to be solved. In this sense, the combination of two materials forming composites in order to improve the characteristics of both, and its photocatalytic application appears as something promising. In this work, the microwave-assisted hydrothermal synthesis of II-type CaMoO4/g-C3N4 (CMO/CN) heterojunctions is reported, varying the synthesis time (between 15 and 60 minutes) and the molar percentage of g-C3N4 (between 40 and 70%). The samples were characterized by the techniques of X-Ray Diffraction, Diffuse Reflectance Spectroscopy in the UV-Visible region, Raman Spectroscopy, Photoluminescence, Field Emission Scanning Electron Microscopy, X-Ray Photoelectron Spectroscopy, Nitrogen Adsorption-Desorption Isotherms and Resonance Spectroscopy Electronic Paramagnetics. The photocatalytic activity of CaMoO4/g-C3N4 composites was evaluated in the degradation of methylene blue and crystal violet dyes under ultraviolet light irradiation. The heterojunction with 70% CN obtained better results than the other samples, reaching 99% degradation of methylene blue in 120 minutes and more than 95% degradation of crystal violet after 180 minutes. Furthermore, reuse tests aiming at photocatalytic stability, scavenger tests in order to observe the active radicals and tests under simulated visible light irradiation and sunlight in order to analyze the influence of the light source on the degradation efficiency were carried out.

6
  • IGOR ZUMBA DAMASCENO
  • Development and caracterization of acrylic and styrenic blends with MBS

  • Líder : EDSON NORIYUKI ITO
  • MIEMBROS DE LA BANCA :
  • EDSON NORIYUKI ITO
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • AMANDA MELISSA DAMIAO LEITE
  • ADRIANO LINCOLN ALBUQUERQUE MATTOS
  • JUCIKLÉCIA DA SILVA REINALDO
  • Data: 13-mar-2024
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The aim of this work was to investigate the influence the chemical structure of the methyl methacrylate-butadiene-styrene copolymer (MBS) in physical mixtures with poly(methyl methacrylate) (PMMA), polystyrene (PS) and styrene-acrylonitrile copolymer (SAN). Polymer blends were produced in a twin-screw extruder and then the specimens were manufactured by injection molding. The results of the optical properties showed a transparency greater than 75% and 90%, respectively, for the blends with PS and SAN. The blends developed with PMMA showed opacity for all compositions. Fourier transform infrared spectroscopy (FTIR) showed the characteristic bands of the specific chemical structures of the polymer blends. The spectra did not show any conformational or structural changes in the polymer blends, and the presence of new absorption bands was not observed. Thermogravimetric (TG) characterization showed that the styrenic blends presented greater thermal stability than the acrylic blend. The mechanical characterization showed that the PS/MBS blend presented synergism in maximum strength, while the PMMA/MBS and SAN/MBS blends were incompatible. The rheological results in the linear viscoelasticity region showed changes in the terminal region due to the addition of MBS, which presented a pseudo-solid behavior, due to the elastomeric domains for the immiscible and miscible blends. The morphological characterizations showed dispersed phase domains in the PMMA/MBS and SAN/MBS blends, highlighting the immiscibility of these polymer blends. The absence of dispersed phase domains confirmed the miscibility in the PS/MBS blend. The study of optical transparency correlated with miscibility and compatibility resulted in a greater understanding of these acrylic and styrenic blends with MBS.

7
  • TOMAS BARROS VASCONCELOS
  • Fatigue performance of double-double glass/epoxy laminates

  • Líder : JOSE DANIEL DINIZ MELO
  • MIEMBROS DE LA BANCA :
  • CARLOS ALBERTO CIMINI JUNIOR
  • EVANS PAIVA DA COSTA FERREIRA
  • JOSE DANIEL DINIZ MELO
  • LUCAS LISBÔA VIGNOLI
  • RAIMUNDO CARLOS SILVERIO FREIRE JUNIOR
  • Data: 29-abr-2024


  • Resumen Espectáculo
  • Double-double (DD) configuration has been proposed as a new concept in which a double set of double helix [±ϕ/±ψ]n angles are stacked up to form a composite laminate.  This concept promises significant advantages over conventional layups for composite design optimization and manufacturing. This experimental study evaluated the performance of two elastically in-plane equivalent glass/epoxy laminates suited for wind blade turbine applications: a quadriaxial (Quad) [±45/(0/90)3]s and a double-double (DD) [±15/±75]4T. Mechanical tests were performed under cyclic uniaxial tensile-tensile load using unnotched and open hole specimens. Delamination initiating from the free edges resulted in premature failure of the unnotched DD specimens.  For open hole specimens, fatigue tests results obtained from both stacking sequences showed similar performance. Ultimately, the study presented constitutes a valuable contribution to the understanding of fatigue behavior of double-double glass/epoxy laminates subjected to tensile cyclic loading.

2023
Disertaciones
1
  • KÍVIA FABIANA GALVÃO DE ARAÚJO
  • Obtaining and Characterrization of nanostructured powders of  CuNb2O6 sinthesized via gas-solid reation prosthetic sol-gel

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • UILAME UMBELINO GOMES
  • MEYSAM MASHHADIKARIMI
  • MARIA JOSE SANTOS LIMA
  • RAFAEL ALEXANDRE RAIMUNDO
  • Data: 23-ene-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • In recent decades, Brazil has been seeking to expand its research on Niobium,
    motivated by the potential of its properties, as well as its abundance in our territory. Among
    these, Copper Niobate (CuNb2O6) has been standing out in science due to its excellent
    properties for very current technological applications such as solar cell devices, microwave
    devices, photocathodes, ultrashort pulsed infrared laser sensors, for example. Aiming at this
    vast possibility of applications, in this study, therefore, CuNb2O6nanoparticles were produced
    using two routes, with simple methodologies, low cost and that allow obtaining nanoscale
    particles, solid state reaction with variation in milling time and gelatin-modified protein
    sol-gel using two combinations of precursors, Nb2O5+ CuO e Nb2O5+ Cu(NO3)2.3H2O. After
    obtaining, the powders were calcined in a muffle with temperatures in the range of 500 °C to
    1000 °C, for 3 h, heating rate of 5 °/min and oxygen atmosphere. Posteriorly the particles
    were characterized by means of X-ray Diffraction (XRD), Scanning Electron Microscopy
    (SEM) and Energy Dispersive Spectroscopy (EDS) analysis. The results for the solid state
    reaction route showed that the increase in milling time led to a reduction in temperature in the
    formation of the monoclinic phase, as well as the complete formation of the orthorhombic
    phase at the typical temperature of obtaining, in a short time, in addition to an improvement in
    the homogeneity of the powder. For the synthesis via protein sol-gel, the XRD results show
    that, at 700 °C, the formation of the monoclinic phase begins for both combinations of
    precursors, being completely obtained at 900 °C when using CuO. The orthorhombic phase
    was obtained completely at 1000 °C in the two combinations of precursors, all samples with
    total formation of polymorphs showed good dispersivity. For both routes, the resulting
    powdersdonotcontainevidenceofcontaminationandthecharacteristicparticle
    morphologies are coherent with the literature. The sizes of the crystallites obtained from the
    XRD,bytheScherrerequation,indicatedanincreaseproportional to the increase in
    temperature, however, all the powders obtained by the two routes presented crystallites in
    nanometric order

2
  • ISABELLA DONADELLO DUARTE
  • Investigation of the healing ability of thermoplastic healing agent in carbon-epoxy composite 

  • Líder : ANA PAULA CYSNE BARBOSA
  • MIEMBROS DE LA BANCA :
  • ANA PAULA CYSNE BARBOSA
  • JOSE DANIEL DINIZ MELO
  • MARCOS YAKUTA SHIINO
  • BRUNA LOUISE SILVA
  • Data: 22-may-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Polymer matrix composites (PMCs) present an exponential growth in structural applications due to its distinct advantages such as high stiffness, strength and lower weight. Still, PMCs are susceptible to damage and degradation during service and environmental exposure. Repairing these structures may be costly and time-consuming, for this reason alternative and promising approaches like adding thermoplastic agents to thermoset matrixes emerged to extend PMCs service life. The aim of this study is to investigate poly (ethylene-co- (acrylic acid) (EAA) as a self-healing agent in carbon/epoxy composites, where damage is introduced in the material by interlaminar shear strength (ILSS) tests and hygrothermal aging. Thermoplastic pellets were ground and spread in prepregs during the fabrication of the laminate. Composite plates with 10wt % of EAA powder and no thermoplastic were investigated. Thermogravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) were employed to evaluate materials thermal properties. Interlaminar shear strength (ILSS), Dynamic mechanical analysis (DMA), Fourier-transform infrared (FTIR) spectroscopy, and Scanning electron microscopy (SEM) were employed to investigate self-healing ability before and after the healing cycle. The addition of thermoplastic to the composite material showed recovery 9% higher of interlaminar shear strength compared to the unmodified composite. SEM images showed good adhesion between thermoplastic and epoxy resin, possible plasticisation effect due to the presence of thermoplastic, and the different healing mechanisms occurring. FTIR spectra showed evidence of good interaction between thermoplastic and epoxy resin. DMA results showed small changes in the glass transition temperature (Tg) and composite stiffness due to the addition of the thermoplastic material.

3
  • PÂMELLA RAFFAELA DANTAS DE FREITAS
  • Sn-Ag-Sb Alloys: Analysis of Solidification and Market Scenario

  • Líder : BISMARCK LUIZ SILVA
  • MIEMBROS DE LA BANCA :
  • BISMARCK LUIZ SILVA
  • CARLOS ALEXANDRE CAMARGO DE ABREU
  • ZULMARA VIRGINIA DE CARVALHO
  • CLAUDIO ALVES DE SIQUEIRA FILHO
  • Data: 30-may-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The use of lead-containing alloys (Pb) in electronic microcomponents is a technological and environmental issue that requires urgent and attention. In this context, the development of new alloys with similar or superior properties to Pb-containing alloys is an alternative. Furthermore, the Fourth Industrial Revolution brought new production possibilities, with the creation of new materials improving properties such as lightweight, better mechanical properties, adaptability and with recyclability characteristics. The 4.0 paradigm demands eco-friendly solutions and the new lead-free alloys are the best alternatives to meet this new window of opportunity. The Sn-Ag alloys have promising properties such as good mechanical strength and creep resistance, but they have low toughness, problems with silver segregation and low wetting on metallic substrates. In this context, the present study aims to analyze the effect of antimony (Sb) additions (0.2 and 2.0% in weight) on the microstructure, thermal parameters of solidification (cooling rate-ṪL and growth rate-VL), phase transformation temperatures, macrosegregation, mechanical properties and fracture modes in the hypoeutectic Sn-2.0wt.%Ag alloy directionally solidified under transient conditions. The microstructural and mechanical characterization occurred through the use of techniques such as Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), Vickers microhardness and tensile tests. Thermodynamic calculations were performed by Thermocalc software, in order to study the evolution of phase fractions and solidification paths. In addition, an analysis of the market scenario in which the Sn-Ag-Sb alloys are inserted was carried out, through prospects on the Espacenet platform and desk research. The microstructures of Sn-Ag-Sb alloys are completely dendritic with an Sn-rich matrix (β-Sn) surrounded by a eutectic mixture, β-Sn+Ag3Sn+SbSn. The Sb additions promoted a microstructural refinement and a slight increase in liquidus and solidus temperatures, when compared to the binary alloy Sn-2wt.%Ag. Ag exhibited a constant and higher than nominal macrosegregation profile, while Sb changed from a constant profile to an inverse type with increasing Sb content. The Ag3Sn intermetallic displayed two morphologies, fibrous and spherical, with prevalence of the latter for ṪL>5.10 °C/s and 2.90 °C/s for the alloys with 0.2wt.%Sb and 2wt.%Sb, respectively. Sb promoted an increase in the Vickers microhardness of both Sn-Ag-Sb alloys, with a higher value for the 2wt.%Sb content. In the market context, Sn-Ag-Sb alloys have high potential for application in nanotechnology, autonomous robots and artificial intelligence.

4
  • CLENILDO DE LONGE
  • DEVELOPMENT OF MATERIALS FOR CO2 CAPTURE WITH ZEOLITIC STRUCTURE USING ALTERNATIVE SILICA SOURCE

  • Líder : SIBELE BERENICE CASTELLA PERGHER
  • MIEMBROS DE LA BANCA :
  • SIBELE BERENICE CASTELLA PERGHER
  • ANTONIO EDUARDO MARTINELLI
  • LUCIENE DA SILVA SANTOS
  • ADONAY RODRIGUES LOIOLA
  • LINDIANE BIESEKI
  • Data: 18-jul-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • In recent decades, carbon dioxide capture has attracted attention and different solutions have been proposed, but the global concentration of CO2 is still increasing along with its environmental impacts. The oil industry has contributed to climate change and is related to greenhouse gas emissions that cause environmental impacts, economic and social problems. Among these technologies, CO2 capture and storage is considered the most effective solution to reduce CO2 emissions. Adsorption is the main potential technique among other technologies such as membrane separation and absorption. Among these adsorbents, Zeolite is considered one of the most effective adsorbents in gas adsorption and separation technologies due to its greater adsorption capacity, abundant availability, low cost and cryogenic separation. In this context, the development of materials for CO2 capture, with zeolite structure using an alternative source of low-cost silica from paria sand, MPI, was evaluated in this work. X-ray diffraction (XRD), X-ray fluorescence (FRX), Fourier transform infrared absorption spectroscopy (FTIR), scanning electron microscopy (SEM), textural analysis of N2 adsorption and desorption and thermal analysis prove that the synthesized silica and zeolites have the structural, morphological, textural and thermal characteristics of these materials. Zeolite-A with MPI silica (ZAM 1h) reached a relative crystallinity of 74.26% in 1 h with pure and crystalline phases. Zeolite ZSM-5 with MPI silica (ZM 15 h) had a relative crystallinity of 92.90% for the time of 15h, with pure and crystalline phases, but smaller crystals than Zeolite with standard silica (ZAP 2 h). Silicalite with MPI silica (SM 3 d) reached a relative crystallinity of 111.90% in 3 days with pure crystalline phases, but with smaller crystals than Zeolite with standard silica (SP 9 d). Standard Zeolite-A and MPI (ZAM 1 h) had the best CO2 capture results with adsorption capacities of 5.25 mmol/g and 4.83 mmol/g CO2, respectively. Silicalite had the second best result with the standard (SP 9 d) and MPI (SM 3 d) with capacities of 3.94 mmol/g and 3.78 mmol/g of CO2, respectively. Standard ZSM-5 (ZMP 3 d) and MPI (ZM 15 h) had capacities of 3.72 mmol/g and 3.22 mmol/g CO2, respectively. The evaluation of the mathematical models indicated that Zeolite-A fitted better to the Temkin model, ZSM-5 to the Freundlich model, and Silicalite (SP 9 d) and MPI (SM 3d) to Langmuir, and (SM 6 d) to Temkin. The modeling results showed the performance of a preponderant model and concomitant contributions of other models in the adsorptive mechanisms of the Zeolites studied.

5
  • ALICE DA COSTA SILVA
  • MICRORHEOLOGICAL STUDY OF RECYCLED POLYPROPYLENETHE WITH MONTMORILLONITE CLAY AND MALEIC ANHYDRIDE 

  • Líder : EDSON NORIYUKI ITO
  • MIEMBROS DE LA BANCA :
  • EDSON NORIYUKI ITO
  • CARLOS ALBERTO PASKOCIMAS
  • JUCIKLÉCIA DA SILVA REINALDO
  • Data: 26-jul-2023


  • Resumen Espectáculo
  • The aim of this work is to investigate the effect of incorporating organophilic montmorillonite clay (OMMT) and polypropylene grafted with maleic anhydride (PP-g-MAH) on the linear viscoelastic rheological behavior of recycled polypropylene (rPP) from mineral water bottles. The polymer nanocomposites were plasticized and homogenized in a twin-screw co-rotational extruder with d = 16 mm and l/d = 40, varying in 1, 3 and 5 wt% of OMMT and using 3 wt% of PP-g-MAH. After mixing, type I specimens were injection molded, according to ASTM D638. To analyze the microrheological behavior, measurements of fluidity index (MFI), parallel plate rheometry and scanning transmission electron microscopy (STEM) were performed. For the mechanical properties, uniaxial tensile and Shore D hardness tests were carried out. To obtain the physical properties of the material, the X-ray diffractogram (XRD) was used. The MFI proved that the addition of OMMT and PP-g-MAH promoted significant modifications in the rPP, being possible to evidence the decrease in the fluidity index proportional to the increase of the clay concentration in the mixture, consequently, an increase in the viscosity. The rheological data obtained at low frequencies in the region of linear viscoelasticity, revealed significant changes in the rheological behavior of the polymer composites when compared to the rPP. XRD showed signs of OMMT exfoliation in the polymeric matrix. Using STEM, the interaction of clay and PP-g-MAH in the rPP matrix was observed. Tensile and Shore D hardness test showed improvements in mechanical properties.

6
  • MARIA MONIQUE DE BRITO LEITE
  • Induzed repair of electropulsing in AA5083 alloy in the oil industry.

     

  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • RUBENS MARIBONDO DO NASCIMENTO
  • MEYSAM MASHHADIKARIMI
  • MAURÍCIO MHIRDAUI PERES
  • SERGIO RODRIGUES BARRA
  • ALBERTO JORGE JUNIOR
  • GUDSON NICOLAU DE MELO
  • Data: 31-jul-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The technique of emitting electrical pulses inside a material can be considered an effective alternative for promoting self-healing mechanisms. This technology can favor the prevention of nucleation, coalescence and propagation of microstructural defects in metallic materials used in several applications in the oil industry. This is because through microstructural regeneration promoted by the acceleration of atomic diffusion, movement of dislocations and, in some cases, nucleation and recrystallization mechanisms, the reduction and/or closure of defects in the microstructure are achieved. Thus, this research was based on carrying out analyzes of the influence of the application of electrical pulses on specimens (cp) of the AA5083-H112 alloy with a width of 3mm and a thickness of 5mm in cross section. These were submitted to tensile tests (speed of 1mm/min) to insert microstructural defects, which could later be repaired. In addition, this test was also used to verify the mechanical behavior. The cp in the state of origin showed a mean total deformation (εrupt) of 21.4%. New cp were pre-deformed to 80% of the εrupt and divided into: groups B (specimens 7 and 10) and C (specimens 8 and 19) were subjected to the emission of electrical pulses in cycles of 7s and 15s, respectively. In group A (specimens 18 and 21) EPE tests were not performed, so that a comparison between the material in the state of origin and the material with EPE could be made. The emission of the pulses was carried out in a closed circuit between the cp and a DigiPlus A7 600 model welding equipment in pulsed TIG mode. In the equipment software, the peak current was defined as 400A during a time of 0.1s and the base current as 0A during a time of 0.1s. The complete pulse emission time ranged from 7s to 15s. At the end, all cp were subjected to another tensile test until the material ruptured. With the use of SAP and SAT acquisition equipment, it was verified that there was current pulsation and that a thermal effect was obtained with the use of electrical pulses for 7s and 15s. The analysis of the results indicated that the electrical pulses performed with a current density of 26.67 A/mm2 were effective in promoting the increase in ductility. Groups B and C showed an average of 9.13% and 10.98% of plastic deformation; while group C 7.62%. The microstructural characterization via scanning electron microscopy (SEM) in electron backscatter and secondary electron modes corroborated to prove the effectiveness of this technique to reduce the defects observed in the material.

7
  • NÍVIA LUCIANA COSTA DE SIQUEIRA
  • Obtention of Scheelite (CaWO4) tapes by aqueous tape casting

  • Líder : WILSON ACCHAR
  • MIEMBROS DE LA BANCA :
  • HUGO PLÍNIO DE ANDRADE ALVES
  • VAMBERTO MONTEIRO DA SILVA
  • WILSON ACCHAR
  • Data: 31-jul-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Scheelite, also known as calcium tungstate (CaWO4), is a mineral from the Wolframites group that holds significant economic importance due to its contribution to one of the largest quantities of tungsten production. In Brazil, the main stratiform scheelite deposits are located in the state of Rio Grande do Norte (RN), in the Seridó region, constituting the country's largest concentration of tungsten. However, the exploitation of this mineral has caused various negative environmental impacts in the mined areas, making it essential to develop technologies to mitigate the damages caused by the extraction and processing of this abundant resource in the state. Thin and solid films made with tungsten compounds exhibit great potential for dielectric, electronic, and optoelectronic applications, and can be produced through different methods. Tape casting is one of the simplest and well-established methods for film and tape manufacturing, being safe and non-toxic when carried out using an aqueous base. With this in mind, the objective of this study was to produce Scheelite tapes and analyze their properties. Five tapes were produced, gradually reducing the content of Scheelite residue (SR) from 100%, 75%, 50%, and 25% until complete substitution with concentrated Scheelite (SC). Physical-chemical characterization of the powders was conducted through fluorescence and X-ray diffraction tests, in addition to evaluating the rheology of the produced suspensions. The green tapes were characterized through Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Thermogravimetric Analysis (TGA), and dielectric measurements, aiming to assess the morphology, surface composition, thermal behavior, and dielectric properties of the tapes. X-ray diffraction identified the presence of scheelite, calcite, and quartz phases. The produced suspension exhibited pseudoplastic rheological behavior, ideal for tape casting. The produced tapes showed dielectric constants ranging from 7 to 3.4, average, in high-frequency ranges (0.1 to 1.5 GHz). However, the dielectric losses found were relatively high for all compositions.

8
  • TANARA CAROLINE NUNES NICÁCIO
  • Effect of zinc and nickel doping on the photocatalytic and antimicrobial properties of hydroxyapatite

  • Líder : FABIANA VILLELA DA MOTTA
  • MIEMBROS DE LA BANCA :
  • ANA PAULA DE AZEVEDO MARQUES
  • FABIANA VILLELA DA MOTTA
  • MARIA CELESTE NUNES DE MELO
  • MAURICIO ROBERTO BOMIO DELMONTE
  • Data: 31-jul-2023


  • Resumen Espectáculo
  • Nanostructured hydroxyapatite (HAp) has been studied in advanced technologies in the catalytic area and in the field of biomedicine, such as drugs and protein transporters. In this work, HAp nanoparticles were synthesized by microwave-assisted hydrothermal method and doped with different concentrations of zinc and nickel ions. The samples were characterized by the X-ray diffraction technique (XRD), Fourier transform infrared spectroscopy (FTIR) and by field emission scanning electron microscopy (FEM-FEG), respectively. Optical properties were estimated in the UV-Vis region to calculate the gap energy value. The hydrothermal method used in this work proved to be efficient for obtaining HAp nanoparticles. The XRD patterns together with the structural refinement, showed the HAp formation for all samples, which corresponds to the hexagonal crystalline structure. There was no secondary phase formation, indicating that doping was successful. The FTIR spectra indicated that Zn2+ and Ni2+ doping in the HAp network did not change the vibrational modes of the main HAp functional groups. The SEM-FEG micrographs illustrated an agglomeration of the particles with the increase in the percentage of dopant ions in the structure, presenting nanorod formats. The gap energy of HAp doped and co-doped with zinc and nickel varied between 5.75 eV and 3.26 eV. The photocatalytic properties through the degradation of methylene blue dye (MB) under UV and solar irradiation were investigated, as well as the antimicrobial activity against gram positive (Staphylococcus aureus) and gram negative (Escherichia coli) bacteria. The results of the photocatalytic activity indicated 66.81% degradation of the MB dye under UV irradiation for the H5Z sample and 97.85% degradation when subjected to solar irradiation. To analyze the reuse applicability of the photometers, the samples were submitted to three cycles of reuse. The H5Z sample showed 55% efficiency after reuse cycles. The antimicrobial activity results showed that the H5Z, H5Z5N, H10Z5N and H15Z5N samples showed an inhibition zone of 18.5; 14.5; 18 and 17mm, respectively, against gram negative bacteria (Escherichia coli), indicating the antibacterial effect of samples with higher percentages of zinc in the synthesized HAp structure. The samples did not show antimicrobial action against S.aureus bacteria.

9
  • ISAAC DE SANTANA BEZERRA
  • Analysis of production of porous scaffolds by 3D printing

  • Líder : EDSON NORIYUKI ITO
  • MIEMBROS DE LA BANCA :
  • CAROLINE DANTAS VILAR
  • EDSON NORIYUKI ITO
  • ERIK DOS SANTOS SILVA
  • FELIPE PEDRO DA COSTA GOMES
  • Data: 18-ago-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • This work analyzed the feasibility of producing porous scaffolds by 3D printing (IMP3D) via melt-deposition modeling (FDM) of Poly(lactic acid) (PLA) with azodicarbonamide (AZDA) blowing agent. A selection of the polymer matrix was carried out based on mechanical, rheological and morphological tests, comparing Poly(acrylonitrile-co-butadiene-co-styrene) (ABS), Poly(ethylene terephthalate) bottle grade (PETG) and PLA, both by means of injection molding, as well as by IMP3D, using nozzles with diameters of 0.3; 0.4; 0.5; 0.6; 0.8; 1.0. After weighing the productive efficiency, the processability, and the mechanical results obtained, IMP3D and PLA were selected as the most suitable technique and material for the production of porous scaffolds. Subsequently, the PLA was subjected to a closed cycle of five consecutive processes in a twin screw extruder, verifying by the visual and rheological changes, that the material maintained good rheological properties after the thermal cycles. Finally, the PLA was mixed with the expanding agent azodicarbonamide (AZDA) in a twin-screw extruder, and plasticized in a single-screw extruder, obtaining PLA filaments with inert AZDA, for subsequent printing of porous scaffolds, in proportions in percentages per hundred resin (PCR) of: 100/0; 100/2; 100/4; 100/6; 100/8. The rheological, morphological and uniaxial traction characterizations of the developed materials were carried out, noting the increase in PLA viscosity when subjected to more thermal cycles. The morphologies pointed to a greater emergence of pores for the compositions with higher concentration of AZDA, so that the larger pores were preferentially present in the central regions of the filaments, in addition to showing that the temperature control influences the size of the pores obtained, reaching biodegradable and biocompatible porous structures.

10
  • AMARALINA LITUÂNIA MORAIS MARINHO
  • Evaluation of the effects of graphene addition in carbide-based coatings applied by HVOF

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • UILAME UMBELINO GOMES
  • MARIA JOSE SANTOS LIMA
  • MEYSAM MASHHADIKARIMI
  • RAMON SIGIFREDO CORTÉS PAREDES
  • Data: 18-ago-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Hard metal-based coatings are widely used in the oil and gas industries to increase the life of steels. However, these coatings are also subject to oxidation, chemical corrosion, and erosion when subjected to working cycles with a combination of physical wear and chemically aggressive environments. Thus, the addition of nanoparticles to the composition of tungsten carbide-based coatings can be an alternative, as they can improve the properties of the carbide, such as wear and corrosion resistance. The anodic polarization technique allows for the electrochemical behavior of a metal to be studied in the laboratory, i.e., its tendency to remain active or passive, by constructing potential curves as a function of current and its susceptibility to pitting corrosion. In this work, graphene oxide was mixed with tungsten carbide-cobalt at different weight concentrations of 0, 0.5, 0.75, and 1% and applied on 1020 steel substrate using the HVOF thermal spray using the HVOF thermal spray method. XRD, SEM-FEG, and cyclic voltammetry tests, also known as reverse anodic potentiodynamic tests, were carried out to characterize the compositions. Thus, it was noted that the anticorrosive properties of WC-Co coating with the addition of graphene oxide were not compromised when at least 1% of graphene was present in the mixture. However, compositions with a lower amount of graphene showed worse anticorrosive properties than the coating with 0% graphene.

11
  • FÁTIMA MARCELIE BRAZ NOGUEIRA FROTA
  • Production of Porous Carbon from tree pruning waste

  • Líder : SIBELE BERENICE CASTELLA PERGHER
  • MIEMBROS DE LA BANCA :
  • EDUARDO RIGOTI
  • RUBENS MARIBONDO DO NASCIMENTO
  • SIBELE BERENICE CASTELLA PERGHER
  • THIAGO DE MELO LIMA
  • Data: 21-ago-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The management of urban trees is inherent to every city and produces waste that is often lost and misallocated. In large cities such as the city of Natal, in Rio Grande do Norte, Brazil, the production of pruning waste reaches more than 18 tons weekly, which implies the allocation of a large area in landfills for disposal. Disposal in vacant lots contributes to eutrophication and visual pollution. As pruning residues are lignocellulosic materials, an alternative to add value to this residue and give it a more appropriate destination is to use it as a raw material for activated biochar. The term biochar has also been used for charcoal produced from lignocellulosic residues, previously this term was used only for charcoal intended for use in soil conditioning or CO2 sequestration. In this work, activation and pyrolysis occurred simultaneously; Mango Tree Residue (magnifera indica) and Pruning Residue (various unidentified species) were used as precursors, KOH was used as activating agent, pyrolysis temperatures of 450°C and 550°C were used, which were maintained for 1 hour, and no gas flow was used; then, the activation product was washed with an HCl solution in order to remove the remaining activating agent and its derivatives. The products obtained were characterized by XRD, FTIR, CHN and adsorption of N2 and CO2. In addition, NO adsorption tests were carried out in dry air for all samples and for the Mango Tree Waste biochar sample produced at 550°C (KM550 LVD) the test was also carried out in air atmospheres with 50% and 75% humidity, besides nitrogen atmosphere. In general, the activated biochars showed similar compositions. The pyrolysis temperature was the factor with the greatest influence on the characteristics of the biochars: those produced at 550°C exhibited larger specific areas and more developed microporosity. Regarding NO adsorption tests in dry air, the KM550 LVD sample had the highest adsorption result (83.91%). However, in humid atmospheres this percentage decreased, indicating a possible interaction of H2O molecules with the functional groups present on the biochar surface. The NO adsorption in nitrogen atmosphere showed the lowest result (0.83%), indicating the need for O2 for the NO adsorption mechanism.

12
  • HENRIQUE TOMÉ BARBOSA
  • Study of the microstructure of DP780 steel punched under room and cryogenic temperatures.

  • Líder : FABIO JOSE PINHEIRO SOUSA
  • MIEMBROS DE LA BANCA :
  • FABIO JOSE PINHEIRO SOUSA
  • SALETE MARTINS ALVES
  • NICOLAU APOENA CASTRO
  • JETSON LEMOS FERREIRA
  • Data: 15-sep-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Dual-phase steels (DP) are advanced high-strength steels (AHSS) used in construction of automotive body parts due to their high strength, formability and ability to absorb energy when deformed. They gained great importance since the Paris Agreement (2016), as their use, in place of conventional steels, makes vehicles lighter and less polluting. To constitute these automotive parts, the dual-phase steels undergo stamping processes, in which they are cut, pressed and folded, in order to compose the final shape of the desired part. During these processes, the quality of the cutting edge of these steels is a very important factor, as an edge with more and greater heterogeneity and defects can lead to failure of the part even during its manufacture. A more homogeneous cutting edge, with less voids and microcracks is necessary for the good formability of these materials. Aiming to present a method to improve the quality of the cutting edges of DP780 steel, the present work carried out a qualitative and quantitative study of the microstructures of cutting edges of this steel cut by punching at cryogenic and ambient temperatures and compared them, in order to verify their quality and homogeneity, as well as the amount of deformation. The analysis of the microstructures was performed using the Electron Backscatter Diffraction (EBSD) technique using a scanning electron microscope (SEM).It was observed that the localized refrigeration by liquid vapor is effective for the induction of brittle fracture in the DP780 dual-phase steel, extending the fractured region and decreasing the sheared area in the cut edges, diminishing plastic deformation in the surface and internal microstructure of the edge. Qualitative results showed the ability of this method to reduce plastic deformation on DP780 cutting edges by up to 37% when performed at cryogenic temperature (≤ -150 oC) and speed of 725 mm/s.

13
  • ANA MELISSA PAULA BRITO
  • Characterization of the photocatalytic and photoluminescence properties of Bi2WO6:xPr3+ with added beetroot extract obtained by microwave-assisted hydrothermal.

     

  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • FABIANA VILLELA DA MOTTA
  • MARIA INES BASSO BERNARDI
  • MAURICIO ROBERTO BOMIO DELMONTE
  • Data: 22-sep-2023


  • Resumen Espectáculo
  • Green synthesis has shown to be a promising for obtaining nanoparticles because it
    is an economical and ecologically correct alternative. Due to its interesting structural and
    electrochemical properties and the use of different ways of obtaining it, bismuth tungstate
    (Bi 2 WO 6 ) stands out as a photocatalyst for environmental remediation. In this work,
    Bi 2 WO 6 :xPr 3+ (x = 0; 1 and 3 %molar) nanoparticles, with addition of beetroot extract (BE),
    were synthesized by the microwave-assisted hydrothermal method at 150°C for 60 min.
    Thus, the samples were structurally characterized by the X ray diffraction (XRD) and their
    morphology was investigated by the field emission scanning electron microscopy (FESEM).
    Photocatalytic activity of the samples was quantified by the UV-visible (UV-Vis)
    spectroscopy technique through the degradation of methylene blue (MB) and crystal violet
    (CV) dyes by ultraviolet and solar irradiation. Optical properties were investigated using the
    photoluminescence (PL) technique. The XRD patterns showed that the samples have an
    orthorhombic crystalline structure and good crystallinity, without the presence of secondary
    phases, which indicates that the presence of the Pr 3+ dopant and the addition of beetroot
    extract do not generate additional phases. In addition, the crystallite size ranged from 6.48 nm
    to 10.27 nm, a slight increase was noted when the Pr 3+ dopant was inserted, but as the amount
    of BE increased, the crystallite size decreased. The FESEM micrographs showed that the
    obtained nanoparticles have a predominantly flower-like morphology. The bandgap energy of
    the Bi 2 WO 6 :xPr 3+ ranged from 3.56 eV to 3.65 eV. Photocatalytic tests indicated that all the
    samples have potential for MB and CV degradation. In addition, PL spectra found that the
    nanoparticles had a color rendering index (CRI) greater than 80%, which makes this
    nanomaterial a potential for applications in high quality white light emitting diodes (LED’s).
    Furthermore, it was observed that the active photocatalytic mechanism consists of superoxide
    and holes. Therefore, Bi 2 WO 6 :xPr 3+ nanoparticles, using green synthesis and sunlight, is a

    promising, efficient and economical alternative for the degradation of organic dyes as well as
    for LED’s applications.

14
  • MARIA PAULA DE CARVALHO FREIRE
  • Optimization of poly(urea-formaldehyde) (PUF) polymeric microcapsules filled with 5-ethylidene-2-norbonene synthesis for self-healing using factorial design methodology

  • Líder : MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • JOSE DANIEL DINIZ MELO
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • MARIA INGRID ROCHA BARBOSA SCHIAVON
  • Data: 29-sep-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • In the recent decades, research on materials with self-healing capacity has progressively expanded, and self-healing systems with polymeric microcapsules are included in the solutions proposed to repair the damage due to the appearance of cracks that structurally compromise the lifetime of the material during use, enabling cost reduction. In this work, poly(urea-formaldehyde) (PUF) microcapsules filled with 5-ethylidene-2-norbonene (ENB) were prepared by in situ emulsion polymerization. A previous analysis of developed works using a Plackett-Burman (PB) design with seven factors helped in the selection of variables to be used in a fractional factorial design 24-1 and, based on this, it was possible to select the significant variables as 90% confidence to perform a complete factorial design with three factors, aiming the optimization of the synthesis process. The chosen parameters for the fractional design include: the agitation speed, the poly(ethylene-alt-maleic) (EMA) content that acts as an emulsifier, the drops of 1-octanol (stabilizes the emulsion inhibiting the formation of bubbles) and the pH of the reaction. The responses evaluated were the medium diameter of the microcapsules, yield, encapsulate content, thermal stability, and the degradation temperature. From the parameters analyzed, the EMA content, the pH of the reaction and the agitation speed must be used in the complete design due to their significant effects on the response variables analyzed, using a confidence level of 90%. In a previous analysis to the complete design, considering the analyzed response variables, microcapsules with satisfactory properties for applications in self-healing were obtained in the condition in which the agitation speed and the EMA content were at higher levels, and the pH was at the lower level, corresponding to the synthesis of PUF/ENB 4 of the fractional design. After realising the full factorial design, no valid mathematical models were found for the yield and encapsulated content response variables at a 90% confidence level. However, a valid mathematical model was obtained for the medium diameter response variable. Microcapsules with satisfactory morphological conditions such as the low residue of U/F on the surface and symmetry were obtained in the conditions in which agitation and pH were at the upper and lower levels, respectively. To define the optimum condition for producing microcapsules, the medium diameter response variable was considered based on the mathematical model obtained, and a combined analysis was perfomed based on yield and encapsulate content. Therefore, using the response surface methodology (RSM) in conjunction with the thermal stability analysis, it was concluded that the synthesis condition (puf/enb 2) showed microcapsules with adequate morphological properties, including a regular shell surface, low residue of U/F, a narrow medium diameter distribution, in addition to a satisfactory yield and encapsulate content.  

Tesis
1
  • HUGO ALESSANDRO ALMEIDA DINIZ
  • Synergistic effects of sand, water and metakaolin incorporation on the properties of 3D printing concretes by experimental mix design

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • JÚLIO CÉZAR DE OLIVEIRA FREITAS
  • KLEBER CAVALCANTI CABRAL
  • ULISSES TARGINO BEZERRA
  • WENDELL ROSSINE MEDEIROS DE SOUZA
  • Data: 30-ene-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The three-dimensional concrete printing (3DCP) is a construction technique that emerged to innovate and insert the construction industry in the context of revolution 4.0. It consists of laying successive layers of a cementitious composite without the need for formwork and with the possibility of making multiple geometric shapes. This enables the execution to occur faster, more accurately, and with less waste. However, for 3DCP to be applied, it is necessary that the composite used allows continuous flow through a printing nozzle (extrusion capability) and, after printing, presents a low deformation, in the fresh state, even after the weight exerted by the successive layers printed above. Coupled with this, high levels of cement are commonly used to achieve these abilities, making this practice damaging to the environment. In this study several tests were performed in order to understand the influence of sand, of metakaolin and of water in the extrudability and buildability in composites for 3D printing. The analysis was based on a statistical experimental planning of mixtures to measure and understand the relationships between the variables: cement replacement content by metakaolin, sand/ binder ratio and water/ binder ratio. To measure extrusion an experimental flow rate test was developed and also by correlation with the spreading (mini slump-flow). To understand the buildability, the maximum number of printed layers, the section deformation index, layer thickness compliance, and squareness variation in printed blocks were analyzed. The squeeze-flow was performed to understand the thixotropy along with complementary tests of characterization of the dry mixtures and in the fresh state. To understand the applicability of the material, the strengths of the mixtures and the printed blocks were measured. The water/ binder factor had a preponderant influence on the extrusion capacity, which was expected, because water is the component responsible for the fluidization of dry materials. However, it can be observed that the granulometry and proportioning of the mix can also have a positive effect on extrusion when there is not a good packaging between the particles of sand and binder, generating internal voids that increase the internal mobility. The sand had a positive effect until the proportion of 1:1.5, however, after 30 minutes, this effect becomes very small. The metakaolin presented the advantage of maintaining a good fluidity over time, due to a slower setting. In buildability, the increase of sand and reduction of water were advantageous to reduce deformation and increase the maximum number of internal layers. The incorporation of metakaolin was negative, increasing the deformation of the section and the layers. The yield stress in squeeze-flow was directly related to the flow rate, validating the experimental methodology created. It was also observed that the printing process, as well as the deformations that occurred, influenced in the final strength of the printed block. Traces that contained higher axial compressive strength of the material, in the prismatic samples, did not correspond directly to a higher compressive strength of the printed block. Strokes that contained a higher strength of the material did not correspond directly to a higher strength of the printed part. For a satisfactory 3D printing process of concrete, sand promoted a higher resistance to deformation and better buildability; the metakaolin up to the percentage of 20% shows positive for maintaining fluidity over the printing time, besides a small reduction in the weight of the structure; and, in the range between 0.37 and 0.43 of water/binder ratio, mixtures with good printing abilities were obtained.

2
  • ANNA KARLA DE CARVALHO FREITAS
  • Production of ceramic tapes for Biomedical applications 

  • Líder : WILSON ACCHAR
  • MIEMBROS DE LA BANCA :
  • CLAWSIO ROGERIO CRUZ DE SOUSA
  • HUGO PLÍNIO DE ANDRADE ALVES
  • SHEYLA KAROLINA JUSTINO MARQUES
  • VAMBERTO MONTEIRO DA SILVA
  • WILSON ACCHAR
  • Data: 31-ene-2023


  • Resumen Espectáculo
  • To overcome the shortcomings existing in conventional dosage forms, the targeted drug delivery system was created. The aim was to deliver drugs to site-specific with a reduced dosing frequency and to mitigate the side effects caused by conventional drug delivery systems. Nanoparticles have been used as carriers of these drugs, including mesoporous silica nanoparticles, carbon nanotubes, and polymeric nanoparticles. In addition, the use of different techniques to produce these systems, such as the tape casting method, is responsible for producing thin films, and flexible ceramic tapes with good surface quality and low cost. In this work, studies were carried out regarding the production of ceramic tapes through the tape casting method, obtaining materials to be used in the biomedical area. Tricalcium phosphate ceramic tapes with different percentages of chitosan were produced. Another composition studied was the clay mineral palygorskite, using neomycin to study drug release. The first step was to study the powders, with X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The slips were identified through the rheological test and then the ceramic tape was tape casting. These were characterized through X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FTIR), elemental analysis (CHN-S), and scanning electron microscopy (SEM). In addition to these, antimicrobial activity tests were carried out, as well as absorption energy calculations. According to the results obtained, the pseudoplastic behavior of the suspension was observed, as suitable for the conformation of ceramic tapes. Reflection peaks referring to the palygorskite phase, with an orthorhombic structure, and the tricalcium phosphate phase, with an orthorhombic structure, were detected. DSC analysis identified exothermic peaks characteristic of neomycin. Therefore, thin films and flexible, biodegradable, biocompatible ceramic tapes were produced, which presented important characteristics for use in the biomedical area.

3
  • JÔNATAS MACÊDO DE SOUZA
  • Evaluation of the use of wood ash and metakaolin in the production of soil-cement lightweight bricks

  • Líder : WILSON ACCHAR
  • MIEMBROS DE LA BANCA :
  • WILSON ACCHAR
  • CLAWSIO ROGERIO CRUZ DE SOUSA
  • HUGO PLÍNIO DE ANDRADE ALVES
  • SHEYLA KAROLINA JUSTINO MARQUES
  • VAMBERTO MONTEIRO DA SILVA
  • Data: 13-abr-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Given the concern with the emission of greenhouse gases, companies in various economic sectors are using biomass as a fuel to generate thermal energy in boilers instead of the fossil fuels usually used. One of the biofuels used is wood chips, a small lignocellulosic material obtained from wood chopping. However, despite the environmental advantage of offsetting carbon dioxide (CO2) emissions, when burned, the material generates ash as a residue that, when not reused in agriculture as fertilizer or for composting, is sent to landfills or dumps, causing environmental impacts.   Thus, there is a need for further studies on the physical and chemical properties of the ash so that new applications are thought of to promote a better destination for the residue. In view of the above, this research aimed to evaluate the influence of wood ash in conjunction with metakaolin - pozzolanic material - as a replacement for clay-silt soil (classified as A-6) in producing soil-cement lightweight bricks. In all, 7 formulations with 10% cement were produced, of which one was a reference (without substitutions), 3 with partial substitution of the soil by the contents of 5%, 10% and 20% of ash and 3 with the same contents of ash plus 5% of metakaolin in place of the soil. The bricks were cured for 7 days in a humid chamber. Then they were submitted to the compressive strength and water absorption tests at 7 and 28 days according to NBR 8492 and the durability test at 7 days according to NBR 13554. The samples with the best performance in the compressive strength test at 28 days, before and after the durability test, were submitted to microscopic characterization tests through X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) techniques. The tested bricks showed low density, less than 1.65 g/cm³ at 28 days, especially the sample with soil replacement by 20% ash and 5% of metakaolin with 1.22 g/cm³. As for the compressive strength at 28 days, except the formulation with soil substitution by 20% of the residue, all others showed results higher than 2 MPa, meeting the NBR 8491. Due to the high fines content in the soil (61.21% passing sieve No. 200), the average absorption of all compositions was above 20%. After being submitted to the durability test by immersion and drying, all formulations presented mass loss below the 7% indicated for soil type A-6 in NBR 13553. The microstructural characterization identified mineralogical phases of the products of the cementitious reactions as CSH and CASH, also confirmed by the microstructure images obtained in SEM. The results are promising and validate the use of ash with or without metakaolin to produce soil-cement lightweight bricks.

4
  • RAYANE DANTAS DA CUNHA
  • Low velocity impact response of non-traditional double-double laminates

  • Líder : JOSE DANIEL DINIZ MELO
  • MIEMBROS DE LA BANCA :
  • LUCAS LISBÔA VIGNOLI
  • CARLOS ALBERTO CIMINI JUNIOR
  • EVANS PAIVA DA COSTA FERREIRA
  • JOSE DANIEL DINIZ MELO
  • RAIMUNDO CARLOS SILVERIO FREIRE JUNIOR
  • Data: 26-may-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • A novel family of composite laminates with simplified stacking sequence in form of two double ply (double-double) [±ø/±ψ]n offers great potential to reduce weight and increase mechanical strength, while facilitating design optimization and simplifying manufacturing process when compared to traditional quadriaxial composite materials (Quad) with ply angles of 0o, ±45o and 90o.. In this study, low-velocity impact response of a double-double (DD) laminate and a quadriaxial laminate of equivalent in-plane stiffness and same thickness were compared. Carbon/epoxy laminates were produced with stacking sequences of [±0/±50]10 and [03/90/±45/02/±45]2S, corresponding to double-double and quadriaxial, respectively. Low- velocity impact tests were conducted at energy of 74 J and damage areas were examined using x-ray computed tomography. Measured compressive strength and compression after impact (CAI) strength were equivalent for double-double and quadriaxial laminates. However, differences in impact damage morphology were observed and are discussed.

5
  • CAMYLA REGINA DANTAS FERREIRA
  • Optimization of synthesis processes to obtain the compound α-MoO3/C3N4 and study of its photocatalytic activity

  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • FABIANA VILLELA DA MOTTA
  • MAURICIO ROBERTO BOMIO DELMONTE
  • RODOLFO LUIZ BEZERRA DE ARAÚJO MEDEIROS
  • NEFTALÍ LENIN VILLARREAL CARREÑO
  • RICARDO LUÍS TRANQUILIN
  • Data: 16-jun-2023


  • Resumen Espectáculo
  • MoO3 is an n-type semiconductor with unique properties such as photocatalytic efficiency and different morphologies, thus attracting considerable attention and being studied both alone and in association with other semiconductors with the aim of further improving its properties. C3N4 is another photocatalyst that has attracted attention due to its low bandgap (2.7 eV), allowing absorption of visible light to generate more electron-hole pairs. of the α-MoO3/C3N4 hybrid material. The work was divided into three stages. In the first stage, using the spray-pyrolysis synthesis method, syntheses were performed at different precursor concentrations (0.1M, 0.2M and 0.3M), temperatures (600 °C to 1000 °C) and atomizer power (70% and 100%), the flow rate, in turn, was fixed at 3 L/min, the different parameters were used in order to obtain a-MoO3 in a single step. Once MoO3 synthesis was optimized, the next step was to use the ultrasonic method (step 2) at different times (5 min, 10 min and 15 min) on the selected sample and analyze the results obtained. With the time for the synthesis with the best results, stage 3 was started, in which the coupling of MoO3 and C3N4 was performed using sonochemical method, obtaining the hybrid material composite MoO3/C3N4. The materials were characterized by the techniques of X-Ray Diffraction (DRX), Spectroscopy in the UV-Visible region (Uv-Vis), Scanning Electron Microscopy by Field Emission (MEV-FEG), Photoluminescence and evaluated their photocatalytic efficiency against to organic dyes. The diffractogram showed the attainment of the α-MoO3 orthorhombic phase with a space group of 62 Pbnm as well as the presence of the hydrated phase in the analyzed samples. The composite samples analyzed showed gap energy values of 3.09 eV. Sample MOCN 1 showed the best photocatalytic activity. Through the micrographs, it was possible to observe the influence of the synthesis parameters and the ultrasonic process itself on the morphology of the samples, variations that influenced the photocatalytic activity and photoluminescence of the samples.

     

6
  • RAYANE RICARDO DA SILVA
  • Study and analysis of NbN and TaN synthesis parameters via gas-solid reaction

  • Líder : CARLSON PEREIRA DE SOUZA
  • MIEMBROS DE LA BANCA :
  • ANDARAIR GOMES DOS SANTOS
  • ANDRE LUIS LOPES MORIYAMA
  • CAMILA PACELLY BRANDÃO DE ARAÚJO
  • CARLSON PEREIRA DE SOUZA
  • CLEONILSON MAFRA BARBOSA
  • UILAME UMBELINO GOMES
  • Data: 19-jun-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • In order to adapt the advancement of technology along with economic growth, new ideas arise for the use of clean energy sources. The studies of new materials have been gaining ground to improve their properties and their performance in the face of their applications. Currently, the development of new methods, processing and compositions have been invested in order to optimize the processes, as well as obtain low cost and less energy expenditure. Niobium and tantalum nitrides are nanocrystalline materials that have good electronic conductivity, high melting point, wear resistance, superconducting properties, among other properties, make these materials promising for many technical applications, including aerospace, capacitor production and anticorrosive materials. Among the various synthesis methods, the gas-solid reaction route has advantages, such as ease of operation, low maintenance cost and shorter processing time, in addition to allowing the control of crystallite size. In this article, niobium and tantalum precursors were used for the synthesis of nitrides, since these precursors have more reactivity than niobium and tantalum oxides. The materials obtained were characterized by XRD, Rieltveld refinement, SEM/FEG, HRTEM, granulometry and crystallite size calculation. Niobium nitride was synthesized through the precursor niobium oxalate under conditions of 1100 ºC with a flow rate of 44.7 L/h and an isotherm of 300 min and the NbN phase with hexagonal structure and absence of impurities was obtained. From the study of tantalum nitride synthesis parameters, it was observed that the variation in the granulometry of the tantalum oxalate precursor influenced the obtaining of the sample with the highest presence of the Ta5N6 phase with hexagonal structure. The synthesis conditions were more effective to obtain pure niobium nitride, while for tantalum nitride, more synthesis conditions must be studied to optimize the process of obtaining the desired material.

7
  • LUANA BARBOSA DA CRUZ CAVALCANTI
  • Tape casting of hydroxyapatite and tricalcium phosphate membranes with added manganese for bone regeneration

  • Líder : WILSON ACCHAR
  • MIEMBROS DE LA BANCA :
  • EDUARDO GALVAO RAMALHO
  • HUGO PLÍNIO DE ANDRADE ALVES
  • SHEYLA KAROLINA JUSTINO MARQUES
  • VAMBERTO MONTEIRO DA SILVA
  • WILSON ACCHAR
  • Data: 20-jun-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • In recent years, damage to bone tissue has been increasing, especially in the elderly population, thus reducing the condition of well-being. The lesions represent an enormous challenge for the repair of the affected regions due to the slow healing rates (especially among the older), the high cost of treatment and the high risk of rejection by the body. Alternative techniques have been increasingly studied to promote improved bone regeneration; among them, one of the most promising is the use of biomaterials based on the application of barrier membranes for guided bone regeneration. They are able to promote tissue integration, since they prevent the invasion of fibroblasts by providing stability to bone grafts and guarantee protection for the osteogenesis process, thus accelerating the healing process and restoration of the affected area. The development of calcium phosphate membranes has been increasingly researched due to their chemical and biological similarity to bone constitution, for their good cell adhesion and relatively low cost as well. In this work, studies were carried out regarding the development of ceramic membranes of tricalcium phosphate and hydroxyapatite through the Tape Casting method with and without the addition of manganese to improve guided bone regeneration. The ceramic suspension was the first part characterized, being carried out through the study of the rheological behavior. Subsequently, the membrane was characterized through X-ray diffraction (XRD), thermal analysis (TGA/DTA), scanning electron microscopy (SEM-FEG), Raman, degree of swelling, bioactivity and cytotoxicity. The results obtained showed a suspension of pseudoplastic behavior suitable for the process via Tape Casting, for the membranes were flexible, with characteristic phases, biodegradable, biocompatible, non-toxic and with good water absorption, which makes it ideal for the desired application.

     

8
  • ALINE ALENCAR EMERENCIANO
  • Novel 2D materials for high-performance gas separation membranes and for epoxy-based composites 


  • Líder : ANA PAULA CYSNE BARBOSA
  • MIEMBROS DE LA BANCA :
  • ANA PAULA CYSNE BARBOSA
  • DACHAMIR HOTZA
  • DANIELA BECKER
  • WILHELM ALBERT MEULENBERG
  • RUBENS MARIBONDO DO NASCIMENTO
  • UILAME UMBELINO GOMES
  • Data: 27-jun-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Gas separation membranes for capturing CO2 from the environment are urgently required to minimize the greenhouse effect. One of the biggest challenges in this field is to produce an efficient gas separation membrane that is mechanically and chemically stable, as well as capable of separating gases through molecular size selection, known as molecular sieving. Currently, among different materials that have been used to produce membranes, graphene and graphene oxide are a potential competitor used for their fabrication trough etching. Due to their strong similarity to graphene, MXenes have become a great candidate to be processed as a membrane due to their ability to form nanochannels. However, some issues regarding purity, quality, waste, and storage of the nanosheets need to be improved. Additionally, due to the hydrophilic and attractive nature of their functional groups, there is a facility for the formation of agglomerates in their anhydrous form during storage, which hinder the reuse of this material to be used as reinforcement in epoxy-based matrices, for example. In this work, investigations were carried out regarding: (I) the production of a MXene membrane able to separate H2 and CO2 by controlling the distance between Ti3C2Tx nanosheets, (II) improvement of the synthesis efficiency of MXenes by creating a drying protocol to improve the purity of the nanosheets, and avoid agglomeration, and (III) improving the dispersion of Ti3C2Tx nanofillers in epoxy resin matrix by studying the influence of reinforcement morphology on dispersion and mechanical properties of epoxy-based composites. The results suggest that Ti3C2Tx was efficiently synthesized. Next, heat treatment under an oxygen-free atmosphere is an alternative for controlling the interlamellar distance by increasing the H2/CO2 separation factor. Additionally, a new protocol for drying and storing MXenes in its foam form was able to produce nanosheets by separating synthesized MXenes and non-etched MAX Phase, while maintaining their quality as well as the nature of their functional groups, which led to the production of well-deposited MXenes films. Finally, the good dispersion of Ti3C2Tx foam in the epoxy-based matrix led to an increase in the mechanical properties of the composite unlike the MXenes powder dried via the conventional method.


9
  • JEVERTON LAUREANO PAIXÃO
  • Effect of Zn microadditions on the microstructure, cytotoxicity and mechanical properties of eutectic Sn-Cu and Sn-Ni alloys

  • Líder : BISMARCK LUIZ SILVA
  • MIEMBROS DE LA BANCA :
  • BISMARCK LUIZ SILVA
  • CLARISSA BARROS DA CRUZ
  • CLAUDIO ALVES DE SIQUEIRA FILHO
  • NICOLAU APOENA CASTRO
  • SUYLAN LOURDES DE ARAÚJO DANTAS
  • Data: 28-jul-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The development of Pb-free solder alloys is an urgent demand for the electronics industry in order to comply with applicable laws and environmental guidelines and provide products with optimized mechanical and physical properties. Among the alternative lead-free solders, can be highlighted alloys of the Sn-Cu and Sn-Ni systems, with properties superior to the alloys of the Sn-Pb system, such as mechanical and corrosion resistances, in addition to the low cost. However, such SnCu and Sn-Ni alloys still exhibit relatively high melting point and insufficient oxidation resistance. One way to optimize its properties and microstructure is through the addition of alloying elements, such as zinc (Zn). Zn, which is also a low-cost element, and is used in Pb-free solder alloys to minimize intermetallic compound growth in soldered joints, to refine the microstructure and to increase mechanical strength. Therefore, this study aims to understand the effects of Zn additions (0.2 and 0.5 wt.%) on thermal parameters (growth rate-V and cooling rate-Ṫ), microstructure, phases transformation, macrosegregation, mechanical properties (ultimate tensile strength-σu and elongation-to-fracture-δ) and cytotoxicity in the eutectic Sn-0.7wt.%Cu and Sn-0.2wt.%Ni alloys directionally solidified under transient conditions against electrolytic copper substrate. For this, samples from both systems were characterized by Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD). The cytotoxicity analysis was carried out based on cell viability with an incubation period of 15 and 30 days for the alloys and subsequent exposure of the extracts with the cells for 24 and 48 h. Zn additions caused slight and significant alterations to the phase transformation temperatures of the Sn-Cu-Zn and Sn-Ni-Zn, respectively. Macrostructures with columnar-equiaxial transition (CET) and fully columnar were observed for the Sn-CuZn and Sn-Ni-Zn alloys, respectively. The microstructures of the Sn-Cu-Zn alloys are predominantly dendritic with a tin-rich matrix (β-Sn phase) surrounded by a eutectic mixture composed of the β-Sn+Cu6Sn5+CuZn phases. In the final positions of the SnCu-Zn castings, eutectic cells of the low growth rate have been observed. For the SnNi-Zn alloys, the microstructure is completely dendritic, composed of a tin-rich matrix (β-Sn phase) surrounded by a eutectic mixture Ni3Sn4+ NiSn + β-Sn, in addition to a probable formation of the intermetallic (Cu,Ni)6Sn5 due to the dissolution of the Cu substrate. Zn additions refined the dendritic arrangement of the Sn-Cu-Zn alloys when compared to the Sn-0.7wt.%Cu alloy. However, increasing the content did not affect the microstructural scale. On the other hand, both Zn additions did not change the scale of the dendritic arrangement, compared to the Sn-0.2wt.%Ni alloy. Zn did not influence the  σu and δ values in the Sn-Cu-Zn alloys, with columnar growth. With the reduction of primary dendritic spacing (λ1), σu increased for both Sn-Cu-Zn and Sn-Ni-Zn systems, however, the behavior of δ was opposite. The Sn-0.2wt.%Ni-0.5wt.%Zn alloy exhibited higher σu values, which are associated with the solid-solution hardening mechanism. A ductile fracture mode has been observed for all alloys examined. Cytotoxicity analyzes showed that the microstructural scale does not influence the toxicity of the examined alloys, but factors such as incubation time and chemical composition do. In general, Zn improved the cell viability of the eutectic Sn-Cu and Sn-Ni alloys, but still with moderate cytotoxic levels.

10
  • CLEBER DA SILVA LOURENÇO
  •  

    Study of the partial substitution of the Co binder with Nb in hard metal  prepared via HEM and sintered in conventional furnace, high vacuum, and spark plasma sintering (SPS)


  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • ARIADNE DE SOUZA SILVA
  • MARCO ANTONIO MORALES TORRES
  • MARIA JOSE SANTOS LIMA
  • NAILTON TORRES CAMARA
  • RAFAEL ALEXANDRE RAIMUNDO
  • UILAME UMBELINO GOMES
  • Data: 25-sep-2023


  • Resumen Espectáculo
  • Hard metal, also known as cemented carbide, is a widely used material in various applications such as turning, milling, and drilling. The most commonly used hard metal consists of a major hard phase of WC (tungsten carbide) and a minor metallic binder phase of Co (cobalt), usually making up less than 25% by mass. However, although the use of Co as a binder results in improved mechanical properties for the cemented carbide, the scientific community has been seeking a partial or complete substitute for this binder due to its toxicity and scarcity. In light of this, this research aimed to evaluate the possibility of partially replacing Co with Nb (niobium). For this purpose, composite powders of WC-10%Co, WC-2.5%Nb-7.5%Co, and WC-5%Nb-5%Co were prepared using wet high-energy milling (HEM) for 2, 15, and 30 hours. The milled powders were compacted at 250 MPa and subsequently sintered in a conventional resistive furnace at 1450°C and 1550°C. The powders processed via 30-hour WHEM were also sintered using two distinct routes to achieve better properties for the hard metal. In the first route, the milled powders were compacted at 250 MPa and sintered in high vacuum (10-4 torr) at a temperature of 1550°C. In the second route, the powders were sintered using spark plasma sintering (SPS) at a temperature of 1300°C. The starting powders, milled powders, and sintered samples were characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), and energy-dispersive spectroscopy (EDS). Particle size distribution measurements were also conducted for the powders. The density of the sintered samples was determined using the Archimedes' method. Additionally, Vickers microhardness measurements were carried out on the sintered samples. The results revealed that the HEM process efficiently promotes phase homogenization and particle size reduction,  facilitating the sintering process of the composite powders. The SPS technique for the 30-hour milled powders proved to be more effective in enabling the partial substitution of Co with Nb, resulting in a relative density of 84.23% for the cemented carbide WC-5%Co-5%Nb.

     
11
  • TALITA GALVAO TARGINO
  • Mechanical Behavior and Mechanisms of Damage in Carbon/Epoxy Laminates with Traditional Layup and Double-Double Layup under Low Speed Impact

  • Líder : JOSE DANIEL DINIZ MELO
  • MIEMBROS DE LA BANCA :
  • CARLOS ALBERTO CIMINI JUNIOR
  • EVANS PAIVA DA COSTA FERREIRA
  • JOSE DANIEL DINIZ MELO
  • LUCAS LISBÔA VIGNOLI
  • RAIMUNDO CARLOS SILVERIO FREIRE JUNIOR
  • Data: 02-oct-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The optimization of composite material structures, aiming at reducing manufacturing time and costs, decreasing weight, and improving mechanical properties, holds great technological importance and has been the subject of numerous studies. This study investigates the mechanical behavior of two carbon fiber reinforced/epoxy laminates (AS4/8552) with equivalent in-plane stiffness and thickness but different stacking sequences: A [±0/±55]3T laminate, of the type double-double (DD) [±Φ/±ψ]n, and a traditional quadriaxial laminate (QUAD) [03/90/±45]S. Strength and stiffness of the laminates were assessed by performing uniaxial compression tests, low-velocity impact tests with three energy levels (30 J, 45 J, and 74 J) and compression after impact (CAI) tests. Additionally, damage mechanisms were evaluated through X-ray computed tomography, and a mathematical model was proposed to study the residual behavior of the laminates. According to this mathematical model, it was observed that the residual strength of the laminates can be related to the delaminated area, although the damage distribution occurs quite differently between the laminates. Ultimately, it was found that the mechanical properties of the two laminates were similar, which supports the possibility of using DD laminates to replace the traditional QUADs, with advantages such as easier fabrication, lower weight, homogenization and optimized stacking sequence.

12
  • REBECCA ARAÚJO BARROS DO NASCIMENTO SANTIAGO
  • EVALUATION OF IRON-BASED INDUSTRIAL ORES AND WASTE AS CARRIERS OF OXYGEN AND THE ENERGY POTENTIAL OF COLORED COTTON WASTE FOR THE BIOMASS CHEMICAL LOOPING GASIFICATION PROCESS – BCLG

     
     
  • Líder : DULCE MARIA DE ARAUJO MELO
  • MIEMBROS DE LA BANCA :
  • JUAN ADÁNEZ ELORZA
  • DULCE MARIA DE ARAUJO MELO
  • IÑAKI ADÁNEZ RUBIO
  • MAURICIO ROBERTO BOMIO DELMONTE
  • RENATA MARTINS BRAGA
  • Data: 14-nov-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The reduction of anthropogenic greenhouse gas (GHG) emissions has become one of the main environmental concerns faced in this century. Limiting global warming to 1.5ºC by 2100, as established in the Paris Agreement, requires minimizing cumulative emissions of CO2 and other GHGs, such as methane (CH4). In this context, using biofuels (biomass) associated with CO2 Capture and Storage (CCS) processes is an attractive solution in order to achieve zero carbon dioxide emissions in industrial processes. Therefore, Biomass Chemical Looping Gaseification – BCLG emerged as an innovative and advantageous option in relation to conventional gasification, as it produces high purity synthesis gas, not diluted in N2 and with less energy and economic penalty. A key criterion in the development of the BCLG process is the proper selection of an oxygen carrier. It should be noted that the use of iron-based ores and tailings are attractive in CL industrial applications due to their low cost, abundance and heterogeneous composition. In view of this, this doctoral thesis aims to evaluate the potential of four oxygen carriers, based on iron, such as iron ore from Brazil (Carajas - CRJ), iron residue from mining (Derramamento - DRM) and from the industrial steel (Carepa - CRP), as well as the physical mixture of DRM with eggshell residue as a source of CaO (DRM-RCO), for application in the BCLG process. The characterization techniques employed were X-Ray Fluorescence (FRX), X-Ray Diffraction (XRD), Laser Granulometry, Pycnometry, Field Emission Scanning Electron Microscopy (MEV-FEG) with X-Ray Energy Dispersive Spectroscopy (EDX), Programmed Reduction Temperature (RTP), mechanical strength, friction loss (Air Jet Index) and evaluation of reactivity by thermogravimetry. After the physical-chemical characterization, it was verified that CRJ had appropriate properties to be evaluated in the discontinuous fluidized bed reactor - Batch Reactor, using H2, CO and CH4 as fuel gas at different temperatures (850 °C, 900 °C and 950 °C). Then, the characterization techniques were performed: XRD, SEM, Mechanical resistance and post-batch analysis of reactivity with H2 and CH4. It was possible to conclude that the CRJ transporter did not present agglomeration problems at the end of the tests in the Batch Reactor, as well as carbon deposition was not identified. It showed good fuel conversion with H2, followed by CO and finally CH4, with minimal friction loss during 12 hours of operation and maintained its reactivity under hydrogen gas. Therefore, this material presents promising characteristics for the BCLG process.

     
     
13
  • WILLIAM CONSTANTINO DA SILVA
  • Cladding Welding of C-Mn stainless steel 309L and Inconel 625 alloys deposited by GMAW processes: operational and metallurgical aspects

  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • CELINA LEAL MENDES DA SILVA
  • GUDSON NICOLAU DE MELO
  • NICOLAU APOENA CASTRO
  • RUBENS MARIBONDO DO NASCIMENTO
  • Data: 27-nov-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Oil exploration in ultra-deep waters has intensified with the discovery of oil in the pre-salt layer. Given this scenario, the development and improvement of materials and engineering components become essential to face the new challenges of this sector. In particular, a service life and corrosion resistance of components and structures must be improved. To achieve this goal, several initiatives have used resistance cladding of alloys with special properties, such as stainless and nickel alloys, on resistant steels. However, dissimilar pain can generate problems, such as the formation of discontinuous regions of high hardness in the interfacial region, known as Partially Diluted Zones (PDZ). In this sense, a study was followed using metallic alloys of high corrosion resistance. The technique of Electron Microscopy by Backscattered Electron Diffraction (EBSD) was used to characterize these interfacial regions and safely and deeply evaluate the microstructure of the claddings produced. For the work, welding electrode from alloys AWS E 309L and AWS ER NiCrMo-3 — stainless 309L and Inconel 625 — are used as filler metals deposited on ASTM A36 steel test plates. Automated single and double layer MIG interface were employed. The metallurgical-mechanical characteristics were evaluated by means of Field Emission Scanning Electron Microscopy (FEG-SEM) using the technique of Backscattered Electron Diffraction (EBSD), Energy Dispersive X-Ray Spectroscopy (SEM-EDS) and Vickers Microhardness. The results appreciated that the Heat Affected Zone (HAZ) had its microstructure
    modified and, consequently, its microhardness directly related to the cladding deposition mode (single or double layer). Regarding the PDZs, they were observed in different morphologies such as beaches, swirl, and islands, with high percentages of iron, chromium, and nickel, along with high microhardness values and a microstructure typically characteristic of martensitic structures. When comparing microhardness percentages between single-layer and double-layer deposition, it was found that double-layer deposition was more beneficial in significantly reducing microhardness values in the PDZs andin the HAZs of the coated components.

14
  • JULIANO AUGUSTO MEDEIROS DE MENEZES E OLIVEIRA
  • Study of the effect of electropulsing on the mechanical and microstructural behavior of the AA7075 alloy (Al-Zn-Mg-Cu) for the self-healing of pre-deformed alloys

  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • RUBENS MARIBONDO DO NASCIMENTO
  • MAURÍCIO MHIRDAUI PERES
  • MEYSAM MASHHADIKARIMI
  • ALBERTO JORGE JUNIOR
  • AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • Data: 07-dic-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Over the past few years, research into self-healing materials has gained increasing scientific attention. In this class of bioinspired materials, engineers and scientists rely on biological mechanisms to design new materials with unique characteristics. Advances in this sense are widely noted in several classes of materials. Specifically for metallic materials processing by electrical pulses, or EPT (Electropulsing Treatment) is a new approach to self-healing that is growing in importance in the technological field. The application of a controlled current of sufficiently high density, but with a low temperature rise, generates a electron flow with energy capable of modifying the microstructure, which may promote stress relief, the reduction of microvoids and microcracks or even the recrystallization. Given the importance of techniques that increase the useful life of aeronautical components, the purpose of this work is to establish a methodology with the development of appropriate parameters for the self-repair process via electrical pulses in the aluminum alloy AA 7075 (Al-Zn-Mg -Cu). Compositional and phase analysis was performed via X-ray fluorescence (XRF) and X-ray diffraction (XRD). The mechanical behavior and generation of crystalline defects was previously evaluated in specimens machined according to the ASTM E8 standard, under interrupted tensile tests at deformations of 60%, 70%, 80%, 90% and 95% relative to rupture, resulting in the increase of yield stresses and reduction of ductility. The hardest samples (90 and 95% deformed) were treated via EPT with peak current (Ip) of 400 A and 500 A; base current 0 A (Ib), peak time (Tp) and base time in 0.1 s (Tb) in a total treatment time of 7s, 14s and 21s totaling 35, 70 and 105 25 cycles respectively. The deformed samples before and after EPT were analyzed by tensile tests, the results of which confirmed the increase in ductility and the reduction in yield stress with the longer period of applied current. The most critical condition, referring to samples deformed to 95% of rupture, treated by EPT (Ip of 400 A) with 7s, 14s and 21s were analyzed via residual stresses by XRD, proving the relief of residual stresses promoted by EPT due to the application period, in agreement with the behavior under tensile test. Despite the evidence supporting the effect of EPT on mechanical properties, surface analyzes of the specimens, via field emission scanning electron microscopy (SEM-FEG), were not sufficient to prove the microstructural effect of self-repair, requiring more detailed analyzes.


15
  • GERLÂNEA SILVA DE OLIVEIRA
  • Influence of Nickel (Ni) Addition on the Microstructure and Mechanical Properties of W-Cu Composite Sintered by SPS.

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • UILAME UMBELINO GOMES
  • MARIA JOSE SANTOS LIMA
  • ARIADNE DE SOUZA SILVA
  • JUSSIER DE OLIVEIRA VITORIANO
  • MARCELLO FILGUEIRA
  • Data: 13-dic-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Tungsten and its composites, such as the tungsten-copper (W-Cu) and tungsten-copper-nickel (W-Cu-Ni) system, have attracted increasing attention to studies, due to their excellent mechanical, physical and chemical properties, for applications in the field of electroelectronics, in addition, they do not present toxicity or environmental risks. In view of this, the present work studied the influence of the addition of Nickel on the microstructure and mechanical and physical properties of the W-Cu composite, obtained by high-energy milling and sintered by Spark plasma sintering (SPS). The effects of Ni percentage variation and sintering temperature on the properties of W-Cu composites were studied. To obtain the powders, tungsten (W) and copper (Cu) were mixed with 2%w and 5%w. of Nickel (Ni), were subsequently ground in a high-energy planetary mill for 10 hours. Sintering was performed by SPS at temperatures of 900 ºC and 1000 ºC. The starting powders (W, Cu and Ni) and those ground in the proportions mentioned above were characterized by X-ray diffraction (XRD); scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS); Particlemetry and FRX. After sintering, the samples were characterized by SEM, EDS, optical microscopy (OM), density and microhardness measurements. The results of scanning electron microscopy and EDS revealed that high energy milling for 10 hours was enough to obtain the composite with good homogeneity and free of impurities. XRD diffractograms showed the peaks of the characteristic phases of the composite. The sintered compacts had densities ranging from 10.71 g/cm³ to 12.35 g/cm³ and microhardness from 258 HV to 371 HV. The W-30%p.Cu sample sintered at 900 ºC showed a higher density value (12.35 g/cm³) and consequently lower porosity. The sample with the addition of nickel (W-28%Cu-2%Ni) sintered at 1000ºC showed the highest density and highest hardness value. Thus, nickel positively influences the mechanical properties of the composite under study, when added in small amounts.

16
  • FÁBIO GUSTAVO LIMA PEREIRA
  • Plasma Sintering and properties of Ni-Cr alloys hardened by oxide dispersion



  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • RUBENS MARIBONDO DO NASCIMENTO
  • ANTONIO EDUARDO MARTINELLI
  • THERCIO HENRIQUE DE CARVALHO COSTA
  • UILAME UMBELINO GOMES
  • CRISTIANO BINDER
  • JORGE MAGNER LOURENÇO
  • Data: 15-dic-2023


  • Resumen Espectáculo
  • Oxide Dispersion Reinforced Alloys (ODS) are known for their high application potential as structural materials in power generation systems or in the petrochemical industry, mainly due to their highly stable microstructure and high creep resistance. These characteristics are associated with the presence of a high density
    of dislocations and grain boundaries that are effectively anchored by ultrafine particles, rich in Y-Ti-O, dispersed along the microstructures of these materials. The traditional method of processing ODS alloys is via mechanical alloying, followed by consolidation by hot isostatic pressing. Recently, a new technique for sintering materials from powder using pulsed DC electrical discharge was developed by LabMat of the Universidade Federal de Santa Catarina. This technique consists of heating the compact through the bombardment of ionic particles and fast neutral chemical species. In the present work, nickel-based alloys were processed by MA in a
    spex mill and sintered in a conventional furnace using a DC electric discharge technique. Furthermore, the nickel-based ODS alloys were developed from the addition of 1.2%𝑌2𝑂3 in a matrix with Ni-20Cr composition. Initially, the properties of starting and milled powders were evaluated using techniques such as x-ray diffraction and scanning electron microscopy, in addition to investigating the effects of processing parameters: milling time (0h, 1h and 2h), temperature (1000 ∘C and 1200 ∘C) and sintering time (30 and 60min) on the microstructural characteristics, density and microhardness of the Nickel based alloy Ni-20Cr-1.2𝑌2𝑂3. Subsequently, 5% by weight of 𝐴𝑙2𝑂3 was added to the alloy Ni-20Cr-1.2𝑌2𝑂3, in order to analyze the effect
    of load transfer hardening . The microstructural characteristics of the consolidated alloys were examined using SEM-FEG, while the mechanical properties were evaluated using the Vickers microhardness test. The densities of the sintered samples were determined using the Archimedes principle. Densities between 6.3 and 7.14 g/𝑐𝑚3 were found and microhardnesses between 114 and 266 HV. The surface porosity of the Ni-20Cr-1.2𝑌2𝑂3 alloy was investigated using the image analysis method, considering parameters such as mean pore diameter, shape factor and elongation factor. All microstructural aspects, surface porosity and mechanical properties suggest that plasma sintering processes in abnormal DC glow discharge and in conventional tube
    furnace are similar.

17
  • WENDEL ANDERSON DANTAS TEIXEIRA
  • Synthesis of zeolites from industrial waste from the oil industry
  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • FABIO GARCIA PENHA
  • MARIELE IARA SOARES DE MELLO
  • RUBENS MARIBONDO DO NASCIMENTO
  • SIBELE BERENICE CASTELLA PERGHER
  • Data: 26-dic-2023
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The more than 255 zeolite structures know today,ony ten (10) are produced industrially. This is because many of the syntheses are not optimized or are too expensive to scale. To enable more structures to be produced industrially synthesis costs can be reduced by replacing tradicional raw materials with alternative sources of Si and Al. Among the alternative sources of Si na Al, natural materials such as clay minerals, industrial waste can be used, between others. We are proposing in this work the use of fragmented materials displaced by the drill to the surface, residue from drilling oil wells called gutter sample. The zeolite to be obtained using this residue will initially be LTA zeolite. The materials obtained materials, as well as the starting ones, were characterized by X-ray difraction, X- ray fluorescence, scanning electron microscopy and Co2 adsorption. As a result, it was possible to observe the formation of zeolite materials through the identification of characteristic Bragg reflections and characteristics cubic morphology of zeolite LTA. The Si/Al ratio of the samples was close to Unity, as expected for this topology. Once the fearsibility of zeolite synthesis using this residue has been proven, it is intended to expand its use to another zeolite structure.

2022
Disertaciones
1
  • THERESA BEATRIZ OLIVEIRA NUNES
  • Influence of  synthesis method on the photocatalytic and photoluminescent properties of Ca1-xInxWO4

  • Líder : FABIANA VILLELA DA MOTTA
  • MIEMBROS DE LA BANCA :
  • ANA PAULA DE AZEVEDO MARQUES
  • FABIANA VILLELA DA MOTTA
  • MAURICIO ROBERTO BOMIO DELMONTE
  • Data: 10-feb-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • CaWO4 is a semiconductor that is currently being investigated for having good optical properties. These properties are related to some processing factors such as different synthesis methods that generate distinct crystal structures and morphologies. Such morphological and structural characteristics will certainly affect the properties of the synthesized material. In this work, the photocatalytic and photoluminescent properties of CaWO4 doped with indium (0, 1, 2, 4 and 8% mol) were investigated for 30 minutes by two different methods: the sonochemical method (MS) and the microwave-assisted hydrothermal method (MHAM). The crystal structures of the pure and doped samples and their morphologies were characterized by X-ray diffraction (XRD) and by field emission scanning electron microscopy (MEV-FEG), respectively. The photocatalytic activity was estimated from the degradation of methylene blue (MB) dye under UV light. CaWO4 powders were tested in 3 cycles of reuse. Optical and photoluminescence properties were estimated from UV-Visible spectroscopy and the photoluminescence (FL) test. The diffractograms indicated no formation of secondary phases and the Rietveld refinement estimated the crystallite sizes where the samples synthesized by MS obtained a crystallite size of 31,85 nm for the pure sample which varied to 31,23 nm with a maximum doping (8% of In). For the samples synthesized by MHAM, the crystallite size varied between 35,98 nm for the pure sample and 36,73 nm for the 8% In sample. The average crystallite sizes of MS and MHAM samples were 33.51 and 34.69 nm, respectively. The SEM-FEG images indicated a clustered morphology with an irregular shape and in the form of rods and kibes. The photocatalytic activity increased in efficiency with increasing doping, and the samples doped with 4 and 8% of indium in each synthesis were the samples that showed the best photocatalytic efficiencies and the lowest bandgaps values. The sample synthesized by the hydrothermal method showed the smallest loss of efficiency during the 3 cycles of reuse, being the best alternative for applications in photocatalysis. The samples with 8% of In+3 ions showed lower FL intensities with maximum peak at 479 and 483 nm suggesting that there is a lower recombination pair e-/h+, which led these samples to have a better photocatalytic performance.

2
  • DÉBORA FERREIRA DOS SANTOS MORAIS
  • Study of the Photocatalytic and Optical Properties of the SrMoO4/g-C3N4 heterojunction via sonochemical synthesis with temperature control

  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • FABIANA VILLELA DA MOTTA
  • MARCIO DALDIN TEODORO
  • MAURICIO ROBERTO BOMIO DELMONTE
  • Data: 11-feb-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Advanced Oxidative Processes (OAP’s) based on heterogeneous photocatalysis have been extensively used as an effective alternative for the treatment of effluents. These processes use the semiconductor as a catalyst due to its electronic band structure. However, many semiconductors undergo charge carrier recombination, limiting their efficiency in degrading the organic contaminant. One of the strategies to overcome this problem is the heterojunction synthesis, which consists of joining materials that share the same interface, providing the spatial separation of charge carriers, consequently increasing the photocatalytic efficiency.

    In this work, particles of the SrMoO4/x g-C3N4 heterostructure, where x = 0; 0.1; 0.3; and 0.5 grams, were synthesized in a single step by sonochemical method, during 30 minutes at controlled temperatures of 15, 30 and 45ºC. The obtained particles were structurally characterized by X-ray diffraction (XRD), morphologically by field emission scanning electron microscopy (SEM-FEG), optical properties were investigated by UV-Vis spectroscopy and photoluminescence (PL) techniques. and photocatalytic properties were evaluated using UV radiation in the degradation of organic contaminants Methylene Blue (MB), Rhodamine B (RhB) and Crystal Violet (VC). The XRD patterns for pure strontium molybdate (SrMoO4) did not show the presence of secondary phases, while the diffractograms for the heterostructures showed a shift from the main peak. SEM analysis showed that pure SrMoO4 particles have agglomerated rod-like morphology, and that in heterojunctions these rods are encased in graphitic carbon nitride nanosheets (g-C3N4). The UV-Vis analysis confirmed the high bandgap of pure SrMoO4 (4.4eV) with absorption for shorter wavelengths (270nm), while the heterostructures had a decrease in the bandgap (~4.2eV) and an increase in the absorption range (~436nm) with increasing presence of g-C3N4. The PL spectra of the pure SrMoO4 samples showed a broad barda with predominant emission in the blue-green region, while the heterojunctions showed a narrower band with much higher intensity than the pure samples, with predominant emission in the blue color. The results of the photocatalytic tests indicated that the increase of g-C3N4 increased the photocatalytic efficiency in the degradation of the contaminants, being the sample with 0.5g of g-C3N4 synthesized at a temperature of 30ºC with greater efficiency in the degradation of the dyes: 99.58% , 100% and 98.65% for MB, RhB and VC dyes, respectively. To analyze the applicability, the dyes used were mixed, where the sample with 0.5g of g-C3N4 degraded the MB, RhB and VC components by 96.5%, 64% and 76.3%, respectively. Three reuse cycles were performed, with final photocatalytic efficiency of 96.4%, 76.3% and 87.4% for MB, RhB and VC dyes, respectively.

3
  • JOYCE MARINA PAIVA DA SILVA

  • Synthesis and characterization of Ag2CrO4:Ag2MoO4 and Ag2CrO4:Ag2WO4 heterostructures with photocatalytic properties

  • Líder : FABIANA VILLELA DA MOTTA
  • MIEMBROS DE LA BANCA :
  • FABIANA VILLELA DA MOTTA
  • MARIO GODINHO JUNIOR
  • MAURICIO ROBERTO BOMIO DELMONTE
  • Data: 18-feb-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The incorrect disposal of organic pollutants into the environment has been increasing interest in materials with photocatalytic properties that are capable of degrading different components, such as dyes present in effluents. In this work, the synthesis method by coprecipitation at 70ºC was used to obtain heterostructures of Ag2CrO4:Ag2MoO4 and Ag2CrO4:Ag2WO4, in which Mo and W were inserted in the proportions of 0; 0.25; 0.5; 0.75 and 1 mol%. The nanoparticles obtained were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (SEM-FEG) and ultraviolet visible spectroscopy (UV-Vis). For the photocatalytic properties, tests were performed against methylene blue dye and against a mixture of dyes (methylene blue, methyl orange and rhodamine-B). The XRD results confirmed the achievement of the investigated phases, indicating the efficiency of the synthesis by coprecipitation for the samples obtained. Raman spectroscopy revealed significant changes in the local order-disorder as a function of the gradual replacement of the lattice former. The images obtained by SEM-FEG indicated that the samples composed of two phases presented a morphology formed by the mixture of the respective pure phases. All heterostructures obtained showed absorption for longer wavelengths, and lower gap energies, when compared to pure Ag2MoO4 and Ag2WO4 phases. The photocatalytic activity was investigated and the results indicated that all samples showed good catalytic activity against methylene blue, and all heterostructured samples were more efficient than pure Ag2MoO4 and Ag2WO4 phases, with efficiency of 95% and 99%, respectively. The reuse cycles indicated high potential for practical application in wastewater, due to the capacity of consecutive cycles for photodegradation. Furthermore, the test against the dye mixture indicated that the efficiency of the photocatalytic activity will be dependent on the complexity of the molecules involved.

4
  • JOÃO FELIPE BARROS PONTES
  • Addition of poly (ethylene-co-acid-meacrylic) (EMAA) as a healing agent in glass fiber-epoxy composites with damage by impact

  • Líder : ANA PAULA CYSNE BARBOSA
  • MIEMBROS DE LA BANCA :
  • ANA PAULA CYSNE BARBOSA
  • BRUNA LOUISE SILVA
  • EVANS PAIVA DA COSTA FERREIRA
  • RAIMUNDO CARLOS SILVERIO FREIRE JUNIOR
  • Data: 30-mar-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Materials with self-healing mechanism offer great potential for new scientific and technological developments. This is a research area with great possibilities for advances in the field of materials science and engineering. In this sense, the present work aims at the manufacture and characterization of a composite material, additive with a thermoplastic repair agent, where the ability to heal localized damage and delamination was evaluated. This repair is activated via heat supply, through an external source, and promotes increased mobility of the thermoplastic agent, poly (ethylene-co-acid-methacrylic) (EMAA). The damage was performed on the specimens in a controlled manner, via impact machine by free fall, thus being characterized as low speed impact.  Fourier Transform Infrared Spectroscopy (FTIR) allowed evaluation of chemical interactions between the epoxy matrix and the repair agent, post fabrication and post-repair cycle. Visual inspection was employed to evaluate affected areas, to compare the behavior of specimens under the influence of impact energy and EMAA effect, in relation to the filling of cracks and energy absorption. Finally, the mechanical post-impact compression test (CAI) was performed to evaluate whether there was recovery of properties after repair.

5
  • MARIZA DE CARVALHO MONTENEGRO FERNANDES
  • Synthesis of polymeric microcapsules filled with castor oil to improve epoxy tribological properties.
  • Líder : MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • EVANS PAIVA DA COSTA FERREIRA
  • JULIANA RICARDO DE SOUZA
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • MEYSAM MASHHADIKARIMI
  • Data: 01-abr-2022


  • Resumen Espectáculo
  • Over the last five years researchers have synthesized microcapsules for smart coatings adding encapsuled agents in polymeric matrices. This field of materials engineering has gained notoriety for allowing specific features from tribology perspective generating self-lubrication and self-healing in systems where the movement between solid surfaces is essential in the functioning of mechanisms both natural and artificial. Thus, in this research, poly (urea formaldehyde)  microcapsules filled with ricin oil were synthesized by in situ polymerization method and added in an epoxy matrix in the following mass percentages: 2.5%, 5% and 10%. The evaluation of tribological properties was developed with pin on disc tests in the conditions of 300 rpm 15N, in epoxy with microcapsules against a 52100 steel sphere, willing to quantify the coefficient of friction and the wear rate of the composite comparing with pure epoxy resin. As expected, spherical microcapsules were obtained with the desired composition and mean size of 413 ±175 µm, confirmed by FTIR and SEM images, respectively. Although all specimens had a decrease in coefficient of friction, the composite with 2.5% wt of microcapsules had a better output in tribological tests. The reduction in coefficient of friction is due to the action of ricin oil released from microcapsules, which forms a film typical of boundary lubrication regimen in the contact between the resin and the steel sphere.

6
  • YURI LEANDRO RODRIGUES LOPES FERNANDES
  •  

    Study, preparation and characterization of Diatomite/Nb2O5/TiO2 mesoporous
    nanocomposites for the treatment of contaminated water

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • ARIADNE DE SOUZA SILVA
  • CARLOS ALBERTO PASKOCIMAS
  • MEYSAM MASHHADIKARIMI
  • UILAME UMBELINO GOMES
  • Data: 13-abr-2022


  • Resumen Espectáculo
  • The emerging need for more efficient water treatment methods has become a
    problem beyond the scientific character: it covers ethical, economic and social
    issues. The advancement of the understanding about the mechanisms of filtration
    and treatment of contaminated water by porous matrix composites, such as
    diatomite, stimulated the development of this work. In this study, white diatomite
    ceramic powder was used to fabricate porous composites incorporated by Nb2O5 and
    TiO2 particles through the Tape Casting technique. Four ceramic-polymer tapes of
    ceramic mass composition (diatomite/TiO2
    /Nb2O5
    ) were obtained: tape a (1/0/0); tape

    b (0.9/0.1/0); tape c (0.9/0.05/0.05); and tape d (0.9/0/0.1). Finally, six-layer
    laminates were arranged, thermo-pressed, calcined at 500 oC and sintered at 1200
    oC, giving rise to the A - E ceramic wafers. The thermal behavior of the tapes was
    determined by thermogravimetric analysis (TG). Aiming to verify the effect of the
    processing route and composition on the morphological characteristics, the
    composition of crystalline phases, flexural strength, porosity profile and the
    adsorptive and photodegradation properties, the wafers were characterized by X-ray
    diffraction, field emission scanning electron microscopy, three-point bending test, N2
    physisorption, photodegradation test and Egap determination aided by UV-vis
    spectrophotometer. The resulting ceramic composites were found to have high
    porosity morphologies and monolithic characters. The crystalline phases cristobalite,
    quartz, anatase, rutile, and H-Nb2O5 were identified; by which an evolution of the
    crystalline structure, elimination of the amorphous zone, as well as the partial
    transformation of anatase-rutile phase was noted in wafers B and C. The bending
    test demonstrated an increase of up to 225% in strength through incorporation of the
    particles into the diatomite matrix, from 4.28 Mpa in wafer A to 13.90 Mpa in wafer C.
    The wafers exhibited a mesoporous structure, with narrowing of the pore size
    distribution and surface areas between 6.161 m2/g and 3.6 m2/g. A decomposition of
    up to 87.3% of methylene blue was observed across the composites, whose Egap
    values are in the range of 3.19 eV – 3.70 eV.

7
  • CELMO HUDSON REIS DE PAULA
  • Microstructural evaluation of graphene effects on carbide-based coatings for petroleum applications
  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • CARLOS ALBERTO PASKOCIMAS
  • MEYSAM MASHHADIKARIMI
  • RAMON SIGIFREDO CORTÉS PAREDES
  • RUBENS MARIBONDO DO NASCIMENTO
  • Data: 27-may-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The addition of graphene in alloys has become an object of interest in the research and development of coatings, as this material tends to improve properties such as wear and corrosion resistance of the material, thus increasing the useful life of assets in the oil and gas industries. gas, automotive, mining, among others. In this study, graphene oxide was synthesized and mixed with tungsten carbide - 12% cobalt for formulations of four compositions with different percentages by weight of graphene oxide (0; 0.5; 0.75; 1). 1020 steel plates were sprinkled through thermal spray - HVOF with each composition. Compositions and coatings were characterized through XRD, SEM-FEG, Raman, bending test, and Vickers microhardness. The results show that there was no phase change of graphene oxide after thermal spray. The coating with 0.5% graphene obtained higher hardness values than the other compositions, thus proving that graphene improves the mechanical properties of the coating. However, the compositions with higher graphene contents showed embrittlement, therefore, the coating began to show defects in its microstructure with a greater amount of graphene in the composition.

8
  • CLEANTO CARLOS DE QUEIROZ JUNIOR
  • STUDY OF THE INFLUENCE OF THE PARTIAL REPLACEMENT OF NATURAL SAND BY THE CUTTING WASTE OF ORNAMENTAL STONES ON THE PROPERTIES OF MORTARS FOR 3D PRINTING

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • KLEBER CAVALCANTI CABRAL
  • ULISSES TARGINO BEZERRA
  • Data: 30-jun-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The substitution of natural raw materials by residues, especially in the construction industry, has been widespread. This is due to the reduction of the environmental impact caused by the extraction of raw materials, as well as the cost reduction with the proper destination of residues. Likewise, the number of researches that study new construction methods has grown, such as 3D printing, an alternative to production of materials in an intelligent way, with less cost and waste, in addition to lower production time. Thus, this work aimed to evaluate the influence of the partial replacement of fine aggregate using the ornamental stone cutting residue (RPPO - acronym in portuguese) on the properties of mortars for 3D printing. Initially, a reference mortar was produced that met the consistency and workability parameters for 3D printing and, later, the fine aggregate was replaced by RPPO in proportions of 5, 10 and 15%. For the determination of the fresh and hardened state properties of the mortars, consistency, squeeze-flow, water absorption, specific mass, and mechanical strength were carried out. In addition, the physical and chemical characterization of the RPPO was carried out by granulometry, X-ray diffractometry (XRD) and X-ray fluorescence (FRX). The results indicate that the addition of RPPO increased the mechanical strength, however, it also increased the absorption and the void index, because of the presence of calcite in the residue. The mortar density also decreased with the presence of RPPO. Therefore, the partial replacement of natural sand by RPPO provided greater mechanical strength to the mortar, but also caused an increase in absorption and void content.

9
  • RAÍ BATISTA DE SOUSA
  • Microstructure, Thermal Parameters and Cytotoxicity of the Ni-Modified Sn-2.0wt.%Ag Hypoeutectic Alloy

  • Líder : BISMARCK LUIZ SILVA
  • MIEMBROS DE LA BANCA :
  • BISMARCK LUIZ SILVA
  • CLAUDIO ALVES DE SIQUEIRA FILHO
  • MAURÍCIO MHIRDAUI PERES
  • Data: 11-jul-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The addition of nickel (Ni) in tin-based alloys applied to microelectronic components has received special attention in recent years. Ni promotes changes in mechanical strength, toughness, creep resistance, and electrical properties. In this context, the present study aims to understand the effect of Ni addition (0.2% by weight) on solidification thermal parameters (for liquidus and eutectic isotherms: cooling rate-ṪL/ṪE and growth rate-VL/VE), microstructure, microhardness and cytotoxicity of directionally solidified Sn-2%Ag (by weight) hypoeutectic alloy under transient heat flow conditions. A wide range of microstructures were acquired via optical (OM) and scanning electron microscopy (SEM), in addition to phase identification and alloy element distribution throughout the Sn-Ag and Sn-Ag-Ni alloy castings, respectively. The effect of Ni on mechanical properties was performed by Vickers microhardness test. Cytotoxicity analyses (cell viability) were performed using Sn-Pb system alloys (Pb-10wt.%Sn and Sn-20wt.%Pb) as reference. The addition of Ni in the Sn-2wt.%Ag alloy increased the values of cooling rate (ṪL/ṪE) and growth rate (VL/VE), especially for the first positions from the metal/mold interface. Thus, Ni caused a microstructural refinement of the dendritic structure (λ2 and λ3), but without affecting the microstructural scale of the eutectic mixture. As-cast microstructures for the Sn-2wt.%Ag and Sn-2wt.%Ag-0.2wt.%Ni alloys are completely dendritic, formed by a Sn-rich matrix (β-Sn) surrounded by a eutectic mixture (β-Sn +Ag3Sn) and (β-Sn +Ag3Sn + Ni3Sn4), respectively. Ag displayed inverse and normal-type macrossegregation profiles for the binary and ternary alloys, respectively, while for Ni, there was a slightly inverse-type profile. The addition of Ni seems to have stabilized the fibrous morphology of Ag3Sn, so that Ag3Sn fibers were observed for cooling rates higher than those reported in the literature. The increase in microhardness for the Sn-2wt.%Ag-0.2wt.%Ni alloy occurred due to microstructural refinement and the presence of the Ni3Sn4 intermetallic. Cytotoxicity analyses demonstrated that the microstructural scale does not affect the toxicity of the alloys examined, but that incubation time and chemical composition are the main influencing factors. The Pb-containing alloys showed higher levels of toxicity compared to Sn-Ag and Sn-Ag-Ni alloys.

10
  • BEATRIZ PINHEIRO DIAS
  • Study of the photocatalytic activity of clays containing Al and Ce for treatment of textile effluents

  • Líder : SIBELE BERENICE CASTELLA PERGHER
  • MIEMBROS DE LA BANCA :
  • SIBELE BERENICE CASTELLA PERGHER
  • WILSON ACCHAR
  • FABIO GARCIA PENHA
  • LINDIANE BIESEKI
  • Data: 29-jul-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The constant use of contaminating materials, often being incorrectly disposed of in the environment, is something that has been worrying society, and "environmental preservation" is one of the most debated topics in congresses and among researchers. Thinking about this aspect of alleviating this problem, the present work has as its main focus the study of photocatalytic properties, through advanced oxidative processes (AOP), for the treatment of textile effluents. To this end, the natural and Al-pillarized clays, both impregnated with cerium, and Al/Ce mixed pillarized clays were used in the photodegradation of methylene blue dye (AZM). The materials were prepared using the traditional pilarization procedure, where materials containing: 5, 10 and 15% Ce in the pilarizing solution were produced. For the Ce impregnated samples, 5, 10 and 15% Ce was also used in the solution to impregnate the samples. All materials were calcined at 450°C. The materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM-FEG), chemical analysis of the samples by X-ray fluorescence (XRF), textural analysis by N2 adsorption and UV-Visible spectroscopy (UV-Vis). The presence of CeO2 can be observed in all techniques, where in XRD it was possible to see the formation of CeO2 phases. It was also possible to observe the morphology of the samples, with the presence of lamellae and also with the presence of CeO2 observed by energy dispersive spectroscopy (EDS), as well as its mapping in the structure of the base material (clays). In the textural analysis made by the BET method - Brunauer, Emmett, Teller, it is possible to see that pilarization occurs in the pilarized samples because there was an increase in the specific area with a value around 239 m2/g. Furthermore, it is possible to see that with the cerium impregnation process, there was a reduction in this specific area, which was already expected for this process. For the samples of the Campos Novos Foundation type clay (FCN) impregnated with cerium and for the commercial Bentonite clay pilarized with Al/Ce pillar it was possible to obtain the best results for photocatalytic activity, with the degradation of more than 80% of the dye used. For the other samples, the degradation did not exceed 10% of the dye.

11
  • ALINE FERREIRA SCHON
  • Assessment of Laser Remelted Al-Cu-Ni Alloys for Application in Additive Manufacturing

  • Líder : BISMARCK LUIZ SILVA
  • MIEMBROS DE LA BANCA :
  • BISMARCK LUIZ SILVA
  • MAURÍCIO MHIRDAUI PERES
  • THIAGO ANTÔNIO PAIXÃO DE SOUSA COSTA
  • Data: 01-ago-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The processing of metals and alloys via Additive Manufacturing (AM) has received special attention in recent years due to the possibility of obtaining parts with complex geometries, quickly and with minimal waste of raw material. Aluminum-based alloys are potential candidates for these processes, however, currently there are few candidates Al-based alloys for use in AM, such as Al-12wt.%Si and Al-10wt.%Si-xMg. This occurs because such alloys are susceptible to the formation of pores, cracks, distortions and roughness, which impair high performance applications. The addition of Ni in Al-Cu alloys makes it possible to improve the mechanical properties at high temperatures and favors the reduction of the solidification interval, which results in a decrease in the amount of hot cracks and porosity in the final material. Given the context, the present research investigates the microstructural changes and the hardness of Al-5wt.%Cu and Al-4wt.%Cu-1wt.%Ni alloys processed by rapid solidification (centrifugation) and treated Laser surface remelting (LSR), in order to reproduce similar AM process conditions (high cooling rates 103-108 K/s). In order to understand the effect of Ni on the solidification interval, fraction of intermetallics and on temperatures and phase transformations, simulations and thermodynamic calculations were carried out by Thermo-calc software. Characterization techniques such as optical microscopy (OM), scanning electron microscopy (SEM) and X-ray diffraction (XRD) were used, in addition to thermal analysis by Differential Scanning Calorimetry (DSC) and Vickers microhardness. The simulations revealed a reduction of the solidification interval of approximately 22% in the Al-4.0wt.%Cu-1.0wt.%Ni alloy, and consequently, a decrease in the porosity of the Laser remelted pools. The microstructure of the rapidly solidified samples is characterized by a α-Al dendritic matrix, surrounded by a eutectic mixture α-Al, Al2Cu and Al7Cu4Ni. In the remelted pools, there was a transition from epitaxial (pool base) to equiaxed (pool center) growth with a significant microstructural refinement around 92% (from λ1=7.63 - 7.41 µm to λ1=0.681 - 0.609 µm), which favored an increase of about 82-90% (Al-5wt.%Cu: from 58.4 HV to 106.9 HV / Al-4wt.%Cu-1wt.%Ni: from 60.5 HV to 117 HV) of the microhardness in the microstructures Laser treated.

12
  • AMANDA RÁVILLA VALÉRIO XAVIER
  • Corrosion and Surface Laser Remelting of Sn-Ag-Cu Alloys

  • Líder : BISMARCK LUIZ SILVA
  • MIEMBROS DE LA BANCA :
  • BISMARCK LUIZ SILVA
  • FELIPE BERTELLI
  • MAURÍCIO MHIRDAUI PERES
  • Data: 29-sep-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The study, selection and feasibility of non-toxic alloys for soldering electronic microcomponents are urgent and necessary demands in a context of accelerated technological advancement and Industry 4.0. Alternative lead-free solder alloys such as Sn-Ag-Cu (SAC) system alloys have stood out for this application, as they have good wettability on metallic substrates, high creep strength and melting temperature close to the eutectic Sn-37wt.%Pb alloy. Laser surface treatments result in significant microstructural changes, but studies for Sn-based alloys are scarce in the literature. In this sense, the present research aims to understand the microstructural characteristics and the respective hardness of the Sn-1wt.%Ag-0.7wt.%Cu (SAC107) and Sn-3wt.%Ag-0.7wt.%Cu (SAC307) alloys treated by Laser Surface Remelting (LSR). The corrosion resistances of the as-cast samples of SAC107 and SAC307 alloys have also been analyzed. In order to understand the solidification paths of the alloys, such as solidification interval and transformation temperatures, thermodynamic calculations were performed via the Thermo-Calc software. Microstructural characterization was performed using optical microscopy (OM), scanning electron microscopy (SEM) and the Electron Backscatter Diffraction (EBSD) technique. The corrosion tests were made possible by potentiodynamic polarization, in addition to the Vickers microhardness tests. The increase in Ag content slightly reduced the liquidus temperature (TL), not changing the solidus (TS) and eutectic (TE) temperatures. As-cast microstructures are composed of Sn-rich dendrites surrounded by a ternary eutectic mixture β-Sn+Ag3Sn+Cu6Sn5. An epitaxial growth has been observed at the base of the Laser remelted pools, as well as a significant microstructure refinement in relation to the microstructural scale of the substrate (as-cast), of 98.5% and 99.4%, for the SAC107 and SAC307 alloys, respectively, associated at cooling rates of the order of 102 °C/s. Microhardness increases of 64.35% and 67.35% were noted for SAC107 and SAC307 alloys, respectively, from coarse microstructures to refined microstructures obtained by Laser. The polarization curves showed a more active behavior of samples with coarser microstructures for both SAC alloys. SAC307 alloy exhibited greater corrosion resistance than SAC107 alloy.

13
  • RONIER ALCÂNTARA OLIVEIRA
  • Influence of the method of obtaining Bi2MoO6:ZnO heterostructures for photocatalytic application

  • Líder : FABIANA VILLELA DA MOTTA
  • MIEMBROS DE LA BANCA :
  • FABIANA VILLELA DA MOTTA
  • MAURICIO ROBERTO BOMIO DELMONTE
  • THIAGO MIELLE BRITO FERREIRA OLIVEIRA
  • Data: 09-dic-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Tthe high consumption and inappropriate disposal of industrial products, from clothes to food products, increasing society's interest in developing materials that have catalytic properties that use means for the degradation of these organic contaminants, which can be dyes, pharmaceutical compounds and among others. The degradation reaction is accelerated using electromagnetic radiation, potential difference or ultrasonic radiation. In this work, the microwave-assisted hydrothermal method was used simultaneously with the sonochemical method (route 1) and only the sonochemical method (route 2) to obtain Bi2MoO6/ZnO heterostructures, with mass ratios of 1:1, 1 :2, 1:4, 1:8, 2:1, 4:1 and 8:1. The particles obtained were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (SEM-FEG) and spectroscopy in the ultraviolet visible region (UV-Vis). To evaluate the photocatalytic properties, photodegradation tests were performed against methylene blue and rhodamine B dyes using UV and solar radiation. The XRD results indicated the presence of ZnO phases with hexagonal structure and Bi2MoO6 with orthorhombic phase. The formation of a secondary phase of bismuth molybdate (Bi4MoO9) in route 1 was observed. Raman spectroscopy revealed the standard vibrational modes of the phases obtained from Bi2MoO6/ZnO, and also confirmed the presence of the secondary phase. The images obtained by SEM-FEG showed an irregular and predominant morphology in route 1 of synthesis, typical of the secondary phase of molybdate, and in route 2 of synthesis, platelet-like morphology was obtained for molybdate and rods and flowers for zinc oxide. The heterostructures with a 1:1 ratio showed absorption for longer wavelengths and smaller bandgap, indicating a high photocatalytic efficiency against methylene blue and rhodamine B dyes, mainly with solar radiation. The reuse cycles indicated high potential for practical application in wastewater, due to the capacity of consecutive cycles for photodegradation, even with the reduction of photocatalytic efficiency.

14
  • CÁSSIA CARLA DE CARVALHO
  • Analysis of thermal variables, microstructure and mechanical strength of directionally solidified Sn-34wt.%Bi-xZn alloys

  • Líder : BISMARCK LUIZ SILVA
  • MIEMBROS DE LA BANCA :
  • BISMARCK LUIZ SILVA
  • CLAUDIO ALVES DE SIQUEIRA FILHO
  • MAURÍCIO MHIRDAUI PERES
  • Data: 29-dic-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Due to environmental and human health issues related to the use of lead-containing alloys for applications in soldered joints of electronic microcomponents, it is necessary to study new soldering alloys with less toxicity and similar properties to the Sn-Pb system alloys. In this sense, Sn-Bi alloys have emerged as promising alternatives, since they have high mechanical and creep resistance and low cost. However, they exhibit surfaces such as thickening of the microstructure during thermal aging, low wettability on metallic substrates and low ductility. One way to improve such characteristics is to add ternary alloying elements such as zinc (Zn), which can refine the microstructure, increase mechanical properties and inhibit Bi segregation in Sn-Bi alloys. Thus, the present proposal aims to evaluate the effect of adding Zn (0.5% and 9% by weight) on the microstructure, thermal parameters (cooling rate-ṪL and growth rate-VL), segregation and mechanical properties of Sn-34%Bi-xZn alloys solidified directly under transient heat flow conditions. For this, the samples have been identified by Optical Microscopy (OM), Scanning Electron Microscopy (SEM), X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD), in addition to mechanical tests such as Vickers microhardness and tensile. Thermodynamic simulations via Thermo-calc have been carried out to obtain information such as transformation temperatures, solidification paths, types of phases and their fractions. The microstructure for Sn-Bi-Zn alloys is completely dendritic, composed of an Sn-rich matrix (β-Sn) with Bi precipitates (with spherical, ellipsoidal and plate-type morphologies) in its interior and surrounded by a eutectic mixture of the β-Sn and α-Bi phases predominantly in the coarse scale, with the Sn-34wt.%Bi-9wt.%Zn alloy exhibiting Zn primary needles. The additions of Zn in the Sn-Bi binary alloy increased the VL values, while the 9wt.%Zn content increased the ṪL values. In addition, the Zn caused a coarsening of the dendritic arrangement, except for the tertiary dendritic spacing for the Sn-34wt.%Bi-0.5wt.%Zn alloy. The Zn content remained constant throughout the Sn-34wt.Bi-0.5wt.%Zn casting, while for the alloy with 9wt.%Zn addition, it presented a normal type macrosegregation profile. Both additions caused inverse-type macrosegregation profiles for bismuth, differing from the Sn-Bi binary alloy. The additions of Zn promoted an increase in Vickers microhardness and yield strength (σy) and ultimate tensile strength (σu), mainly for more refined microstructures, however, not reflecting on specific elongation values (δ). The Sn-34wt.%Bi-0.5wt.%Zn and Sn-34wt.%Bi-9wt.%Zn alloys exhibit ductile and brittle, and brittle (cleavage) fracture modes, respectively.

Tesis
1
  • AMANDA REGINA DE SOUZA MACEDO
  • EFFECTS OF DIATOMITE AS PARTIAL REPLACEMENT FOR PORTLAND CEMENT IN THE PROPERTIES OF CONVENTIONAL CONCRETES

     
  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • ARIADNE DE SOUZA SILVA
  • CARLOS ALBERTO PASKOCIMAS
  • DIANA CARLA SECUNDO DA LUZ
  • RICARDO PEIXOTO SUASSUNA DUTRA
  • UILAME UMBELINO GOMES
  • Data: 20-ene-2022


  • Resumen Espectáculo
  • ABSTRACT:

    Concrete is a composite, being considered the most used construction material in the
    world. Its main component is Portland cement, responsible for the formation of calcium
    silicate hydrates (C-S-H) formed during hydration and which are mainly responsible for
    the compressive strength of concrete. However, currently, the search for alternative,
    more sustainable materials has increased, aiming to reduce CO2 emissions and
    consequently minimize environmental impacts. This is possible through the use of
    supplementary cementitious materials (SCM), which can be used as clinker substitutes
    or as addition or replacement in the production of concretes. Diatomite is considered a
    natural SCM, with high SiO2 concentration is able to react with calcium hydroxide
    (CH) released during cement hydration to produce additional calcium silicate hydrate
    (C-S-H). Thus, the present work aims to study the effects of replacing Portland cement
    by diatomite in the proportions of 0%, 10%, 15% and 20% by volume, in the production
    of conventional concretes with fck estimated at 30Mpa. Initially the starting materials
    were characterized as to their physical, chemical, mechanical, structural and
    microstructural properties). Then, concretes were produced with a mass ratio of 1:
    1.33:2.33 and a/c ratio=0.44. The concretes were evaluated for their properties in the
    fresh state (slump test) and in the hardened state (compressive strength, porosity, water
    absorption, capillary water absorption and chloride ion diffusion). Cement pastes with
    the same proportions of the concretes were analyzed by XRD (X-ray diffraction) and
    TGA (thermogravimetry) techniques at 7, 28 and 91 days. The results showed that the
    incorporation of diatomite caused a small reduction in the compressive strength of the
    concretes. Despite this, the concretes produced with 15%v. and 20%v. of diatomite
    presented a greater evolution in the values of compressive strength (20.07% and
    16.16%, respectively) from 28 to 91 days, as a consequence of the pozzolanic reaction.
    While the 0%v. and 10%v. concretes presented an evolution of 4.33% and 5.20%,
    respectively. This observation was confirmed in the results of XRD and TGA, where it
    was observed that there is a greater consumption of portlandite and a greater amount of
    combined water in these mixtures. The total porosity, water absorption and capillary
    absorption decreased in the concrete with 10%v. of diatomite, due to the filler effect.
    The incorporation of diatomite reduced the chloride ion diffusion coefficient of the
    concretes due to the refinement of the pore structures.


2
  • ROBERTA ARAUJO CAVALCANTE DE MENEZES

  • Study of the effect of niobium oxide addition on the microstructure and properties of the eurofer steel processed through powder metallurgy

     
  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • UILAME UMBELINO GOMES
  • RUBENS MARIBONDO DO NASCIMENTO
  • JOSE HUMBERTO DE ARAUJO
  • ANGELUS GIUSEPPE PEREIRA DA SILVA
  • MARIA JOSE SANTOS LIMA
  • Data: 28-ene-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • ABSTRACT 

     

    EUROFER is a reduced activity ferritic-martensitic (RAFM) structural steel used for the construction of nuclear fusion reactors. However, when used at temperatures above 500 ºC, this material presents flaws mainly due to creeping and swelling. In this context, studies were developed to solve this problem without compromising the properties already acquired. The solution found was yttrium oxide dispersion strengthened (ODS). Pure EUROFER alloys and innovative EUROFER-ODS composites, obtained from EUROFER chips and niobium pentoxide (Nb2O5), were processed and developed by powder metallurgy (PM) in this work. The manufacturing processes used for obtaining EUROFER powder were also innovative for this steel, as it uses a green route, within mechanisms of self-sustainability and reuse of this material. The pure EUROFER chips were milled in a high energy ball miller (HEM), being studied at different times (5h, 10h, and 15h), and with the addition of Nb2O5(0% w., 3% w., 5% w. and 7 % w.) at the same time intervals. The powders were sintered via Spark Plasma Sintering (SPS) and Conventional Furnace (CF). The effect of varying the milling time and Nb2O5concentration, in addition to the sintering methods, on the physical, mechanical, electrical, and magnetic properties of the sintered materials were analyzed. The results have shown that, increasing the milling time, has reduced the average particle size distribution by 57%, improving the sinterability of the milled powders. XRD analyzes suggested the formation of martensite and austenite phases retained in the sintered samples obtained via SPS. The microhardness of the alloys obtained from pure EUROFER chips sintered by SPS (≈ 560 HV), were superior to those sintered by CF (≈ 65 HV) and the raw material's (410 HV). The addition of Nb2O5 in the EUROFER-ODS alloy maintained the microhardness of the SPS sintered samples in the same proportion of the raw material. However, the CF sintered samples showed lower microhardness values (≈ 78 HV). Furthermore, the densities of samples sintered via SPS were higher than those sintered via CF. Therefore, the results have showed that this new manufacturing method for the raw material is promising for the development of these new materials.

     
3
  • NIVALDO FREIRE DE ANDRADE NETO
  • Synthesis, characterization and study of the photocatalytic properties of the stable (a) and metastable (b and g) phases of silver tungstate
  • Líder : FABIANA VILLELA DA MOTTA
  • MIEMBROS DE LA BANCA :
  • ALBERTHMEIRY TEIXEIRA DE FIGUEIREDO
  • ANA PAULA DE AZEVEDO MARQUES
  • FABIANA VILLELA DA MOTTA
  • JOSE HERIBERTO OLIVEIRA DO NASCIMENTO
  • MAURICIO ROBERTO BOMIO DELMONTE
  • Data: 04-feb-2022


  • Resumen Espectáculo
  • In this work, all phases of silver tungstate (Ag2WO4) were obtained by the co-precipitation method. The stable phase (a-Ag2WO4) was studied by varying the precipitation temperature between 10 and 90 °C, while the metastable phases (b-Ag2WO4 and  g-Ag2WO4) were obtained by increasing the pH and using Polyvinylpyrrolidone (PVP) as surfactant. The diffractograms indicate that the temperature range used for the stable phase provides powders with high crystallinity and absent from secondary crystalline phases. Increasing the precipitation temperature from 10 to 90 °C alters the cross section of the square to hexagonal rods, and also changes the character of the particles, as shown by the tests against anionic and cationic dyes (methyl orange and methylene blue), the particles with square cross section have cationic character, while the hexagonal, anionic. The character of the particles directly influences the photocatalytic activity, where the powders obtained at higher temperatures have greater photocatalytic efficiency over methylene blue, while those obtained at lower temperatures, to orange. The metastable phases were obtained by raising the reaction pH to 10 and using PVP as a surfactant. The diffractograms indicated inhibition of a-Ag2WO4 when at least 0.1 g PVP was used. The g-Ag2WO4 phase, the main objective of this study, was stabilized using 0.3 g of PVP, without formation of any secondary phases, while in higher or lower amounts there is formation of the b-Ag2WO4 phase. SEM images indicate that the increase in reaction pH, in parallel to the non-use of PVP, forms agglomerated particles with brittle appearance. On the other hand, the addition of PVP results in the formation of phases b-Ag2WO4 and g-Ag2WO4 with well-defined rod and octahedron morphology, respectively. The photocatalytic activity indicates that the g-Ag2WO4 phase presents the best result compared to the others, resulting from the great effect of the H2O2 species generated during the process.

4
  • ANA CAROLINA MARÇAL PIRES FERREIRA LUCAS
  • STUDY OF THE EFFECT OF THE ADDITION OF TITANIUM CARBIDE ON THE MICROSTRUCTURAL AND MECHANICAL PROPERTIES OF WC-FE CARBIDE

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • ARIADNE DE SOUZA SILVA
  • MARIA JOSE SANTOS LIMA
  • NAILTON TORRES CAMARA
  • RAFAEL ALEXANDRE RAIMUNDO
  • UILAME UMBELINO GOMES
  • Data: 21-abr-2022


  • Resumen Espectáculo
  • The present work aimed to study the effect of adding 1.5%, 3.0% and 4.5%, by mass, of TiC, to a WC-10%Fe composite powder, prepared by high energy milling. The composite powders were processed in a humid environment, using 99% ethyl alcohol, in a high energy planetary mill, with a container and carbide balls, under agitation of 400 rpm, with a ball/powder ratio of 5:1 during 10 hours. Subsequently, the ground powders were compacted at 200 MPa, in a uniaxial 8 mm stainless steel cylindrical matrix, and sintered in a resistive furnace at 1300 °C, 1400 °C, 1500 °C and 1600 °C for 1 h, under of argon and with a heating rate of 10 °C/min. To evaluate the composition, microstructure and properties, materials characterization techniques were used, such as Vibrating Sample Magnetometer (VSM), Granulometry, Scanning Electron Microscopy (SEM), X-Ray Diffractometry (XRD). In the consolidated samples, microstructural analysis was performed, microhardness measurement and density measurement by the Archimedes method. The results showed that high energy milling is an efficient method for homogenization and particle size reduction and the addition of TiC to WC-Fe contributes significantly, reflecting in samples with improved properties. 

     

     

5
  • MATHEUS DE MEDEIROS TAVARES
  • STUDY OF MICROSTRUCTURE AND PROPERTIES OF THE HARDMETAL WC-(Fe-Nb/NbH-C)
  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • CLODOMIRO ALVES JUNIOR
  • MARIA JOSE SANTOS LIMA
  • MEYSAM MASHHADIKARIMI
  • RAFAEL ALEXANDRE RAIMUNDO
  • RUBENS MARIBONDO DO NASCIMENTO
  • UILAME UMBELINO GOMES
  • Data: 16-may-2022


  • Resumen Espectáculo
  • ABSTRACT

    The search for alternative binders for hardmetals, also called cemented carbides, has
    moved the scientific community. Alternative Fe-based binders have been widely studied
    and used in selected applications. An unprecedented addition to this ligand would be the
    use of niobium, a metal of high global interest, few explored and abundant in Brazilian
    territory. This work aims to investigate the properties of the Fe-Nb/NbH-C system,
    using it as an alternative binder to produce WC-(Fe-Nb/NbH-C) cemented carbides. For
    this purpose, high energy ring and planetary milling techniques were used, using
    controlled atmosphere sintering and spark plasma sintering (SPS) techniques in a
    sintering temperature range from 1150ºC to 1450ºC. To evaluate the composition,
    microstructure and properties, the ThermoCalc software was used, in addition to the
    XRD, MO, SEM, EDS, density, Vickers hardness and fracture toughness techniques.
    The preliminary results pointed to planetary mill as the most efficient method for
    homogenization and particle size reduction, resulting in samples with better mechanical
    properties. Controlled atmosphere sintering for this application proved to be unfeasible,
    on the other hand, spark plasma sintering proved to be an efficient method for the
    production of densified samples. The sintering temperature of 1250ºC provided the best
    microstructure and properties results for all SPS processing conditions. Replacing Nb
    for NbH, it was possible to obtain samples with more homogeneous and densified
    microstructure by reducing the size of the niobium particles, absence of eta phase, and a
    remarkable microstructural gradient formation, as well as hardness values of up to
    1620Hv, meaning an increase of approximately 15% in relation to pure niobium
    compositions.

6
  • ANDERSON DE AZEVEDO GOMES SANTIAGO
  • Study of the photoluminescent properties of Mg1-xSrxMoO4 and Zn1-yCayWO4 heterostructures obtained by the ultrasonic spray pyrolysis method

  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • SAYONARA ANDRADE ELIZIÁRIO
  • FABIANA VILLELA DA MOTTA
  • JOSE HERIBERTO OLIVEIRA DO NASCIMENTO
  • MAURICIO ROBERTO BOMIO DELMONTE
  • NEFTALÍ LENIN VILLARREAL CARREÑO
  • Data: 20-may-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Molybdates and tungstates are inorganic materials with immense potential in application as white light-emitting diodes (wLEDs), which are an alternative to traditional lighting sources. In this study, the synthesis and characterization of the composite MgMoO4:SrMoO4 (with molar ratios of 1:0; 0.75:0.25; 0.5:0.5; 0.25:0.75 and 0:1) and ZnWO4:CaWO4 (with molar ratios of 1:0; 0.8:0.2; 0.6:0.4; 0.4:0.6; 0.2:0.8 and 0:1), prepared by the ultrasonic spray pyrolysis method and their photoluminescent properties were investigated. Using X-ray diffraction, for the composite MgMoO4:SrMoO4, the monoclinic β-MgMoO4 phase was observed at a molar ratio of 1:0 and the tetragonal scheelite phase of SrMoO4 at a molar ratio of 0:1. However, for the composite ZnWO4:CaWO4, the monoclinic phase ZnWO4 was obtained at a molar ratio of 1:0 and the scheelite-type tetragonal phase of CaWO4 when the molar ratio was 0:1. The formation of a particulate material composed of both phases was observed for the intermediate molar ratios. Scanning electron microscopy images showed that MgMoO4:SrMoO4 and ZnWO4:CaWO4 particles show a spherical morphology formed by primary nanoparticles. Raman scattering spectroscopy allowed the precise identification of Raman modes for different compositions and their assignment to SrMoO4 or β-MgMoO4 modes. Bandgap energies were found in a range between 4.2 eV and 4.4 eV for the MgMoO4:SrMoO4 composites and between 3.8 eV and 4.0 eV for ZnWO4:CaWO4, influenced by the order/disorder structural degree of the materials. The photoluminescence emission spectra of the particles showed neutral- and cool-white emission with high quality white light (CRI>80%). The MgMoO4:SrMoO4 samples synthesized with a molar ratio of 1:0, 0.25:0.75 and 0.5:0.5 formed materials with potential for application in LED lamps (6,500 K) and pure white light sources (5,500 K) while the samples of ZnWO4:CaWO4 can be considered as promising white light sources, mainly for the sample with molar ratio 0.2:0.8, for application in LED lamps (6,500 K).

7
  • RÍSIA AMARAL ARAÚJO
  • EVALUATION OF CEMENT MIXTURES FOR 3D PRINTING WITH OPTIMIZED THERMAL PERFORMANCE

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ROGERIO VALENTIM GELAMO
  • ANA CECILIA VIEIRA DA NOBREGA
  • ANTONIO EDUARDO MARTINELLI
  • KLEBER CAVALCANTI CABRAL
  • MARCOS ALYSSANDRO SOARES DOS ANJOS
  • Data: 27-may-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • 3D printing of concrete (3DCP) has gained increasing attention over the past few years. However, mixtures capable of optimizing the thermal comfort of printed structures still need to be studied. Thus, the objective of the present work is to evaluate the influence of the replacement of natural sand by light expanded clay aggregate (LECA) on the mechanical, physical and thermal properties of Portland cement-based mixtures for 3DCP. The mixtures were formulated using a 2² factorial design, having the replacement content (%sub) of sand by LECA and the aggregate to binder ratio (a/b) as independent factors. The replacement of natural sand by LECA was in volume% to account for the difference in density between them and to maintain the same volume of particles in the mixture. Squeeze-flow and flow-table tests were used to evaluate the rheological behavior of mixtures for 3DCP containing aggregates up to 1.2 mm in maximum diameter. The results showed that the replacement of sand by LECA increased the yield strength from 8 to 13 KPa and the viscosity of the mixture increased from 5x105 to 3x106 Pa.s, which resulted in improved constructability, while still showing workability equivalent to the reference mixture. The results showed that the total replacement of sand by LECA reduced the thermal conductivity from 1.19 to 0.68 W/m.K, and was accompanied by small variations in physical properties, such as water absorption and porosity. In addition, the replacement provided a decrease of ~ 16% in the modulus of elasticity without compromising important structural properties, such as mechanical strength, which was in the range of 60 ± 3 MPa. The thermal behavior of the mixtures was modeled and an equation dependent only on the substitution content factor (%sub) was found.

8
  • ELISÂNGELA BARROS DANTAS
  • MICROSTRUCTURAL EVOLUTION OF SINTERIZED NICKEL AND NI-SiC AFTER UNIAXIAL COMPACTION OR THERMOPLATIC PROCESSING

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO AUGUSTO COUTO
  • ANTONIO EDUARDO MARTINELLI
  • ARMANDO MONTE MENDES
  • FRANK JORG CLEMENS
  • RUBENS MARIBONDO DO NASCIMENTO
  • Data: 17-jun-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Mixtures of Ni and SiC powders can be sintered resulting in materials with superior properties, especially at high service temperatures, such as corrosion resistance, mechanical and wear resistance, allied to low production costs. This set of properties is important, for example, for the automotive and aerospace industries. This work aimed to study mixtures of sintered Ni and SiC powders shaped by uniaxial pressure or thermoplastic processing. The nickel powder and the mixture Ni + 3 wt.% SiC were drum granulated with 2.5 wt.% of paraffin, uniaxially pressed at 600 MPa and sintered in a conventional oven at 1200 °C for 1 h (heating rate of 10 ºC/min). The samples obtained by thermoplastic processing were produced from Ni and a mixture of Ni + 1 wt.% SiC with 50% polymeric binders, homogenized in a co-rotating conical mixer with double screw and molded in a capillary rheometer. After thermal extraction of the binders, they were sintered at a heating rate of 5 °C/min up to 1200 °C. The sintering time was for 4 h. XRD, FTIR, microstructural characterization by MO and SEM/EDS analyses were carried out, as well as measurements of green and sintered density and Vickers microhardness tests. The nickel samples, produced by thermoplastic processing, showed larger pores concentrated in certain areas, greater diametral shrinkage and lower Vickers microhardness, with a higher standard deviation than the compacted samples. However, there was no interference of the production techniques in the densities of the sintered nickel samples. The addition of 3 wt% of SiC influenced the densification and also increased the microhardness of the sintered samples after compaction. Microscopic and XRD analyzes suggested that uniaxial compaction under 600 MPa and thermoplastic processing produced Ni-Si-type materials with carbon precipitates.

9
  • MARIANA CHIANCA LÚCIO DA SILVA
  • DIATOMITE MEMBRANE WITH NANO-SIZED CALCIUM OXIDE OBTAINED AND CHARACTERIZED VIA TAPE CASTING FOR APPLICATION IN DESALINIZATION SYSTEM

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • CARLOS ALBERTO PASKOCIMAS
  • JOSE HERIBERTO OLIVEIRA DO NASCIMENTO
  • MARIA JOSE SANTOS LIMA
  • MEYSAM MASHHADIKARIMI
  • TERCIO GRACIANO MACHADO
  • UILAME UMBELINO GOMES
  • Data: 13-jul-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Currently, in a scenario of growing unsustainability regarding water resources, two main aspects are becoming alarming: the increase in the frequency of climate disasters (such as droughts and floods) and also the dangerous rise of watercourses contamination, which can lead to higher freshwater costs and its own scarcity. In this context, the process of desalination (distillation or reverse osmosis) has been one of the alternative solutions to obtain drinkable water and it has been widely used in Middle East countries such as Turkey, Kuwait, Saudi Arabia, among others. In this work, multilayer membranes with laminates of 4, 5 and 6 layers of diatomite tape reinforced with nanometric calcium oxide were manufactured via tape casting and consolidated via thermal route, thermopressing, calcination and sintering. The starting powders were characterized via particle size and textural analysis (diatomite), X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM-FEG) and thermogravimetric analysis. After the consolidation of the membrane, the transformation of amorphous silica into cristobalite via XRD was verified, the reduction of pore sizes, as well as the consolidation of the membrane, presenting monolithic behavior causing the reduction of the cross section via SEM, and
    bending tests were performed. made to investigate the influence of pore size on the
    mechanical properties of the nanocomposites produced. The results showed that the
    presence of calcium oxide promotes, the high sintering temperature and a greater number of laminates promoted the reduction of the pore size. Also, the gradual addition of layers increases bending resistance.

     

10
  • PEDRO PAULO LINHARES FERREIRA
  • Effect of Mn doping on MgAl2O4 spinel, heat treatment and addition of Aloe Vera on the synthesis of Carbon Nanotubes.

  • Líder : DULCE MARIA DE ARAUJO MELO
  • MIEMBROS DE LA BANCA :
  • DULCE MARIA DE ARAUJO MELO
  • RENATA MARTINS BRAGA
  • RODOLFO LUIZ BEZERRA DE ARAÚJO MEDEIROS
  • DENER DA SILVA ALBUQUERQUE
  • GILVAN PEREIRA DE FIGUEREDO
  • Data: 10-oct-2022


  • Resumen Espectáculo
  • Discovered in the mid-1990s, carbon nanotubes (CNTs) have special properties that expand their range of applications. CNTs can be produced from the decomposition reaction of methane in the presence of catalysts. However, the quality and quantity of CNTs produced strongly depends on the structure and properties of the catalysts. Thus, the objective of this thesis was to evaluate the relationship of the synthesis parameters of Mn-doped Ni catalysts in MgAl2O4, obtained using the green extract of Aloe Vera for the production of carbon nanotubes. For that, the supports of the catalysts were synthesized via microwave combustion, achieving two routes. The first was using only water; and the second using Aloe Vera as a chelating agent. Both routes had the objective of doping Mn ions in the A and B sites of MgAl2O4 for the evaluation of its characteristics. From the synthesized support, part was subjected to calcination at 900 °C for 3 h and part remained without heat treatment. Then, the materials were impregnated with 50% nickel and subjected to heat treatment (550 °C/3h). The formed catalyst was taken to the catalytic unit for activation and then to the synthesis of carbon nanotubes. The supports were characterized by X-ray diffraction (XRD). The catalysts were also subjected to XRD and thermal analysis (TG). The nanotubes were characterized by Raman, MEV-FEG and TG. XRD results indicated that the supports were replaced with the ion in different proportions, as well as the same analysis showed successful nickel impregnation. The CNTs along with the catalysts were analyzed by Raman spectroscopy, thermal analysis (TG) and scanning electron microscopy (SEM). The Raman results showed the formation of carbon nanotubes in all catalysts, with a GI/ID ratio > 1, indicating a crystallinity of the material formed. The relationship between the results of thermal analysis (TG) and Raman spectroscopy indicates that the nickel catalyst impregnated in MgAl2O4 with Mn2+ substituted in the A site, synthesized using Aloe Vera and calcined at 900 °C (Ni/Mn-SAAV900) produced less defective CNT's (GI/ID = 1.42), but with lower CNT production (4%p). In contrast, the nickel catalyst impregnated in MgAl2O4 with Mn2+ substituted in the B site, synthesized using Aloe Vera and calcined at 900 °C (Ni/Mn-SBAV900) showed a GI/ID ratio = 0.77, revealing more defective NTC's , but with a little more than twice as many NTC's formed. The micrographs corroborated the other analyses, indicating the formation of carbon nanotubes. The methodology adopted using green synthesis proved to be a way to produce carbon nanotubes.

11
  • ALLANA AZEVEDO DO NASCIMENTO
  • Fatigue behavior of self-healing glass fiber/epoxy composites with addition of poly (ethylene-co-methacrylic acid) (EMAA)

  • Líder : ANA PAULA CYSNE BARBOSA
  • MIEMBROS DE LA BANCA :
  • ANA PAULA CYSNE BARBOSA
  • JOSE DANIEL DINIZ MELO
  • PEDRO DOLABELLA PORTELLA
  • RAIMUNDO CARLOS SILVERIO FREIRE JUNIOR
  • SÉRGIO HENRIQUE PEZZIN
  • Data: 28-oct-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • The interest in repair technologies for polymer composites has increased significantly over the last decades due to the growing use of these materials in structural applications. In this study, poly (ethylene-co-methacrylic acid) (EMAA) was used as self-healing agent to glass fiber/epoxy composite. Preliminary results showed that, for EMAA as healing agent, particle concentration has greater effect on properties of neat epoxy than particle size. Glass fiber reinforced composites with EMAA contents of 2 wt.% and 5 wt.% were manufactured using Resin Transfer Molding (RTM) and the effects of the healing agent on the composites properties were investigated using quasi-static tensile tests, fatigue tests and Dynamic Mechanical Analysis (DMA). Results show slight variation of properties, which was more pronounced as the content of EMAA increased. The healing efficiency was also investigated through fatigue tests and the addition of higher content of EMAA increased the number of cycles to failure after the healing activation cycle. In addition, EMAA was shown as more efficient healing agent when activated at early stages of damage.

12
  • ÉRICK STÉFANO SILVEIRA GUERRA
  • Microscale evaluation of epoxy matrix composites containing thermoplastic healing agent.

  • Líder : JOSE DANIEL DINIZ MELO
  • MIEMBROS DE LA BANCA :
  • ANA PAULA CYSNE BARBOSA
  • GERHARD KALINKA
  • JOSE DANIEL DINIZ MELO
  • LAURA HECKER DE CARVALHO
  • PEDRO DOLABELLA PORTELLA
  • Data: 01-dic-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Epoxy matrix composites are often subjected to adverse service conditions leading to the formation of microcracks. Microcracks are of great concern because they can act as nucleation sites for more prejudicial types of damage, such as delamination. Among the solutions to mitigate the deleterious effect of matrix microcracking is the use of thermoplastic healing agents. Poly(ethylene-co-methacrylic acid) (EMAA) has been particularly used as a thermoplastic healing agent because of its suitable chemical and physical properties. When the material is heated, the thermoplastic phase dispersed in the epoxy matrix is allowed to flow into microcracks and restore mechanical properties. The addition of EMAA particles, however, may cause alterations in chemical and thermomechanical properties of epoxy composites. These changes may also affect other fundamental features of epoxy composites, such as their fiber-matrix interfacial properties. The objectives of this work are, therefore, (1) study the effects of EMAA addition on epoxy formation, (2) investigate the effect of EMAA addition on fiber-matrix interfacial properties, and (3) study the potential for self-healing through micromechanical testing. The effect of a 10 wt.% EMAA modified epoxy was investigated through infrared spectroscopy and differential scanning calorimetry (DSC) experiments. The results suggested that EMAA addition may cause changes during the epoxy network formation. Following that, single fiber pull-out tests were used to characterize the fiber interfacial shear strength (IFSS) of pure and modified epoxy systems, as well as between fiber and pure EMAA. IFSS results of pure and modified epoxy were quite similar, revealing that epoxy modification did not alter significantly fiber-matrix interfacial properties. On the other hand, IFSS measurements of fiber-EMAA presented considerably lower values than fiber-epoxy, suggesting that healing is most likely held by fiber-epoxy or EMAA-epoxy interactions. A novel method to assess the healing efficiency (η) using optically monitored single fiber pull-out testing was proposed. According to the results, healing efficiency of EMAA modified epoxy was lower than that of pure epoxy systems. The attenuated matrix shrinkage effect due to the addition of rubbery EMAA particles, along with the lower IFSS results of EMAA-fiber are proposed to explain the observed low η values. Complementary tests investigated thermomechanical properties and the cure of the EMAA modified epoxy, along with the effect of healing on the chemical structure and its IFSS properties. 

13
  • JAKELINE RAIANE DORA DOS SANTOS
  • Green synthesis and doping effect of Maganese on properties of  electrods based on mixed valence oxides to oxygen evolution reaction (OER).

     


  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • UILAME UMBELINO GOMES
  • MEYSAM MASHHADIKARIMI
  • DANIEL ARAÚJO DE MACEDO
  • MARIA JOSE SANTOS LIMA
  • RAFAEL ALEXANDRE RAIMUNDO
  • Data: 28-dic-2022
    Ata de defesa assinada:


  • Resumen Espectáculo
  • In recent decades, with the exponential growth of the population, the intensification of fossil fuel use has generated major impacts on the environment. In this scenario, the worldwide interest in the development and use of clean, sustainable, and renewable energy resources has become necessary. An increasing solution is the use of Hydrogen (H2) that has been considered as the most promising renewable energy source to supply the growing global demand. Thus, among the methods for producing Hydrogen that has received a lot of attention is water splitting, which occurs through two half-reactions: the Hydrogen evolution reaction (HER) and the Oxygen evolution reaction (OER). However, the OER is a slow reaction, due to the many steps involved in the process. Therefore, the development of effective electrocatalysts to accelerate the reaction and reduce the overpotential is of extreme value. Within this perspective, mixed valence oxides present themselves as efficient electrocatalysts for OER due to their multiple valence states, their abundance in nature, their low cost, and the possibility of obtaining them by several synthesis methods. Among the methods for obtaining mixed valence oxides, the green synthesis using organic precursors has stood out because it allows the preparation of single phase nanoparticles, with good homogeneity and in a sustainable way, minimizing the waste generated to the environment. In this context, this work presents the green synthesis of mixed valence oxide of the MnXCo3-XO4 (0≤X ≤1) type, using Agar-Agar as organic precursor. In view of this, the powders were calcined at 1173 K and characterized by various analyses such as X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Transmission Electron Microscopy (TEM), Raman spectroscopy, ultraviolet-visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), Vibrating Sample Magnetometer (VSM) and were also investigated as electrocatalysts for the oxygen evolution reaction (OER) in alkaline medium. Through XRD analysis, it was observed that pure cubic phase was obtained for all samples. The presence of Co3+, Co2+, Mn2+, Mn3+ and Mn4+ was confirmed by X-ray photoelectron spectroscopy (XPS). With respect to OER, the best result was observed for the MnCo2O4 sample (X=1,0), which obtained an overpotential of  299 mV vs. RHE, thus, the good electrocatalytic performance of this material compared to electrodes in the literature is explained by the presence of Manganese doping in the MnXCo3-XO4, system especially Mn+3, which due to its electronic configuration, has a distortion in the structure, which favors charge and mass transport processes. Moreover, the same sample showed a lower Tafel value of 52 mV dec-1 and excellent electrochemical stability for 15 h. Therefore, the green synthesis method presented in this work, showed great potential for obtaining electrocatalysts used in the oxygen evolution reaction for water electrolysis

     

     

     

2021
Disertaciones
1
  • CAROLINA LIMA DE ALMEIDA
  • Biodegradable polymeric fiber mats produced via Solution Blow Spinning as a biomimetic model of cocoon of Rothschildia sp.

  • Líder : JOSE DANIEL DINIZ MELO
  • MIEMBROS DE LA BANCA :
  • JOSE DANIEL DINIZ MELO
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • ELITON SOUTO DE MEDEIROS
  • Data: 29-ene-2021


  • Resumen Espectáculo
  • There has been great interest in the study of biomimetics for several fields of science, such as medical applications. In this work, biodegradable polymeric fiber mats were produced with properties compatible with those found in cocoons of the moth Rothschildia sp. Initially, the cocoon was studied using techniques of thermogravimetry (TG), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and mechanical tensile tests. The results indicated a structure composed of fibroin fibers in a sericin matrix, in addition to hydroxyapatite. The mats were produced from polycaprolactone (PCL) and poly (lactic acid) (PLA) fibers, which have a chemical structure comparable to fibroin, with the addition of hydroxyapatite (HA). Solution Blow Spinning (SBS) technique was used to produce the polymeric fibers with a multi-nozzle matrix and a rotating collector. After the spinning process, the mats were hot pressed, with processing temperature and number of layers varying in five groups, to form a PCL matrix and produce a structure equivalent to that of the cocoon. The mats were also characterized by DSC, FTIR, SEM and mechanical tensile tests. The chemical composition of the PCL and PLA mats were equivalent to that found in the cocoon, as well as fibrous morphology resulting from the SBS processing. SEM images confirmed the formation of a PCL matrix phase that binds the PLA fibers after the hot press processing. Tensile strength of the mats varied according to the number of layers and processing temperature used. The best results were obtained for mats with six layers of PCL and PLA with the addition of HA, processed in a hot press at 90 ° C, for 30 min. Although the strength of the mats produced were lower than that of the cocoon, the results indicated that this material has a potential to be used in biological media.

2
  • FABRICIO PEREIRA FEITOZA DA SILVA
  • EVALUATION OF PERMEABILITY IN THE INTERFACE STEEL CASING - CEMENT SHEATH IN WELLS SUBJECTED TO VAPOR INJECTION

  • Líder : MARCUS ANTONIO DE FREITAS MELO
  • MIEMBROS DE LA BANCA :
  • MARCUS ANTONIO DE FREITAS MELO
  • JÚLIO CÉZAR DE OLIVEIRA FREITAS
  • FABÍOLA DIAS DA SILVA CURBELO
  • Data: 19-feb-2021


  • Resumen Espectáculo
  • For better efficiency and increase in the production factor of mature fields or heavy oil, recovery methods are used, being the thermal method with the highest success rate. Exposure of the metallic casing and the cement sheath to thermal cycling conditions can cause cracks to appear, allowing the passage of fluids through the cement sheath due to the difference in expansion coefficient between the two materials. This leads to serious socioeconomic and environmental risks, compromising the productive life of the well. Latex of the SBR type has been widely used in order to improve the mechanical properties of cementing materials for oil wells. However, few studies have presented new methodologies for evaluating the performance of these materials by physically simulating the condition of a well (cement / casing). Within this context, this work aimed to evaluate the permeability between a steel casing and a cement sheath with Latex SBR, simulating thermal cycling conditions in which oil wells are subjected during the recovery of heavy oils by thermal methods. From an experimental design for 2 independent variables, defined as SBR Latex concentration, varying between 0 L / m³ and 267.36 L / m³ (0 gpc and 2 gpc), and cement slurry density between 1.75 g / cm³ (14.6 lb / Gal) and 1.89 g / cm³ (15.8 lb / Gal), the permeability behavior was studied. The results showed that the variation in density was more significant in samples that were subjected to static well temperature conditions (68 ° C). It was also observed that the increase in the concentration of Latex SBR contributed to a better adherence of the cement matrix to the casing, favoring positively the results of the samples that were exposed to steam injection temperature (300 ° C). The experimental design helped to reduce the number of experiments or repetitions and improves the interpretation of the results obtained, consequently, to determine the best conditions for the formulation of slurrys applicable in cementing operations of oil wells subject to steam injection.

3
  • IGOR ARAUJO DE CARVALHO ROCHA
  • Effects of Alkalinization Treatment on Curauá Fibers for Polymer Matrix Composites.

  • Líder : ANA PAULA CYSNE BARBOSA
  • MIEMBROS DE LA BANCA :
  • ANA PAULA CYSNE BARBOSA
  • CARLOS ALBERTO PASKOCIMAS
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • MARIA ODILA HILÁRIO CIOFFI
  • Data: 26-feb-2021


  • Resumen Espectáculo
  • With increasing environmental awareness and stronger government regulations on environmental issues throughout the world, there has been an ever-increasing interest in natural fiber composite materials. Studies on structure and properties of natural fibers show that materials using this natural complement combine good mechanical properties with a low density. However, one of the reasons why the use of cellulosic natural fibers has been limited is their poor compatibility with polymeric matrices, decreasing the mechanical properties in the final composite. Therefore, these fibers normally undergo chemical treatments (such as alkaline treatment) in order to improve their properties and adhesion to the polymer matrix. The treatment used in this work will be an alkaline treatment with sodium hydroxide (NaOH), the concentrations used were 5% and 10%, this treatment allows results of superficial cleaning of the fiber as well as the increase of its roughness. In this study, Curauá fibers will be treated by alkaline solution, and characterized to evaluate the effect of the treatment in the fibers, as well as the use of these treated fibers as reinforcement in the epoxy polymer, to form a composite with polymeric matrix, with the intent to increase the interfacial bond between the matrix and the natural fiber. The fibers will be investigated by scanning electronic microscopy (SEM), Fourrier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA). The polymer was processed and characterized also by Fourrier transform spectroscopy (FTIR). A final dynamic mechanic analysis (DMA) will be used to characterize both the polymer and the curauá/ epoxy composite.

4
  • ARTUR DE MORAIS
  • SYNTHESIS OF SCHEELITE-TYPE MATERIALS BY MICROWAVE-ASSISTED HYDROTHERMAL AND ITS LUMINESCENCE AND PHOTOCATALYTIC PROPERTIES

     
  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • FABIANA VILLELA DA MOTTA
  • MAURICIO ROBERTO BOMIO DELMONTE
  • NEFTALÍ LENIN VILLARREAL CARREÑO
  • RICARDO LUÍS TRANQUILIN
  • Data: 31-mar-2021


  • Resumen Espectáculo
  • Scheelites are widely researched materials due to their excellent properties and applications in light emission technologies, in addition to good chemical and thermal stability. Combining functional materials with efficient and clean synthesis techniques is becoming increasingly necessary in our world. In this work, Scheelites CaMoO4, CaWO4 and CaWO4 doped with 1% europium were obtained using the microwave-assisted hydrothermal method for 1, 2, 4 and 8 minutes and their photoluminescent and photocatalytic properties in the degradation of methyl orange and rhodamine B dyes were evaluated. Individual material formulations were developed for the composite emission to become white. The compounds were characterized by x-ray diffraction (XRD), photoluminescence (PL), UV-Vis spectroscopy and scanning electron microscopy (FE-SEM). The XRD results show that the samples are pure, without secondary phase precipitation, showing that the europium is introduced in the structure. The results of UV-Vis show that the energy band gaps are within the range commonly reported in the literature. The micrographs show well-defined morphologies and help in the discussion about the growth process of the particles. Photoluminescence shows emissions in the blue, green and pink regions for CaWO4, CaMoO4 and CaWO4:Eu, respectively. Europium emissions are very visible and dominate the red region in the PL spectrum. The formulations developed showed emissions very close to the white region of the spectrum. The photocatalytic activity showed that the formulations were not efficient in the degradation of methyl orange, removing only 20% of the dye after 120 minutes under UV light irradiation. However, they proved to be very efficient in removing rhodamine, reaching values close to 75% of dye removal.

     
5
  • REGINA BERTÍLIA DANTAS DE MEDEIROS
  • Tantalum as a novel binder of polycrystalline diamond

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • UILAME UMBELINO GOMES
  • RUBENS MARIBONDO DO NASCIMENTO
  • MEYSAM MASHHADIKARIMI
  • ALESSANDRA AGNA ARAÚJO DOS SANTOS
  • MARCELLO FILGUEIRA
  • Data: 28-jun-2021


  • Resumen Espectáculo
  • Polycrystalline diamond (PCD) is widely applied in the cutting and drilling industry due to its excellent mechanical properties. Currently, several researchers have been studying the use of different binders in its manufacturing, seeking to improve their properties and reduce the use of traditional metals that are harmful to human health and the environment. This work aimed to study the viability of tantalum as an alternative binding agent for PCD. The products developed here were processed using powder metallurgy and High Pressure-High Temperature (HPHT) sintering. The effect of different tantalum concentrations (2.5, 5.0, 7.5, and 10.0 wt. %) was investigated using X-ray diffraction (XRD), Confocal Microscopy, Density measurement, Particle Size Analysis, and Scanning electron microscopy (SEM). Mechanical properties and failure behavior were employed to evaluate the products. The PCD-Ta system was also tribologically tested against ferrous and ceramic materials, in order to simulate industrial machining conditions. The results suggest that increasing Ta quantity on PCD mixtures promoted reduction of milling contaminations and enhanced the mechanical properties of the as-sintered bodies by modifying the fracture mechanism predominance. No occurrence of chemical reactions between the two compounds was observed on the milling, but the formation of TaC resulting from a reaction between the free carbon and the metallic Ta was identified on all as-sintered compositions. The PCD-Ta ratio directly influences the tribological behavior of the present system with ceramic and ferrous materials, and severest wear was provoked by samples with the lowest binder content. Furthermore, abrasive and adhesive were the predominant wear mechanisms detected in all studied compositions. Finally, the overall microstructural, mechanical, and tribological outcomes demonstrated that all studied composites presented satisfactory performance, which may indicate that tantalum can be a viable alternative to act as a PCD BINDER

6
  • FERNANDA KARINE FONSECA DE OLIVEIRA
  • Synthesis and characterization of cerium molybdate by the microwave-assisted hydrothermal method: application as ozone gas sensor

     

  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • FABIANA VILLELA DA MOTTA
  • LUIS FERNANDO DA SILVA
  • MAURICIO ROBERTO BOMIO DELMONTE
  • Data: 27-ago-2021


  • Resumen Espectáculo
  • Materials based on metallic molybdates have attracted many studies, due to their properties leading to numerous technological applications in several areas, such as: photoluminescence, photocatalysis and gas detection sensors. In this work, we performed the synthesis of cerium molybdate (Ce2(MoO4)3) nanocrystals via the co-precipitation method followed by the microwave-assisted hydrothermal (MAH) at 150 °C during different synthesis times s (15, 30, and 60 min). This study showed that the effect of the MAH treatment time influenced the microstructural, optical and ozone gas-sensing properties. X-ray diffraction (XRD) and Raman spectroscopy measurements revealed that the samples presented a single-crystalline phase with scheelite-type tetragonal structure. Field emission gun scanning electron microscopy (FEG-SEM) images showed that MAH conditions favored changes in the morphology of the Ce2(MoO4)3 nanocrystals. In addition, transmission electron microscopy (MET) revealed that the interplanar distances corresponding to the main peak found in the XRD diffractogram, and the SAED confirmed that the samples are polycrystalline with concentric rings. The photoluminescence (PL) measurements indicated a significant increase in the PL emission with the time MAH, suggesting an increase in the intrinsic defects formed during the synthesis. The gas-sensing performance of cerium molybdate nanocrystals in relation to ozone sub-ppm levels was also investigated. The experiments revealed complete recovery and good repeatability as well as a good sensor response, which was improved in the sample synthesized in the longer time of the HMO. 

7
  • CARLOS HENRIQUE RODRIGUES MILFONT
  • "EFFECT OF COCONUT OIL AND NANOCLAY ON PROCESSING AND PROPERTIES OF THERMOPLASTIC STARCH"

  • Líder : EDSON NORIYUKI ITO
  • MIEMBROS DE LA BANCA :
  • EDSON NORIYUKI ITO
  • JUCIKLÉCIA DA SILVA REINALDO
  • KATIA NICOLAU MATSUI
  • MEN DE SÁ MOREIRA DE SOUZA FILHO
  • Data: 06-sep-2021


  • Resumen Espectáculo
  • The aim of this work was to evaluate the effect of incorporating coconut oil (OC) and organophilic montmorillonite clay (OMMT) on the physical, chemical and mechanical properties of thermoplastic starch (TPS) obtained from cassava. The materials were mixed in a twin screw extruder and then processed in a single screw extruder with a flat ribbon matrix. The mixtures of TPS, OC, and OMMT produced easily processable materials with a good visual appearance. The results of the melt flow index (MFI) measurements showed that OC and OMMT promoted a reduction in the fluidity of the materials. Fourier transform infrared (FTIR) spectroscopy results showed the characteristic bands of the TPS, OC and OMMT structures. Colorimetric analysis showed a change in the color of materials with varying concentrations of OC and OMMT. The results of X-ray diffraction indicated the occurrence of clay exfoliation and the formation of polymeric nanocomposites of TPS. The mechanical behavior under tensile and Shore D hardness showed a sign of improvement in these properties with the addition of OC and OMMT. The water absorption test showed that the simultaneous addition of OC and OMMT in TPS reduced the hydrophilic character of polymeric nanocomposites. The results of the biodegradation test showed that the OC reduced the biodegradability process, while the OMMT accelerated the process. The polymeric nanocomposites obtained with TPS/OC indicated the potential for applications of new ecologically correct products developed on a large scale.

8
  • ÂNGELO GABRIEL MELO DOS REIS DE ALBUQUERQUE
  • SYNTHESIS OF GRAPHENE FOR FLEXIBLE FILMS PRODUCTIN OF POLY (METHYL METHACRYLATE) WITH REDUCED GRAPHENE OXIDE (PMMA/RGO)

  • Líder : MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • MOACY PEREIRA DA SILVA
  • EVANS PAIVA DA COSTA FERREIRA
  • LUIZ GONZAGA DE QUEIROZ SILVEIRA JUNIOR
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • Data: 08-sep-2021


  • Resumen Espectáculo
  • Graphene, discovered in the 90s, became one of the main objects of study in present time and thousands of researches on this material are developed in institutions around the world. This work was developed with the purpose of discovering high efficiency and clean synthesis routes for graphene oxide (GO) and reduced graphene oxide (rGO) production. Studies were based in methods already known by scientific community, such as Hummer’s Method and thermal reduction of GO. Preliminary results from DRX, FTIR and FRX analysis show that both GO and rGO were obtained successfully. In the next stages of the work the synthesised materials will be incorporated in poly (methyl methacrylate) (PMMA) for flexible films production that can be applied in electronic sensors.

9
  • BRUNO SILVA SOBRAL
  • Directional Solidification of  Sn-3.5wt.%Ag-xZn alloys

  • Líder : BISMARCK LUIZ SILVA
  • MIEMBROS DE LA BANCA :
  • BISMARCK LUIZ SILVA
  • CLARISSA BARROS DA CRUZ
  • MAURÍCIO MHIRDAUI PERES
  • Data: 27-sep-2021


  • Resumen Espectáculo
  • Alloys of the Sn-Ag system are of interest to the electronic microcomponent industry, as they have superior mechanical properties to the alloys of the Sn-Pb system, as well as good wetting  in copper substrates and great fluency resistance and thermal fatigue. The microstructure of the eutectic Sn-3,5% Ag alloy solidified non-equilibrium consists of tin-rich dendrites (β-Sn) surrounded by an eutectic mixture Sn+Ag3Sn, where the morphology of the Ag3Sn intermetallic is controlled by the cooling rate. In this sense, this work aims to study the influence of Zn additions (0.5 and 1.0 wt%) in the thermal parameters such as cooling and growth rates (ṪL/VL-liquidus isotherm and ṪE/VE-eutectic front), microstructure and microhardness of the eutectic directionally solidified Sn-3.5wt.% Ag alloy  under unsteady state conditions. The samples were characterized by Optical Microscopy (MO), Scanning Electron Microscopy (SEM), X-Ray Fluorescence (FRX), X-Ray Diffraction (DRX) and Vickers Microhardness. The microstructure of the Sn-3.5wt.% Ag alloy is completely dendritic, composed of a Sn-rich matrix (β-Sn) surrounded by a eutectic mixture of the Sn and Ag3Sn phases. On the other hand, the Zn-modified alloy with 1wt.% Zn exhibited a fully cellular eutectic microstructure, where its interior is formed by a mixture of the β-Sn, ε-Ag3Sn and ζ-AgZn phases. The Sn-3.5wt.% Ag-1wt.% Zn alloy showed a cellular/dendritic transition to VL= 1.15 mm/s and ṪL= 8.55 °C/s. The decrease in the Ṫ and V values caused a coarsening of the dendritic and cellular eutectic arrangements. Additions of 0.5wt% and 1wt.% Zn promoted increases of 42.6% and 47.5% in hardness of the Sn-3.5wt.% Ag alloy, respectively.

10
  • PAULO HENRIQUE CHIBÉRIO
  • Incorporation of Boronnitride and niobium carbide in a alumina matrix 

  • Líder : WILSON ACCHAR
  • MIEMBROS DE LA BANCA :
  • Antonio Carlos Silva da Costa
  • CLAWSIO ROGERIO CRUZ DE SOUSA
  • HUGO PLÍNIO DE ANDRADE ALVES
  • WILSON ACCHAR
  • Data: 05-nov-2021


  • Resumen Espectáculo
  • In research and manufacture of new advanced ceramics and occurs seems to favor the use of high post-purity and ultrafine combined with less time and lower sintering temperature. This faster process with lower temperatures can be used as a new way to produce ceramic cutting tools, usually produced with aluminum oxide (Al2O3) as the only material, or with the addition of metal carbides in its matrix to improve its properties, such as: Niobium carbide (NbC), Silicon carbide (SiC) and tungsten carbide (WC). Another material that has been used in the machining industry is Boron nitride (BN), as it has a high melting point (2800K) which is a very important parameter for the material used at the tip of the cutting tool. Aiming at new forms of cutting tool production, the Tape Casting technique was used for manufacturing, thus being able to obtain complex geometries and desired thicknesses. The present work has as general objective to study how properties and mechanics of ceramic composites of alumina incorporated with Boron Nitride and Niobium Carbide. The work was carried out with two different types of, a group was built from SPS, this being the composite of Al2O3 + 30% wt of NbC, sintered at 1350,1400 and 1450 °C; the other group was included via Tape Casting, where h-BN (3, 5 and 10 %) was incorporated into the ceramic alumina matrix. As green ribbon, laminates were awarded, these were mainly calcined at 500 °C with a heating rate of 1 °C / min and subsequently sintered at 1500, 1550 and 1600 °C. The results obtained, for the samples produced by SPS, showed to be promising, showing good properties at lower temperature and sintering time. The results of samples obtained via Tape Casting demonstrated that BN does not significantly contribute to improvements in the mechanical properties of nanocomposites.

11
  • CARLOS GOMES DE MOURA FILHO
  • Pressure delivery mechanism for self-healing of epoxy with embedded polyethylene-co-methacrylic acid (EMAA) particles

  • Líder : JOSE DANIEL DINIZ MELO
  • MIEMBROS DE LA BANCA :
  • FELIPE PEDRO DA COSTA GOMES
  • JOSE DANIEL DINIZ MELO
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • Data: 19-nov-2021
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Materials with self-healing capability offer great potential to improve life and long-term reliability in many applications. Poly (ethylene-co-methacrylic acid) (EMAA) has been studied as repair agent for thermosetting polymers and the formation of bubbles has been described as a pressure delivery mechanism to push the molten thermoplastic into the crack plane, thus promoting healing. This study investigates the effects of temperature, time, and particle size of EMMA particles as parameters related to the self-healing mechanism. EMMA particle size of ≥ 355 μm and ≥ 125 μm and temperatures of 130 °C, 155 °C, and 180 °C were considered. Thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC) were performed to investigate thermal properties and material degradation. Melt Flow Rate (MFR) tests were also performed on EMAA. Hot stage microscopy was used to investigate the dynamics of bubble formation resulting from condensation reactions between EMAA and epoxy. The results were compared with those observed using EMAA on a glass substrate. Thermal analysis showed no degradation of EMAA and epoxy at the temperatures considered for the healing process. The results suggest that the number of bubbles increased with time, irrespective of temperature and particle size for EMAA on epoxy or glass substrate, for promoting the pressure delivery mechanism. Then, the number of bubbles decreased with time for EMAA on the glass substrate, regardless of temperature and particle size. The collapse of bubbles was not observed in epoxy substrate for the processing times evaluated.  Ultimately, the results suggest that self-healing cycles using smaller particles (≥ 125 μm) at a temperature of 180 °C and processing times enough to consume reactional functional groups available are parameters that favor the pressure delivery mechanism with a subsequent collapse of bubbles. 

12
  • LUAN DO NASCIMENTO DE MOURA
  • SBA-15 and its Carbon replica CMK-3 for Rhodamine B adsorption

  • Líder : SIBELE BERENICE CASTELLA PERGHER
  • MIEMBROS DE LA BANCA :
  • EDUARDO RIGOTI
  • FERNANDO JOSÉ VOLPI EUSÉBIO DE OLIVEIRA
  • RUBENS MARIBONDO DO NASCIMENTO
  • SIBELE BERENICE CASTELLA PERGHER
  • Data: 29-nov-2021


  • Resumen Espectáculo
  • Water-soluble contaminants have been of great concern to the scientific community due to their unpredictable harmful effects on biomes and human health. Dyes are widely applied in industrial processes and discharged into water bodies without proper treatment. There are several studies of different techniques applied to the removal of industrial dyes from wastewater. Adsorption has been widely studied due to its low application cost and high performance in effluent treatment. The application of molecular sieves in adsorption enables the study of the dynamics and optimization of such physical-chemical process. Mesoporous materials have great accessibility to bulky molecules such as organic compounds and dyes. However, the chemical composition, specific area, and morphology of porous systems play a fundamental role in the adsorption of these compounds. Rhodamine B is an organic dye widely used in industry and was used in this study as a model molecule. Ordered mesoporous silica (SBA-15) and carbon-based (CMK-3) materials were used for the adsorption of Rhodamine B. The materials were synthesized and characterized by X-ray diffractometry (XRD), textural analysis by N2 adsorption, and infrared spectroscopy. The results show materials with a high specific area (> 600 m2/g) and hexagonal arrangement of the pore system. Adsorption measurements show the high efficiency of CMK-3 in removing Rhodamine B (>99%), while SBA-15 only removes ~5%. The results indicate that the composition plays an important role in the adsorption process. Carbon materials are more interactive with the dye molecule than silica materials. The morphology and size of the channels have a strong relationship with the accessibility and adsorption of Rhodamine B. The arrangement of the straight pores of the SBA-15 (6.5 nm average diameter) makes it difficult for the dye molecules dissolved in the solution to access, blocking the entry of pores by the first adsorbed molecules preventing the continuation of the adsorption process. Such behavior does not occur with CMK-3, since the mesopores of the material are open and guarantee good accessibility.

13
  • RAFAEL RABELO DE CARVALHO
  • REDOX BEHAVIOR OF THE Fe 2 O 3 /ZrO 2 OXYGEN CARRIER SYSTEM ON THERMAL CYCLES FOR POSSIBLE CLC APPLICATION

  • Líder : DULCE MARIA DE ARAUJO MELO
  • MIEMBROS DE LA BANCA :
  • DULCE MARIA DE ARAUJO MELO
  • RODOLFO LUIZ BEZERRA DE ARAÚJO MEDEIROS
  • ROSANE MARIA PESSOA BETANIO OLIVEIRA
  • Data: 07-dic-2021


  • Resumen Espectáculo
  • Chemical Looping Combustion (CLC) is a technique that has been utilized as an energetically efficient method for CO 2 capture and storage by the combustion of gaseous fuels. This technique involves the use of an oxygen carrier that transfers the oxygen obtained from air to the fuel, without direct contact between them. The oxygen carrier is a metal oxide (in example of Fe, Cu, Mn, Ni or Co) that acts as an active phase and is generally supported by an inert phase (in example Al 2 O 3 , TiO 2 , ZrO 2 ). Recent works on the literature indicate that the primary mechanism of charge mobility in a ceramic lattice, and consequently transport of oxygen, during combustion, is more related to ionic diffusivity on the material rather than intraparticle gaseous diffusion. Considering that it’s well known that stabilized zirconias have a high degree of oxygen vacancy, which leads to high charge mobility, and that there are very few studies in the literature about the Fe 2 O 3 /ZrO 2 system with stabilized ZrO 2 , the present work aims to present the preparation of oxygen carriers in this system, their characterization and application in oxidationreduction thermal cycles. The preparation of oxygen carriers was done using the incipient wetness impregnation method, with samples varying from 20%, 35% to 50%mol Fe, followed by high energy ball milling for zirconia stabilization. In some samples, almost all the iron was incorporated into the zirconia structure. The samples were analyzed using XRF, XRD, SEM-FEG, TGA and Mossbauer Spectroscopy. For the thermal cycles at a temperature of 900ºC, synthetic air was used as oxidating gas, a mixture of 15%CH 4 /20%H 2 O/N 2 was used as reducing gas and N 2 as a flush gas between the oxidation-reduction steps. The results were satisfactory for use in CLC systems, with oxygen transport capacities reaching values as high as about 200%, indicating multiple reductions of the active phase.

Tesis
1
  • RICARDO EUGENIO BARBOSA RAMOS FILHO
  • Study of scheelite residue, stone powder and cassava wastewater combination with binders for production of ecological bricks

  • Líder : WILSON ACCHAR
  • MIEMBROS DE LA BANCA :
  • JAQUELIGIA BRITO DA SILVA
  • PRISCYLLA CINTHYA ALVES GONDIM
  • SHEYLA KAROLINA JUSTINO MARQUES
  • VAMBERTO MONTEIRO DA SILVA
  • WILSON ACCHAR
  • Data: 15-ene-2021


  • Resumen Espectáculo
  • One of the largest consumers of natural resources on the planet is the civil construction industry, which can reduce this high consumption through the reuse of residues from mineral and vegetal extraction, which are generated in large volumes, causing environmental and social impacts in their regions of extraction. Several researches have been carried out with the use of residues in construction materials, with emphasis on the soil-cement brick, also called ecological brick, as there is no need for thermal treatment to sinter the clay minerals. Carrying out a systematic research it was verified the use of several solid residues incorporated in the soil as the scheelite residues and stone powder, that are generated in great quantities in the State of Rio Grande do Norte. In substitution, water has been used in soils such as manipueira, the liquid residue of cassava, which has agglutinating properties. A study of the combination of scheelite residue, stone powder and manipueira with the addition of binders is carried out aiming at an ecological brick with physical and chemical properties suitable for use in society that substitutes soil and water for waste. The physical, chemical and mineralogical characterization of the materials was carried out and then the compaction test to evaluate the best combination of the solid waste mixture, being determined in 50% of each residue. Technological essays were carried out on cylindrical specimens of solid residues with the addition of cement and / or lime hydrated with water, obtaining satisfactory results for cement formulations, being used for the production of bricks with the addition of manipueira instead of water in 11.5% with respect to the mass of the solid wastes. The technological tests of the bricks showed satisfactory results, justified by the high packaging between the residues and properties of the manipueira, with cement phases being observed in the analysis of scanning electron microscopy and X-ray diffraction. The ecological brick is promising for use as sealing masonry, being competitive in the market due to the low cost and easy availability of waste. The ecological brick is promising for use as sealing masonry, being competitive in the market due to the low cost and easy availability of waste, highlighting the formulation with 9% addition of cement to the waste mixture.

2
  • ANDERSON PARODIA
  • Development of new materials based on pillared clays containing nickel and aluminum


  • Líder : SIBELE BERENICE CASTELLA PERGHER
  • MIEMBROS DE LA BANCA :
  • FABIO GARCIA PENHA
  • FERNANDO JOSÉ VOLPI EUSÉBIO DE OLIVEIRA
  • KATIA BERNARDO GUSMÃO
  • RUBENS MARIBONDO DO NASCIMENTO
  • SIBELE BERENICE CASTELLA PERGHER
  • Data: 24-feb-2021


  • Resumen Espectáculo
  • Three bentonite clays from deposits located in the interior of Paraíba State were used to study the pillarization parameters such as the temperature and dilution of the aluminum pillaring agent. As well as the synthesis of pillarization using nickel as the pillar-forming metal, in addition, the impregnation of nickel in pillarized clays was studied for application in ethylene oligomerization reactions. The samples were characterized by X-ray diffraction and nitrogen sorption at 77 K. It was observed through the study of the temperature decrease that it is possible to obtain a pillar material without heating during the preparation of the pillar agent, as well as If pillar samples were obtained with 25% and 50% of the amount of aluminum pillaring agent commonly used, with these samples it was possible to prove that it is possible to insert new pillars in an already pillarized material. It was observed that during the synthesis studies of a nickel abutment the best result was obtained by preparing an Al / Ni mixed abutment, in addition to studying the impregnation of nickel in columnar clay samples with different aluminum percentages. As next steps, more characterization of the materials already obtained will be performed besides their application in the ethylene oligomerization reaction.

3
  • KARINE FONSECA SOARES DE OLIVEIRA
  • Active charcoal from the Cashew Nut Bark as a bioadsorber of metals in Produced Water.
  • Líder : MARCUS ANTONIO DE FREITAS MELO
  • MIEMBROS DE LA BANCA :
  • MARCUS ANTONIO DE FREITAS MELO
  • RENATA MARTINS BRAGA
  • RODRIGO CESAR SANTIAGO
  • FABÍOLA DIAS DA SILVA CURBELO
  • VÍTOR RODRIGO DE MELO E MELO
  • Data: 23-mar-2021


  • Resumen Espectáculo
  • The use of biomass for the production of bio-adsorbents has been gaining emphasis in the last decades, since it presents a high performance and a low cost of production, in addition to avoiding waste of the waste and minimizing the environmental problem due to its improper disposal in the place. The cashew nut shell (CNS) is a residue from the processing of cashew almonds, and this process is abundant in the northeastern region of Brazil. The objective of this research is to use a CNS as a bioadsorber of renewable origin, through the valorization of this by-product and, consequently, to promote the local economy with its commercialization. The material was subjected to thermal and chemical treatment, in order to obtain a more efficient bioadsorber. The characterizations performed without material density were, pH (pcz), X-Ray Fluorescence (FRX), Fourrier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM). Then, the kinetics and adsorption isotherm tests were carried out in mono and multi-element synthetic solutions using Cu2+, Pb2+ and Cr3+ metals, all at room temperature. The adsorption kinetics were evaluated using the mathematical models of pseudo-first order, pseudo-second order and intraparticle diffusion and as isotherms were adjusted following the models of Langmuir, Freundlich and Redlich-Peterson. Then, the fixed bed adsorption study was carried out, as well as the material regeneration. The residual metal ions were formed by Atomic Absorption (AA) spectroscopy. The material treated with NaOH was the one that obtained the best response for the removal of metals, for this material it was carried out in the experimental planning, the optimized end of the material activation, variation of the contact time of the base with the biomass and concentration of NaOH. The FTIR spectra show that there are anionic groups (carboxylics, hydroxyls and amines) on the surface of the bioadsorber and the micrographs of the SEM imposed a heterogeneous, irregular and spongy surface, both positive characteristics for adsorption. The mass used for adsorption was 0.1g with equilibrium time of 3h. A maximum removal of Cu2+, Pb2+ and Cr3+ is 46%, 96% and 56% respectively. In the adsorption kinetics of the model that best fit for the pseudo-second order and requires the predominance of chemisorption as an adsorption mechanism. The Langmuir model was favorable for the adsorption of Cu (II) and Cr (III), whereas the Freundlich model for Pb (II), it is suggested that chemical adsorption occurs in mono and multilayer. The breaking point was 75 mL, 75 mL and 60 mL for Cu2+, Pb2+ and Cr3+ respectively. The desorption of the metal ions retained in the column was efficient using HCl 1.0 mol / L and the regeneration cycle that can be used only one cycle. Thus, it is concluded that the bio-absorbent produced from the cashew nut shell has a high potential for the removal of metals and other contaminants in liquid effluents, since there was no chemical treatment and, consequently, the production cost was low, besides not having generated residues in the solution.

4
  • IANE MAIARA SOARES DE SOUZA
  • Development of new carriers for zeolite-based drugs: study of Faujasite, Beta and Mordenite zeolites as tools for modified isoniazid and olanzapine release.

  • Líder : SIBELE BERENICE CASTELLA PERGHER
  • MIEMBROS DE LA BANCA :
  • ANA CLÉCIA SANTOS DE ALCÂNTARA
  • CESAR VISERAS IBORRA
  • JOSÉ MANUEL PAREDES MARTÍNEZ
  • MANUEL SÁNCHEZ POLO
  • PABLO BOTELLA ASUNCION
  • RUBENS MARIBONDO DO NASCIMENTO
  • SIBELE BERENICE CASTELLA PERGHER
  • Data: 03-may-2021


  • Resumen Espectáculo
  • Zeolites are aluminosilicates that present as one of their main characteristics pores and
    cavities of well-defined dimensions, high specific area and cation exchange capacity,
    conferring ability to sieve and store molecules, making them widely applied and studied for
    various purposes. Isoniazid is one of the drugs used to treat tuberculosis; an infectious and
    contagious disease that has a high worldwide mortality rate has high water solubility and low
    permeability. On the other hand, olanzapine is an antipsychotic agent used for the treatment of
    schizophrenia and diseases of mental disorder, presenting low solubility and little oral
    bioavailability. Considering these premises, this thesis has the central objective of studying
    the application of the synthetic zeolites Beta, Mordenite and Faujasita as tools in the
    technological improvement of the drugs isoniazid and olanzapine. For that, the zeolites and
    drugs were previously characterized and the parameters related to adsorption and release were
    evaluated. For the study conducted with isoniazid, adsorption kinetics were performed at
    different pH's, results that were adjusted to the Langergren mathematical models, the pseudo-
    second order equation and the intraparticle diffusion of the Weber and Morris model. Based
    on the kinetic results, adsorption isotherms were constructed, considering the most favorable
    pH and the time in which the adsorption equilibrium is reached, pH 3 and 4 hours for
    Faujasita and pH 6 and 10 hours for Beta, the data isotherm were adjusted to Langmuir and
    Freündlich mathematical models. Hybrid materials composed of each type of zeolite and
    isoniazid were formulated and characterized by several techniques and the hybrids composed
    with zeolites Faujasita and Beta studied regarding the release of isoniazid in two release
    media, acid medium and phosphate buffer, with the purpose of to evaluate if these hybrids are
    able to provide control over the release of isoniazid in these media. These results of the
    release kinetics were adjusted to the mathematical models of Korsmeyer-Peppas and Higuchi.
    In parallel, as a way to better understand the interactions between zeolite and isoniazid,
    molecular modeling studies were carried out, exploring classical molecular mechanics,
    applying force fields based on empirical interatomic potentials with a better fit for the drug

    zeolite system, COMPASS27. Adsorption studies were also conducted with olanzapine where
    the influence of pH, contact time and the initial concentration of the drug solution was
    evaluated, as well as a release study. The results showed that Beta and Faujasita zeolites
    showed the best retention capacity, where for Faujasita only a considerable adsorption of
    olanzapine is observed with a change in the pH of the medium to 6. For the study with
    olanzapine, it was also observed greater protection against thermal degradation and more
    resistance at the release in the acid medium of the drug retained from the zeolite.

5
  • THAÍS MARIA ALVES MARINHO DE MELO
  • EVALUATION OF THE INFLUENCE OF VARIABLES ON THE SYNTHESIS PROPERTIES OF MICROCAPSULES PUF / ENB USING PLACKETT-BURMAN PLANNING (PB)

  • Líder : MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • ANA PAULA DIONISIO
  • JOSE DANIEL DINIZ MELO
  • LAURA HECKER DE CARVALHO
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • ROSANGELA DE CARVALHO BALABAN
  • Data: 24-may-2021


  • Resumen Espectáculo
  • Polymers and polymer composites are constantly susceptible to damage due to the emergence of microcracks that may compromise the structure as well as the life of the material during use. Thus, self-repairing systems have been increasingly studied and the use of polymeric microcapsules is one of the effective solutions for repairing damage during application, eliminating the need to remove the component for repair and thereby reducing costs. In this work, poly (urea formaldehyde) (PUF) microcapsules with 5-ethylidene 2 norbornene (ENB) core material were prepared by in situ polymerization. For this, a Plackett-Burman (PB) experimental design was used to evaluate the effect of the synthesis process variables on the obtained microcapsule properties. Factors manipulated include stirring speed, pH, poly (ethylene-alt-maleic anhydride) (EMA) content, urea / formaldehyde (U / F) molar ratio, ammonium chloride, resorcinol and 1-octanol droplets. The responses evaluated were mean microcapsule diameter, encapsulated content, microcapsule wall roughness, thermal stability and degradation temperature. It was observed that, of all analyzed parameters, the stirring speed and the EMA content had the most significant effects on the analyzed response variables, at a confidence level of 90%. Microcapsules with larger diameters were obtained when agitation and EMA content were at the lower level of the PB planning. On the other hand, the thermal stability and degradation temperature of the microcapsules increased with agitation and the EMA content. In addition, the high significance of curvature in the Pareto graphs of some response variables analyzed indicated that microcapsules with satisfactory properties can be obtained under center point conditions. No parameters analyzed were statistically significant at a 90% confidence level for yield and encapsulated content.

6
  • ANDREY JOSÉ MORAES DE LIMA
  • Fe-doped calcium cobaltites as electrocatalysts for oxygen evolution reaction

  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • DANIEL ARAÚJO DE MACEDO
  • MARCO ANTONIO MORALES TORRES
  • RODOLFO BEZERRA DA SILVA
  • RUBENS MARIBONDO DO NASCIMENTO
  • THIAGO ARAUJO SIMÕES
  • Data: 21-jun-2021


  • Resumen Espectáculo
  • The electrolysis of alkaline solutions is one of the most used strategies for producing hydrogen (H2). This process distinguishes itself by breaking the water molecule (water splitting) through two semi-reactions: Hydrogen Evolution Reaction (HER, cathodic reaction) and Oxygen Evolution Reaction (OER, anodic reaction). The OER is fundamental for several electrochemical technologies related to generate and storage energy. New research for developing low-cost electrocatalysts with a good electrochemical activity using more earth abundant elements has intensified in recent years. The current work aims to study the effect of Fe doping on the OER of calcium cobaltites, Ca3Co4-xFexO9 (x = 0, 0.1, 0.4, and 0.8). Powders were obtained by a proteic sol-gel method using gelatin with calcination at 900 °C for 2 h. The resultant samples were characterized by X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM). X-ray photoelectron spectroscopy (XPS) provided information on the surface chemical states, while Mössbauer spectroscopy indicated that Fe has a strong preference for octahedral sites in the CoO2 layer rather than in the Ca2CoO3 layer in the calcium cobaltite misfit-type structure. Linear sweep voltammetry (LSV), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS) were used to analyze the electrochemical performance. The results indicate that Ca3Co3.2Fe0.8O9 needs the lowest overpotential of 320 mV to generate a current density of 10 mA cm-2.

7
  • DIÊGO PIRES GURGEL
  • Study of the addition of niobium in polycrystalline diamond (PCD) obtained by high pressure and high temperature (HPHT)

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • ALESSANDRA AGNA ARAÚJO DOS SANTOS
  • MARCELLO FILGUEIRA
  • MEYSAM MASHHADIKARIMI
  • RUBENS MARIBONDO DO NASCIMENTO
  • UILAME UMBELINO GOMES
  • Data: 27-ago-2021


  • Resumen Espectáculo
  • The main objective of the studies developed in this work was to verify the influence of the variation of the niobium concentration as binder on the mechanical properties, wear resistance and thermal stability of the polycrystalline-niobium diamond system prepared by HPHT. This compound has great applicability in several areas of engineering, such as aeronautics, civil, metallurgical and even in drilling. The studied concentrations of niobium were 2.5%, 5.0% and 10%.High energy grinding in Spex type mill was used to reduce the initial particle size of the PCD and for its mixture with the niobium, the effects of reduction of the average particle size verified were to values of 35.01 μm, 32.91 μm and 31.91μm (for, respectively, the concentrations of 2.5%, 5.0% and 10% of niobium as binder). The HPHT conditions used for the consolidations of cylindrical samples 5mm in diameter by 5mm in height were the temperature of 1750 ° C, the pressure of 7.7GPa and three cycles of 3 minutes. The density values obtained were about one hundred per center, with no porosity in the samples and no graphitization effects were observed. For the PCD with concentrations of 2.5%, 5.0% and 10% of niobium as binder, density values of 3.72 g / cm³, 3.81 g / cm³ and 3.90 g / cm³ and elasticity moduli of 946GPa, 998.4GPa and 1196GPa. Good dispersion of the metal phase was observed both on the surfaces and inside of the specimens, and it was also observed that the increase in the amount of binder allowed a greater tendency to the occurrence of intergranular rupture than to the cleavage. The tribological tests on pin-on-disc apparatus with a load of 150N and rotation of 500rpm allowed to observe that, when interacting with steel (with abrasion being observed as the predominant mechanism of wear), the wear trend is higher than in the case of its interaction with aluminum (where the great occurrence of adhesion is seen). The concentration of 10% of niobium as binder ensured lower wear resistance of the compound than that of 2.5%, in addition also higher values of temperatures were observed in regions close to the contact of the tribological pair, which are justified by the greater metallic interaction and by the decrease of the hard phase of diamond PCD.
8
  • MIRELLA LOPES DA ROCHA
  • Accelerated aging effects of composites employed as repair materials for steel pipelines in the oil industry

  • Líder : ANA PAULA CYSNE BARBOSA
  • MIEMBROS DE LA BANCA :
  • ANA PAULA CYSNE BARBOSA
  • EVANS PAIVA DA COSTA FERREIRA
  • JOSE DANIEL DINIZ MELO
  • LAURA HECKER DE CARVALHO
  • MIRABEL CERQUEIRA REZENDE
  • Data: 10-sep-2021


  • Resumen Espectáculo
  • Pipelines are structures used in large scale in the oil industry for transportation of fluids which are, in turn, highly corrosive to the duct, leading to damages over time. Moreover, besides corrosion itself, failures can occur during the manufacturing or installation of these ducts. Considering these defects, the degradation of the pipelines and the high cost of their implementation, repairs with composite material reinforced with glass fiber becomes a viable alternative, considering its high chemical resistance and its excellent thermal and mechanical performances. However, studies on the effects of aging on these repairs are still necessary for greater reliability on their usage at oil industry. Therefore, the objectives of this study are to evaluate the effects of accelerated aging on the composite used at pipelines repair by exposing them to accelerated aging in two types of environment: salt water and UV exposure with water condensation, for two, four and six months. The tests conducted to evaluate the material where: mass variation, scanning electron microscopy (SEM), dynamic-mechanical analysis (DMA), Fourier-transform infrared spectroscopy (FTIR), permeability test and lap shear. The results showed that samples submitted to aging in salt water presented mass gain, while the ones aged at UV and humidity exposure presented mass loss. FTIR spectroscopy showed chemical modifications in all studied aging conditions. SEM showed changes in the aged materials such as cracks, fiber-matrix detachment and exposure of fibers. DMA showed an increase in the glass transition temperature for aged materials when compared to the unaged one. Permeability tests showed an increase at gas permeability for aged samples when compared to the unaged material. Finally, lap shear tests showed a reduction in shear strength of aged materials, for all aging conditions.

9
  • PATRÍCIA ALVES SOBRINHO RODRIGUES
  • Study of the zeolite of Zeolites ZSM-35 (FER) and ZEM-5 (MFI) and application of these materials as catalysts for biomass pyrolysis.

  • Líder : SIBELE BERENICE CASTELLA PERGHER
  • MIEMBROS DE LA BANCA :
  • DAVID PEDRO SERRANO GRANADOS
  • ANDERSON JOEL SCHWANKE
  • DULCE MARIA DE ARAUJO MELO
  • LINDIANE BIESEKI
  • SIBELE BERENICE CASTELLA PERGHER
  • VINÍCIUS PATRÍCIO DA SILVA CALDEIRA
  • Data: 15-oct-2021


  • Resumen Espectáculo
  • Zeolites are porous materials with a crystal structure belonging to the class of molecular sieves. The syntheses of zeolitic materials can be modified, varying the parameters according to the needs of the final material. The purpose of these variations, usually, are to obtain a more crystalline structure and a possible change in morphology to improve the catalysis reactions. This study presents the characterizations of the different syntheses carried out of the ZSM-35 zeolite (FER) and the characteristics of the commercial ZSM-5 zeolite (MFI) with zirconia impregnation. The ZSM-35 syntheses were initially studied using the recipe presented at the IZA (International Zeolite Association) and later varying some parameters, such as the sources of silicon and aluminum, the variation of the Si/Al ratio and the use of the cationic surfactant, bromide hexadecyltrimethylammonium (CTAB). In addition to possible changes in the final material, the use of alternative sources of silicon and aluminum, which are sources easily found in nature, brings great cost-benefit to the process. For the characterization of these materials, the techniques of X-ray diffraction (XRD), X-ray fluorescence (FRX), scanning electron microscopy (SEM), thermogravimetric analysis (TG), and textural analysis by N2 adsorption were used ( BET method). It was observed that in the syntheses studied following the IZA recipe and with the different sources of silicon and aluminum, a good crystallinity of the FER structure was obtained in an optimized time in relation to the literature, as well as in the syntheses with the use of surfactant. However, with the addition in the syntheses using the surfactant, with Si/Al ratio 30.4, we obtained another structure, ZSM-5 (MFI), instead of ZSM-35 (FER). After the step of studying the syntheses, it was followed by their applications as catalysts for biomass pyrolysis. Three biomasses were tested for bio-oil production by rapid pyrolysis. In the characterization of the products obtained in the reactions, the techniques of gas chromatography, elemental analysis CHNS-O, thermogravimetric analysis and moisture analysis (Karl Fisher) were used. It was observed that the use of the catalyst in the reaction led to a drastic reduction in the bio-oil, however it led to a greater production of CO and CO2, which are molecules that reduce the oxygen content in the bio-oil.

10
  • ALLAN JEDSON MENEZES DE ARAÚJO
  • OPTIMISATION OF ELECTROLYTES AND OXYGEN ELECTRODES FOR REVERSIBLE SOLID OXIDE CELLS

  • Líder : CARLOS ALBERTO PASKOCIMAS
  • MIEMBROS DE LA BANCA :
  • CARLOS ALBERTO PASKOCIMAS
  • RUBENS MARIBONDO DO NASCIMENTO
  • DOMINGO PÉREZ-COLL
  • ANDREI KAVALEUSKI
  • FRANCISCO JOSÉ ALMEIDA LOUREIRO
  • DUNCAN PAUL FAGG
  • Data: 05-nov-2021
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Reversible solid oxide cells (r-SOCs) are promising and efficient technologies for converting electricity into fuel and fuel back into electricity. Such devices are targeted to operate in a wide range of temperatures and oxygen partial pressures. Hence, the cell components require materials that possess high levels of performance with good stability. In this respect, due to its high oxide-ion conductivity at intermediate temperatures, the gadolinium-doped ceria oxide, Ce1-xGdxO2-δ (CGO), is one of the most promising electrolyte choices. However, its poor sinterability is a challenge to be faced to obtain high-performance devices. Hence, to try to overcome this limitation, a soft chemical synthesis route known as “proteic sol-gel synthesis” is used to prepare CGO ceramics exhibiting excellent sinterability at 1350 °C. Materials are fully characterised by their structural, chemical, microstructural, and electrical properties. Higher bulk conductivity is demonstrated for a sample with 10 mol% Gd when compared to one with 20 mol% Gd and explained by the formation of defect associates  with lower mobility. In contratst, similar specific grain boundary conductivities, calculated based on the brick-layer model, are observed as a possible result of the comparatively low sintering temperature. A Mott-Schottky model is used to determine the space-charge characteristics, where the lower barrier height of the sample with 20 mol% Gd is suggested to be due to the increased segregation of  species to the grain boundaries, attenuating the depletion of oxide-ion vacancies near the grain boundary core.

    Another critical component is that of the oxygen electrode. The misfit calcium cobaltite electrode, [Ca2CoO3-δ]0.62[CoO2] (C349), has emerged as an interesting option for possessing a thermal expansion coefficient similar to that of the CGO electrolyte, a feature that could benefit this compound among the state-of-the-art electrodes. Nonetheless, its poor oxygen-ion conductivity precludes its use as oxygen electrode. Therefore, in the current work, we attempt to address this problem by providing a thorugh investigation of its electrochemical behaviour, experimenting different strategies to improve its performance. It is demonstrated that the C349 electrode requires a higher volume of solid fraction close to the electrolyte to maximise the ionic current into the bulk. Such an improvement can be achieved by increasing the number of deposited electrode layers due to the better packaging of the grains.

    In a different perspective, an active interlayer made of Ce0.8Pr0.2O2-δ (CPO, + 2 mol% Co) is used between the C349 electrode and the CGO electrolyte to improve the electrode performance. A combination of three different approaches using the distribution function of relaxation times (DFRT) analysis reveals the existence of parallel reaction paths. At higher temperatures, the pathway through the C349 is expected, given by its high electronic conductivity and sufficient ionic conductivity. However, at lower temperatures, the CPO + Co interlayer pathway becomes increasingly predominant due to its higher ionic conductivity compared to the C349.

    C349/CGO and C349/CPO composite electrodes are also compared. The DFRT analysis demonstrates a preferential series pathway for the oxygen reaction in the CGO-based electrode, being notably faster on the CGO particles. In contrast, parallel pathways are suggested for the CPO-based electrode, with comparatively better performance at lower temperatures and under more oxidising conditions, due to the higher electronic conductivity of the CPO phase in these conditions. When used as composite matrix instead of an active interlayer, CPO provides a greater enhancement of electrode performance. Electrochemical measurements under applied polarisation indicate the CGO/C349 composite electrode offers a promising potential for r-SOCs, performing better as an anode in electrolyser mode.

    As a final part of this thesis, we study an alternative layered structure, the promising barium cobalt oxide (Ba2Co9O14 – BCO), as a r-SOC electrode. We firstly study the electrochemical behaviour of a 40 vol% CGO composite, which is found to provide a much lower polarisation resistance under cathodic polarisation. On the other hand, its electrochemical performance is slightly impaired under anodic polarisation. In a second work, we study attempt further optimisations by evaluating the influence of volume fraction of the CGO phase in the composite, with the composition being optimised with 50 vol% CGO due to an increased triple-phase boundary (TPB) length.

    Overall, the current thesis provides a systematic investigation on the development of r-SOC materials with promising performances, trying to carefully address the fundamental mechanisms involved. The work, therefore, provides a solid advance on the research of these components for r-SOCs; a topic that is still in its infancy.

     

11
  • PEDRO ALIGHIERY SILVA DE ARAÚJO FERREIRA
  • EFFECTS OF THE ADDITION OF ASH RESIDUE FROM THE COFFEE HULL ON THE MICROSTRUCTURE AND PROPERTIES OF CORDIERITE-BASED CERAMICS

  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • CAROLINE GOMES MOURA
  • DANIEL ARAÚJO DE MACEDO
  • JOÃO PAULO DE FREITAS GRILO
  • RICARDO PEIXOTO SUASSUNA DUTRA
  • RUBENS MARIBONDO DO NASCIMENTO
  • Data: 15-dic-2021
    Ata de defesa assinada:


  • Resumen Espectáculo
  • Cordierite is one of the compounds in the MgO-Al2O3-SiO2 system that has the lowest thermal expansion coefficient among inorganic oxides. Despite this advantage, which results in high resistance to thermal shock, monophasic cordierite is difficult to prepare, and the existence of secondary phases increases its thermal expansion coefficient. Therefore, the elimination of undesirable phases is one of the key points in the preparation of cordierite ceramics with low thermal expansion. Many sintering additives (TiO2,CaO, Li2O, Na2O, Fe2O3, ZnO, e ZrO2) have been used to stimulate the sintering of cordierite precursor powders and modify the microstructures and properties of ceramics. Unfortunately, many of these sintering additives increase the thermal expansion coefficient of the obtained ceramics. In this context, this doctoral work proposes to study the effects of different levels of rare earth oxide (CeO2) and coffee ash residue on the elimination of secondary phases, sintering mechanisms, microstructure and properties of cordierite-based ceramics. The samples will be obtained by reactive sintering (in a conventional oven) of stoichiometric mixtures of magnesium, aluminum and silicon oxides (reference sample) from natural raw materials rich in these elements. Both K2O, contained in the ash residue from the coffee husk, and CeO2, in low amounts, can stimulate the reaction of cristobalite and spinel to form cordierite.

2020
Disertaciones
1
  • SERGIO AUGUSTO NASCIMENTO DE FRANÇA JUNIOR
  • Obtaining dielectric substrates based on calcium silicate with different additions of h-BN by tape casting.

  • Líder : WILSON ACCHAR
  • MIEMBROS DE LA BANCA :
  • Ana Paula da Silva Peres
  • Antonio Carlos Silva da Costa
  • WILSON ACCHAR
  • Data: 08-ene-2020


  • Resumen Espectáculo
  • In recent years, the considerable progress of the IoT, microwave telecommunications, satellite transmission systems and dense microelectronic circuits has resulted in a growing demand for new low dielectric loss materials. Ceramic substrates for these purposes should generally have low relative dielectric constant and have low dielectric loss under high operating frequencies and high thermal conductivity. Hexagonal boron nitride (h-BN) has great potential as a substrate for high frequency applications due to low constant and dielectric loss, as well as high thermal conductivity. Glass ceramic materials have also been widely used due to their low cost and excellent dielectric properties. In view of this, the objective of the present work was to obtain multilayer calcium silicate ceramic substrates with h-BN additions (1 wt. %, 3 wt. % and 5 wt. %) conformed by tape casting in order to evaluate their use as high frequency substrates. The viscosity of the ceramic suspensions was analyzed by rheological tests and the green ceramic tapes were subjected to thermal analysis (ATG). The ceramic tapes were laminated and sintered at three temperatures: 950 ° C, 1000 ° C and 1050 ° C. The Sintered laminates were characterized by X-ray diffraction, Raman spectroscopy, density and porosity assays, and field emission scanning electron microscopy (SEM-FEG). Finally, dielectric properties of green and sintered laminates were obtained. Reflection peaks concerning wolastonite and cristobalite phases were found in all compositions, as well as a characteristic hexagonal boron nitride peak in compositions containing h-BN. The high relative apparent porosity values found in all compositions determined the low relative dielectric constant values (between 1.99 and 2.35), In general, the obtained compositions showed low dielectric losses, mainly in the samples containing h-BN, and this was evident in a wide frequency range, from 0.1 GHz to 1.5 GHz. The composition containing 5 wt. % h-BN showed dielectric losses in the order of 10-4 , thus having great potential for application as a high frequency substrate.

2
  • ANGEL ROBERTA OLIVEIRA DE SOUSA
  • Tuning the electrical conductivity of an N-type organic semiconductor by means of solution doping for thermoelectric applications

  • Líder : CARLOS ALBERTO PASKOCIMAS
  • MIEMBROS DE LA BANCA :
  • CARLOS ALBERTO PASKOCIMAS
  • ANA PAULA CYSNE BARBOSA
  • JOÃO PAULO DE FREITAS GRILO
  • Data: 09-ene-2020


  • Resumen Espectáculo
  • Organic thermoelectric devices are composed of conductive polymers capable of converting thermal energy into electrical energy, and vice versa, through Seebeck and Peltier Effects. Organic doping is one of the most important approaches used to improve and tune the electrical properties of polymers, especially n-type organic semiconductors, which are known to be the obstacle to improving the performance of thermoelectric devices, since their performance lags behind when compared to the p-type semiconductor polymers and also due to their inefficient doping process. Systems using Poly{[N,N′-bis(2-octyldodecyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene) P(NDI2OD-T2), also known as N2200, as the host material, have been extensively investigated with 4 - ( 1 , 3 - Dimethyl - 2 , 3 - dihydro - 1 H - benzoimidazol - 2 - yl ) phenyl) dimethylamine (N-DMBI), Mesitylene pentamethylcyclopentadienyl ruthenium dimer ((RuCp*mes)2), 4 - ( 1 , 3 - Dimethyl - 2 , 3 - dihydro - 1H - benzoimidazol - 2 – yl)-N,N-diphenylaniline (DPBI), Tetrabutilamonium fluoride hydrate (TBAF), among others, but nothing has been reported about the interaction of the N-DMBI dimer with the P(NDI2OD-T2). Given this, the present work aimed to investigate the effect of the concentration increase of (N-DMBI)2 in the N2200 used as a matrix, mainly evaluating the impact on the electrical conductivity and on the morphology of the produced film. The characterizations used in this study were Visible ultraviolet spectroscopy (UV-vis), Electronic Paramagnetic Resonance Spectroscopy (EPR), Atomic Force Microscopy (AFM), Kelvin Probe Microscopy (KPM), two-point probe station and the Thin Film Analyzer (TFA) from Linseis. The electrical characterizations were able to measure a 4 orders increase in the electrical conductivity for the 20% doped N2200-dimer sample when compared to the neat material N2200. The Seebeck coefficient for the 10% sample was -80 uV/K and for the 20% was -66 uV/K at 30ºC. The AFM and the KPM helped to better understand the morphology and miscibility of the dopant in the host material.

3
  • RENNÁH FRANCISCO FIGUEIREDO GONÇALVES
  • STUDY OF THE SYNTHESIS COMPOSITE POWDERS AND SYNTERIZATION OF W-NI SYSTEM

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • ARIADNE DE SOUZA SILVA
  • MARIA JOSE SANTOS LIMA
  • MEYSAM MASHHADIKARIMI
  • SUYLAN LOURDES DE ARAÚJO DANTAS
  • UILAME UMBELINO GOMES
  • Data: 13-ene-2020


  • Resumen Espectáculo
  • In this work, we studied the use of W-Ni composite powders by high energy milling at different times (2h, 5h and 10h), nickel ammonium paratungstate (APT) precursors (20% p. Ni) and tungsten with nickel (20% p.Ni). Make an ammonium paratungstate (APT) mixed with nickel at a ratio of 20% p.Ni, reducing it with hydrogen gas (H2), at a temperature of 850 °C and with an isotherm time of 60 minutes, compaction and afterwards. sintering of reduced green compacts with heating rate of 10 °C/min. Post and precursors were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The effects of different measurement times (2h, 5h and 10h), compaction loads (500 MPa and 600 MPa) and sintering temperatures (1450 °C and 1550 °C) on the allowed W-Ni properties were investigated. The influence of grinding times on the evolution of hardness and microstructure was analyzed. They were also selected for color densities by the Archimedes method. At the same time, tungsten and nickel metal parts were selected under the same experimental conditions for comparison fins. From the obtained results, it was possible to conclude that the images recorded by SEM of the W-Ni mixtures revealed after the publication of the morphology with display of varied and quite agglomerated sizes and shapes. No case of W-Ni blending from APT-20% p.Ni reduction, the smallest selected post-engravings with good dispersion and phase homogenization. An XRD analysis showed the W and Ni4W phases, and the reduction of ammonium content was confirmed. The compacted dimensions with pressure of 500 MPa and the sintering temperature of 1450 °C presented higher density; and a grinding performed without time 10h allowed the hardening with greater microstructural homogeneity, presenting longer duration value (400.9 HV).

4
  • MORENA BRITO DE FARIAS
  • Production of glass ceramic based on coffee husk ash (CCC) obtaining the diopside and nepheline phases.
  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • RUBENS MARIBONDO DO NASCIMENTO
  • AURISTELA CARLA DE MIRANDA
  • DANIEL ARAÚJO DE MACEDO
  • Data: 02-mar-2020


  • Resumen Espectáculo
  • Glass-ceramic materials are produced from original glass by controlled crystallization, in which it is possible to obtain a material with certain properties due to its microstructural control. These materials have a wide range of applications such as cooktops, ceramic tile enamels, insulators, sealants when applied to solid oxide fuel cells (SOFCs), glass-ceramic enamels and/or biomaterial. In this study, the production of the glass-ceramic material was obtained through the homogenization of the base glass reagents that will go through the process of casting, maceration, compaction, and crystallization in the oven. One of the reagents used in the work was potassium oxide, produced through coffee husk ash (CCC), as it is a low-cost material, of great production in the country and of possible reuse, considering that this material is very sometimes disposed of improperly. The material in question was characterized by X-ray Diffraction, X-ray Fluorescence, Dilatometry and Field Emission Scanning Electron Microscopy. The analyzes indicated the formation of the Diopside and Nepheline crystalline phases. The coefficients of thermal expansion (CTE) of glass and glass-ceramic have values between 9.17-1.8 x 10-6 ºC-1. However, in the results of the SEM-FEG analysis of the CC_GC1 sample, a porous glass-ceramic was observed, where the existing pores have a circular shape, arranged at random. However, it was possible to obtain a glass-ceramic material using coffee husk ash as a K2O substitute reagent.

5
  • VINÍCIUS SOARES MEDEIROS
  • Production and Characterization of Rice Hull Ash Vitroceramics
  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • RUBENS MARIBONDO DO NASCIMENTO
  • CARLOS ALBERTO PASKOCIMAS
  • AURISTELA CARLA DE MIRANDA
  • DANIEL ARAÚJO DE MACEDO
  • Data: 02-mar-2020


  • Resumen Espectáculo
  • In the production of industrial wastes, and agricultural land is one of the most pressing problems at the time in the world. Increasingly, the wastes are to be characterized as a material that has the capacity to generate wealth, which can then be used in the production of ceramic materials. The procedure of processing that generates as a waste product of the rice husk which is used as a source of energy, it is the grey of the hull of the rice, and the incorporation of this ash in the production of new products, in particular ceramics, and glass-ceramics. The main objective of this study was to develop a glass-ceramic from this natural source, the rice husk ash (RHA) is used as the source of the silica from the waste stream in the industry. The formulation used in SiO₂-Al₂O₃-CaO-Na₂O-K₂O-MgO was adjusted by means of the composition of a glass-ceramics (DE MIRANDA (2015) by replacing the source of the silica in the same thing. A mixture of 23g of these compounds was melted at 1500ºC for 1 hour, to obtain a glass-precursor, where it was subjected to the analysis of XRX, XFR, DIL and TGA to the characterization of glass and glass-ceramic. Subsequently, they were sintered for three samples of glass, with a temperature of 850ºC 5°C/min, while varying the amount of time between 30 and 40 minutes.Through the analysis of dilatométrica, it was possible to obtain the coefficient of thermal expansion for the glass, which was de -9,54231  and the glass-ceramic cooking surface have been obtained, and the values for samples CA-GC1, the CA-GC2 and CA-GC3 2,34938 , -3,46648  e -2,76026 , respectively. Through the analysis of dilatométrica, it was possible to obtain the coefficient of thermal expansion for the glass, which was de -9,54231  and the glass-ceramic cooking surface have been obtained, and the values for samples CA-GC1, the CA-GC2 and CA-GC3 2,34938 , -3,46648  e -2,76026 , respectively. The structure of the glass-ceramic obtained has been analyzed by XRD, being by demonstrating the presence of crystalline phases, the Nepheline (), and Diopside . The results obtained from the SEM images confirmed the presence of crystalline phases and on the EDS, there was the acknowledgement of the constituent elements of the composition that is used.

     

6
  • ARTHUR GABRIEL BEZERRA DE AZEVEDO
  • Characterization of the surface properties of nanocomposite polymer- functionalized montmorillonite

  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • MAURICIO ROBERTO BOMIO DELMONTE
  • VINÍCIUS DANTAS DE ARAÚJO
  • Data: 02-jun-2020


  • Resumen Espectáculo
  • Nanocomposites with thermofixed polymeric matrix and nanostructured inorganic filler have been presenting greater industrial demand in recent years. Recent research in this area seeks to incorporate filler at low percentages of mass (less than 5%) in order to maximize the properties of the nanocomposite without prejudice factors such as toughness. In this work, polymer-clay nanocomposites were produced from epoxy resin and montmorillonite clay. A content of 3 %wt of clay was incorporated into the resin through dispersion in acetone, mechanical agitation and application of vacuum. The nanocomposites obtained were deposited in the form of films, on stainless steel plates. The commercial clay was treated using ethylene glycol to remove interlamellar compounds and allow exfoliation of the structure. The material was functionalized with three different coupling agents, denominated silanes, (3-Aminopropyl) triethoxysilane (APTES), Triethoxyvinylsilane, (TEVS) and 3- (Trimethoxysilyl) propyl methacrylate (MEMO). The modified minerals were evaluated using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and specific surface area analysis using the BET method. The analyzes suggest that the materials obtained showed exfoliated structure before incorporation in the resin, with the silane agents incorporated in the interlayer space of the clay, which was observed through the significant modification in the basal spacing of its structure and modification of specific surface area. The analyzes of atomic force microscopy (AFM) and contact angle performed on the obtained nanocomposites indicated that the presence of coupling agents superficially modified the nanocomposites, varying their roughness and obtaining an increase of approximately 45% in the contact angle for the nanocomposite containing TEVS. Materials modified with MEMO showed slight changes in the contact angle. For the nanocomposite containing APTES, the analyzes indicated a tendency to increase hydrophilicity.

7
  • VALONE SANTOS NUNES
  • Evaluation of the effect of the partial replacement of cement for limestone residues on the mechanical and thermal properties of light concrete

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • JOSE AIRTON CUNHA COSTA
  • KLEBER CAVALCANTI CABRAL
  • Data: 29-oct-2020


  • Resumen Espectáculo
  • The use of lightweight concrete was first recorded over 3000 years ago. Due to their thermal properties, lower cost and greater production capacity, both lightweight concrete and ultra-lightweight concrete have been explored in the construction of prefabricated structural lightweight concrete buildings, bridges, marine platforms and fair-faced concrete buildings. Therefore, this work aimed to evaluate the effects on the mechanical and thermal properties of lightweight concrete (CL), with partial replacement of cement by limestone residue, using fine quartz sand, expanded clay, and expanded vermiculite, as leaf aggregates. The mechanical behavior was performed through tests of resistance to compression, dynamic elasticity module and indirect traction by diametrical compression, and the physical behavior through tests of water absorption by immersion, void index, porosity, specific mass, thermal conductivity in addition to microstructural analysis (FRX and DRX) of the limestone residue. For comparison purposes, a reference concrete mix was made without any substitution and, from it, a partial substitution of cement was made in 5%, 10%, 15%, 20% and 25%, by limestone residue. Another important factor considered in the study was the consumption of cement, which remained between 262.5 and 350 kg / m³. All concrete density less than 1.0 g / cm³, with a reduction of up to 7.78% with the replacement of 25% of cement with limestone waste.

8
  • JOYCE CAVALCANTE DA SILVA
  • Preparation, characterization and analysis of Diatomite and Crystalline Nanocellulose nanocomposites for application as biomembranes
  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • UILAME UMBELINO GOMES
  • CARLOS ALBERTO PASKOCIMAS
  • MEYSAM MASHHADIKARIMI
  • ARIADNE DE SOUZA SILVA
  • CLODOMIRO ALVES JUNIOR
  • Data: 06-nov-2020


  • Resumen Espectáculo
  • Diatomite nanocomposites have become the subject of significant interest in the research and development of reliable filter materials which can enable the democratic access to freshwater with fair quality. This holds true due to the safe chemical composition and the naturally standardized porous microstructure of this unique material. In this study, the White Diatomite Ceramic Powder was used in the fabrication of biomembranes with controlled porosity. Ceramic laminates (with 3 and 4 layers of tape-casted tapes) were subjected to warm pressing followed by binder removal and sintering. The White Diatomite powder was characterized via Laser Diffraction Particle Size Analysis, XRF, XRD and FE-SEM. The determination of the viscosimetric behavior of the ceramic suspension used on the tape casting process, fabricated with the addition of the Diatomite powder, was carried out with rheological tests on a cone-plate system. TG/DT analysis were performed to investigate the thermogravimetric behavior of tape-casted Diatomite tapes. The thermal treatment route implemented in this work fostered the observation, via XRD, of the transformation of biogenic amorphous silica into tetragonal cristobalite and low quartz with hexagonal symmetry. Thus, polymeric nanoparticles of NCC were applied, via Silk Screen Coating, onto the surface of Diatomite sintered laminates, leading to the final nanocomposite obtained in this study: Diatomite biomembranes superficially coated with NCC. Subsequently, FE-SEM analysis signaled the partial reduction on the pore size distribution near the surface of the produced biomembranes, on account of the identification the NCC nanoparticles on the interior of the Diatomite-matrix’s pores.

9
  • THYALLE TRINDADE DE ARAÚJO REZENDE
  • Study of Photocatalytical Degradation of Methylene Blue in the presence of WO 3 /SnO 2 /CuO Thin Films obtained by Dip Coating

  • Líder : FABIANA VILLELA DA MOTTA
  • MIEMBROS DE LA BANCA :
  • FABIANA VILLELA DA MOTTA
  • MARIO GODINHO JUNIOR
  • MAURICIO ROBERTO BOMIO DELMONTE
  • NEFTALÍ LENIN VILLARREAL CARREÑO
  • Data: 11-dic-2020


  • Resumen Espectáculo
  • Recently, the interest in materials with photocatalytic properties for the degradation of dyes from textile industries has been increasingly studied, since the incorrect disposal of these dyes causes serious environmental problems. The tungsten trioxide (WO 3 ) has a band gap of 2,7 eV which makes it a promising element for the absorption of photons in the visible spectrum range. Tin dioxide (SnO 2 ) is a band gap semiconductor equal to 3,6 eV with a high surface area, making it essential for the photocatalysis process. In turn, copper oxide (CuO) presents an expansion of the light spectrum from the ultraviolet to the visible regions due to its narrow band gap of 1,2 eV. In this work W, Sn and Cu based resins were synthesized by the complex polymerization method (MPC) for the production of thin films of WO 3 , SnO 2 , CuO and WO 3 /SnO 2 /CuO with 9 layers using the dip coating  technique. Two heat treatment pathways (Route 1 and 2) were used during the process of obtaining the nanocomposites, with all samples calcined at a temperature of 500 °C. The films were characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), scanning electron microscopy with field emission (SEM-FEG), energy dispersion spectroscopy (EDS), spectroscopy in the region UV-Visible (UV-Vis) and wettability test. The XRD results confirmed the formation of orthorhombic, monoclinic and tetragonal crystalline structures, there was also the formation of a sub stoichiometric phase (WO 2,63 ) and tin tungstate in the route 2 nanocomposite, indicating chemical interaction between the interfaces. The images of the surface and the cross section of the thin films indicated regular morphologies with small porosity and uniform thicknesses. The contact angle measurements indicated that the nanocomposites remained hydrophilic even after UV irradiation and storage in the dark. The optical absorption spectra by UV-Vis characterized thin films as semiconductors. The photocatalytic activity was evaluated and the results showed that the films degrade the MB dye when exposed to UV and solar radiation. The maximum photocatalytic activity (89%) was obtained under sunlight and remained practically unchanged after six cycles of use, indicating that the nanocomposites studied are promising for degradation of MB dye.

10
  • MÚCIO DANTAS DE MEDEIROS
  • Directional solidification and wear resistance of Zn-8% Al-x% Cu alloys
  • Líder : BISMARCK LUIZ SILVA
  • MIEMBROS DE LA BANCA :
  • BISMARCK LUIZ SILVA
  • MAURÍCIO MHIRDAUI PERES
  • WASHINGTON LUIS REIS SANTOS
  • Data: 30-dic-2020


  • Resumen Espectáculo
  • Zinc is one of the most non-ferrous metals produced after aluminum and copper, being the most used in functional and decorative applications. The main advance in the foundry industry for zinc-based alloys in recent years has been in the development of new zinc-aluminum alloys. However, Zn-Al alloys have a low lubrication level, low ductility at room temperature and reduced mechanical strength  at high temperature. In this sense, this work aims to study the effects of Cu additions on the solidification thermal parameters such as cooling and growth rates (ṪL/VL-liquidus isotherm and ṪE/VE-eutectic front), microstructure (dendritic and eutectic arrangements), hardness and wear resistance of a hypereutectic Zn-8wt.%Al alloy. Techniques such as X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Optical Microscopy (OM) and Scanning Electronics (SEM) were used to characterize the as-cast samples. The results showed that Zn-Al-Cu alloys are formed by an eutectic matrix [(Zn)+(Al+Zn)] with lamellar and fibrous morphology also containing τ'-Al4Cu3Zn intermetallic particles and Al-rich pro-eutectic dendrites (Al'), with alternating lamellae of Al and Zn, from the eutectoid transformation [(Al')↔(Al)+ (Zn)]. The addition of 0.8wt.% Cu did not change the secondary dendritic arm spacing (λ2), while a 1.3wt.% Cu content generated a slight dendritic refinement. The Cu additions have coarsen the fibrous (λEF) and lamellar (λEL) eutectic of the binary Zn-8wt.%Al alloy, with exception of the Zn-8wt.% Al-1.3wt.% Cu alloy, which showed a refinement of the fibrous eutectic for VE> 0.30 mm/s. Increase in hardness has been observed for both Cu-modified alloys due to the solid-solution strengthening mechanism and presence of the τ'-Al4Cu3Zn intermetallics. An expressive increase of about 73.4% has been observed due to the addition of 1.3% Cu, which is also related to lower eutectic fibrous spacings. The Zn-8wt.%Al-0.8wt.% Cu alloy showed higher wear resistance associated with a lower fraction of τ’-Al4Cu3Zn.

Tesis
1
  • JORGE DANIEL ARAUJO PINTO
  • Evaluation of the mechanical behavior of Portland-micronized PU blends under vapor injection conditions

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • EVANS PAIVA DA COSTA FERREIRA
  • MARCOS ALLYSON FELIPE RODRIGUES
  • KLEBER CAVALCANTI CABRAL
  • ULISSES TARGINO BEZERRA
  • Data: 07-ago-2020


  • Resumen Espectáculo
  • Steam injection is an economically viable alternative and it’s widely used for heavy oil recovery in oil wells. In this technique the temperature of the fluids present there is increased and consequently that of the well. This temperature increase causes the dilate of casing, which returns to its initial dimensions with the end of the injection cycle, generating stresses and cracks in the cement sheath. For this reason an appropriate cementation design should be done to avoid future failure of the cement sheath due to thermal stresses. For this goal, this work focused on the addition of a micronized polyurethane powder to the cement mass to increase its mechanical properties such as compressive strength and fracture energy during breakage. For this purpose, were accomplished compressive strength tests and  technological tests in fresh state. Slurries with 0, 1 and 4% polyurethane powder were formulated in addition to the cement and cured at temperatures of 38 ° C and 300 ° C for 1 and 7 days respectively and pressure of 2kpsi for slurries cured at 300 ° C, because they are slurries that simulate the injection of steam. A characterization was also made in SEM, XRD, TG / DTG and DSC. The results showed that the polymer had a good adhesion to the matrix which provided a good strength gain and absorbed energy before the fracture in the order of 75.48% and 61.99% respectively considering the formulation with 1% of the additive under study which was the one that got the best results.

2
  • HUGO PLÍNIO DE ANDRADE ALVES
  • Structural and magnetic properties of the zirconia-magnetic particle and zirconia-graphene ceramic tapes

  • Líder : WILSON ACCHAR
  • MIEMBROS DE LA BANCA :
  • LISZANDRA FERNANDA ARAÚJO CAMPOS
  • Antonio Carlos Silva da Costa
  • DANIEL ARAÚJO DE MACEDO
  • MARCIO ASSOLIN CORREA
  • WILSON ACCHAR
  • Data: 17-ago-2020


  • Resumen Espectáculo
  • The search for improvement in the integration of materials with magnetic advantages in ceramic matrices is an attractive topic since there is a lack of literature. Materials such as magnetic particles and graphene become candidates for improving the magnetic performance of ceramic matrices. In this work, the magnetic particles were produced by the microwave-assisted combustion method to obtain iron oxides. The tape casting technique was used to produce the ceramic tapes. This thesis aims to study the structural and magnetic properties of zirconia-magnetic particles and zirconia-graphene ceramic tapes, mainly after sintered at 1200 ºC. The suspensions of the ceramic materials presented the pseudoplastic behavior, which is recommended for the tape casting technique, verified by the viscosity test. X-ray diffractograms revealed the phases of monoclinic zirconia, tetragonal zirconia, magnetite, and hematite. The presence of graphene in the sintered ceramic tape was confirmed by Raman spectroscopy analysis. The ceramic tapes presented irregular morphologies and grains of different sizes. However, the tape incorporated with graphene has an appropriate amount of pores and agglomerates. The magnetic behavior of the zirconia ceramic tape was affected by the incorporation of materials, magnetic particles (magnetite and hematite), and graphene. The considerable increase in the hematite phase, after sintering, led to a change in the ferrimagnetic order (green tape) to antiferromagnetic order (sintered tape). Graphene, in turn, boosted the ferromagnetic behavior in the sintered tape. Based on these results, ceramic tapes become excellent candidates for technological applications in magnetic devices and carbon-based composite materials.

3
  • JOÃO BATISTA DUARTE
  • STUDY THE JOINT ADDITION OF ASH OF SUGARCANE BAGASSE AND CERAMIC WASTE IN THE PRODUCTION OF AGGLOMERANT (S) SOIL BRICKS.

  • Líder : WILSON ACCHAR
  • MIEMBROS DE LA BANCA :
  • OLAVO FRANCISCO DOS SANTOS JUNIOR
  • PRISCYLLA CINTHYA ALVES GONDIM
  • SHEYLA KAROLINA JUSTINO MARQUES
  • VAMBERTO MONTEIRO DA SILVA
  • WILSON ACCHAR
  • Data: 20-ago-2020


  • Resumen Espectáculo
  • The civil construction and agribusiness industries are under enormous pressure from the improvement of environmental legislation, aiming at the elaboration of processes and products that require less energy production and that can be reused at the end of their life cycle. In Brazilian agribusiness sugarcane is an agricultural product with the lowest production costs in the world. Calcination of sugarcane bagasse generates sugarcane bagasse (CBC) ash which is an environmental liability that can contaminate the soil and groundwater. This reality, concerning the generation of expressive volumes of waste, is repeated in the productive chain of civil construction, especially the losses resulting from the breaking of ceramic bricks, in the transportation, storage and use processes for the construction of masonry without structural purposes. The ceramic residue (RC), from the breaking of the ceramic brick, when comminuted will increase the specific surface of its particles and allow greater reactivity. Therefore, the use of BCC and RC in the process of manufacturing solid bricks of soil-binder (s) is technically feasible due to the possibility of occurrence of pozzolanic activity, that is, the formation of hydrated calcium silicates and aluminates resulting from recombination of the disorganized silica and alumina existing in the same and in the lateritic soil, with the portlandite phase (Ca(OH)2), formed from the hydration of the cement and the chemical constitution of the hydrated lime. This scientific study carried out the mineralogical and chemical characterization of soil, lime, cement, CBC and RC. Then solid bricks of soil-binder (s) with and without 2% and 4% of RC and 2% of CBC were molded and subjected to tests of resistance to simple compression, water absorption and modified durability. The samples that presented the most significant results in the experiments were sent to perform the XRD and SEM tests. The ternary composition soil, 12% cement and 4% RC and the quaternary soil, 12% cement, 2% CBC and 2% RC showed the best results in relation to the aforementioned physical and mechanical properties.

2019
Disertaciones
1
  • LEULOMAR ENEDINO DO NASCIMENTO
  • STUDY OF THE NANOCOMPOSITS’ PHOTOCATALITIC ACTIVITY TiO2-x% CeO2 E CeO2-x% TiO2 OBTAINED BY THE HYDROTHERMIC METHOD ASSISTED BY MICROWAVES

  • Líder : FABIANA VILLELA DA MOTTA
  • MIEMBROS DE LA BANCA :
  • FABIANA VILLELA DA MOTTA
  • MAURICIO ROBERTO BOMIO DELMONTE
  • VINÍCIUS DANTAS DE ARAÚJO
  • Data: 22-feb-2019


  • Resumen Espectáculo
  • The accelerated industrial growth allied to the expansion of agriculture has been causing concern with the generation of polluting effluents, being their methods of treatment, the target of several studies to mitigate the damage caused by such waste. A widely studied method is the advanced oxidation process (POA), which aims for the treatment of organic effluents. In this work, heterostructured nanocomposites were obtained from titanium oxide and cerium oxide, forming compounds CeO2-x% TiO2 and TiO2-x% CeO2, varying x = 10, 30 and 50%. The nanocomposites were synthesized by the microwave assisted hydrothermal method, with subsequent calcination at 500 ° C, with the aim of investigating the photocatalytic activity through the degradation of methylene blue dye under UV radiation, commonly used in the textile industry. The compounds were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), surface area analyzed by the BET method (Brunauer, Emmett, Teller) and UV-Vis spectroscopy (UV-Vis). The XRD results showed formation of TiO2 and CeO2 phases, with no indication of chemical interaction between the two compounds. Morphologies of nanocubes and nanospheres with different levels of agglomeration and average particle size varying from 2 to 24 nm were observed, as well as a specific surface area ranging from 20.24 m2 / g to 62.80 m2 / g. For the nanocomposite using CeO2-x% TiO2, the compounds with x = 50% presented better photocatalytic activities, with degradation of approximately 80% of the dye. From the compounds with TiO2 as the matrix, the TiO2-x% CeO2 nanocomposite with x = 10% degrading the entire dye.

2
  • ALINE ALENCAR EMERENCIANO
  • SYNTHESIS AND CHARACTERIZATION OF Ca3Co4O9 AS A THERMOELECTRIC MATERIAL

  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • ANA PAULA CYSNE BARBOSA
  • CARLOS ALBERTO PASKOCIMAS
  • DANIEL ARAÚJO DE MACEDO
  • RUBENS MARIBONDO DO NASCIMENTO
  • Data: 27-feb-2019


  • Resumen Espectáculo
  • Faced with the requirement for cleaner and higher energy efficiency technologies, we have noticed a significant focus on the research of thermoelectric materials, capable of converting thermal energy into electric energy. The Ca3Co4O9 metal oxide is a great alternative, since its specific properties added to the improvement of its microstructure allow the production of a compound with considerable thermoelectric characteristics in relation to others reported in the literature. The stable phase Ca 3 Co 4 O 9, present in a very restricted range in the CaO-CoO phase diagram, can be obtained by controlling the composition and the temperature. In order to improve the production of calcium cobalt (C349) three different synthesis techniques were implemented in this project followed by thermal treatment (precalcination at 350 ° C / 2h, calcination at 900 ° C / 2h and sintering at 900 / 24h). The synthesis by the amorphous citrate method without the use of dispersant, the synthesis by the Sol gel protein method and the synthesis by Solid State Reaction with mechanical activation by high energy grinding - CaCO3 being one of its precursors, coming from shellfish, which further reinforces the environmental motivation in this work. In all samples there was the formation of subsystem [Ca2CoO3-δ] q [CoO2], identified by X-ray diffraction with Rietveld's refinement; the secondary Ca3Co2O6 phase was present in samples from the Citrate method. Their microstructures were analyzed by Electron Transmission Electron Microscopy (STEM) and X-ray Spectroscopy by Energy Dispersion (EDS) and the determination of the electrical properties of the compound was analyzed by obtaining the Seebeck Coefficient, electrical conductivity, electric resistivity and Power Factor. The processes presented grains in micro and nano scale, and in all of them there was the formation of the subsystem [Ca2CoO3-δ] q [CoO2]. In the three different methods, with relative densities around 66%, the highest value of the Power Factor at ~ 700 ° C was obtained in the pellets from the synthesis of C349 by the Sol-gel Proteico method (0.21 mW / mK2).

3
  • LUAN MAYK TÔRRES COSTA
  • INFLUENCE OF ADDING COATINGS BASED ON PVC AND ALUMINUM IN THE DEPOSITED METAL BY COATED ELECTRODES E-7018

  • Líder : AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • MIEMBROS DE LA BANCA :
  • AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • NICOLAU APOENA CASTRO
  • ALEXANDRE QUEIROZ BRACARENSE
  • Data: 12-mar-2019


  • Resumen Espectáculo
  • The shielded metal arc welding (SMAW) presents competitive advantages that this union process as one of most important in industrial scale. However, the humidity absorption is a problem that requires special cares to stock the electrodes, to avoid the mechanical properties degradation. Trying to control the H, PVC films and aluminum ink coatings were applied in E-7018 electrodes to weld ASTM SA36 steel. In this paper was realized a comparative study among different welded samples: E-7018, pure and with coating, and using BRH4-R electrode. The molten zone characterization of these samples is a sequential continuation of the works developed by RAMOS (2015) and SOUZA (2017). Through the optical and scanning electron microscopies, it was observed that the molten zone microstructure, in all samples, is composed by acicular, polygonal and Widmanstatten ferrite, upper bainite, ferrite-carbine aggregates and, in some regions, MA micro-constituent. The EBSD technique, in addition to the others methods, confirmed that the welding using BRH4-R electrode formed coarser grains than the others samples, less amount of acicular ferrite and also AF with lower aspect ratio. Among the E-7018 electrodes, it could be observed the coating was responsible to refine the monten zone microstructure, comparing with the pure condition, to form AF grains in greater quantity and smaller. In all cases, the acicular ferrite aspect ratio variated between 2 and 10. Though the EBSD, it was possible to note the coating provided higher MA microconstituent formation and this condition could reduce the steel toughness. The BRH4-R presented the lowest formation of MA.

4
  • JOSÉ NAELSON DA CUNHA
  • EFFECT OF THERMAL TREATMENTS CYCLES OF RELIEF THE MICROSTRUCTURE AND MECHANICAL PROPERTIES OF THE API 5L X80 STEEL AFTER DISSIMILAR WELDING WITH AISI 4130

  • Líder : AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • MIEMBROS DE LA BANCA :
  • ALEXANDRE QUEIROZ BRACARENSE
  • AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • NICOLAU APOENA CASTRO
  • Data: 12-mar-2019


  • Resumen Espectáculo
  • This work aims to study the modifications in the microstructures and mechanical properties in the Heat Affected Zone - HAZ, of API 5L X80 steel, caused by the welding processes and Post-Weld Heat Treatment - PWHT. The motivation for this work is to understand the effects on ZAC of API 5L X80 steel, after welding processes and PWHT, in dissimilar welding with AISI 4130 steel, used in the manufacture of drilling risers. For this study, a tubular welded joint with a TIG root pass and filling passes with a coated electrode was submitted to 5 (five) cycles of PWHT, always with the same parameters, from which the coupons for the manufacture of samples, with 1 (one), 3 (three) and 5 (five) cycles of PWHT were extracted. The were used for metallographic analyzes (macrography, optical microscopy and scanning electron) and mechanical tests (traction, microhardness and Charpy-V), characterization of microstructure and mechanical properties, in the three situations studied. The results obtained in the microstructures and in the mechanical properties of the ZAC of the API 5L X80 steel, after the welding process and the TTAT cycles, show that the decomposition of the MA constituent and the reduction of the ferrite-carbonate volumetric fraction initially did not cause losses in the mechanical properties, due to the hardening caused by the precipitation of carbides, but with the increase of the TTAT cycles, the microstructural changes continue to occur, without the precipitation of the carbides, promoting significant losses in the mechanical properties. The impact toughness for all conditions studied was above 200 J, higher than the minimum limit of 68 J, for the temperature of 0ºC, as determined by the standard. The average values of the microhardness in the ZAC of the X80 steel showed reduction with the increase of the TTAT cycles. Some regions presented an average of less than 200 HV, for an expected value close to 250 HV, as determined by the standard.

5
  • TOMAZ RODRIGUES DE ARAÚJO
  • NICKEL-BASED CATALYSTS SUPPORTED ON PEROVSKITES IN CÉRIO (CexAl2-xO3) FOR THE DRY METHANE REFORM

  • Líder : MARCUS ANTONIO DE FREITAS MELO
  • MIEMBROS DE LA BANCA :
  • ELEDIR VITOR SOBRINHO
  • MARCUS ANTONIO DE FREITAS MELO
  • RENATA MARTINS BRAGA
  • RODOLFO LUIZ BEZERRA DE ARAÚJO MEDEIROS
  • RODRIGO CESAR SANTIAGO
  • Data: 15-mar-2019


  • Resumen Espectáculo
  • Cerium aluminate is a perovskite of the type AmBnO3 what has catalytic properties little studied when synthesized by microwave assisted autocombustion. In this context, the objective of this work was to produce cerium aluminates in one-step microwave assisted combustion using a single fuel (urea, 250% excess) and apply them as a support in the dry reforming of methane. The variation of the cerium content was: 0.25; 0.50; 0.75 and 1 mol; after the synthesis the supports were impregnated with 10% nickel by mass, and then calcined at 500 °C for 3 h by heating them to 10 °C.min-1 . The X-ray diffraction, scanning electron microscopy (MEV-EDS), thermogravimetric analysis, specific surface area (BET-BJH), helium gas density, MEV-FEG, programmed temperature reduction, in-situ X-ray diffraction (XPD) and absorption spectroscopy in the ultraviolet and visible region were the techniques used in the characterizations. The results show that the formation of the aluminate in the synthesis with reflectance band (380 nm), density (5.06 to 5.96 g.cm- ³), specific area (20.44 to 24.74 m².g-1 ), heterogeneous morphology expressed by diverse surface and rugged reliefs, in addition to conversions above 60% for CO2 and CH4, even though there was coke formation with nanotube morphology, however, there was no deactivation of the catalysts after 20 h of reaction. These results shows if relevants, once the work produced single-stage perovskites Ce1Al1O3 with stable crystalline structure and promising catalytic performance for the syngas gas industry, besides optimize the manufacturing process of these catalysts with the elimination of the calcination step of the support.

6
  • VANESSA SANTOS FONSECA PINHEIRO
  • SYNTHESIS, CHARACTERIZATION AND STUDY OF THE PHOTOCATALITICAL PROPERTIES OF CuO AND COMPOUND CuO / ZnO

  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • JOSE HERIBERTO OLIVEIRA DO NASCIMENTO
  • JUAN ALBERTO CHAVEZ RUIZ
  • MAURICIO ROBERTO BOMIO DELMONTE
  • Data: 12-abr-2019


  • Resumen Espectáculo
  • Due to the large number of industries and the excessive amount of pollutants they produce, the environment and humans are increasingly exposed to risks. One of the main agents in water pollution is the toxic dyes, produced mostly by the textile industries. Because they have complex structures, they are difficult to degrade, and advanced oxidative processes (POAs) are an efficient alternative in the degradation of these organic compounds. In this work, copper oxide (CuO) nanoparticles were synthesized by microwave assisted hydrothermal method, with the addition of ethylenediamine surfactant. Synthesis of pure CuO and addition of 1, 2 and 3 ml of EDA were performed at 140 ° C for 30 min. The nanoparticles were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (SEM-FEG) and UV-Vis (UV-Vis) spectroscopy. In order to verify the photocatalytic property, degradation tests of the methylene blue dye were carried out. The results of X-ray diffraction confirmed CuO formation, and all the samples showed photocatalytic activity. In addition, ZnO nanoparticles were synthesized in this work and a CuO 3 EDA / ZnO composite was prepared by microwave assisted hydrothermal method at 140 ° C for 30 min in order to obtain more satisfactory results of photocatalysis than those obtained for CuO samples previously done. This material was characterized via DRX, MEV-FEG and degradation tests of the methylene blue dye were performed. The results confirmed the formation of the composite and it showed superior photocatalytic activity than the CuO samples.

7
  • REBECCA ARAÚJO BARROS DO NASCIMENTO SANTIAGO
  • IRON ORE OF BRAZIL AS OXYGEN CAREERS FOR APPLICATION IN COMBUSTION PROCESSES WITH CHEMICAL RECIRCULATION.

  • Líder : DULCE MARIA DE ARAUJO MELO
  • MIEMBROS DE LA BANCA :
  • DULCE MARIA DE ARAUJO MELO
  • JUAN ALBERTO CHAVEZ RUIZ
  • MAURICIO ROBERTO BOMIO DELMONTE
  • RODOLFO LUIZ BEZERRA DE ARAÚJO MEDEIROS
  • Data: 12-abr-2019


  • Resumen Espectáculo
  • The greenhouse effect is a natural and essential process for sustaining life on earth, however, since the pre-industrial era, anthropogenic emissions of greenhouse gases (GHGs) have increased in large part by economic and population growth. In this context, the growing energy demand is mainly supplied by fossil fuels, resulting in a scenario of significant impacts on the environment, since the burning of these fuels for the generation of energy produces CO2, which is considered the main gas of anthropogenic origin more aggravating this It is made. Because of this, researchers around the world have suggested measures and technologies that meet the energy needs with low levels of CO2 emissions. Among the technologies, the Chemical Looping Combustion (CLC) process, which promotes indirect fuel combustion through oxygen carriers, is considered one of the best alternatives to reduce costs in capturing carbon dioxide without energy penalties. In view of this, this dissertation aims to evaluate iron and manganese ores from different regions of Brazil to select the most promising ones to be applied in CLC processes. The techniques and methodologies used were X-ray diffraction (XRD), reduction and oxidation at programmed temperature (RTP and OTP), oxygen transport capacity (Roc), fracture resistance, X-ray fluorescence (FRX) and reactivity by thermogravimetry. The chemical composition of each ore was obtained by FRX. Through DRX the main reactive phases were identified as Fe2O3 for iron ores and Mn3O4 for manganese ores. During the TPR and TPO analysis, these active phases were submitted, respectively, to the atmosphere of H2 and later to synthetic air and presented good reduction and oxidation capacity. Through the consumption of H2 used to reduce each phase, the experimental Roc of the oxygen transporters was calculated. Due to the structural characteristics and the reactivity tests of these materials, it was concluded that iron ores had better reactivity compared to manganese ores, in addition to their high mechanical strength when used in natura. Therefore, due to the abundance of iron ore in Brazil and its low cost, it is possible to infer them as promising materials for application in CLC processes.

8
  • ONÉCIMA BIATRIZ DE MEDEIROS RAMALHO
  • STUDY OF PHOTOCATALITICAL AND ANTIMICROBIAL ACTIVITY OF TiO2 DOPED WITH Fe+3 AND Pb+2 OBTAINED BY SONOCHEMICAL METHOD

  • Líder : FABIANA VILLELA DA MOTTA
  • MIEMBROS DE LA BANCA :
  • CARLOS ALBERTO PASKOCIMAS
  • FABIANA VILLELA DA MOTTA
  • VINÍCIUS DANTAS DE ARAÚJO
  • Data: 31-may-2019


  • Resumen Espectáculo
  • With the growth of the economy and industries, effluents are eliminated in the environment, grow exponentially, making it necessary to act in a socio-environmental way so that the waste disposed of does not cause damage to the environment or a society. Effluents from textile industries are not successful in your degradation by traditional treatment methods, making new methods to be researched and used. Advanced oxidative processes (AOPs) are an effective alternative to the degradation of organic pollutants and have been widely used because of their potential to clean effluents. TiO2 is a very abundant material in the earth's crust and has good photocatalytic properties, especially when coupled with metal and/or semi-metallic dopants and co-dopants. In this work, TiO2 nanoparticles were doped and co-doped with Fe+3 and Pb+2, using different concentrations of dopant ions. The samples were prepared by the sonochemical method and didn’t require a subsequent heat treatment. The phases were characterized by X-ray diffraction (XRD), the particle morphologies analyzed by transmission electron microscopy (TEM), and the optical properties by UV-Vis spectroscopy (UV-Vis) and surface area by BET method. The photocatalytic activity was verified by the degradation of methylene blue dye (MB) irradiated by UV radiation and sunlight radiation and the antimicrobial activity compared to gram positive (Staphylococcus aureus) and gram negative bacteria (Escherichia coli). The XRD patterns exhibited only the anatase phase of TiO2, even using the maximum percentage of dopants. TEM analysis showed that the particles of pure TiO2 are agglomerated and that with the addition of the Fe3+ ion these particles are deagglomerated. UV-Vis analysis showed that the addition of dopants in the titania lattice reduces the band energy (Egap) and surface area decreased with the introduction of dopants. The results of the photocatalysis tests indicated that the addition of dopants and co-dopants improved photocatalytic activity for compositions with concentrations below 1% in UV light and up to 1% in sunlight. The antimicrobial activity was also investigated and samples TiO2:1%Fe:3%Pb, TiO2:1% Pb:1%Fe and TiO2:1%Pb:3%Fe showed a zone of inhibition, indicating the antibacterial effect of the samples synthesized.

9
  • JEVERTON LAUREANO PAIXÃO
  • Influence of the Antimony additions on the Directionally Solidified Hypoeutectic Sn-52wt.%Bi alloy: Thermal Parameters, Microsctructures and Mechanical Resistance

  • Líder : BISMARCK LUIZ SILVA
  • MIEMBROS DE LA BANCA :
  • BISMARCK LUIZ SILVA
  • CLAUDIO ALVES DE SIQUEIRA FILHO
  • MAURÍCIO MHIRDAUI PERES
  • Data: 17-jul-2019


  • Resumen Espectáculo
  • The search for sustainable and less toxic materials is a global trend and should draw even more attention in the coming years due to the new and current restrictions/directives of environmental agencies. Lead-free solder alloys used in the electronics industry are examples of this scenario. In this context the present investigation aims to establish correlations between the solidification thermal parameters (cooling rate-ṪL and growth rate-VL) and microstructural parameters (primary-λ1, secondary-λ2 and tertiary-λ3 dendritic; and fine λF and coarse-λC eutectic spacings) for the directionally solidified (DS) Sn-52wt.%Bi-1wt.%Sb and Sn-52wt.%Bi-2wt.%Sb alloys under transient heat flow conditions. A dendritic array was identified for the Sn-Bi-Sb alloys formed by a Sn-rich matrix with Bi precipitates at its core, surrounded by lamellar eutectic structures (Sn-rich+Bi-rich), Bi trifolis and fishbone-like eutectic. The significant fraction of eutectic mixture (Sn-rich+Bi-rich) in the Sn-Bi-Sb alloys induced the -1/4 and -1/2 exponents, proposed by Jackson and Hunt for eutectics, characterize the evolutions of λ1, λ3 and λ2, as a function of ṪL and VL, respectively. These exponents also characterized evolutions of λF and λC against ṪL and VL for the modified alloy containing 1wt.%Sb. Hall-Petch type correlations for Sn-Bi-Sb alloys displayed that additions of 1wt.% and 2wt.%Sb have beneficial effects on the ultimate tensile strength-σu and the yield tensile strength-σy, but does not affect ductility (elongation to fracture-δ). Sb additions did not modify the fracture mode of the Sn-52wt.%Bi alloy.

10
  • LINDOLPHO SALES DANTAS DA COSTA LIMA
  • DEVELOPMENT OF PHASE'S QUANTIFICATION METHOD IN DUAL PHASE BY EBSD

  • Líder : FABIO JOSE PINHEIRO SOUSA
  • MIEMBROS DE LA BANCA :
  • FABIO JOSE PINHEIRO SOUSA
  • MAURÍCIO MHIRDAUI PERES
  • NICOLAU APOENA CASTRO
  • AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • Data: 15-ago-2019


  • Resumen Espectáculo
  • Dual Phase steels are advanced high strength steels widely used in the automotive industry. The microstructure is based on martensite-austenite (MA) islands, dispersed in a ferrite matrix, its properties are high mechanical strength and good deformability. These features are differential in the automobile’s applications, because provide improve toughness and safety to the vehicle, as well as weight and fuel consumption reduction. Dual Phase steels are commonly characterized by optical microscopy (OM). The quantification of these phases, in general, occurs through the binarization of the image obtained by OM. However, the evaluation of these steels by OM presents problems related to the contrast between the phases, because one of its most used reagent (LePera) has a complex etching and reveal wrong microstructures after the attack. Characterization, in Dual Phase steels, using electron backscattered diffraction (EBSD) has been used more frequently, mainly using the pattern quality (PQ) analysis. In this paper, the EBSD PQ technique was used with the OM technique to develop a method to quantify Dual Phase steels by EBSD. For this, the microstructure and the second constituent’s fraction were compared, using Dual Phase steels submitted to different soaking temperatures (720 ° C, 740 ° C and 760 ° C), previously obtained by LIMA (2018). Thus, it was observed an evolution in the second constituent’s fraction, caused by the increase of the soaking temperature, in both methods. However, the quantification results showed the Threshold MA quantification method by Threshold attributed by the deconvolution's intersection standard, by the EBSD, showed the most representative MA values, because their values were not distant as the quantification by the area calculation of deconvolved histogram method. Furthermore, the intersection method was superior to the MA quantification method using arbitrary Threshold thought EBSD and OM, once there are not errors’ accumulation linked to the repeatability of the MA fractions, compared to these methods.

11
  • LIDIANE SILVA RAMOS
  • Directional solidification of the eutectic Sn-9wt.%Zn alloy: Inter-relations of microstructure, thermal parameters and mechanical properties

  • Líder : BISMARCK LUIZ SILVA
  • MIEMBROS DE LA BANCA :
  • BISMARCK LUIZ SILVA
  • NICOLAU APOENA CASTRO
  • CRYSTOPHER CARDOSO DE BRITO
  • Data: 15-ago-2019


  • Resumen Espectáculo
  • The manufacture and use of electronic devices have grown every year in the various applications, however the sustainable control of the materials used still needs to advance. It’s at this moment that lead-free solder alloys enter as alternatives to sustainable materials in the electronics industry. In this context, the present investigation aims to study the growth eutectic in the Sn-9wt%Zn alloy solidified on different substrates (steel and copper). Microstructural features (phases, morphologies, distribution and microstructural scale such as eutectic and cellular spacings), thermal parameters (growth rate-VE and cooling rate-ṪE), experimental growth laws and tensile mechanical properties (ultimate tensile strength-σu, yield tensile strength-σY and elongation-to-fracture-δ) have been discussed. Sn-Zn alloy castings displayed a microstructure with eutectic colonies formed by Zn-rich phase, α-Zn, dispersed with two morphologies, globular-λg and needles-λn, in the Sn-rich matrix. Considering two Sn-Zn ingots, it can be seen that for VE>1,38 mm/s e ṪE>4,75 °C/s values, a globular morphology prevails in the microstructure, while for VE<0,88 mm/s e ṪE<1,86°C/s values, α-Zn needles predominate. Higher mechanical resistance (σu and σY) and ductility (δ) values have been observed for refined structures in both Sn-Zn alloy castings. The fractographs revealed a mode of ductile fracture for the Sn-Zn ingots analyzed, with higher fraction of dimples.

12
  • ARIKLÊNIO ALVES DA SILVA
  • Iron and nickel based oxygen carriers for application in the chemical looping reforming of methane process 
  • Líder : DULCE MARIA DE ARAUJO MELO
  • MIEMBROS DE LA BANCA :
  • DULCE MARIA DE ARAUJO MELO
  • ELANIA MARIA FERNANDES SILVA
  • RODOLFO LUIZ BEZERRA DE ARAÚJO MEDEIROS
  • TIAGO ROBERTO DA COSTA
  • Data: 25-oct-2019


  • Resumen Espectáculo
  • The actual global energy demand has caused an increase in anthropogenic emissions of greenhouse gases from the burning of fossil fuels. Because of that, energy production processes that release smaller amounts of these gases into the atmosphere have been the target of studies in recent years. Among these processes, Chemical Looping Reforming (CLR) of methane has gained attention because, through this process, methane is converted into synthesis gas, a mixture of carbon monoxide and hydrogen, without the release of CO2. Moreover, hydrogen is a clean combustion energy source, that means it does not release pollutants into the atmosphere, since its burning results in only water and heat. One of the determining factors of the CLR process efficiency lies in the performance of a solid oxygen carrier, which is a metal oxide-based material that promotes the conversion of the fuel into its reaction products, and it is necessary the development of a material that possess favorable properties and characteristics to this process. Based on this, this master's thesis aims to synthesize and characterize iron and nickel-based solid oxygen carriers supported in calcium aluminate and to evaluate the most promising to be applied in CLR processes. Calcium aluminate support was synthesized from eggshell as the only calcium source, since it is a rich CaCO3 residue; then, iron and nickel were impregnated in this support through the incipient wetness impregnation technique, in order to obtain 4 oxygen carriers: one with iron only, one with nickel only and two containing iron and nickel in different proportions (30% and 70%). Oxygen carriers were characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), scanning electron microscopy (SEM) with EDS and reactivity by thermogravimetry techniques. Through XRD results, CaFe2O4 and FeAl2O4 phases were identified as the most reactive for iron-based oxygen carriers and NiO phase for nickel-containing oxygen carriers. The observation of the reduction profiles of the oxygen carriers indicates that the increase in the iron content leads to an increase in the reduction temperatures, suggesting a decrease in the oxygen transport rate. Additionally, it was observed through SEM images that the oxygen carriers exhibited different morphologies depending on the content of each metal, and a fine dispersion of the active phases on the support surface was observed in EDS mapping. From the reactivity tests by thermogravimetry it was observed that the oxygen carriers presented the capacity of reduction and oxidation in successive chemical cycles using methane, and an increase in the oxygen transport rate was reported as the nickel content increased. A maximum conversion of solids in the order of 89,5% was achieved in 66 seconds for the sample containing 70% of iron and 30% of nickel. Samples with 70% e 100% of nickel content showed better solids conversions compared to the one with 30% of nickel, but this difference is not that significative when taking into account the smaller nickel content of this last sample, which was classified as the most promising of this study. The evaluated materials, except for the iron-only based oxygen carrier, are suitable for application in CLR processes.

13
  • JOSUÉ SANTIAGO DE ALMEIDA
  • Thermocatalytic degradation of HDPE and PP using zeolites H-Y and H-Beta for liquid fuel production.

     

  • Líder : VALTER JOSE FERNANDES JUNIOR
  • MIEMBROS DE LA BANCA :
  • ANTONIO SOUZA DE ARAUJO
  • CAMILA GISELE DAMASCENO PEIXOTO MORAIS
  • GLAUBER JOSÉ TUROLLA FERNANDES
  • VALTER JOSE FERNANDES JUNIOR
  • Data: 20-dic-2019


  • Resumen Espectáculo
  • The problem of environmental pollution caused by the inadequate disposal of plastics in the environment has become the subject of several discourses among researchers the last decades. Polymers, which are essential  in many industries, have low biodegradability, whose degradation time can vary from a few decades to several hundred years.

    In recent years, one of the alternatives that has drawn researchers' attention to try to overcome this problem concerns the thermocatalytic degradation of thermoplastic materials. This type of process aims to generate low molecular weight and high added value compounds such as hydrocarbons with carbon chain size similar to fossil fuels.

    In this study, high density polyethylene (HDPE) and polypropylene (PP) samples were subjected to thermal (without catalysts) and thermocatalytic degradation using the HY and H-Beta zeolites in a thermogravimetric balance and a reactor. For thermogravimetric analyses, the kinetics chemistry, such as activation energy, and for tests with reactor, the products were collected and further analyzed by gas chromatography, with for a test of the composition of the distribution of the carbon chains of the formed products. Zeolitic materials were characterized by X-ray diffractometry, X-ray fluorescence, scanning electron microscopy and n-butylamine desorption acidity assays.

    From the results obtained, it can be concluded that it is possible to generate hydrocarbon fractions in the range of gasoline and diesel in the two thermal degradation processes. However, the use of zeolitic catalysts, in addition to decreasing the degradation temperature, contributes to the final product having a distribution of smaller carbon chains, getting closer to gasoline.

Tesis
1
  • ANNA RAFFAELA DE MATOS COSTA
  • POLY (B-HYDROXYBUTYRATE) AND POLY (BUTYLENE-ADIPATE-CO-TEREPHTHALATE) BLENDS AND THEIR COMPOSITES WITH BABAÇU: EFFECT OF COMPOSITION AND PROCESSING CONDITIONS

  • Líder : EDSON NORIYUKI ITO
  • MIEMBROS DE LA BANCA :
  • AMANDA MELISSA DAMIAO LEITE
  • EDSON NORIYUKI ITO
  • ELITON SOUTO DE MEDEIROS
  • LAURA HECKER DE CARVALHO
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • Data: 19-feb-2019


  • Resumen Espectáculo
  • This work deals with PHB/PBAT blends as well as their composites with fibers extracted from two parts of the babassu fruit (epicarp and endocarp). The effect of processing conditions on the rheological, thermal and morphological properties of the composites as a function of load type and content was evaluated. PHB/ PBAT blends were processed in an internal mixer. They were characterized by torque rheometry and their crystallization and melting behavior were analyzed by differential scanning calorimetry (DSC). Composites having three different blends as the matrix and reinforced with 10 and 20 %wt. of the two kinds of fibrous loads were melt processed in an internal laboratory mixer and characterized by torque rheometry. Degradation rates, estimated by the reduction of the torque and molar mass during processing, were associated to blend composition as well as to the filler kind (epicarp or mesocarp) and content. Scanning electron microscopy was used to analyse the interface of the blends and composites, while optical microscopy was used to reveal the filler dispersion. DSC results showed that PBAT crystallizes completely during cooling while PHB and PHB/PBAT blends incompletely crystallized from the melt, the process achieving completion during the reheating step. These characteristics were independent of the heating rate and are the same for the pure polymers and for the blend with 50 %wt. of the PBAT. Pseudo-Avrami, Ozawa and Mo classical macrokinetic models were employed to describe the evolution of crystallization from the melt and it was found that none of the three classical kinetic models tested could accurately predict the experimental data for the blend. Some models can be used - as predictive tools - for pure components (Ozawa for PHB, Mo for PBAT) with a reduced validity range. The results of torque rheometry showed that PHB degraded faster during processing than PBAT and that the combination of PHB with PBAT provided significant protection against excessive degradation of PHB. Both the presence and level of the two types of filler increased the incipient degradation of the blend. The images obtained by optical microscopy (OM) showed uniform filler distribution in the matrix in all cases, without agglomerates. SEM of the fracture surface morphology indicated better matrix/fiber adhesion in mixtures rich in PHB and composites with babassu epicarp.

2
  • JOSE AIRTON CUNHA COSTA
  • Formulation of phase change materials by the addition of vermiculite, diatomite and paraffin and application in cemetning mortars.

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • RUBENS MARIBONDO DO NASCIMENTO
  • GEORGE SANTOS MARINHO
  • ANA CECILIA VIEIRA DA NOBREGA
  • ULISSES TARGINO BEZERRA
  • Data: 19-mar-2019


  • Resumen Espectáculo
  • In order to ensure the thermal comfort of its users, residential and commercial buildings consume a large amount of energy to heat and cool the indoor environments and, consequently, air conditioners emit significant amounts of greenhouse gases in urban agglomerations. Concerns in the current century to reduce energy consumption and emission of gases, therefore, lead to advances in the use of materials capable of storing energy in the phase transition process, with special dedication to PCMs (Phase Change Materials). In this study, a material with phase change, PCM, with potential for improving thermal performance in cement mortars, consisting of two solid and liquid paraffins (naphthenic oil) and two minerals as a support matrix (calcined diatomite and vermiculite expanded). First, characterizations by DSC and FT-IR were performed to determine the best ratio between paraffins for application in residential and commercial buildings. The starting minerals were characterized by TG, DTA, FRX, MEV, BET and FT-IR. PCM samples (paraffin + vermiculite) and PCM (1 + 2) (paraffin + diatomite + vermiculite) were prepared from the selected paraffin mixture and the minerals, and then named PCM1 (paraffin + diatomite), PCM2 characterized by MEV, FT-IR, BET. Cement mortars were prepared in volume ratio: 1: 4 cement: sand (control trace), 1: 4: 1 cement: sand: diatomite, cement 1: 4: 1: sand: vermiculite and 1: 4: 1 cement: sand: PCMs, and had their thermal properties measured. Finally, the thermal properties of PCM(1 + 2) were evaluated, varying to the sand volume, in the proportions of 0%, 25%, 50%, 75% and 100%. The DSC results of the paraffin blends pointed to the composition at 20% liquid paraffin as being ideal because it has adequate solid-liquid temperature and latent heat suitable for buildings. All PCMs had lower thermal conductivities than the control (1.47W / m.K), with PCM (1 + 2) being the lowest of them (0.82W / m.K). The PCM (1 + 2) also presented better diffusivity, volumetric heat capacity and thermal resistance. The simultaneous addition of vermiculite and diatomite to the composition of PCMs results in the improvement of their thermal properties, maintaining their fundamental characteristics as chemical and structural stability.

3
  • YANA LUCK NUNES
  • BIONANOCOMPOSITES PRODUCED FROM TILAPIA (Oreochromis niloticus) SKIN GELATIN AND DIALDEHYDE CELLULOSE NANOCRYSTALS.

  • Líder : MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • JOSE HERIBERTO OLIVEIRA DO NASCIMENTO
  • ROSANGELA DE CARVALHO BALABAN
  • ADRIANO LINCOLN ALBUQUERQUE MATTOS
  • MEN DE SÁ MOREIRA DE SOUZA FILHO
  • Data: 22-mar-2019


  • Resumen Espectáculo
  • The development of biodegradable polymers obtained from renewable sources is a research area that has been progressively growing. Gelatin has been widely used to produce films, but, like most biopolymers, has limitations due to its mechanical properties, which can be improved by the addition of crosslinking agents and nanocellulose as reinforcement. Thus, the aim of this work was to produce and characterize bionanocomposites obtained from tilapia skin gelatin with dialdehyde cellulose nanocrystals and compare them with bionanocomposites produced with unmodified cellulose nanocrystals. The gelatin was extracted from tilapia (Oreochromis niloticus) skins, and the nanocrystals of dialdehyde nanocellulose were obtained by sodium periodate oxidation of commercially available nanocrystals. The films were produced by casting and characterized by their mechanical, barrier, visual, thermal, structural and water interaction properties. Regarding the visual aspect, the films presented high transparency. It was observed that the addition of the oxidized and non-oxidized nanocrystals caused an increase in the values of Young’s modulus and tensile strength, indicating increase in the resistance of the films. Regarding the permeability to water vapor, no significant increase was observed in the bionanocomposites when compared to the pure gelatin film. Meanwhile, for the crosslinked films, lower values of water solubility and water absorption were observed. Thermal analyzes indicated an increase in thermal stability for films containing non-oxidized nanocrystals while there was no significant increase in thermal stability for most film compositions containing dialdehyde nanocellulose. The presence of the two types of nanocrystals induced a decrease in the crystallinity of the films. It was concluded that the bionanocomposite films produced have potential application in the packaging area, being less susceptible to water action and having good mechanical resistance. However, the oxidized nanocrystals had a greater effect decreasing the water susceptibility of the films, thus presenting a greater applicability for this purpose.

4
  • LARISSA BEZERRA DA SILVA
  • Development of Ceramic with high Sinterability based on Nano Alumina reinforced with CBC produced by tape casting

  • Líder : WILSON ACCHAR
  • MIEMBROS DE LA BANCA :
  • WILSON ACCHAR
  • Ana Paula da Silva Peres
  • Antonio Carlos Silva da Costa
  • MICHELINE DOS REIS ARAÚJO
  • SHEYLA KAROLINA JUSTINO MARQUES
  • Data: 25-mar-2019


  • Resumen Espectáculo
  • The current trend in the research and manufacture of new advanced and structural ceramics seems to favor the use of high purity and ultrafine powders combined with shorter sintering time and lower sintering temperature. Compositions with oxides aides (Cu2O, CuO, TiO2, MgO, B2O3, SiO2, K2O, Na2O, Li2O, ZrO2, ZnO) and the sugarcane bagasse ashes waste (CBC) were prepared with alumina to evaluate the effect of the sintering, density, hardness and microstructural. Thereafter ceramic tapes were produced by tape casting with the most promising formulation. Almost all of the composites showed densification below 1100 ° C. Higher density values (~ 95%) were obtained for compositions based respectively on borosilicate (F3 and F7) and soda lime glass (F8) containing Na on the precursor in powder, and F1, F2, F3 having TiO2 and Cu2O as precursors, and finally the composition with 10% of the ash from the sugarcane bagasse waste. Samples F5 (based on K), F9 (without K or Na in the powder precursor of glass) and F4 presented irregular morphology with the presence of intergranular porosity. The compositions F6, F7 and F8 presented uniform morphology corresponding to densification. And finally, from the mixture of alumina with CBC (AR) waste with addition of reinforcing particles and sintered at 1200ºC was chosen for the production of ceramic tapes. The ceramic suspension showed a decrease in viscosity with increasing shear rate, which characterizes a pseudo plastic behavior, allowing the production of tapes with homogeneous and flat surfaces. The average from the bending test value was 20.14 MPa for the 6 layer laminates.

5
  • ARMANDO MONTE MENDES
  • SOLVOTHERMAL SYNTHESIS OF BaTiO3: EFFECT OF PRESSURE ON THE MORPHOLOGY AND PARTICLE SIZE

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • DANIEL ARAÚJO DE MACEDO
  • DULCE MARIA DE ARAUJO MELO
  • MARCOS TADEU D'AZEREDO ORLANDO
  • SIBELE BERENICE CASTELLA PERGHER
  • Data: 02-may-2019


  • Resumen Espectáculo
  • In the constant effort for the development of materials free from agglomeration and with controlled morphology, it is necessary to understand the influence of the process parameters on the characteristics of the obtained material for later proposal of new experimental procedures. This work present a new methodology for the solvothermal synthesis of barium titanate (BaTiO3), followed by the investigation of the effect of parameters such as temperature, time and especially pressure on the morphological characteristics of the material. At first, a 316L stainless steel autoclave was built with a configuration that allows not only the temperature and time control, but also the control of pressure by ultra-pure gas injection. The precursor solutions were formed by titanium tetra-isopropoxide (C12H28O4Ti) and barium nitrate (Ba(NO3)2) as sources of metallic cations, a mixture of deionized water and ethanol was used as solvent and a potassium hydroxide (KOH) was used as mineralizer and pH adjustment agent. The syntheses were then performed at temperatures ranging from 80 °C to 180 °C, times between 15 minutes and 24 hours, and both inherent and induced pressures of 20 bar to 80 bar. The synthesized materials presented the tetragonal phase stabilization and a more expressive amount of a metastable pseudo-cubic, free from contaminations such as BaCO3. The different combinations of process parameters allowed the observation of a morphological evolution of particles and also the nucleation and crystal growth mechanisms, as well as the Ostwald ripening phenomena. Under conditions of inherent pressure, particles showed from amorphous rough spheres, trough agglomerates of nanocubes (mesocrystals) and irregular particles with anisotropic growth. The high pressure synthesis produced dendritic and flower-like morphologies with high surface area even without any surfactant agent. All samples were free from agglomerations.

6
  • FRED GUEDES CUNHA
  • Effect of the addition of fibers to reinforce lightweight concrete formulated using multiple residues

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • LEONARDO FLAMARION MARQUES CHAVES
  • PAULO ALYSSON BRILHANTE FAHEINA DE SOUZA
  • WENDELL ROSSINE MEDEIROS DE SOUZA
  • ZODINIO LAURISA MONTEIRO SAMPAIO
  • Data: 20-may-2019


  • Resumen Espectáculo
  • The final destination of residues originated from industrial and mining activities has gained growing attention from governmental representatives involved in environmental issues. One of the economic alternatives is their use as concrete additions, exploring their potential to reduce the consumption of Portland cement and concrete weight, and at the same time improve concrete strength and durability, aiming at structural applications. In this scenario, the objective of the present study was to evaluate the effect of fiber addition on the properties of a lightweight concrete mix formulated using expanded clay and multiple residues (porcelain polishing, tire rubber and limestone residues). The volume contents of steel, polypropylene, glass and carbon fibers added to the lightweight concrete mix were 0.2%, 0.4% and 0.6%. The resulting fiber-reinforced mixes were characterized by specific weight, void ratio, water absorption slump, mechanical (compressive and tensile) strength and fracture resistance. A fiber-free mix was also prepared and characterized for reference purposes. The results revealed that the addition of fibers generally reduced the workability of the mixes, as well as their specific weight and compressive strength. On the other hand, the void ratio and water absorption increased along with the tensile strength and fracture resistance.


7
  • ANDERSON LUIZ SOARES LEÃO
  • Alkaline lignin as an additive for Class C Portland cement pastes and its influence on the carbonation process
  • Líder : DULCE MARIA DE ARAUJO MELO
  • MIEMBROS DE LA BANCA :
  • CARINA GABRIELA DE MELO E MELO BARBOSA
  • DULCE MARIA DE ARAUJO MELO
  • ELEDIR VITOR SOBRINHO
  • RODOLFO LUIZ BEZERRA DE ARAÚJO MEDEIROS
  • RODRIGO CESAR SANTIAGO
  • Data: 24-may-2019


  • Resumen Espectáculo
  • Portland cement is a binder used globally in oil wells, as well as carbon capture and storage (CCS) and Carbon Capture and Storage (CCS) wells. Portland cement is highly reactive with carbon dioxide, a substance found on a large scale in the most diverse types of oil reservoirs, including pre-salt formations. The reactions of the Portland cement with the CO2 result in the formation of carbonates and bicarbonates, causing the degradation of the cement and consequent loss of mechanical resistance. Alkaline lignin is a natural polymer that has a long three-dimensional chain with active functional groups that change the cement grains surface energies and interactions of certain cement phases with CO2. In this study, SIGMA alkaline lignin was added in formulations with Portland Class G, at concentrations of 0.3% and 0.5% by weight of cement. The samples were divided into two groups, one group maintained in a bath without exposure to CO2 and, in the other, the samples were submerged in water and exposed for 90 days to the reactor under conditions of 2200 psi (149.7 ATM) CO2 and 70 ° C. Both groups were compared with samples of standard/reference formulation (cement and water). Results of pH, x-ray diffraction, infrared, scanning electron microscopy and thermogravimetric analyzes showed that the addition of lignin improved the cement resistance to reactions with CO2, reducing the advance of the carbonation front. Ettringite (Aft) and calcium silicate hydrate (C-S-H) presented significant interactions with the additive. The samples with 0.5%wt of additive presented in the area of longitudinal section an average of 87% preservation in the alkalinity and, the standard samples, average of 65% preservation of the alkalinity. The XRD results show a significant reduction in the formation of aragonite and carbonation of the hydrated calcium silicates in the samples with lignin. The additive does not appear to change the consumption of Ca(OH)2 in the carbonation process.

8
  • HÉRIK DANTAS DE LIMA
  • Study and development of a new material for electrical contacts based on Nb-15% pCu via high energy grinding and sintering by SPS

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • ARIADNE DE SOUZA SILVA
  • MARCELLO FILGUEIRA
  • NICOLAU APOENA CASTRO
  • RUBENS MARIBONDO DO NASCIMENTO
  • UILAME UMBELINO GOMES
  • Data: 04-jun-2019


  • Resumen Espectáculo
  • Several materials are currently used for the production of electrical contacts, heat sinks and coils with similar characteristics with those of the Nb and Cu alloy studied in this work. The objective of this work is the study and development of a new material for possible application in electrical contacts, using high energy grinding, with and without cryogenics, and sintering through SPS (Spark Plasma Sintering). For this, two powders of Nb and Cu, containing 15% by mass of Cu, were prepared and then milled by high energy grinding in a planetary type mill. The first powder was ground during the times of 1, 2 and 5 hours and the second was ground cryogenically for 26 hours. The powders appearance was obtained by MEV, EDS, XRD and IMAGE J. Subsequently the samples of the powders ground for 1.2 and 5 hours were sintered in the liquid phase via SPS at temperatures of 1100, 1400 and 1600 ° C. The powders ground for 26 hours were sintered via SPS at temperatures of 1000 ° C and 1100 ° C. The sintered bodies were observed and evaluated by CONFOCAL, SEM, EDS, XRD, EBSD, computed tomography, Vickers hardness, density and electrical conductivity. The bodies consolidated from the ground powders with the highest grinding time had higher values of density. Densified samples with up to 99.82% of the theoretical density were obtained for the sintered bodies of the crushed powders without cryogenics, and 97.8% for the sintered bodies of the crushed powders.

9
  • RAMON FERNANDES FAGUNDES
  • DEVELOPMENTS IN THE SERIAL PLASMA-MIG HYBRID PROCESS POTENTIALIZED BY THE HIGH PENETRATION MIG / MAG

  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • MARCELO FERREIRA MOTTA
  • NICOLAU APOENA CASTRO
  • RUBENS MARIBONDO DO NASCIMENTO
  • RÉGIS HENRIQUE GONCALVES E SILVA
  • Data: 27-jun-2019


  • Resumen Espectáculo
  • The search for new technologies related to welding processes with the prerogative of adding the concept of better efficiency allowed the rising alternate procedures from those considered “conventional”. In instance, high penetration GMAW welding is possible, in which it is possible to work with low electric arc lengths and high currents, resulting among other factors, increased penetration. Another example is the hybrid processes, characterized by the union of at least two procedures in a single one, in order to provide results that would not be possible taking them individually. Based on this theme, the objective of this work was to investigate the Plasma-MIG hybrid process in its serial version, using high penetration GMAW, in order to collect technological knowledge about the process, verify potentialities and limitations and thus, giving subsidies for advances in its study/development and boosting its industrial applicability. Critical aspects to be approached are the operational parameterization ranges and the study of the phenomena resulted from hybridization on the melting pool and the formation of the string. Additionally, the application of the Plasma-MIG serial was evaluated in ½" welding joints. As a way of validating these experiments, was used, high speed filming, evaluation of the cross sections of the weld beads, as well as the interpretation of current vs voltage oscilograms and the non - destructive X - ray test were used. The results obtained in this work indicate that the Plasma-MIG serial hybrid process (applying along the High Penetration MIG/MAG), potentially achieves results superior to those achieved only with the high penetration MIG/MAG process, regarding the morphology of the bead. However, the large amount of liquid material in the melting pool, limits the process with the use of some backing material.

10
  • GIRLENE GONÇALVES DO NASCIMENTO
  • STUDY OF THE PHOTOCATALITIC AND PHOTOLUMINESCENT ACTIVITY OF MULTICAMATED CuO/ZnO FILES DEPOSITED BY SPIN COATING

  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • MAURICIO ROBERTO BOMIO DELMONTE
  • FABIANA VILLELA DA MOTTA
  • JUAN ALBERTO CHAVEZ RUIZ
  • LAURENIA MARTINS PEREIRA GARCIA
  • MAXYMME MENDES DE MELO
  • Data: 19-jul-2019


  • Resumen Espectáculo
  • Recent studies investigate a new inorganic materials class which appears as a promising option for high performance applications in photoluminescence and photocatalysis field. Material development has opened new prospects of development photoluminescence and photocatalysis devices highly efficient which presented a particular relevance for reduction of effluent pollution from both industrial sources. Among the promising technological applications materials, the semiconductors ZnO and CuO stand out, due to a good performance of photocatalytic and optical properties. In this work, zinc oxide and copper oxide resins have been synthesized by polymeric precursors method, being deposited in multilayers on a silicon substrate, using the spin coating technique. The resins have been deposited in 6 layers ZnO/CuO; CuO/ZnO; CuO/CuO and ZnO/ZnO and, they have been heat-treated with temperatures 400ºC and 500ºC.The specimens were characterized by X-ray diffraction (DRX), UV/VIS spectroscopy, atomic force microscopy (AFM), scanning electron microscopy with field emission (MEV-FEG) and an energy dispersive X-ray spectrometer (EDS). The results of the X-ray analysis confirmed that there has been insufficient chemical interaction to form secondary stages among the oxides, in other words, multilayers have been formed. Absorption spectra UV/VIS characterized the thin as semiconductors, indicating optical gap from 1,53 eV to 3,35 eV. Scanning electron microscopy with field emission (MEV-FEG) showed films are homogenous and presented average pore size 25nm. Photoluminescent films emissions in multilayers change due to a decrease on the electronic recombination. Results of degradation from the cationic dye methylene blue show that pure films presents a diminished capacity compared to the films in the multilayers; and calcination at rising temperature and the increased of roughness improving catalytic performance of the films. The samples at multilayers CUZN400 and CUZN500 possessed the capability to degrade 98% of the blue dye in 120 minutes of sun exposition without addition of any other reagent to improve the photocatalytic capacity.

11
  • ARTHUR GABRIEL FERREIRA DE OLIVEIRA
  • OBTANING OF Al2O3 – 5%Ni e Al2OCOMPOSITES USING POWDER TECHNOLOGY AND MECHANICAL ALLOYING

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • ARIADNE DE SOUZA SILVA
  • CLODOMIRO ALVES JUNIOR
  • FRANCINE ALVES DA COSTA
  • MARCELLO FILGUEIRA
  • UILAME UMBELINO GOMES
  • Data: 26-jul-2019


  • Resumen Espectáculo
  • The materials for alumina-based cutting tools have been extensively studied, especially with regard to optimizing properties such as fracture toughness, which is often deficient in these materials. The aim of the present work was to study the influence of high energy grinding on the preparation of alumina based composites with nickel and niobium addition using the route of the powder technology in the processing of the material. The alumina-based composites with 5% nickel and 5% niobium were prepared using powders subjected to mechanical mixing and mechanical alloying. The mechanical mixing was performed manually and milling was performed in a high energy planetary mill using the times of 5, 10, 20 and 40 hours. The mixed and milled powders were uniaxial press compacted at 700 MPa and sintered in a vacuum oven at 1450 ° C for 1 hour. Samples were characterized for physical and mechanical properties. The microstructure was analyze by Scanning Electron Microscopy (SEM). Dispersive Energy Spectroscopy (EDS) with mapping was performe. X-ray diffraction (XRD) with Ritveld refinement was used to calculate crystallite sizes. The density was obtained by the Archimedes method and the hardness and fracture toughness by the critical crack length. The results of the processing of the powders indicated the gradual reduction of the particle size of the powders with increase of the surface area, besides the reduction of the crystallite size and the beginning of the amorphization process. Regarding the consolidation of powders after sintering, it was observed that the increase of the grinding time for the Al2O3 - 5% Ni composite, in general, improved the properties. It was obtained density around 96%, hardness of 1480 HV and fracture toughness of 4.75 MPa.m1 / 2 for the time of 40 hours of milling. For Al2O3- 5% Nb system, mechanical alloying in up to 5 hours already causes an increase in the density values to 95.5%, hardness of 1329 HV and fracture toughness of 4.30 MPa.m1 / 2 .

12
  • LÍVIA CRISTINA DE OLIVEIRA FELIPE SANTANA
  • Effects of Mg Substitutions by La in La-Ni-O Perovskite-Type Oxides in Low-Temperature Dry Reforming of Methane

  • Líder : DULCE MARIA DE ARAUJO MELO
  • MIEMBROS DE LA BANCA :
  • DULCE MARIA DE ARAUJO MELO
  • RENATA MARTINS BRAGA
  • RODOLFO LUIZ BEZERRA DE ARAÚJO MEDEIROS
  • RODRIGO CESAR SANTIAGO
  • SILVIA LETICIA FERNANDES
  • Data: 26-ago-2019


  • Resumen Espectáculo
  • Perovskite type catalysts are potential candidates for the dry reforming of methane due to their low cost, thermal stability, improved active-metal dispersion and sintering resistance. Due to thermodynamic constraints, DRM has been mainly investigated at high temperatures (>700 °C) to obtain high conversions of CH4 and CO2, however, from an industrial point of view, it is desirable to operate at lower temperatures (≤600 °C). The present study reveals the effect of the substitution of La by Mg on perovskite type La-Ni-O oxides for dry reforming methane at low temperature, besides evaluating the gas hourly space velocity (GHSV) of the standard catalyst (LaNiO3). The catalytic precursors were prepared by a one-step method using chitosan as chelating agent, and their activities for DRM were investigated. For stoichiometric calculations, the formula La1-xMgxNiO3 (x = 0.2, 0.5, and 0.8) was taken as general formula. The catalysts were calcined at 900 °C for 3h and characterized by XRD and TPR. The structure of the catalysts during the reduction under H2 atmosphere and during the dry reforming reaction was investigated by in situ X-ray diffraction. The catalytic tests were performed at temperature of 600 °C with space velocity of 36 Lh-1.g-1 for 10h, and after the tests the catalysts were characterized by XRD, TGA, FTIR, Raman and SEM-FEG. In reactions varying the gas hourly space velocity, increasing GHSV decreases CH4 conversions, indicating that a greater amount of catalyst in the catalytic bed is favorable for DRM. The XRD patterns of replaced samples show characteristic peaks of the formation of the solid solution Mg0,5Ni0,5O, and as the substitution of La by Mg increases, the amount of this solid solution also increases. It is also observed an increase in the maximum reduction temperature as the Mg content in the structure increases, this may be due to the strong interactions that Ni presents with Mg. Results after DRM indicate that a fraction of the starting oxide catalyst is converted to La2O2CO3 and that the presence of the mentioned characteristics strongly confirms the formation of carbon nanotubes. The catalyst La0,2Mg0,8NiO3 showed the best result, with high stability and high conversions of CH4 and CO2.

13
  • DENER DA SILVA ALBUQUERQUE
  • Copper and Iron Titanates as Solid Oxygen Carrier for use in Chemical Looping Combustion process

  • Líder : DULCE MARIA DE ARAUJO MELO
  • MIEMBROS DE LA BANCA :
  • DULCE MARIA DE ARAUJO MELO
  • HELOÍSA PIMENTA DE MACEDO
  • RODOLFO LUIZ BEZERRA DE ARAÚJO MEDEIROS
  • RODRIGO CESAR SANTIAGO
  • TIAGO ROBERTO DA COSTA
  • Data: 09-sep-2019


  • Resumen Espectáculo
  • The emission of CO2 from the combustion of fossil fuels associated with the growing global demand for energy is a factor that contributes directly to global warming. In the desire to reduce emissions, as well as the severe consequences of this gas, several researchers around the world have developed technologies that minimize these emissions and produce a cleaner CO2, facilitating the process of CO2 capture and storage (CAC). Among the technologies, the Chemical Looping Combustion (CLC) combustion by chemical recirculation process, which promotes the indirect combustion of the fuel through oxygen carriers, produces a free combustion of N2, which avoids the formation of compounds such as NOx and facilitates the capture of CO2 without additional separation costs. Thus, this doctoral thesis aims to synthesize, characterize and test oxygen carriers based on titanates copper and iron for use in combustion processes with chemical looping. Oxygen transporters (TO) were synthesized from stoichiometric calculations by the polymer precursor method (Pechini). The techniques and methodologies used were: X-Ray Fluorescence (XFR), X-Ray Diffraction (XRD), Mössbauer Spectroscopy (EM), Scanning Electron Microscopy (EDS) with EDS, Programmed Temperature Reduction ), reactivity by thermogravimetry, oxygen transport capacity (Roc) and the index rate of the reduction and oxidation cycles. The chemical composition of each iron and copper titanate was obtained by XFR. Through XDR with Rietveld and EM refinement, the main reactive phases were identified as Fe2TiO5 and Fe2O3 for iron titanates and Cuo for copper titanate. Through MVE-FEG with EDS analyzed the morphology of the (TO) and the distribution of the active phases by the surface of each one. During the TPR analysis, these active phases were submitted, respectively, to the atmosphere of H2 and later to synthetic air and presented good capacity of reduction and oxidation. Through the consumption of H2 used to reduce each phase, the experimental Roc of the oxygen transporters was calculated. The reactivity of the samples was evaluated by thermogravimetry with methane gas (CH4) for cycles of reduction and oxidation. Due to the structural characteristics and reactivity tests of these materials, it is concluded that both copper titanate has the necessary requirements to be used in chemical looping (CLC) combustion processes.

14
  • GUDSON NICOLAU DE MELO
  • BARKHAUSEN NOISE AS A TOOL FOR THE IDENTIFICATION OF MICROSTRUCTURAL MODIFICATIONS IN WELDED AISI 1020 STEEL

  • Líder : FELIPE BOHN
  • MIEMBROS DE LA BANCA :
  • AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • FELIPE BOHN
  • JOSÉ FERNANDO MORAIS LOPES MARIANO
  • NICOLAU APOENA CASTRO
  • RUBENS MARIBONDO DO NASCIMENTO
  • Data: 19-sep-2019


  • Resumen Espectáculo
  • Barkhausen Magnetic Noise (RMB) has been studied an alternative for application to principles of techniques for non-destructive testing (NDT) of ferromagnetic materials. These materials are widely used in industry critical components that require stringent monitoring and inspection by international standards. The MBN phenomenon consists of electrical voltage pulses that occur in the release of energy due to the movement and annihilation of the magnetic domain walls in the magnetization process of ferromagnetic materials. The behavior of MBN have be directly related to the microstructural aspects in the materials because they act by counteracting the movement of the domain walls. Therefore, this work proposes to relate the microstructure obtained in heataffected regions when welding an AISI 1020 steel plate through specimens extracted from points of interest of the weld bead to use them in magnetization experiments by means of open circuit induction technique. Through the aid of a sensor coil, it is possible to identify voltage pulses along the magnetization that are relative to the effect of MBN. Microscopic analyzes were performed on the specimens to identify specific weld zones and the predominant microconstituents. The Backscattered Electron Diffraction (EBSD) technique made possible to estimate microstructure data regarding grain size and distribution and phase percentage. The MBN behavior have measured by the RMS (mean square root) curves calculated for the noise detected by the sensor coil. Grain boundary length, possible bainitic microconstituents and dislocation density significantly influenced the noise RMS profiles, especially in the amplitude and position of the main peaks.

15
  • AMANDA LUCENA DE MEDEIROS
  • Microwave-assisted hydrothermal synthesis of Ce1-XGdXO2-δ and characterization aiming at its application as SOFC electrolytes.

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • RUBENS MARIBONDO DO NASCIMENTO
  • ARMANDO MONTE MENDES
  • DANIEL ARAÚJO DE MACEDO
  • FAUSTHON FRED DA SILVA
  • Data: 30-sep-2019


  • Resumen Espectáculo
  • Fuel cell electrolytes require high operating temperatures, resulting in high operating and manufacturing costs. Materials based on rare earth doped ceria are an alternative, as they have higher electrical conductivity than zirconia-yttria at lower operating temperatures. However, some difficulties remain unresolved in obtaining ceria-based solid electrolytes, such as the low sinterability of the material and the low conductivity of grain boundaries, usually associated with the presence of impurities. In this context, the present work aimed at studying the microwave-assisted hydrothermal synthesis to obtain Ce1-xGdxO2-δ nanoparticles, and to analyze the compatibility of the properties of the resulting powders with those required by SOFC electrolytes. Samples of Ce1-xGdxO2-δ (x = 0.1, 0.2 and 0.3) were synthesized. The obtained materials were characterized by density measurements, FRX, XRD, TG, BET, SEM-FEG, TEM and impedance spectroscopy. The results showed that shorter hydrothermal processing times result in nanometer powders with smaller particle sizes, high specific surface area, and strong tendency to agglomeration, which directly influences the densification of the obtained materials. Despite the introduction of Gd into the cerium oxide lattice, all powders crystallized into the fluorite-like structure, typical of ceria. The impedance spectroscopy results indicate that the increase of the dopant concentration decreases the grain conductivity, due to the increase of the interaction of the doping defects, and that the impurities presented act as ionic blocking agents.

16
  • FILIPE JOHNATAN MARTINS DANTAS COSTA
  • THERMAL AND MECHANICAL BEHAVIOR OF CMENTING COMPOSITES CONTAINING CHITOSAN

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • EVANS PAIVA DA COSTA FERREIRA
  • JÚLIO CÉZAR DE OLIVEIRA FREITAS
  • PETRUS D AMORIM SANTA CRUZ OLIVEIRA
  • WENDELL ROSSINE MEDEIROS DE SOUZA
  • Data: 15-oct-2019


  • Resumen Espectáculo
  • Cementing oil wells requires pastes possessing mechanical properties that are capable of supporting crack growth and propagation to ensure casing integrity. High-temperature environments such as steam injection wells are considered critical and capable of causing changes in the chemical and physical properties of hydrated Portland cement products. Failures in the integrity of the cement sheath increase the risk of negative environmental impacts. Polymers are capable of increasing the interaction between hydrated phases by forming films in cement pastes. Chitosan is a biopolymer and has been studied as an additive for mortars and concretes in the construction industry, acting as a thickener and retarder and capable of reducing pore volume. The aim of this study was to evaluate the thermal and mechanical behavior of chitosan-containing cementitious composites for cementing oil wells subjected to steam injection. Formulations containing up to 5% by weight of chitosan solution were evaluated in fresh and hardened state. The mixtures were cured for 14 days under different conditions. Mechanical compressive and tensile strengths were evaluated by destructive methods. The thermal properties were characterized by heat flow analysis, dilatometry and thermogravimetry. The microstructure was characterized by X-ray diffraction and scanning electron microscopy. Chitosan-containing composites showed improved compressive strength as a result of increasing polymer concentration, being able to absorb up to 50% more energy until fracture compared to a the reference chitosan-free paste. Tensile strength of composites increased after steam injection. Chitosan decreased the dehydration of hydrated calcium silicates, reducing thermal shrinkage and attributing greater thermogravimetric stability to cement pastes. Chitosan showed potential applicability as bio-additive, acting as a dispersed reinforcement in the Portland cement matrix to improve fracture behavior of cement sheaths from steam-injected oil wells.

17
  • TARCÍSIO SANTIAGO GOMES FILHO
  • ANALYSIS OF THE INFLUENCE OF THE INCORPORATION OF GESSOALFA, FROM SALINE INDUSTRY WASTE, AND BETA RECYCLED PLASTER PASTE FOR CIVIL CONSTRUCTION COVERAGE

  • Líder : MARCUS ANTONIO DE FREITAS MELO
  • MIEMBROS DE LA BANCA :
  • HELOÍSA PIMENTA DE MACEDO
  • MARCUS ANTONIO DE FREITAS MELO
  • RODOLFO LUIZ BEZERRA DE ARAÚJO MEDEIROS
  • VALTENCIR LUCIO DE LIMA GOMES
  • VÍTOR RODRIGO DE MELO E MELO
  • Data: 29-nov-2019


  • Resumen Espectáculo
  • Gypsum is a material widely used by various industries, ranging from cement to dental, construction being the largest consumer. The search for the technical and economic feasibility of recycling their waste, as well as for new mineral sources that can alleviate the intense exploitation of the soil resulting from this activity, has become increasingly important. In this context, it has been studied in recent years the possibility of recycling their waste through recalcination and to obtain the calcination of waste generated by the saline industry, known as “carago crú” or malachacheta. The objective of this work is to evaluate the influence of recalcined plaster and the plaster produced from the calcination of "carago". The experiments involved chemical and mineralogical characterization through the following techniques: X-ray diffraction (XRD), X-ray fluorescence (FRX), thermogravimetric analysis (TG / DTG) and scanning microscopy (SEM). The mechanical and workability properties of the plaster were evaluated from the analysis of initial and final adhesion time, mini-stroke, axial compressive strength, tensile strength and mass constancy. The STATISTICA 7.0 software in the design of the experiments and in the analysis of the obtained results. The recycled plaster was obtained by calcination under atmospheric pressure, temperature of 150 ° C and cycle time of 1.5 hours. Carago was autoclaved at 1.8 Bar, 129 ° C and a 2 hour cycle. The analyzes showed that the paste formulated with 33% alpha salt and 67% commercial plaster presented satisfactory results in all the performed analyzes, although it was also found that the highest values of direct tensile strength were found in recycled plaster paste. composition.

2018
Disertaciones
1
  • EDUARDO DE OLIVEIRA GOMES
  • Study of the photoluminescent and photocatalytic properties of BaMoO4 and its synthesis by microwave assisted hydrothermal method

  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • MAURICIO ROBERTO BOMIO DELMONTE
  • FABIANA VILLELA DA MOTTA
  • VINÍCIUS DANTAS DE ARAÚJO
  • Data: 21-feb-2018


  • Resumen Espectáculo
  • BaMoO4 particles were synthesized by the co-precipitation method at room temperature followed by the microwave assisted hydrothermal method at different times (1, 2, 4 and 8 minutes) with and without surfactants. The crystals formed acquired geometric morphologies similar to octahedra, and were structurally characterized by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) techniques. The optical properties were investigated by photoluminescence (PL) and ultraviolet-visible (UV-vis). The X-ray diffractograms shown that the octahedra have a tetragonal crystalline structural classification of the scheelite type and without the presence of second phases. The FTIR showed active modes in the infrared region F2 (ⱱ3) and F2 (ⱱ4) which are respectively for BaMoO4 assigned to the antisymmetric stretching and bending mode modes, where F2 (ⱱ3) is related to antisymmetric Mo-O vibration within the Group [MoO4]2-. It also indicated the characteristic band of BaMoO4 in the range of 900-800 cm-1. Optical data from UV-Vis revealed that the values of gap energy (Egap) were around 4.27 and 4.49 eV. Field emission electron microscopy (FEG-MEV) was used to observe the several morphologies and it was proposed the mechanism of particle growth and formation. The photocatalytic properties of BaMoO4 particles were investigated through photocatalysis test by dye degradation.

2
  • CAMYLA REGINA DANTAS FERREIRA
  • COMPOUND OF COMMERCIAL ZIRCONIA WITH PURE HYDROXIAPATITA PRODUCED BY SOL GEL METHOD FOR BIOMEDICAL APPLICATIONS

  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • MAURICIO ROBERTO BOMIO DELMONTE
  • FABIANA VILLELA DA MOTTA
  • MARIA INES BASSO BERNARDI
  • Data: 23-feb-2018


  • Resumen Espectáculo
  • Due to its excellent mechanical properties such as toughness, mechanical strength and modulus of elasticity similar to that of stainless steel alloys, in addition to low toxicity, zirconia is a ceramic biomaterial with several applications. However, zirconia has low affinity with cells and tissues, since it is a bioinert material, and because of its high mechanical properties in relation to the bone, irregular concentrations of tension can appear, resulting in fracture. Hydroxyapatite, in turn, belongs to the calcium phosphate family and has a high modulus of elasticity, and is present in natural compounds such as hard tissue, bone, dentin and dental enamel, being a bioactive material without adequate mechanical resistance. In order to obtain a material with high fracture toughness and affinity with cells and tissues, zirconia and hydroxyapatite composites were developed and investigated. For this work the zirconia used was doped with 8% of yttria, commercial, and the hydroxyapatite was synthesized by sol-gel method at different temperatures and calcination times (500°C/2h, 500°C/4h, 500°C/6h, 700°C/1h, 700°C/2h, 700°C/4h, 900°C/4h). The samples showed commercial yttria doped zirconia layer followed by composite material layer produced with commercial zirconia and hydroxyapatite calcined at 700°C/4h in the following proportions YSZ/HA 95/5, YSZ/HA 90/10, YSZ/HA 85/15 and YSZ/HA 80/20. The samples were characterized by: X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), BET Method, Archimedes Assay, Vickers Microhardness and Scanning Electron Microscopy (SEM). The XRD results showed the formation of the hydroxyapatite major phase at different temperatures and calcination times, with the formation of the composite materials with surface area and hardness decreasing with increasing presence of hydroxyapatite. The samples YSZ/HA 85/15 and YSZ/HA 80/20, presented the best mechanical behavior with higher fracture toughness values of 9.2 and 9.3 MPa.m1/2 , respectively. The sample YSZ/HA 85/15 with lower apparent porosity (0.60%) and water absorption (0.10%).

3
  • FERNANDO SÉRGIO DE MACÊDO CALDAS
  • STUDY OF THE MECHANICAL RESISTANCE OF A POLYMERIC MATRIX COMPOSITE WITH ALUMINUM ADDITION

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • UILAME UMBELINO GOMES
  • FRANCINE ALVES DA COSTA
  • ALESSANDRA AGNA ARAÚJO DOS SANTOS
  • ARIADNE DE SOUZA SILVA
  • CLODOMIRO ALVES JUNIOR
  • Data: 09-mar-2018


  • Resumen Espectáculo
  • Currently, research for the development of biocompatible materials has been widely developed. These materials, also known as biomaterials, are used in the medical field in order to treat, replace or repair biological systems (tissues and / or organs) partially or totally. In the area of orthopedic surgery, bone cements, besides the use for fixation of implants, are applied in the repair of bone failures resulting from fractures caused by high energy trauma, as in the case of accidents involving automotive vehicles and / or human aging, in the face of osteoporosis, which is a disease characterized by the reduction of the mineral part of bones, making them more fragile, and consequently, more susceptible to fractures. Bone cement based on polymethylmethacrylate (PMMA) is already widely applied in the field of orthopedic surgery; In this work the effect of the addition of alumina (Al2O3) on the polymeric matrix (PMMA) on the mechanical properties, mainly flexural strength, was studied. The composite formed by PMMA and Al2O3, besides its possible applicability in the orthopedic area, will allow a reduction of cost, since the alumina is abundant in nature. For the development of this work the powders of PMMA and alumina were characterized, and to obtain the composites the polymer mixtures (powder) were carried out in the presence of the liquid reducer (monomer) with addition of alumina, in the proportions of 0.5 %, 1% and 2% by weight. The mixture releases heat (exothermic chemical reaction), reaching 110 ºC, and the hardening occurs at room temperature, taking in average of 1 to 2 minutes. The hardened samples were obtained in the form of bars. The starting powders and the mixed powders were characterized by scanning electron microscopy (SEM), dispersive energy spectroscopy (EDS), X-ray diffraction (XRD), and already the hardened samples were submitted to the tests of mechanical resistance to flexure, and characterized in SEM, EDS. The results showed that the addition of alumina to the PMMA influenced the mechanical resistance to flexure with increasing modulus of elasticity, and the capacity of deformation and, finally, the progressive reduction of porosity.

4
  • RIVALDO LINS ROCHA FILHO
  • CHARACTERIZATION OF VOLTAGE INDUCED TRANSFORMATION IN THE MICROSTRUCTURE OF A SUPERELASTIC NiTi LEVEL

  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • RUBENS MARIBONDO DO NASCIMENTO
  • FABIO JOSE PINHEIRO SOUSA
  • NICOLAU APOENA CASTRO
  • JORGE MAGNER LOURENÇO
  • Data: 24-may-2018


  • Resumen Espectáculo
  • In the present work, the influence of transformations induced by deformation of a superelastic NiTi alloy with approximately equiatomic chemical composition was studied. In a 1 mm diameter Nitinol wire, the phases present in the analyzed material were identified by microstructural characterization techniques, as received and submitted to different radii of curvature. According to the gradual decrease in the radii of curvature an increase in the volume of mechanically induced transformations was observed, as well as a granulometric decrease of the microstructure, being able to be quantified and measured manually and with the aid of software. Microhardness tests were performed in order to verify variations in mechanical properties. In contrast to investigations of NiTi alloys in asymmetric induced stress, phase transformation behaviors in polycrystalline NiTi-form memory alloys were very limited. The asymmetric transformation characteristics and related microscopic mechanisms in polycrystalline NiTi materials have much to be studied.

5
  • ANNA KARLA DE CARVALHO FREITAS
  • Obtaining paligorskite / PVA based nanocomposites via tape casting for wound healing
  • Líder : WILSON ACCHAR
  • MIEMBROS DE LA BANCA :
  • Ana Paula da Silva Peres
  • Antonio Carlos Silva da Costa
  • CESAR VISERAS IBORRA
  • SIBELE BERENICE CASTELLA PERGHER
  • WILSON ACCHAR
  • Data: 26-jul-2018


  • Resumen Espectáculo
  • There are several efforts to develop nanocomposites that present the combination of organic polymer networks and bioactive inorganic nanoparticles for wound healing. Palygorskite has been extensively applied in drug delivery systems because it has interesting physical chemical properties. Neomycin has been considered an active principle indicated for the treatment of open wounds, which acts to inhibit the protein synthesis of gram-negative and some gram-positive bacteria. Tape casting is a technique widely used in the production of flat thin films with high specific area. In this work, ceramic tapes based on palygorskite, the drug neomycin, and the polymer PVA were obtained in order to investigate the controlled release of drug for topical administration. The stability of the suspension was analyzed by rheological tests, and the powders and ceramic tapes were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD) thermal analysis (TGA/DTA), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), elemental analysis (CHN-S), scanning electron microscopy (SEM-FEG). Tests of antimicrobial activity and minimum bactericidal concentration were performed in order to investigate the potential for drug inhibition in the sheets. Finally, calculations of classical mechanics were carried out in order to estimate the energy, for possible calculation of adsorption energy. According to the rheology results, a pseudoplastic behavior was observed, suitable for the tape casting technique. Reflection peaks related to the paligorskite phases - H9AlMgO15Si4, of orthorhombic structure (JCPDS 98-007-7211) and quartz - SiO2, of hexagonal structure (JCPDS 98-003-5110) were found. DSC analysis identified exothermic peaks characteristic of neomycin in the Pal-Neo hybrid. Elemental analysis results showed that less than 3% of neomycin was incorporated into palygorskite. Tests of antimicrobial activity and minimum bactericidal concentration demonstrated that the Pal-Neo hybrid had an inhibitory effect on the growth of bacteria, proving being capable of damaging the cytoplasmic membrane of the tested bacteria.

6
  • JULIANE GERMANO DE SOUZA GONDIM
  • STUDY OF THE PHOTOLUMINESCENT PROPERTIES OF CALCIUM ALUMINATE DOPED WITH THE EUROpio III.
  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • BRAULIO SILVA BARROS
  • CARLOS ALBERTO PASKOCIMAS
  • MAURICIO ROBERTO BOMIO DELMONTE
  • Data: 27-jul-2018


  • Resumen Espectáculo
  • Luminescent materials have been widely applied in many areas, such as illumination, movies, artificial fibers, painting, optical markers and others. Among luminous materials, aluminates have been showed its quality, even more when they are doped or codoped with rare soil, due to its great chemical and thermal stability, not forgetting its lasting photoluminescent property. In this paper, structural and optical behaviors of calcium aluminate doped with europium III (Ca1-xEuxAl2O4 with x = 0%, 1%, 2% and 4% mole) were studied. The formulations were synthesized through sol-gel method and calcined at 1300°C and 1500°C, with fractions of deionized water and 1, 4-butanediol (diol) on its medium of reaction. Those parameters affected the crystalline structure, and the photocatalytic and luminescent properties of each sample. The x-ray diffraction (XRD) indicated the obtention of the desired phase and with great crystallinity on both temperatures, but the lowest temperature indicated secondary phases formation. The scanning electron microscopy (SEM) indicated that temperature increase makes the three-dimensional morphology become more compact and with a high degree sintering. The increase in fractions of europium in the diol reactional medium made the particles presente a significant reduction on its size. On photocatalytic activity, the referred addition was unsatisfactory because the samples that indicated a higher influence on dyes degradation were the base samples with 0% of diol on the reaction and 0% of europium element. The sample’s photoluminescent spectra indicated narrows and well-defined bands that are characteristics of europium element transitions. They also indicate that the increase in fraction of both dopant and diol generated a photoluminescent properties increment and a photocatalysis reduction. The increase also affects samples’ color emission. On this paper, it was possible to evaluate that the base samples presented bluish and greenish colorations, and with the increase, mainly of europium, they presented warmer colorations that went from orange to red.


7
  • FELIPE FERNANDES BARBOSA
  • Synthesis of the FeCo alloy encapsulated in carbon filaments with chemical strength from the dehydrogenation of ethylbenzene

  • Líder : SIBELE BERENICE CASTELLA PERGHER
  • MIEMBROS DE LA BANCA :
  • FABIO GARCIA PENHA
  • MAURICIO ROBERTO BOMIO DELMONTE
  • RAFAEL SARAIVA NUNES
  • TIAGO PINHEIRO BRAGA
  • Data: 30-jul-2018


  • Resumen Espectáculo
  • The catalytic dehydrogenation of ethylbenzene was used to study the nature of deposited carbon and to verify the formation of organized structures in the form of FeCo magnetic alloys encapsulated in carbon filaments via chemical vapor deposition (CVD). The reducing environment from the dehydrogenation (H2 generated in situ) was used to synthesize an FeCo alloy from the metal oxide. The program is organized in four different temperatures (700, 650, 600 and 550 °C), in the times of 2h and 4h. X-ray diffraction (XRD), programmed temperature reduction (TPR), thermogravimetric analysis (TGA), scanning electron microscopy (FEG-MEV) and X-ray dispersive energy (EDS) were characterized. , vibration sample magnitude (VSM), Raman, transmission electron microscopy (TEM) and gas phase (GC) chromatography. The diffractograms indicate an FeCo alloy formation and a presence of crystalline carbon. The H2-TPR profiles confirm that the alloy can be formed at the reaction temperature from 370 °C. Since the images elaborated by FEG-SEM and TEM indicated a formation of carbon filaments and a FeCo alloy favor the growth of the carbon structurally organized. The images also confirm that the alloy encapsulates the force against the acid. The ratio of the Raman D and G bands confirms that carbon growth on an FeCo alloy is favored at higher temperatures. Chromatograms indicate that the filaments were formed from the methane and/or ethene generated in situ in the reaction, which were seen were not identified. The magnetic properties were confirmed by the VSM, a variable according to the reaction time and temperature. The saturation magnetization of a direct relationship with the crystallite size of the alloy.

8
  • KATHARINA GABRIELA SPANIOL
  • Production of ceramic tapes based on TCP/PVA with addition of silver particles via tape casting for bone dressing

  • Líder : WILSON ACCHAR
  • MIEMBROS DE LA BANCA :
  • Ana Paula da Silva Peres
  • EDUARDO GALVAO RAMALHO
  • JOSE HERIBERTO OLIVEIRA DO NASCIMENTO
  • WILSON ACCHAR
  • Data: 03-ago-2018


  • Resumen Espectáculo
  • Bone defect repair procedures present many challenges due to low cure rates, which has a negative impact on patients' quality of life and hospital costs. A promising alternative for the regeneration of these damaged tissues has been the use of biomaterials in the engineering of bone tissue, especially with the use of barrier membranes. For the production of these membranes, tricalcium phosphate (TCP) has been widely investigated for their chemical and biological similarity to bone tissues and excellent properties of biocompatibility and cell adhesion. However, there are some drawbacks in its use: it degrades a little faster than bone regeneration and its mechanical resistance is relatively low. To overcome these shortcomings, much research has been done to produce composites formed by TCP and polymers with the purpose of improving its mechanical properties. Among these polymers, polyvinyl alcohol (PVA) is a synthetic material that has properties of biocompatibility and non-toxicity being an important raw material for film making. However, its rapid degradability interferes negatively with osteogenesis due to a reduced time of interaction between the material and the bone. A possible solution to this problem is the use of a crosslinking agent, for example citric acid. Infections are considered to be one of the most serious complications during the postoperative period. One answer to this problem is the use of an antibacterial system. The antibacterial activity of silver ions is known to have strong bactericidal effects as well as a broad spectrum of antimicrobial activities. Regarding the methods of film production, tape casting technique has the advantage of producing thin films, of homogeneous structure, with controlled thickness and in large scale. Therefore, the objective of this work is to produce ceramic tapes based on a ceramic, tricalcium phosphate, and a polymer, PVA, containing silver nanoparticles through the production of thin films by the tape casting method with the potential to be used as barrier membranes, with antibacterial effect. The methodology consisted in the production of suspensions (characterized by rheological tests) and ceramic sheets, submitted to thermal analysis (ATG and ATD), X-ray diffraction (XRD), X-ray fluorescence (FRX) scanning electron microscopy (SEM-FEG), bioactivity and cytotoxicity assays. The results show that the suspensions exhibit pseudoplastic behavior, suitable for the process via tape casting. The ATG curves of the tapes show similar profiles, in which the total mass loss process occurred in the temperature range of 30 ° C to 450 ° C. The XRD patterns of the ceramic tapes reveal the formation of β-TCP phase according to standard form (JCPDS 009-0169). The chemical composition of the material confirms the presence of the elements composing the β-TCP phase and the silver element for compositions containing the antimicrobial agent. The water uptake of the samples validates that crosslinking of the sheets by increasing the water resistance of the compositions containing the crosslinking agent. It is possible to observe in the SEM images homogeneous structures and the presence of macropores and that the citric acid modifies the structure of the samples, making it more compact and less porous. The bioactivity assay reveals the formation of a precipitate on the surfaces of the ceramic tapes, proving that the material is bioactive. The results obtained from the cytotoxicity analysis confirm that the material enables cell propagation. It is concluded that the method employed and the processing conditions favored the production of ceramic tapes based on TCP/PVA with potential to be used as barrier membrane for bone regeneration.

9
  • WILLIAM CONSTANTINO DA SILVA
  • MICROSTRUCTURAL EVALUATION OF PARTIALLY MIXED ZONES (PMZ) OBTAINED BY DISSIMILAR WELDING USING ALLOY INCONEL 625 FILLER METALS AND 309L STAINLESS STEELFILLER METAL

  • Líder : AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • MIEMBROS DE LA BANCA :
  • RUBENS MARIBONDO DO NASCIMENTO
  • MEYSAM MASHHADIKARIMI
  • NICOLAU APOENA CASTRO
  • CELINA LEAL MENDES DA SILVA
  • Data: 06-ago-2018


  • Resumen Espectáculo
  • In order to investigate the influence on Partially Mixed Zones (PMZ), of the heat input and the filler metals employed, the present work is predicted for the metallurgical profile of interfacial regions, using alloy Inconel 625 filler metals and 309L stainless steel filler metal, both deposited by the GMAW process on low carbon steel. However, for cladding to achieve its intended purpose, during the cladding process with low dilution, the choice of cladding with high dilution should be ensured to evaluate this parameter at the interface of the substrate with the cladding. Therefore, changes in the welding speed, to obtain claddings with different metallurgical characteristics, to influence the substrate / cladding interaction and to obtain several percentages of dilution. The welds were deposited on specimens of 200 x 100 x 10 mm, forming test pieces with one cladding layer, formed by three weld beads. For each filler metal used, two heat input of welding were imposed, 1500 J / mm and 550 J / mm. From these specimens were removed for analysis of the metallography, followed by analysis by optical microscopy, scanning electron microscopy with field emission gun and microhardness test. The results are a direct indication between the PMZ thicknesses and the filler metals employed, so that claddings using 309L stainless steel presented thicker PMZ when compared to PMZ cladding produced with Inconel 625. For both filler metals, higher welding speed contributed to higher dilution percentages, because of a smaller reinforcement area formed in the in the cladding. Another important result was evidenced by microhardness analysis, where it was possible to observe a considerable increase in the hardness values in the interfacial region, more precisely in the Partially Mixed Zones (PMZ) and in the Heat-Affected Zones (HAZ) closest to the fusion line.

10
  • ALICIANE CÍNTIA MAIA GAMA
  • Synthesis and characterization of La2Ce2O7 pure and doped with iron from the EDTA-Citrate combined complexation method

  • Líder : CARLSON PEREIRA DE SOUZA
  • MIEMBROS DE LA BANCA :
  • ANDARAIR GOMES DOS SANTOS
  • ANDRE LUIS LOPES MORIYAMA
  • CARLSON PEREIRA DE SOUZA
  • Data: 16-ago-2018


  • Resumen Espectáculo
  • This work had as objective to synthesis of La2Ce2O7 pure and Fe-doped (LaFeCe2O7) from the EDTA-Citrate combined complexation method. For the synthesis of powders were used reagents with oxidation state Ce3+ and Ce4+. Calcination temperatures taken in getting the La2Ce2O7 and phases LaFeCe2O7 were 550, 725, 900 and 1000° C, and 500, 675 and 850 ºc, respectively. The materials obtained have been characterized by x-ray diffraction (DRX), Rietveld refinement, scanning electron microscopy (SEM) and diffuse reflectance spectroscopy. There was the formation of two phases (LaFeO3 e CeO2) when the La2Ce2O7 pure was doped with Fe, LaFeO3 this phase in greater quantity (59%), and to a lesser extent CeO2 (41%). The synthesis of LaFeCe2O7 with the Ce4+ and calcination temperature equal to 850° C produced powders with smaller average crystallite size and lower band gap energy.

11
  • ERIK ALEXANDER CUNHA FERREIRA
  • Study of the influence of pH on the production of silver molybdates modified by the sleepchemical method.

  • Líder : FABIANA VILLELA DA MOTTA
  • MIEMBROS DE LA BANCA :
  • FABIANA VILLELA DA MOTTA
  • RUBENS MARIBONDO DO NASCIMENTO
  • MARIO GODINHO JUNIOR
  • Data: 30-ago-2018


  • Resumen Espectáculo
  • Silver-based semiconductors have attracted significant attention because of their unique photosensitivity which provides these materials with excellent photocatalytic activity due, among other factors, to the effects of plasmon resonance. Silver molybdates are a family of semiconductor materials belonging to the group of transition metal oxides with high technological value due to their diverse applications, among which are those of catalysis. In this dissertation, the study of the structural and morphological properties of silver molybdates was carried out, as well as their influence on the degradation of the methylene blue dye. Silver molybdates were obtained by coprecipitation of solutions in a controlled chemical environment in the range of pH 2 to pH 7, followed by sonochemical treatment. For a reaction medium of pH 1 and pH 8, no precipitation is observed, with powders being formed only after the sonochemical synthesis. Through the X-Ray Diffraction Technique, it was observed that the synthesized materials crystallize in the structures indexed to the crystallographic cards Ag2Mo3O102H2O, Ag2Mo2O7 and Ag2MoO4, as a function of the pH of the reaction medium. Field Emission Electron Microscopy analysis showed that the Ag2Mo3O10•2H2O and Ag2Mo2O7 structures exhibit nanorods morphology, while the Ag2MoO4 structures show irregular morphology, with both morphologies obtained after the sonochemical treatment, presenting a high number of silver precipitates on the surface. UV-Visible spectroscopy analysis by diffuse reflectance was performed to estimate the optical band-gap value. The degradability of the methylene blue dye (MB) as well as stability for the reuse of the synthesized materials were evaluated. Complete discoloration of the MB dye containing solution was observed after 5 minutes exposure of the Ag2Mo3O10•2H2O powders and 15 minutes exposure of Ag2Mo2O7 without external irradiation and without loss of efficiency after 3 cycles of adsorption. The degradation of methylene blue dye under UV irradiation was observed for Ag2MoO4 structure, where complete discoloration of MB dye was observed after 60 minutes, with stable semiconductor result in reuse.

12
  • ELLA RAQUEL DO VALE SOUZA DE LIMA
  • Sintering Ni/SiC composites from NiO

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • MARIA ROSEANE DE PONTES FERNANDES
  • MAURÍCIO MHIRDAUI PERES
  • Data: 04-sep-2018


  • Resumen Espectáculo
  • Metal matrix composites reinforced by carbide particles are promising engineering materials as a result of a combination of mechanical, corrosion and wear resistance at high service temperatures. However, the toxicity of Ni impairs the use of its powder. Alternatively, NiO can be used as starting material and be reduced during processing of the composite. The present study aimed at the production of Ni-SiC composites from NiO-SiC mixtures. The effect of the pressing load on the dilatometric behavior of the mixtures was investigated. NiO powders with average particle size 14 µm were mixed (0, 3, 10 and 20 wt.%) with SiC of average particle size 14.75 µm and attrition-milled during 1 h. The mixtures were then granulated using 1.5 wt.% paraffin in hexane solution and uniaxially pressed under 200 MPa or 400 MPa. The cylindrical pellets were then sintered in a dilatometer at heating rates of 5 ºC or 10 ºC/min. The density of the sintered samples was evaluated according to the combination of pressing load and dilatometric profile. The results revealed that homogenous NiO-SiC mixtures could be produced. Pellets pressed under 400 MPA depicted higher density. Sintering at 5 /C/min heating rate resulted in improved densification. The addition of 10 wt. % of SiC in the Ni matrix allowed the hardening with greater microstructural homogeneity and better continuity of the matrix, presented higher hardness and surface dense value, proved by SEM images.

13
  • LILIAN MAIARA MORAIS E SILVA
  • Study of the addition of the thermoplastic poly(ethylene-co-methyl acrylate-co-glycidil methacrylate) (E-MA-GMA) as healing agent in glass fiber – epoxy composites

  • Líder : ANA PAULA CYSNE BARBOSA
  • MIEMBROS DE LA BANCA :
  • ANA PAULA CYSNE BARBOSA
  • JOSE DANIEL DINIZ MELO
  • EVANS PAIVA DA COSTA FERREIRA
  • MARIA ODILA HILÁRIO CIOFFI
  • Data: 24-oct-2018


  • Resumen Espectáculo
  • A critical problem of epoxy matrix composites is their susceptibility to nucleate microcracks during service, which can cause catastrophic failure or shortening the service lifetime of the components. An alternative to overcome this problem is the use of self-healing materials, where the formed microcracks are repaired, preventing catastrophic failure propagation and reducing maintenance costs. One of the mechanisms suggested in the literature for self-healing of microcracks is the application of thermoplastic particles. The aim of this work is to analyze the effect of the addition of poly (E-MA-GMA) thermoplastic as a healing agent in a fiberglass-epoxy composite. The materials studied were characterized by interlaminar shear strength (ILSS), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and dynamic mechanical analysis (DMA). The addition of thermoplastic did not cause significant reduction in the Tg of the composite. ILSS results after healing showed that the stiffness and strength of the samples were reduced, as compared to values before the healing cycle. Nevertheless, strength reduction was lower when the thermoplastic was inserted in between all prepreg plies. MEV images showed that E-MA-GMA functioned as an adhesive agent, preventing delamination in the mid-plane of the laminate.

14
  • CLARA JÉSSICA DE MEDEIROS SILVA
  • CHARACTERIZATION OF AUTOPOLYMERIZING DENTAL ACRYLIC RESIN WITH DIFFERENT CONCENTRATIONS BY WEIGHT

  • Líder : EDSON NORIYUKI ITO
  • MIEMBROS DE LA BANCA :
  • EDSON NORIYUKI ITO
  • CAROLINE DANTAS VILAR
  • SERGIO ADRIANE BEZERRA DE MOURA
  • JOSÉ KAIO MAX ALVES DO RÊGO
  • Data: 30-oct-2018


  • Resumen Espectáculo
  • Autopolymerizing dental acrylic resin is one of the most used materials for denture applications due to its easy manipulation, its physical and mechanical properties, its chemical stability and aesthetic appearance, its biocompatibility and the inherent low cost. The commercial product has two components: a powder solid containing pre-polymerised poly (methyl methacrylate) (PMMA) particles and a liquid containing the MMA monomer. Changes in the proportion of powder and liquid can occur, due to the working conditions of the places where the resin is handled, leading to modifications of the physical properties of this material. For this reason, the aim of this study was to evaluate the changes in the physical properties of the autopolymerizing dental acrylic resin as a function of the proportions of powder and liquid. The used materials were from three manufacturers, identified in this work as AM1, AM2 and AM3, and they were used in three different proportions: one recommended by the manufacturer of the material, one with the same concentration of powder and monomer and one with two parts more than than monomer. The materials were analysed and characterized by porosity, water absorption, contact angle, atomic force microscopy (AFM), Shore D hardness, Izod impact, scanning electron microscpy (SEM), biodegradability testing, and cell viability. Among the analyzed compositions, the AM3 in the AM3- group was the one that presented better properties, reaching higher than those according to the manufacturer's standard specifications. The advantage of this change is that the amount of material used in processing is lower, reducing purchase costs. Thus, even for compositions already available on the market, it was possible to modify and improve various properties for the resin. The cell viability assay also do it clear that the material is hydrophobic in character, which is recommended for denture and dental materials. This work proved efficient in the search for new routes of synthesis and also in obtaining better properties and reducing the raw material used. It was concluded that the sample AM3 presented a reduction in the costs of synthesis and of obtaining, being economically more viable among the evaluated materials.

15
  • CAMILA BEATRIZ SOUZA DE MEDEIROS
  • Evaluation of printed PLA parts for biomedical applications

  • Líder : ANA PAULA CYSNE BARBOSA
  • MIEMBROS DE LA BANCA :
  • ANA PAULA CYSNE BARBOSA
  • CAROLINE DANTAS VILAR
  • JOSE DANIEL DINIZ MELO
  • LAURA HECKER DE CARVALHO
  • Data: 30-oct-2018


  • Resumen Espectáculo
  • Poly (lactic acid) (PLA) has attractive properties for use in the biomedical area because of its biocompatibility, which can be defined as the ability of a material to interact with living tissues without toxicity. PLA is biodegradable, since it is capable of being disintegrated by biological agents, being also bioreabsorbable, since the product of its degradation participates in the metabolic process of the human organism. Among the manufacturing techniques of PLA parts for biomedical applications, 3D printing stands out as promising, mainly due to the possibility of production of customized and individualized pieces, as well as production by prototyping with high level of detail. However, more studies involving the alteration of the properties of the material when in contact with biological medium are still necessary to evaluate the application of parts in implantable devices. The objective of this work was to evaluate changes in the properties of PLA parts made by 3D printing when immersed in phosphate saline solution for periods of 7, 14 and 30 days. The samples were evaluated for mass change, chemical changes (Fourier transform infrared spectroscopy - FTIR), changes in glass transition and crystallization temperatures (differential scanning calorimetry - DSC), changes in dynamic-mechanical properties mechanical dynamics - DMA), mechanical tests in 3-point bending and fatigue. Results showed an increase in mass after immersion for 7 days and a decrease in mass for samples immersed for 14 and 30 days. Results suggest chemical alterations, changes in glass transition temperature, reduction in fatigue life of immersed samples as compared to the material which was not immersed in phosphate saline solution.

Tesis
1
  • BRUNO LEONARDO DE SENA COSTA
  • Corrosive attack on oil Portland cement class G: Studies on the effects of carbonation
  • Líder : DULCE MARIA DE ARAUJO MELO
  • MIEMBROS DE LA BANCA :
  • DULCE MARIA DE ARAUJO MELO
  • MARCUS ANTONIO DE FREITAS MELO
  • JÚLIO CÉZAR DE OLIVEIRA FREITAS
  • CRISTIANE RICHARD DE MIRANDA
  • ULISSES TARGINO BEZERRA
  • Data: 15-ene-2018


  • Resumen Espectáculo
  • In this study the phenomenon of Portland cement carbonation is investigated by different approaches, but converging towards the same objective: to deepen the knowledge of the processes and the effects in the cement matrix. The phenomenon occurs through chemical reactions between carbonic acid, formed by the reaction of CO2 with water, and some hydrated products of cement. In subsurface due to the increase of temperature and pressure the medium becomes more damaging, being therefore, in the area of oil and gas, mainly cementing, has a great interest by this problematic. In view of the above, in this study three articles were developed and published entitled: [Article I] Effects of carbon dioxide in Portland cement: a relation between static sedimentation and carbonation, [Article II] Carbonation in oil well Portland cement: Influence of hydration time prior to contact with CO2 and [Article III] Study of carbonation in a class G Portland cement matrix at supercritical and saturated environments. In the first study, a model was proposed for sedimentation and carbonation behavior in unstable slurry, the static sedimentation based on fluid mechanics. In another study, three slurries of the same formulation were investigated, but were cured for periods of 8 hours, 7 days and 28 days before CO2contact. The results showed distinct processes, but with similar carbonation effects at the end. In addition, in one last study samples were exposed at the same time in supercritical and saturated CO2. The analyzes showed significantly different results, where the samples exposed to the saturated medium suffered a 35% higher attack. This work presents studies that seek to promote a greater understanding of phenomenology and give subsidies for the development of technologies that combat carbonation.

2
  • LAURA XIMENA LOVISA
  • Photoluminescent Properties of ZnMoO4 encoded with rare earth ions obtained from the sonochemical method

  • Líder : FABIANA VILLELA DA MOTTA
  • MIEMBROS DE LA BANCA :
  • FABIANA VILLELA DA MOTTA
  • MAURICIO ROBERTO BOMIO DELMONTE
  • JOSE HERIBERTO OLIVEIRA DO NASCIMENTO
  • MAXYMME MENDES DE MELO
  • VINÍCIUS DANTAS DE ARAÚJO
  • Data: 09-feb-2018


  • Resumen Espectáculo
  • A new class of inorganic materials, which emerge as a promising option in high-performance applications in the field of photoluminescence, has gained special attention. This group consists of the molybdates, XMoO4 (X: metal ion), doped with rare earth elements (RE). The characteristics that describe these materials are: high luminous efficiency, long decay time and emission presentation in the visible. In this work ZnMoO4 and ZnMoO4: 1% Tm3+, 1% Tb3+, x Eu3+ (x = 1, 1.5, 2, 2.5 and 3 mol%) particles were synthesized from the sonochemical method. The influence of dopant content and heat treatment on photoluminescent behavior was investigated. The X-ray diffraction results confirmed the formation of α- ZnMoO4 phase with triclinic crystalline structure for the particles. The values of the gap energy are in the range of 3.58 and 4.22 eV. The images of the FE-SEM show an evolution of the morphology of the particles in accordance with the increase of the doping. The morphology of samples are interpreted based on a comparative analysis of the calculated and experimental field emission scanning electron microscopy (FE-SEM) images. First-principle calculations at a density functional theory level were performed to obtain the values of surface energies and relative stability of the (120), (001), (011), (201), and (100) surfaces by employing the Wulff construction. The results of photoluminescence clearly show the specific emissions of Tb3+ and Eu3+. The values of the chromaticity coordinates were influenced by the increase in the treatment temperature, showing emission in the yellowish orange, green and white regions.

3
  • RODOLFO LUIZ BEZERRA DE ARAÚJO MEDEIROS
  • One-pot Synthesis of Ni, Co and Fe based Catalysts by Microwave-Assisted Combustion for H2 Production via Dry Reforming of CH4

  • Líder : DULCE MARIA DE ARAUJO MELO
  • MIEMBROS DE LA BANCA :
  • DULCE MARIA DE ARAUJO MELO
  • MARCUS ANTONIO DE FREITAS MELO
  • RENATA MARTINS BRAGA
  • BRAULIO SILVA BARROS
  • EDISSON MORGADO JUNIOR
  • Data: 23-feb-2018


  • Resumen Espectáculo
  • Catalysts based on Ni, Co and Fe supported in Al2O3 were prepared simply and quickly by the one-pot microwave-assisted combustion method, using nitrates as precursors and low fuel content (urea). The catalysts were calcined at 550 ° C for 3 h and characterized by X-ray diffraction (XRD), temperature programmed reduction (TPR), N2 adsorption/desorption (BET-BJH), energy dispersive X-ray (EDX), scanning electron microscopy (SEM-EDX), transmission electron microscopy (TEM) and thermogravimetry (TG) with coupled Fourier Transform Infrared Spectrophotometry (FTIR). The structure of the catalysts during reducibility under H2 atmosphere and in the dry reforming reaction were investigated by in-situ X-ray diffraction. The catalytic tests were performed at a temperature of 700 ºC (activation and reaction) using a space velocity of 72 Lh-1g-1 and a CH4/CO2 ratio of 1 for 20 h. The design of experiment was applied to study different formulations of the catalysts and to verify their effects on H2 yield. The results indicate that the active phases have particle sizes below 20 nm, high degree of reduction and specific surface area around 200 m²g-1. In the catalytic tests different behaviors were observed, being the bimetallic Ni-Fe catalysts more stable and active than the bimetallic Ni-Co catalysts, due to the formation of NiFe alloy. The mathematical model for H2 yield with a correlation coefficient (R²) of 0.9977 complemented the results of the catalytic tests and was used to formulate the TA1 trimetallic catalyst (8.7%wt. Ni and 1.3%wt. Co and Fe). Finally, in the optimization stage, the TA1 catalyst was promoted with Ce and Mg and activated at 800 ºC, aiming to reduce the coke formation that caused the encapsulation of the active phase, observed in all the catalysts tested. The activity of the oxygen vacancies and the modification of the surface acidity by Ce and Mg, respectively, strongly influenced the performance of the TA1 catalyst, in which deactivation levels were observed below 12%, while the catalysts without the promoters presented deactivations above 40%. Therefore, the materials prepared in this thesis have potential for applications in heterogeneous catalysis, since the proposed route is simple, fast and uses low fuel, producing nanoscale catalysts with high resistance to coke formation, high stability and high yield of H2, in addition to allowing the partial replacement of Ni by components of lower cost.

4
  • YARA FELICIANO GOMES
  • Synthesis and Characterization of YInMnO blue pigment using the complex Polymerization Method (CPM)

  • Líder : FABIANA VILLELA DA MOTTA
  • MIEMBROS DE LA BANCA :
  • FABIANA VILLELA DA MOTTA
  • JOSE HERIBERTO OLIVEIRA DO NASCIMENTO
  • MARIA INES BASSO BERNARDI
  • MAURICIO ROBERTO BOMIO DELMONTE
  • THARSIA CRISTIANY DE CARVALHO COSTA
  • Data: 23-feb-2018


  • Resumen Espectáculo
  • The system YIn1-x MnxO3, a new bright blue inorganic pigment, discovered in 2009, notable bright blue pigment, used in the ceramic and paint industry applications. These pigments are promising to reflectivity, durability, energy saving and produced at low cost. This studied was divided into two stages: the first consisted of the validation of the complex polymerization method (CPM) in which the YIn1-x MnxO3 powders (x = 8, 12 and 16 mol%) were calcined at temperatures of 800 ºC, 900° C and 1000 ° C characterized by X-ray diffraction (XRD), Rietveld Method (MR), Scanning Electron Microscopy (SEM), Spectroscopy of Uv-vis and colorimetric system CIEL*a*b* confirmed the maximum absorption range of 400 to 520 nm for blue at the temperature of 900 ° C and 1000 ° C. The second stage confirmed the  XRD, MR results showed that powders synthesized temperatures at 1300 ° C have a single phase of YIn2O3, JCPDS (70- 133), hexagonal structure, and smaller crystallization peaks, also confirmed by MR. CIEL*a*b* showed that powders, when compared method through CPM and Solid State reaction, exhibit the same coloration at 1300 ° C, shown a change from light blue to deep blue. The CPM method demonstrated efficiency at low temperatures a brilliant blue color, reflecting more than 80%, the lower absorption in NIR infrared spectroscopy, less heat accumulation and, therefore, lower cooling costs (ie "cool pigments") the temperature of 1000 ºC, advantages for application at low temperatures, with energy and economic efficiency and, therefore, being promised use in the ceramic and paint industry.

5
  • BEATRIZ SIMÃO DE SOUZA NETA MENDES
  • Synthesis of microcapsules filled with epoxy for application in self-healing systems.

  • Líder : MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • JOSE DANIEL DINIZ MELO
  • MAURICIO ROBERTO BOMIO DELMONTE
  • EVANS PAIVA DA COSTA FERREIRA
  • AMELIA SEVERINO FERREIRA E SANTOS
  • JOSIANE DANTAS VIANA BARBOSA
  • Data: 08-mar-2018


  • Resumen Espectáculo
  • Engineering design involving self-healing materials have been increasingly developed through the use of different strategies, such as microencapsulation, molecular interdiffusion in thermoplastic polymers, photoinduced self-healing, recombination of polymer chain ends, among others. This work focuses on the microencapsulation strategy through interfacial polymerization; where the diglycidyl ether of bisphenol A monomer (DGEBA) was used as encapsulated agent. From the mixtures diagram the proportions of reagents to be used in the synthesis with the objective of obtaining microcapsules with satisfactory characteristics for application in self-healing systems were studied. The influence of gum arabic emulsifiers and Tween 80 and their concentrations on the particle diameter were analyzed. The use of gum arabic as an emulsifier gave rise to microcapsules with a mean diameter of 73 μm, however, the stabilization of the emulsion was not adequate, leading to a reduction in reaction yield. On the other hand, when Tween 80 was used, microcapsules with a mean diameter of 19 μm were obtained, however, a greater stabilization of the emulsion resulted in a higher yield of the polymerization reactions. Fourier transform infrared spectroscopy (FTIR) analyzes showed the characteristic vibrations of the microcapsule material. Differential scanning calorimetry (DSC) analysis showed the characteristic thermal transitions of the encapsulated epoxy monomer and microcapsule shell. The self-healing effect was verified for microcapsules synthesized with the two types of emulsifier separately, and it was possible to observe that, despite the smaller diameter of the microcapsules synthesized with Tween 80, satisfactory results were obtained for the coating containing these microcapsules.

6
  • LAURENICE MARTINS PEREIRA
  • STUDY OF POLY (METHYL METHACRYLATE) BLENDS WITH STYRENIC POLYMERS

  • Líder : EDSON NORIYUKI ITO
  • MIEMBROS DE LA BANCA :
  • EDSON NORIYUKI ITO
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • AMANDA MELISSA DAMIAO LEITE
  • GUSTAVO DE FIGUEIREDO BRITO
  • TOMÁS JEFERSON ALVES DE MELO
  • Data: 26-mar-2018


  • Resumen Espectáculo
  • Rheological and mechanical behavior of polymers blends obtained using acrylic polymers poly (methyl methacrylate homopolyer (PMMAh) and poly (methyl methacrylate) with elastomers (PMMAe) together with styrenic polymers polystyrene (PS), styrene-acrylonitrine copolymer (SAN) and acrylonitrile-butadiene-styrene copolymer (ABS), all with distinct chemical structures, was elucidated and the effect of addition has been evaluated. Blends samples were obtained by twin-screw extrusion followed by injection molding. Elementary chemical analyses of SAN and ABS showed that acrylonitrile (AN) percentage is suitable for mixing with PMMA, once the results of 25 and 21 %, respectively, are within miscibility window. Thermogravimetric analysis of styrenic polymers has demonstrated higher thermal stability over acrylic polymers. Capillary rheometry tests show that PMMAe exhibited higher viscosity in comparison to others, due to dispersed core-shell particles into PMMA. Increasing in fluidity was achieved when styrenic polymers were added to PMMA samples, resulting in improvements in processability. Mechanical results have shown that addition of SAN has improved both Elastic modulus and tensile strength, which was attributed to the presence of acrylonitrile. Blends with PMMAe have shown better elongation at break and impact strength in comparison to other acrylic compositions. For styrenic compositions, ABS has exhibited higher elongation at break. Results of impact strength of SAN and ABS were close, likely due to the insufficient amount of butadiene in blends, making impossible to absorb pendulum energy, due to its high-velocity. The hardness testing (Shore D) showed improvements in hardness when styrenic polymers were added to acrylics. Transition glass of polymers and blends were obtained from dynamic mechanic thermal analysis. Blends presented Tg values between their constituents. Tests at heat deflection temperature and Vicat softening point has indicated that upon the addition of styrenic polymers in the acrylic polymers, the thermal resistance increased.
7
  • JOSÉ ELSON SOARES FILHO
  • INFLUENCE OF THE MICROSTRUCTURE ON THE POLISHING PROCESS OF PORCELAIN STONEWARE TILES CONTAINING INDUSTRIAL WASTES

  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • DACHAMIR HOTZA
  • FABIO JOSE PINHEIRO SOUSA
  • RICARDO PEIXOTO SUASSUNA DUTRA
  • RUBENS MARIBONDO DO NASCIMENTO
  • WILSON ACCHAR
  • Data: 25-may-2018


  • Resumen Espectáculo
  • Nowadays the concern with the conservation of the natural sources of raw materials is in evidence, generating a notorious environmental awareness worldwide. For a long time, the society discusses the importance of environmentally friendly products. The ceramic tiles sector is perfectly capable of absorbing a range of industrial products in ceramic compositions. Since the last two decades, research has been carried out aiming at obtaining eco-friendly ceramic tiles with the porcelain stoneware tile typology from the incorporation of industrial wastes as alternative raw materials. However, most of these investigations on the technical feasibility of the insertion of industrial waste were focused on technological and mechanical performance. The behavior regarding the glossiness gain of eco-friendly ceramic tiles remains unknown both in the field of scientific research and in the industrial scope. Thus, the present work aims to evaluate the influence of the microstructural difference, caused by the insertion of industrial wastes, on the final surface quality, considering the polishing process. For the purpose, eco-friendly porcelain stoneware tiles compositions were developed from different industrial residues from the state of Rio Grande do Norte, Brazil. The surface characteristics prior to polishing were characterized and 3D mapped. The kinematic parameters of polishing were kept constant, as well as the polishing time intentionally saturated, in order to ensure that the microstructural difference is the only variable to be related to the final glossiness reached. In total, six eco-friendly compositions were polished, three of them with different proportions of the waste from the breakage of bricks and roof tiles and another three from different proportions of the waste from the beneficiation of primary kaolin ore. The surface quality of the compositions was characterized by determination of glossiness and roughness curves as well as the morphology of the samples. The patterns were compared to a waste-free composition. The experimental results validate the full potential of using of industrial wastes as alternative raw materials for the production of polished porcelain stoneware tiles, enabling the direct transfer of knowledge to the productive sector, in addition, contributing to the diversification of the Brazilian industrial matrix towards more technologically advanced and of greater added value.

8
  • VANESSA CASTRO DE SOUZA
  • STUDY OF THE PROPERTIES OF NATURAL ZEOLITES MODIFIED BY ACID AND / OR BASIC TREATMENTS

  • Líder : SIBELE BERENICE CASTELLA PERGHER
  • MIEMBROS DE LA BANCA :
  • AMANDA DUARTE GONDIM
  • JHONNY VILLARROEL ROCHA
  • Manuel Karim Sapag
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • MARIELE IARA SOARES DE MELLO
  • SIBELE BERENICE CASTELLA PERGHER
  • Data: 24-jul-2018


  • Resumen Espectáculo
  • The zeolites are crystalline materials constituted by the union of tetrahedra (SiO4 and AlO4) that generate channels and cavities of molecular dimensions, with pore openings of up to 2nm. The natural zeolite Clinoptilolite (Si / Al ≥ 4), belonging to the Heulandite group, presents selectivity for small ray ions due to the size of its cavities. These natural materials are not obtained in their pure form, making treatments necessary for later application. Among the possible treatments to improve the properties, there is the crystal-particle modification that can be obtained by demetallization methods with hydrothermal, acidic, basic or steam treatment. Thus, it becomes feasible the use of natural zeolites, which present low cost, after modifications, so as to obtain improvements of properties and consequently are promising for treatment of effluents, catalytic cracking and gas storage. In this work structural modifications were carried out in natural zeolites Clinoptilolite, with acid and basic treatments, to improve textural properties using experimental statistical planning to control process variables. The acid treatment was the most effective for improving the textural properties (SBET increased from 27 to 165 m2/g), although the basic treatment, despite not having greatly increased the textural properties of the material, considerably increases the Brönsted acidity of the sample for preserving the aluminum. The zeolites clinoptilolites obtained from different deposits (ZNcelta, ZNchile and ZMcelta) were treated with acid (ZNceltaac, ZNchileac and ZMceltaac) that showed improvements in their textural properties. These samples were used in CO2 adsorption (308K) and presented efficient with an increase in the capture of 1.33mmol/g (ZNchile) to 1.9mmol / g (ZNchileac) and for storage of H2 (77K) showed with a considerable increase in storage capacity from 0.17 mmol/g (ZMcelta) to 2.52 mmol/g (ZMceltaac).

9
  • LEONARDO LEANDRO DOS SANTOS
  • Beta-spodumene lithium extraction through mechanisms with obtaining zeolites structures.

  • Líder : SIBELE BERENICE CASTELLA PERGHER
  • MIEMBROS DE LA BANCA :
  • SIBELE BERENICE CASTELLA PERGHER
  • RUBENS MARIBONDO DO NASCIMENTO
  • TIAGO PINHEIRO BRAGA
  • LINDIANE BIESEKI
  • Manuel Karim Sapag
  • Data: 25-jul-2018


  • Resumen Espectáculo
  • The expected increase in the demand for lithium salts results in a growing concern about lithium scarcity and environmental problems in the national lithium extraction industry from renewable reserves whose extractive methodologies are associated with sulfates, organic solvents and the base of actinides, resulting in the formation of sulphated silicoaluminous byproducts and radioactive waste. Currently alternative sources of silicon and aluminum constitute new technologies in the synthesis of molecular sieves involving catalysis, separation, purification and gas storage as a great promise to scale-up applications. Therefore the objective of this study was to develop and design an environmentally efficient route for the extraction of lithium in salt form from beta-spodumene (β-LiAlSi2O6) and technologically viable to obtain by-product with zeolitic properties and properties. Literature studies describe methodologies for the extraction of lithium using sulphated additives, with post-synthesis by-product recovery, ie, this study is unprecedented in the development of zeolite crystalline microstructures en route from litiniferous extraction from beta-spodumene. Firstly in order to develop and design an efficient and economically feasible extraction route, it was important to understand the characteristics of molecular sieves, specifically zeolites. As a result the lithium extraction efficiency with Na2CO3, NaOH and NaCl additives was evaluated by means of atomic absorption measurements in the supernatant, resulting in up to 85% of lithium extracted, based on the chemoselective ion exchange between Li+ of β-LiAlSi2O6 and Na+ Na2CO3 and NaCl. The addition of NaOH promoted mineralizing action for the dissolution of β-LiAlSi2O6, facilitating Li recovery and Si and Al availability for nucleation and growth of zeolitic structures. Finally, two routes were developed, each operating in a closed and continuous circuit (HTS: high-throughput screening), comprising steps such as calcination, solubilization, hydrothermal treatment and bicarbonation, leading to lithium extraction and by-product with zeolite-cage (LTA and FAU) or zeolite-channel topology (LTT, MOR and MFI). The materials were characterized by several techniques such as XRD, TGA/DTA, ICP, adsorption isotherms of N2, SEM, TEM and FTIR with adsorbed pyridine to validate the strategies used.

10
  • MARIA JOSÉ GOMES DE ARAÚJO
  • CARBON FOAMS: SYNTHESIS, CAHARACTERIZATION AND APPLICATION.

  • Líder : SIBELE BERENICE CASTELLA PERGHER
  • MIEMBROS DE LA BANCA :
  • DALVA LÚCIA ARAÚJO FARIA
  • EDUARDO RIGOTI
  • JHONNY VILLARROEL ROCHA
  • Manuel Karim Sapag
  • RUBENS MARIBONDO DO NASCIMENTO
  • SIBELE BERENICE CASTELLA PERGHER
  • Data: 26-jul-2018


  • Resumen Espectáculo
  • The advancement of science and the search for new materials has been outstanding in recent years. Among these new materials are the carbon foams porous structure materials consisting mainly of macropores, which present high specific area, light weight, thermal and electrical conductivity, high thermal stability, being applied as adsorbents, electrodes, supports for catalysts, thermal insulation at high temperatures and others. Several methods and raw materials have been used to synthesize carbon foams, these include petroleum sources and derivatives, but the limit and scarcity of these materials makes it necessary to search for raw materials from renewable sources or biomass. As a result, this research aimed to synthesize carbon foams using sucrose as the carbon source and the aluminum, iron and silver nitrates as blowing agents, besides these, carbon foams using montmorillonite as reinforcing agent were also produced. Finally, we studied the substitution of the traditional sucrose carbon source for glycerol (biomass) and the materials were applied to remove CO2 from the environment. Therefore, a methodology known for obtaining these materials called blowing of the carbon precursor through the addition of chemical agents was adopted. Morphology, structure, texture properties, mechanical strength and CO2 adsorption capacity at 35 ° C were evaluated in the obtained samples. It is observed that nitrates of iron, silver and aluminum were efficient as blowing agents in the production of carbon foams, contributing to the structure of interconnected pores and high porosity in the 90% range, the samples have a good BET specific surface, especially were synthesized with aluminum nitrate (EsAl) and iron nitrate (EsFe) with values of 600 and 380 m2/g, respectively. The addition of the reinforcing agent (montimorillonite) in the production of carbon foams shows a trend in improving the mechanical strength of the EsAlAr foams (2.28 MPa) attributed good dispersion of the reinforcement on the surface of the samples. Efficient substitution of up to 50% sucrose content by glycerol in the synthesis of carbon foams, shows an increase in the BET specific surface as the proportion of glycerol increases in the foams. All samples synthesized with iron nitrate present a more ordered structure with larger domain size. The capture of CO2 at 35 ° C is efficient in the foams obtained, highlighting in the samples synthesized with aluminum nitrate (EsAl) and in samples with glycerol proportions of 10 and 30% (EsGl10 and EsGl30) with CO2 capture value of 5.3 mmol.g-1.

11
  • HELOÍSA PIMENTA DE MACEDO
  • Hybrid Porous Ceramics Derived from Polysiloxanes Containing Ni Nanoparticles for Production of CH4 via Hydrogenation of CO2

  • Líder : DULCE MARIA DE ARAUJO MELO
  • MIEMBROS DE LA BANCA :
  • DULCE MARIA DE ARAUJO MELO
  • MAURICIO ROBERTO BOMIO DELMONTE
  • RENATA MARTINS BRAGA
  • BRAULIO SILVA BARROS
  • MICHAELA WILHELM
  • Data: 27-jul-2018


  • Resumen Espectáculo
  • Preceramic polymers are Si-based organic–inorganic materials that can be converted to ceramics under inert atmosphere, resulting in hybrid materials with adjustable characteristics and interesting physico-chemical properties. Hybrid ceramic materials with dispersed Ni nanoparticles were prepared by pyrolytic conversion of polysiloxane precursors in order to evaluate their applicability in CO2 methanation. Materials with tailorable characteristics were synthesized by varying the precursors (polysiloxanes with either methyl or methyl phenyl groups) and by ranging the pyrolysis temperature from 400 to 600Ž, leading to the formation of porous materials in a hybrid state where the polymer is just partly converted to ceramic. The siloxane bistrimethoxysilylpropylamine (BisA) was used as complexing agent of the metal precursor. The materials were characterized by thermogravimetric analysis (TGA), N2 adsorption-desorption isotherms (BET-BJH), water and n-heptane adsorption, X-ray diffraction (XRD) and transmission electron microscopy (TEM). Catalytic CO2 methanation tests (CO2 + 4 H2 → CH4 + 2 H2O) were performed between 200 – 400Ž at atmospheric pressure. In-situ X-ray diffraction analysis (in-situ XRD) was used to evaluate the Ni particle structure and size during a simulated catalytic reaction. Ceramers with hierarchical porosity (micro, meso and macropores), high specific surface areas (100-550 m2.g-1), hydrophobic or hydrophilic surfaces and different Ni particle sizes (4-7 nm) were obtained by changing the pyrolysis temperature and polysiloxane composition. Regarding the catalytic performance, ceramers prepared from methyl polysiloxane precursor exhibited less hydrophilic surfaces and, thus, improved catalytic performance compared to the ones preparaded from metyl phenyl polysiloxanes. A negative effect on the catalytic performance of ceramers was observed with increasing pyrolysis temperatures, which led to an increase in the Ni particle size (from 4 to 7 nm), and consequently, lower levels of conversion and selectivity. The ceramers pyrolyzed at 400Ž exhibited the best catalytic performance, showing selectivity up to ~77% and good stability during a 10 h test, whereas preserving the Ni crystallite size as shown by the in-situ XRD. Therefore, Ni based hybrid ceramers derived from polysiloxanes are promising catalysts with highly distributed metal particles and tunable surface properties.

12
  • RANNIER MARQUES MENDONÇA
  • CURE KINETICS OF POLYESTER WITH THE ADDITION OF CUPUACU SHELL POWDER

  • Líder : JOSE DANIEL DINIZ MELO
  • MIEMBROS DE LA BANCA :
  • JOSE DANIEL DINIZ MELO
  • ANA PAULA CYSNE BARBOSA
  • ROSANGELA DE CARVALHO BALABAN
  • CECILIA VERONICA NUNEZ
  • LAURA HECKER DE CARVALHO
  • Data: 26-sep-2018


  • Resumen Espectáculo
  • The growing awareness of environmental issues and the consequent increasingly rigid international legislation in this area have attracted the interest of researchers to the development of materials containing components derived from renewable sources. Among vegetable resources with potential application in the industrial area, cupuaçu (Theobroma grandiforum), a fruit native to the Amazon region, offers pulp and seeds used in the production of food products. In this process, the shell is usually discarded in landfills. This material has in its composition organic compounds that can affect the curing kinetics of polymer resins, with potential to be used as a cure accelerator or retardant. The objective of this research was to study the effect of the chemical compounds present in the cupuaçu fruit shell on the curing kinetics of polyester resins. Laser granulometry, Scanning Electron Microscopy (SEM), thermogravimetry, Differential Scanning Calorimetry (DSC), tensile tests, Dynamic-Mechanical Analysis (DMA), reaction kinetics and phytochemistry analyses were performed. Polymers were produced with the addition of 0.5, 1.0, 2.0 wt.% of vegetable material. According to the results obtained from the kinetic studies by the temperature sweep method, the temperature of the beginning of the cure reaction was shifted to higher values as the percentage of vegetal material was increased, indicating a delay of the reaction process. The vegetable-based additive also affected the degree of conversion throughout the curing process of the unsaturated polyester resin. The activation energies of the reactions were increased with the increase in content of the vegetable material. Using the isothermal method, it was observed that the partition phases of the raw extracts of the shell also affected the curing process of the polymer resin, suggesting more than one reagent molecule in the vegetable material. The addition of the vegetable material did not affect the thermal properties - glass transition temperature and degradation temperature – or mechanical properties - tensile strength and modulus of elasticity - of the cured polyester resin. Chromatographic fractionation of phases of the vegetable material allowed the isolation of caffeine from the ethyl acetate phase, which was identified by mass spectrometry and comparison by High performance liquid chromatography (HPLC) with the standard substance. Its structural characteristic explains its interference in the healing process of the pericarp, delaying the process. In summary, the results of this research demonstrate that cupuaçu pericarp can be used as a curing retardant of the unsaturated polyester resin without any significant effect in its mechanical and thermal properties. 

13
  • MURILO JOSE PEREIRA DE MACEDO
  • Modification of kapok fibers by cold plasma surface treatment for the production of composites of recycled polyethylene.

  • Líder : JOSE DANIEL DINIZ MELO
  • MIEMBROS DE LA BANCA :
  • EDSON NORIYUKI ITO
  • ELITON SOUTO DE MEDEIROS
  • JOSE DANIEL DINIZ MELO
  • MARIA ODILA HILÁRIO CIOFFI
  • THERCIO HENRIQUE DE CARVALHO COSTA
  • Data: 24-oct-2018


  • Resumen Espectáculo
  • The worldwide production of plastic products has increased significantly over the last decades and their disposal has become an important environmental concern. Recycling provides great opportunities for waste reduction and lower environmental impact. As a recycling alternative, there has been growing interest on addition of biomass residues to polymers to produce composite materials for technological applications. In this study, composites from recycled polyethylene waste and kapok fibers were prepared. Cold plasma treatment was used to improve fiber/matrix adhesion. The effects of plasma treatment on fiber morphology were evaluated using Field-emission gun scanning electron microscopy (FEGSEM) and on chemical structure of the fibers were evaluated by Fourier-transform infrared (FTIR) spectroscopy. Changes in water uptake (WU), mechanical properties and thermal decomposition kinetics behavior of the kapok fibers were studied. The results suggest an increase in water absorption after plasma treatment. Composites using untreated and treated fibers were manufactured and characterized. Dynamic mechanical thermal analyses (DMTA) of composites made using plasma treated fibers indicated an increase in storage moduli as well as an increase in glass transition as compared to the pure polymer. Thermogravimetric Analysis (TGA) indicated that the addition of plasma treated fiber produced changes in thermal degradation as compared to the pure polymer due to matrix/fiber interaction. Differential Scanning Calorimetry (DSC) analysis suggested that the plasma treatment also produced changes in degree of crystallinity of the fibers. The thermal parameters results also indicated an improvement in thermal insulating characteristic of the composites with the increase in fiber content. Field-emission gun scanning electron microscopy (FEG-SEM) images of fractured surfaces of the composites suggest that fiber/matrix adhesion was improved for composites made using plasma treated fibers. Thus, cold plasma is demonstrated as a viable alternative to treat cellulosic fibers and improve fiber/matrix interface of polymer-based composites.
2017
Disertaciones
1
  • GRAZIELE LOPES DE SOUZA
  • Synthesis of alternative oxides for intermediate temperature solid oxide fuel cells

  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • RUBENS MARIBONDO DO NASCIMENTO
  • ANTONIO EDUARDO MARTINELLI
  • RICARDO PEIXOTO SUASSUNA DUTRA
  • Data: 30-ene-2017


  • Resumen Espectáculo
  • La2-xNiO4+d cathode, series materials with structure K2NiF4, have been considered as very promising materials due to their high mixed ionic electronic to intermediate temperature. The interest in these oxides as functional material for cathode increased because of its oxygen permeability and its stability. This material has coefficient of thermal expansion compatible with electrolytes from the La10-x(SiO4)6O2+-d family and apatite structure. These electrolytes have higher conductivities than zirconia-based electrolytes if used in the same temperature range as the above-mentioned cathode. This work reports the synthesis of apatite-type lanthanum silicate powders with nominal composition La10Si6O27 and Lanthanum nickelate (La2NiO4) for using as electrolyte and cathode materials, respectively, in solid oxide fuel cells. The lanthanum silicate was obtained from a co-precipitation chemical route, while the cathode was obtained by the citrate method. The herein proposed synthetic procedure is advantageous in reducing energy consumption and processing time, key elements to decrease the total manufacturing cost. At the end of the syntheses, the precursors powders were characterized by thermogravimetric analysis. The lanthanum silicate powders as prepared were calcined between 500 and 900 °C and characterized X-ray diffraction (XRD), Rietveld refinement and scanning electron microscopy (SEM). Already the lanthanum nickelate was calcined in a single temperature 1200 °C for 4h and characterized by SEM. The structural characterization of the electrolyte indicated the formation of biphasic material after calcination at 900 °C. The effect of sintering temperature, ranging from 1400 to 1450 °C, on the electrical properties was investigated by impedance spectroscopy. Electrical measurements were recorded in the 400 – 800 °C temperature range in air. The lanthanum silicate electrolyte sintered at 1450 °C exhibited total electrical conductivity 2.12 x 10-3 S.cm-1 in 700 °C comparable with samples from literature prepared and sintered at 1500 °C. The electrochemical performance as cathode material was evaluated in a symmetrical cell configuration (cathode/substrate/cathode) using the electrochemical impedance spectroscopy. Lanthanum nickelate cathodes obtained by screen printing and sintered at 1300 ° C for 4 h had an area specific resistance (ASR) of 2.85 ohm.cm2 at 800 ° C under an oxygen atmosphere. Lanthanum nickelate was mixed with the electrolyte material and sintered at the same temperature used for sintering of the cathode film, in order to evaluate possible chemical reactions between them and characterized by X-ray diffraction and SEM. The materials showed good electrochemical results compared to the literature and chemical stability up to 1300 ° C.

2
  • THATIANA CRISTINA PEREIRA DE MACEDO
  • PROCESSING AND CHARACTERIZATION OF POLY (METHYL METHACRYLATE) (PMMA) WITH ELASTOMIC PARTICLES AND POLYCARBONATE (PC) BLEND

  • Líder : EDSON NORIYUKI ITO
  • MIEMBROS DE LA BANCA :
  • EDSON NORIYUKI ITO
  • ROSANGELA DE CARVALHO BALABAN
  • MARCELO MASSAYOSHI UEKI
  • Data: 13-feb-2017


  • Resumen Espectáculo
  • The aim of this work was to study the rheological, mechanical and microstructural behavior of poly (methyl methacrylate) / polycarbonate (PMMA/PC) blends using a PMMA with elastomeric particles until phase inversion. The PMMA/PC blends were processed in single screw extruder and co-rotational twin screw extruder, with subsequent injection molding. The changes in the physical and chemical characteristics of the polycarbonate were analyzed by viscosimetry and by Fourier transform infrared spectroscopy (FTIR) before and after processing. The mechanical characterizations were performed by uniaxial tensile test and Izod impact. The rheological tests were done by melt flow index (MFI) and capillary rheometry. Microstructural analysis of the polymer blends was performed using atomic force microscopy (AFM) and scanning electron microscopy (SEM). The thermal degradation temperature was determined by thermogravimetric analysis (TGA). The results of the MFI in the processing conditions indicated a higher flowability of the polycarbonate among all the studied compositions, most of them present higher value of MFI for the materials processed in twin screw extruder. In the capillary rheometry of the unprocessed materials a lower PC viscosity variation was observed as a function of the shear rate increase, but the processing of this material caused significant changes in the rheological curves. TGA showed a higher degradation onset temperature for the PC, but the processing altered the thermal stability of that polymer more than for poly (methyl methacrylate). The intrinsic viscosity measurements of the polycarbonate indicated a possible degradation by chain scission after processing due to the decrease in the molar mass of the material. The FTIR did not identify distinct bands for the PC before and after the processing. The mechanical characterization by uniaxial tensile revealed higher tensile strength, higher modulus of elasticity and greater elongation at break for polycarbonate, and the compatibility of PMMA/PC blends varied with PC concentration, with some compositions that showed synergism in the properties. Izod impact strength showed a high PC impact strength when compared to PMMA, but the addition of 20 wt% of PC in the PMMA matrix significantly increased the impact strength of PMMA/PC blends. The morphological analysis by AFM visualized the presence of spherical elastomeric particles with an average size of about 182 ± 20 nm in the PMMA, evenly distributed along its microstructure, while the PC presented only one homogeneous phase. The PMMA/PC blend showed two well-defined phases throughout all the compositions, and showed evidence of morphology with co-continuity characteristics for the compositions between 70/30 and 50/50 wt%, both for the materials processed in songle screw extruders as well as twin screw extruders. The compositions with the highest percentage of PMMA in the PMMA/PC blends were the ones with the best results of rupture strength and elongation at break, and the Izod impact resistance showed intermediate properties. The results in the phase inversion followed the characteristics of the polycarbonate, not showing significant gains of properties. It was concluded that the use of PMMA with elastomeric particles as the matrix phase in the PMMA/PC blend enhanced the applicability of the material.

3
  • MARIANA CHIANCA LÚCIO DA SILVA
  • STUDY THE EFFECT OF ALUMINA IN THE WC-Al2O3 SYSTEM BY POWDER METALLURGY

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • ARIADNE DE SOUZA SILVA
  • LEILIANE ALVES DE OLIVEIRA
  • UILAME UMBELINO GOMES
  • Data: 16-feb-2017


  • Resumen Espectáculo
  • Tungsten Carbide (WC) is best known for its excellent physical and mechanical properties. However, it has limitations, mainly when the tougher and lighter material is requested. An alternative to minimize these problems is a composite of WC and alumina (Al2O3) to reducing density and promoting toughness at certain temperatures. Thus, in this work, the effects of the different amount of alumina and powder metallurgy processing parameters on microstructure of particulate and sintered composite (WC-Al2O3) were studied and the mechanical properties, particularly the microhardness, of the product were analyzed to find an alternative cutting tool material. In the study, the particulate materials production route was applied. The composite powders have the following compositions: WC with 5, 10 and 15wt% of Al2O3 processed by high energy milling in a planetary milling for 1, 4 and 10 hours. Compacting of mixed powders was done using a uniaxial press in a cylindrical die of 5 mm diameter under a pressure of 400 MPa. Solid phase sintering was performed in a resistance furnace at 1450 and 1550 °C with 1 hour of holding time and heating rate of 10°C/min in argon atmosphere. The raw materials were characterized by particulometry, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The milled powders and sintered samples were subjected to the same tests and microhardness test was also done for sintered samples as well. The results showed that high energy milling met the targets for particle size and dispersion of composite components. However, due to partial sintering or consolidation of green compact, the microhardness did not achieve to significant results and microstructures with high porosity were observed.

4
  • JOSÉ RAELSON PEREIRA DE SOUZA
  • EFFECT OF SINTERING AND HIGH-ENERGY MILLING ON MICROSTRUCTURE AND MECHANICAL PROPERTIES OF ALUMINUM ALLOYS RECYCLED FROM BEVERAGE CANS


  • Líder : MAURÍCIO MHIRDAUI PERES
  • MIEMBROS DE LA BANCA :
  • MAURÍCIO MHIRDAUI PERES
  • RUBENS MARIBONDO DO NASCIMENTO
  • BRUNO BELLINI MEDEIROS
  • Data: 24-feb-2017


  • Resumen Espectáculo
  • This work presents the study of the obtaining and characterization of aluminum recycling from beverage cans composed of aluminum alloys AA3004, 5042 and 5182, through the technique of high energy milling and powder metallurgy. The cans were selected, drilled and milled to obtain the metallic powder under different milling times (1h, 1h30min and 2h). The obtained powder was compacted at a load of 400 MPa and sintered at 600 ° C for two hours. For characterization of the aluminum poder were realized XRD, SEM and EDS, and laser granulometry analyzes; while the material consolidated by sintering, in addition to the analyzes via DRX, SEM and EDS, was also characterized by dilatometry, compression and microhardness Vickers tests. The size of the particles and their relationship to the properties of the aluminum alloy were evaluated. The processing route adopted resulted in the effective compaction of the aluminum powder from the beverage can milling, but with a clear presence of porosity, typical of sintered metals. A large incidence of precipitates of the dispense Al6Mn phase in the Al-alpha matrix (CFC) was observed. The samples presented variations in their mechanical properties as a function of milling time. The compressive strength increased from 105 N / mm² with 1h grinding to 120 N / mm² with 1h30min and decreasing to 110N / mm² with 2h grinding, but the ductility presented little variation. The hardness was 56.43 HV, 66.52 HV and 92.21 HV for the times of 1h, 1h30min and 2h, respectively.

5
  • RAYANE RICARDO DA SILVA
  • Analysis of the synthesis parameters of NbN via gas-solid reaction.

  • Líder : CARLSON PEREIRA DE SOUZA
  • MIEMBROS DE LA BANCA :
  • CARLSON PEREIRA DE SOUZA
  • ANDRE LUIS LOPES MORIYAMA
  • ANDARAIR GOMES DOS SANTOS
  • Data: 02-mar-2017


  • Resumen Espectáculo
  • The aim of this work is to study the synthesis of Niobium Nitride, starting from the precursor tris (oxalate) oxiniobilato ammonium hydrate, through the gas-solid reaction in a fixed-bed reactor. The heat treatment conditions to obtain the NbN were at temperatures 700, 800, 900, 1000 and 1100°C varying the time in the isotherm between 3, 4 and 5 hours. The gas mixture is composed of nitrogen and hydrogen. The composition and the total flow of the gas flow were varied. The obtained materials were characterized by X-ray diffraction (XRD), Rietveld Refinement and Scanning Electron Microscopy (SEM). Increasing the reaction temperature and time in the isotherm it was observed the phase change of niobium oxide to niobium nitride. There was formation of two phases of nitride, and the hexagonal phase is present in greater quantity, and the tetragonal phase in less quantity. These results are not observed in the literature.

6
  • CAROLINE SUZY DO NASCIMENTO GARCIA
  • STARCH LAURATE OBTAINED FROM STARCH EXTRACTED THE SEED OF MANGA TOMMY ATKINS: SYNTHESIS, CHARACTERIZATION AND APPLICATION IN NON-AQUEOUS DRILLING FLUIDS.

  • Líder : EDSON NORIYUKI ITO
  • MIEMBROS DE LA BANCA :
  • EDSON NORIYUKI ITO
  • ROSANGELA DE CARVALHO BALABAN
  • MARCOS ANTONIO VILLETTI
  • NÍVIA DO NASCIMENTO MARQUES
  • Data: 03-mar-2017


  • Resumen Espectáculo
  • After processing of mango in pulp and juices industries, tons of residues such as shell and seed are discarded without proper use. About 15% to 20% of the weight of the mango, depending on its variety, is due to the seed, from which it is possible to obtain the starch. In order to add value to this residue, this study aimed to produce an ester from mango starch (Tommy Atkins), through the transesterification reaction of vinyl laurate (LV) with starch. The synthesis was performed in the presence of a basic catalyst (K2CO3) in dimethyl sulfoxide (DMSO) at 110 ° C and N2(g). The product was purified by precipitation in methanol and characterized by Fourier Transform Infrared Spectroscopy (FTIR), thermal gravimetric analysis (TGA), solubility tests and scanning electron microscopy (SEM). FTIR confirmed the starch laurate was obtained, by displacing the C=O band from the vinyl ester at 1759 cm-1, to 1743 cm-1 in vinyl laurate, due to satured ester in the modified starch. 1H NMR indicated that the starch laurate showed a degree of chemical modification at 1.13 and 13C NMR showed a signal at 173 ppm, which can be attributed to the carbonyl of the starch laurate. Thermogravimetric analysis showed that the modified starch has higher thermal stability than its precursors and than a physical blend of starch and vinyl laurate. Solubility tests also confirmed the chemical modification, since, unlike the starch, the product was soluble in toluene and chloroform, and remained insoluble in water and DMSO. SEM data showed that crystalline domains on starch were broken after chemical modification and the appearance shown in micrograph is unstructured (amorphous). From the hydrophobic starch product obtained the present work sought the use of this starch in petroleum well drilling fluids based on invert emulsion (W/ O), due to the high interest in developing non-aqueous fluids of low toxicity and high performance under very high temperature and pressure conditions. The physical-chemical experimental results of the studied fluids indicate that the obtained product of the synthesis presented similar performance to the fluid with commercial additive in the control of the filtrate.

7
  • CICERO LEONARDO PEREIRA DE SOUZA
  • An investigation of the influence of heat imput and adittion of Al and PVC films on the microstructure of the welded metal deposited by basic coated electrodes E7018

  • Líder : AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • MIEMBROS DE LA BANCA :
  • AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • MOACIR BISPO RAMOS
  • NICOLAU APOENA CASTRO
  • RUBENS MARIBONDO DO NASCIMENTO
  • Data: 10-mar-2017


  • Resumen Espectáculo
  • The shield metal arc welding (SMAW) is one of the oldest welding processes and the first one to be used in large industrial scale. During the XX century the SMAW was the most applied process for metal joining, remaining until nowadays as one of the most used in the Brazilian market. In this kind of welding one of the biggest problems is to avoid the hydrogen induced cold cracking, what imposes rigid requirements in the storing of the weld consumables. In order to avoid the humidity absorption, the consumables must be dried out in special ovens at temperatures in the order of 450 C, what implies in additional and higher manufacturing costs. In this context a recent research suggested modifications in coating of electrodes providing an alternative for execution of welding with low hydrogen electrode AWS E7018 without having to dry it, The welds were developed with basic coated electrodes (hygroscopic) externally painted with aluminum spray paint for high temperatures or wrapped with thin plastic films (PVC) and aluminum foil films. The induced metallurgical changes in the deposited metal, associated with the addition of new materials to the electrode coating, were investigated, wereby the microconstituents in the fusion zone were quantified using a software for image analysis. In the actual work, with the use of a field emission microscope, MEV-FEG, high contrast images could be obtained, this allowed a detailed characterization of the various microconstituents and a more precise description of their morphology. In special it was possible to evaluate the influence of the protective films in the grain size and aspect ratio of the microconstituent AF (acicular ferrite). On base of a literature review a critical analysis is presented, that embraces the effect of the more relevant parameters on the final microstructure and resulting mechanical properties. The results showed that for higher values of heat input the microstructure, especially the acicular ferrite, tends to be coarser. With the use of PVC coatings and aluminum paint, a slight reduction was achieved in this granulometry, since the microstructure was more refined than with reference electrodes (E7018 pure and BRH4R).

8
  • FÁBIO GUSTAVO LIMA PEREIRA
  • Fadigue and fracture of the nickel base superalloy, inconel 625, submited cyclic stress R = -1

  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • JORGE MAGNER LOURENÇO
  • JOSÉ DE ANCHIETA LIMA
  • NICOLAU APOENA CASTRO
  • RUBENS MARIBONDO DO NASCIMENTO
  • Data: 17-mar-2017


  • Resumen Espectáculo
  • The fatigue process in materials is the failure mechanism with the presence
    of cyclic stresses. Surface flaws and stress concentrators may lead to nucleation of
    cracks during this process. The cracks propagate and cause component fracture after
    a sufficient number of cycles. This failure mechanism has become increasingly
    important as soon as the technological progress has enabled the implementation of
    a larger number of structures subjected to different modes of loading and vibrations
    such as the equipment used in the pre-salt industry. New materials are being developed
    especially for this sector and they have to meet some specifications to work
    on this harsh environments. Examples of materials used under such circumstances
    are the resistant nickel-based alloys. In this context, this study aims to evaluate the
    behaviour of the Nickel-based superalloy, Inconel 625, under load with load ratio R
    equal to -1 as well as its mechanical and microstructural properties. The mechanical,
    microstructural and morphological characterization of Inconel was analyzed
    by axial fatigue, tensile, hardness, optical microscopy, SEM and XRD tests. The
    results indicated that Inconel 625 is able to associate high mechanical strength and
    moderate hardness with good ductility. The diffractometry allowed to verify the
    presence of a matrix phase 𝛾 and carbides of the types 𝐶𝑟23𝐶6, MoC e NbC. The
    development of the S-N curve made it possible to estimate the fatigue strength of
    the material to be approximately 255 MPa. The fracture surfaces were observed by
    scanning electron microscopy, in order to investigate the effects produced by fatigue
    cracks. The presence of beach marks and fatigue striations were observed, they are
    typical characteristics of the fatigue process.

9
  • ANA CAROLINA MARÇAL PIRES FERREIRA LUCAS
  • Diagnosis of a petroleum derivative contamination in soil and groundwater in a Waterway Terminal: a case study in the city of Natal-RN.

  • Líder : MARCUS ANTONIO DE FREITAS MELO
  • MIEMBROS DE LA BANCA :
  • CARINA GABRIELA DE MELO E MELO BARBOSA
  • DJALMA RIBEIRO DA SILVA
  • MARCUS ANTONIO DE FREITAS MELO
  • Data: 31-mar-2017


  • Resumen Espectáculo
  • The Aquaviários Terminal Unit's main function is to receive, store and distribute oil, oil products and liquid renewable fuels, ensuring the supply of domestic and international markets. The great logistic movement generated by the exploration, processing, storage, transportation and commercialization of oil and its derivatives has generated worries related to its potential contamination of the environment. Because of the numerous accidents with fuel spills, which cause contamination of soils and waters by oil-derived hydrocarbons, research in this context makes it a challenge for professionals working in the area, due to the complexity of interactions occurring in the soil and in the water. The Terminal, object of study, is located in the city of Natal-RN and occupies an area of 110,000 m2. The aim of this study is to evaluate soil and groundwater contamination by petroleum by-products in the 1430-04 basin, characterizing the presence of substances with potential contamination in soil and groundwater through the collection of soil and water samples for the analysis of TPH fractional parameters, BTEX, VOC, SVOC and metals. As well as the analysis of soil physical parameters (particle size, total and effective porosity, particle density and total soil, natural moisture) and organic carbon fraction. The chemical analyzes of soil samples did not present concentrations of the analyzed parameters (TPH, BTEX, VOC, SVOC and metals). Concentrations of benzene were detected in the groundwater samples, in addition to xylenes and TPH. For metals, concentrations of lead were detected in addition to iron. For dissolved metals, only lead had concentrations above the values investigated. All results of the chemical analyzes were compared with the values of CONAMA Resolution 420/2009.


10
  • ÉRICK STÉFANO SILVEIRA GUERRA
  • Study of the addition of poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) thermoplastic to epoxy resin for use in self-healing composites

  • Líder : ANA PAULA CYSNE BARBOSA
  • MIEMBROS DE LA BANCA :
  • ANA PAULA CYSNE BARBOSA
  • EVANS PAIVA DA COSTA FERREIRA
  • JOSE DANIEL DINIZ MELO
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • MARIA ODILA HILÁRIO CIOFFI
  • Data: 28-abr-2017


  • Resumen Espectáculo
  • Repair of damaged composite structural elements to restore pristine conditions and meet regulatory requirements can be a great challenge. Thus, materials capable of self-healing when damaged are of great interest. In one of the self-healing approaches studied in the literature, thermoplastic is added to a thermosetting matrix and the damaged material partially recovers its mechanical properties after a healing cycle. This technique employs heat to partially re-establish the mechanical properties of the composite material. In the present study, modification of epoxy resin with poly(ethylene-co-methyl acrylate-co-glycidyl methacrylate) (E-MA-GMA) termoplastic was evaluated. The influence of the employed type of hardener (anhydride and amine) on the properties of the material was also investigated. Dynamic mechanical analysis (DMA) was performed to evaluate changes in viscoelastic properties due to the thermoplastic addition. Fourier transform infrared (FTIR) spectroscopy was used to evaluate chemical alterations in thermoplastic-epoxy systems. Atomic force microscopy (AFM) was employed to examine the role of thermoplastic addition on epoxy network structure. Healing ability was assessed by comparing areas damaged by standard indentations on the surface of samples before and after healing cycle for materials with and without E-MA-GMA addition. Results suggest the presence of a E-MA-GMA second phase after curing, an increase in glass transition temperature (Tg) for all thermoplastic blended samples as compared to neat epoxy, the presence of one single Tg for epoxy anhydride hardened E-MA-GMA mixtures and chemical and structural alterations on epoxy network due to addition of E-MA-GMA. Further, the disappearance damage caused by indents on areas of the material modified with thermoplastic after a heating cycle supports the potential use of E-MA-GMA as healing agent.

11
  • NIVALDO FREIRE DE ANDRADE NETO
  • STUDY OF THE PHOTOCATALITICAL AND ANTIMICROBIAL ACTIVITIES OF AGCl PARTICLES IMPREGNATED WITH WHAT IS OBTAINED BY SONOQUÍMICA SYNTHESIS

  • Líder : FABIANA VILLELA DA MOTTA
  • MIEMBROS DE LA BANCA :
  • FABIANA VILLELA DA MOTTA
  • MAURICIO ROBERTO BOMIO DELMONTE
  • KATIA NICOLAU MATSUI
  • BRAULIO SILVA BARROS
  • Data: 16-jun-2017


  • Resumen Espectáculo
  • The growth of industrial activities led to an increase in the generation of effluents, which led environmental agencies to propose the creation of regulatory frameworks to limit the generation of effluents. The effluents generated by the textile industries are difficult to be degraded by traditional methods of treatment. Advanced oxidative processes (POAs) are an efficient alternative for the degradation of organic pollutants such as dyes (methylene blue). In this work, silver chloride particles (AgCl) impregnated with copper oxide (CuO) were synthesized via sonochemistry. AgCl/CuO 1:1 and 2:1 compositions, respectively, were prepared. Such compositions went through three distinct procurement routes. To characterize the particles, X-ray diffraction (XRD), scanning electron microscopy with field emission (SEM-FEG), and UV-visible (UV-vis) spectroscopy were performed. To verify the applicability of the compound were carried out in the samples of AgCl/CuO photocatalytic tests for degradation of the methylene blue dye and the antimicrobial activity against the bacteria Escherichia coli and Staphylococcus aureus. The results of X-ray diffraction confirmed the formation of AgCl and CuO in all samples, with no evidence of doping for any route used. The results of the photocatalytic activity indicate that increasing the ratio of AgCl (1:1 to 2:1) accelerates the degradation of methylene blue on average by 25%.

12
  • THIAGO SOUZA VIANA

  • INFLUENCE OF THERMAL HEAT TREATMENTS IN THE MICROSTRUCTURE OF A PSEUDOPLASTIC NiTi LEVEL.

  • Líder : AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • MIEMBROS DE LA BANCA :
  • AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • NICOLAU APOENA CASTRO
  • RUBENS MARIBONDO DO NASCIMENTO
  • WALMAM BENÍCIO DE CASTRO
  • Data: 30-jun-2017


  • Resumen Espectáculo
  • In the present work, the influence of heat treatments on the microstructural transformations of an approximately equiatomic NiTi memory form alloy was investigated. A NiTi wire with 2.5 mm in diameter, received in the work hardened state, was submitted to annealing heat treatments at 450°C and 500°C in order to verify the calorimetric and microstructural changes. Optical and electronic microscopy and X-rays diffraction were employed to characterize the structure and the phases morphology. The analysis via differential scanning calorimetry allowed the determination of the transition temperatures (As, Af, Ms, Mf) and the change in the transformation temperatures between the as received worked hardened and annealed material is discussed. The microstructure in the work hardened condition and after the annealing heat treatments was analyzed in detail via field emission scanning electronic microscopy (MEV-FEG), which showed a coarsening of the martensite plates for higher temperatures and longer heat treatment times. Microhardness measurements did not reveal any significant influence of the annealing or subzero heat treatments on the mechanical behavior of the alloy.

13
  • AMANDA REGINA DE SOUZA MACEDO
  • OBTAINING AND CHARACTERIZING A DIATROMETRIC DIATOMIC TAPE THROUGH THE TAPE CASTING PROCESS

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • ARIADNE DE SOUZA SILVA
  • CARLSON PEREIRA DE SOUZA
  • LEILIANE ALVES DE OLIVEIRA
  • UILAME UMBELINO GOMES
  • Data: 31-jul-2017


  • Resumen Espectáculo
  • Diatomitehas a widevarietyofapplicationsdueto its physicalandchemicalpropertiesandiswidelyused as a filter material becauseof its high porosity. It is a material thatalsohasdielectricpropertieswhenin its naturalstate. In thiswork, a ceramic tape producedfromthediatomitewasstudiedthroughthe tape castingprocess, tobeapplied as in dielectriccapacitors. The raw material (diatomite) wascharacterizedbyparticulometry, X-raydiffraction (XRD), X-rayfluorescence (FRX), scanningelectronmicroscopy (SEM) and Fourier transforminfraredspectroscopy (FTIR) ). The ceramic tape wasobtainedbypreparing a slipwithdiatomitepowder, solvent, dispersant, binder, plasticizeranddefoamer; The mixingofthematerialswascarried out in a ballmill. The rheologytestwasperformedtoevaluatetheviscosityofthesuspension. The slipwasgluedonto a filmandafter 24 hours thegreenribbonwasremoved, whichwascharacterizedbydifferentialthermalandthermogravimetricanalysis (ATD \ ATG), DRX, FRX and MEV. A dielectricceramic capacitor (prototype) wasbuiltwiththegreen tape, in whichtheelectricalcapacitanceandresistancemeasurementswereperformed, andthedielectricconstantofthe material (diatomite tape) wasobtained. The green tape underwent a heattreatment for theremovaloforganicsat a temperatureof 600 ° C and a heating rate of 0.5 ° C / min. The sinteringwasperformedatthreedifferenttemperatures (1000 ° C, 1150 ° C and 1250 ° C), with a heating rate of 5 ° C / min. And 60 min isotherm. It wasthencharacterizedby XRD, SEM, anddensityandporositymeasurements. It wasobservedthatthesinteredsamplespresented high porosity in theirmicrostructure, however, for thehighersinteringtemperatures, therewas a reductionofthisporosity. The diatomitemorphologywasmaintained for thegreenandsinteredbands, showingits navicularand tubular shape. The presenceof pores isdueto a typicalcharacteristicofthefeedstock (diatomite) used, as well as totheprocessingparameters, whichsignificantlyinfluencedthedielectricpropertiesofthe material, particularlygreen tape.

14
  • EDUARDO RODRIGUES DA SILVA
  • EFFECT OF HEAT INPUT IN THE MICROSTRUCTURE OF WELD BEADS DEPOSITED WITH E81T1-Ni1C TUBULAR WIRE IN 3 VARIANTS OF API X-65 STEELS

  • Líder : AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • MIEMBROS DE LA BANCA :
  • AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • MAURÍCIO MHIRDAUI PERES
  • NICOLAU APOENA CASTRO
  • CELINA LEAL MENDES DA SILVA
  • Data: 23-ago-2017


  • Resumen Espectáculo
  • The objective of the present work is the microstructural characterization of weld beads deposited with E81T1-Ni1C tubular wire in 3 variants of X65 API steels. These are alternative materials used in the assembly of pipelines for the transportation of oil and gas, where the qualification of the welding procedures is a prerequisite for guaranteeing the mechanical properties of the component in service. In this context, the detailed characterization of the microconstituents that compose the three sub-regions of the weld is an essential tool, since it contributes with important elements to the understanding of the correlation between process variables and the final properties of the fabricated assembly.

    For this research weld beads were deposited under controlled conditions by the FCAW process, which allowed thermal inputs of 7.3; 11.3 and 22.1 KJ / cm corresponding to cooling times (Δt 8/5) estimated at 3.5; 6.5 and 20s. The microstructural characterization was made by optical microscopy and scanning electron microscopy with Field Emission Gun, where the high quality of the contrast in the images allows the identification and more detailed classification of the microconstituents present. The results for the welding deposits with medium thermal input and Δt 8/5 = 6.5 s, showed that the fused zone (ZF) of the three alloys is predominantly formed by the microconstituint acicular ferrite (AF), with average hardness of the order of 240 HV0,3, aspects that according to the literature are requirements of excellent toughness. When welded with low thermal input, the ZF had AF and average hardness of 260 HV0.3 and Δt 8/5 = 3.5 s. The high thermal input provided a hardness lower than 200 HV0.3 and AF formation in the ZF, and greater Δt 8/5 of approximately 20s. The area affected by the coarse grain heat (ZAC-GG) showed for the 3 steels microstructure basically formed by second phase ferrite (FS) and small fraction of primary ferrite. According to the microhardness profile along the sub-regions of the weld, the maximum peaks located in the ZAC-GG are lower than 340 HV for the bead made with medium heat input, which is indicative of absence of martensite and good toughness for this critical region of the heat affected zone. A hardness profile made in ZAC-GG, with values higher than 350 HV0,3, indicates the risk of formation of martensite in the three alloys of API X65 welded steel with low thermal input.

15
  • JULIANO AUGUSTO MEDEIROS DE MENEZES E OLIVEIRA
  • Microstructural Characterization of Eutectic Aluminum Alloys in the As-Cast State and Heat Treated by Homogenization 

  • Líder : MAURÍCIO MHIRDAUI PERES
  • MIEMBROS DE LA BANCA :
  • MAURÍCIO MHIRDAUI PERES
  • RUBENS MARIBONDO DO NASCIMENTO
  • WANDERSON SANTANA DA SILVA
  • Data: 25-ago-2017


  • Resumen Espectáculo
  • The aluminum alloys in the eutectic composition have a characteristic low melting temperature and a complex microstructure formed by eutectic constituents. They can be applied in the foundry industry, as they additionally present high fluidity and low tendency to the formation of porosity and hot cracking. The Al-Cu (binary), Al-Cu-Si and Al-Cu-Mg (ternary) and Al-Cu-Si-Mg (quaternary) systems were produced by sand casting. The alloys were analyzed microstructurally in the as-cast condition and after homogenizing heat treatment at 495 ° C for until 24 hours, via x-rays fluorescence (FRX), x-rays diffraction (XRD) and scanning electron microscopy (SEM) with dispersive scanning energy system (EDS). The results showed the formation of the main constituent phases in the thermodynamic equilibrium state, the significant formation of eutectic constituents and the formation of a small amount of intermetallic Al5FeSi (platelets) and AlFeSiMgCu (chinese writing), commonly found due to the intrinsic presence of iron as an impurity In aluminum alloys.
16
  • LUANA BARBOSA DA CRUZ CAVALCANTI
  • Production of NiO/CDG ceramic tapes by Tape Casting

  • Líder : WILSON ACCHAR
  • MIEMBROS DE LA BANCA :
  • WILSON ACCHAR
  • Ana Paula da Silva Peres
  • Antonio Carlos Silva da Costa
  • LUCIANNA DA GAMA FERNANDES VIEIRA
  • SHEYLA KAROLINA JUSTINO MARQUES
  • Data: 08-sep-2017


  • Resumen Espectáculo
  • Solid oxide fuel cells (SOFCs) are electrochemical devices that are increasingly used because they have high energy conversion capacity and are minimally polluting. Several materials are used in the composition of the anode, among them NiO / CDG, since they promote an increase of intragranular ionic conductivity, improving the properties of the fuel cell, besides minimizing production costs, since there is a decrease in the operating temperature of SOFCs. One of the most widespread fine-film production techniques today is Tape Casting, which has been widely used in the electronics industry in capacitors, ferromagnetic memories, ceramic circuit substrates, among other applications, thanks to the great versatility of this method. This process requires a slurry homogeneous and stable slip, which composition of the formula can be varied according to the powder used. In this work, NiO/CDG slurries were prepared in aqueous medium, with the addition of polymers responsible for stability, flexibility and resistance to the body in green. The characterization was performed from the study of the stability of the suspension through rheological analysis, which showed a pseudoplastic behavior, in which there is a decrease of the viscosity as the shear rate increases. Studies were performed to verify the apparent density and porosity of the sintered bodies, X-ray diffraction, Differential Thermal Analysis (DTA), Thermogravimetric (TGA) and mechanical resistance. The XRD results allowed to observe the phases present in the tapes produced after the sintering stages at temperatures of 1250oC, 1300oC and 1400oC. The thermal analysis tests demonstrated the stability of the samples from 450oC, the mechanical strength tests showed a good flexural strength between 80 and 90 MPa for multilayer tape and 10 MPa for single tapes, allowing to observe that there is a better performance in tapes with multilayers, as there is an increase in mechanical resistance. The tapes produced were porous, dense and resistant.

17
  • ALLANA AZEVEDO DO NASCIMENTO
  • Addition of poly (ethylene-co-acid-methacrylic) (EMAA) as a self-repair agent in carbon-epoxy composites
  • Líder : ANA PAULA CYSNE BARBOSA
  • MIEMBROS DE LA BANCA :
  • ANA PAULA CYSNE BARBOSA
  • EVANS PAIVA DA COSTA FERREIRA
  • JOSE DANIEL DINIZ MELO
  • MARIA ODILA HILÁRIO CIOFFI
  • Data: 16-oct-2017


  • Resumen Espectáculo
  • Self-healing techniques in epoxy resins have been developed to improve the life-span and reduce costs associated with repairs of these materials during service. The addition of thermoplastics into the thermoset matrix producing mendable resins appears as a promising self-healing technique. In this study, poly(ethylene-co-methacrylic acid) (EMAA) was added to carbon fiber-epoxy composites to produce a self-healing system. Specimens with different percentages of thermoplastic were manufactured and interlaminar shear strength test (ILSS), dynamic mechanical analysis (DMA), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM) and field-emission gun scanning electron microcopy (FEG-SEM) were employed in order to evaluate the effect of the addition of the thermoplastic to the composite and its behavior before and after a healing cycle. The healed samples had similar mechanical properties to the properties presented by the samples before healing. However, for higher percentages of EMAA, there was a reduction of these properties, besides a reduction of Young’s modulus and Tg, in relation to the values presented by the unmodified composite. SEM images confirmed the strong adhesion between EMAA and epoxy resin, producing an adhesive layer that prevented the formation of delamination in the mid-plane of the laminate.

18
  • PABLO RODRIGO PADILHA HONÓRIO
  • DEVELOPMENT OF MARKERS BY TRACES OF CHEMICAL ELEMENTS FOR IDENTIFICATION OF ELECTRICAL CABLES VIA X-RAY FLUORESCENCE.

  • Líder : AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • MIEMBROS DE LA BANCA :
  • AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • JORGE MAGNER LOURENÇO
  • NICOLAU APOENA CASTRO
  • Data: 24-oct-2017


  • Resumen Espectáculo
  • The present work has as objective the study and development of markers based on traces of chemical elements for the identification of electrical cables of aluminum and copper by means of a X-ray fluorescence (XRF) portable equipment. The development of chemical markers has as purpose try to solve or minimize the problem of theft of electric cables in the country, which has caused huge losses and disorders for companies and population. In this sense, the markers were developed using a polyester-based varnish and an epoxy resin, which were doped with Cr2O3 particles. The markers were produced with additions of 1 %, 2 %, 5 % and 10 % of bulk weight of Cr2O3 in polymer resins and they were applied on cables of bare aluminum and isolated copper. After the markers were applied, the cables were analyzed via XRF, then fused, and again analyzed by XRF, whit the objective to check the remained of the Cr element, even after a possible recycling of cables. The results showed that the chemical markers are efficient for identifying the Cr element via laboratory FRX even with only 1 % bulk addition of Cr2O3 on the surface of Al and Cu cables, with both types of resins, however, it is not sufficient for identification after re-fusion of the conductors. The markers containing 2 % and 5 % of Cr2O3 Showed little efficiency in the identification of Cr after re-fusion. Only the markers made with polyester resin containing 10 % of Cr2O3 proved to be efficient after the Al re-fusion and were identified in all analyzed samples.

19
  • ANDERSON DE AZEVEDO GOMES SANTIAGO
  • Characterization of the photoluminescent properties of Ba1-xZnxMoO4 synthesized by the ultrasonic pyrolysis spray method

  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • FABIANA VILLELA DA MOTTA
  • MARIO GODINHO JUNIOR
  • MAURICIO ROBERTO BOMIO DELMONTE
  • Data: 18-dic-2017


  • Resumen Espectáculo
  • Ba1-xZnxMoO4 (x = 0, 0.25, 0.5, 0.75 and 1) powders were synthesized, in a one-step, by the ultrasonic spray pyrolysis method, using temperatures of 1000 ºC and 1100 ºC. Time for particle formation within the reactor was approximately 1 min. The samples were structurally characterized by the X-ray diffraction and morphologically by the field emission scanning electron microscopy (FESEM). Optical properties of the samples were studied using UV-visible and photoluminescence (PL) spectroscopies. The DRX patterns showed that the samples with x = 0 and x = 1 have crystalline tetragonal scheelite and triclinic structure, respectively, without the presence of secondary phases. On the other hand, Rietveld refining of the DRX patterns of samples with x = 0.25, 0.5 and 0.75 revealed the formation of a heterostructure tetragonal/triclinic, in which atomic substitution of Ba2+ by Zn2+ in the tetragonal structure of the BaMoO4 and triclinic structure of the ZnMoO4 occurring the atomic substitution of Zn2+ by Ba2+, perceiving a slight increase portion of the tetragonal phase when the pyrolysis temperature increases. Thus, these modifications promote small structural distortions in these materials, being easily observed in the angles and edges of the base that delimit the tetrahedron [MoO4] of these molybdates. FESEM micrographs showed that the particles obtained have predominantly spherical morphology with diameters ranging from 100 to 1500 nm. It was found that the primary particles forming microspheres of samples with x = 0 have high dimensions relative to the final size of microspheres, on the other hand for samples with x = 1 the primary particles exhibit low dimensions relative to microspheres. Thus, the decrease of the primary particles forming the microspheres was noted with the increase of x of Ba1-xZnxMoO4, that is, with increase of the atomic substitution of Ba2+ by Zn2+. This fact is given by the difference in solubility of the barium and zinc precursor reagents, because solutes with a high degree of supersaturation, such as zinc nitrate, tend to form a larger number of crystallites of nanometric sizes. The gap energy of the Ba1-xZnxMoO4 ranged from 4.56 eV to 4.17 eV, with the powders with x = 0, obtaining the highest values (4.54 eV and 4.56 eV) and the powders with x = 1 the lowest values (4.17 eV and 4.26 eV). In this way, it was noticed that the gap energies of the samples decrease with the increase of the value of x, that is, with increasing substitution of the Ba2+ for the Zn2+ atoms. Therefore, this phenomenon occurs due to atomic substitution raising the degree of disorder of the samples, increasing the intermediate intervals between the conduction and valence bands, which will result in the decrease of the gap band. Photoluminescent (PL) spectra of the samples showed broad band behavior, with predominant emission in the orange-red region and small emission contribution of the blue-green region. For samples with x = 0, the PL emission phenomenon is related to order-disorder degree of the [BaO8] complexes and oxygen vacancies of the [MoO4] complexes. For samples with x = 1, this phenomenon is related to the order-disorder degree of the [ZnO6] complexes and oxygen vacancies of the [MoO4] complexes. While, for samples with heterostructure tetragonal/triclinic, the PL emission is given by the degree of order-disorder and the charger transfer between the [BaO8] and [ZnO6] complexes, and oxygen vacancies of the [MoO4] complexes. The chromaticity coordinates x and y showed that the samples with x ≤ 0.75 exhibit in orange emission, however, the samples with x = 1 presented white emission.

Tesis
1
  • ROGERSON RODRIGUES FREIRE RAMOS
  • PROCESSO DE PRODUÇÃO DE MANTAS NÃO TECIDAS TUBULARES DE MICRO E NANOFIBRAS POR FIAÇÃO POR SOPRO EM SOLUÇÃO
  • Líder : JOSE DANIEL DINIZ MELO
  • MIEMBROS DE LA BANCA :
  • JOSE DANIEL DINIZ MELO
  • ANA PAULA CYSNE BARBOSA
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • ELITON SOUTO DE MEDEIROS
  • JULIANO ELVIS DE OLIVEIRA
  • Data: 02-feb-2017


  • Resumen Espectáculo
  • Structures produced from bioresorbable polymers are of great interest because of their potential uses in medical applications. In this work, a process of production of micro and nanofibrous tubular structures by solution blow spinning (SBS) was developed, using a multi-ejection matrix and a collection system based on a rotational conical collector. The process also includes an extracting step and post-spinning process by heat treatment in oven. Poly(D, L lactic acid), PDLLA, fibrous tubules were produced. The effects of collection and heat treatment on their morphological properties (SEM), crystallinity (DSC and DXR), diameter distribution, hydrophobicity (contact angle) and mechanical properties such as modulus of elasticity, stress and strain at rupture (tensile test) were evaluated. DSC analyzes indicated an increase in fiber crystallinity with increasing heat treatment time and temperature and SEM images indicated that the average fiber diameter tends to decrease at the beginning of crystallization. Wettability tests indicated that the surface energy of the material does not change significantly as a function of the degree of crystallinity. The results of the tensile tests showed that the degree of crystallinity is determinant for the mechanical performance of the mats that form the wall of the tubular structures and that the heat treatment raises the modulus of elasticity and reduces the deformation at break. The tubules submitted to the intermediate levels of heat treatment (85 ° C for 3.5 min) presented mechanical performance similar to that of samples treated at the highest levels (115°C for 6.5 min) and the tensile properties were comparable to those of Saphenous vein of an adult person. Analysis of the influence of the collection variables on mechanical properties of the tubules indicated that an increase in spinning gas pressure and a reduction in the diameter of the extractor increases elastic modulus and the tensile strength without significantly affecting the deformation at break. The angular velocity of the conical collector did not interfere in the mechanical behavior of the tubules. In summary, it was possible to produce micro and nanofibrous tubules with great potential in angiogenesis by combining SBS with an appropriate winding and extraction process.

2
  • ROBERTO RODRIGUES CUNHA LIMA
  • APPLICATION OF MODIFIED CLAYS FOR HARD WATER SOFTENING

  • Líder : VALTER JOSE FERNANDES JUNIOR
  • MIEMBROS DE LA BANCA :
  • VALTER JOSE FERNANDES JUNIOR
  • ANTONIO SOUZA DE ARAUJO
  • NEDJA SUELY FERNANDES
  • ANA CATARINA FERNANDES CORIOLANO
  • FRANCISCO LAERTE DE CASTRO
  • Data: 03-mar-2017


  • Resumen Espectáculo
  • The need to diversify the ways of treating water from different sources and for different purposes becomes more urgent every day, especially when considering the economic and social impacts associated with management of an irreplaceable natural resource. Clays can be applied for softening hard water, expanding perspectives of water use, with the development of sustainable technological devices and processes. In this study, in addition to those that were kept untreated, bentonite samples were activated with HCl and H2SO4, while vermiculite samples were modified with HCl, NaOH and NaCl, for adsorption tests of Ca2+ ions using standard calcium solution and real hard water adequately collected from wells in the central region of the state of Rio Grande do Norte, Brazil. A reduction of 22.8% in the hardness of the standard calcium solution was verified with H2SO4-activated bentonite, while higher efficiency was verified with vermiculites treated with HCl, NaOH and NaCl, with hardness reductions on the standard calcium solution of 43.6%, 46.3% and 57.5%, respectively, and reduction of up to 45.2% in the hardness of the real sample, with NaCl-modified vermiculite, which generated the best results. It has been proven that it is possible to recondition the vermiculite, and that electrolyte concentration and successive treatment influence the adsorptive capacity of this NaCl-modified clay. Vermiculite saline treatment can be performed simultaneously with a combination of Na+ and K+ as exchangeable cations. Clay modifications were tracked with XRD, SEM, TG, DTG, EDX, BET and physical-chemical parameter measurements. Further research should be encouraged for the refinement of techniques and methods applying clays for the recovery and management of water resources.

3
  • SAMARA MELO VALCACER
  • STUDY ON THE EFFECT OF ALUMINA (Al2O3) ADDITION ON THE COMPOSITE WC-3% Ni SINTERIZED WITH LIQUID PHASE

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • UILAME UMBELINO GOMES
  • FRANCINE ALVES DA COSTA
  • ARIADNE DE SOUZA SILVA
  • GILSON GARCIA DA SILVA
  • LEILIANE ALVES DE OLIVEIRA
  • TERCIO GRACIANO MACHADO
  • Data: 17-mar-2017


  • Resumen Espectáculo
  • The need for materials with high performance has driven the study of new systems as an alternative to existing ones. The composite materials are indicated when there is this necessity, therefore, can unite characteristics of different materials in a single body. A composite well known for its properties is tungsten carbide and cobalt (WC-Co). It is known that the mentioned material presents high hardness being indicated for use in cutting tools, however, as the cutting speed increases, the studies indicate that there is oxidation, thus generating a break in the composite. As an alternative to the WC-Co system, the cobalt substitution is currently studied by nickel, however the WC-Ni composite presents a low hardness when compared to the WC-Co. The present study proposes the study of a new material, which is a mixture of carbide of tungsten, alumina (Al2O3) and nickel. The study aims to establish characteristics of the composite WC-3% Ni when added with 5, 10 and 15% w Al2O3. The process of obtaining it was via powder metallurgy. High energy milling (400 rpm), uniaxial compaction at 400Mpa and vacuum sintering were carried out and in a dilatometric oven at temperatures of 1450 and 1550 ° C with a sintering level of 1h. The samples were characterized by: laser particulometry, XRD, SEM, hardness, density and densification of the samples. The results were promising since there was interaction between WC-Ni in all compositions. The sintering in dilatometric furnace presented better densities and hardnesses being the composition with addition of 5% p of alumina the more dense in the two processing temperatures, with relative density superior to 90%.

4
  • ZODINIO LAURISA MONTEIRO SAMPAIO
  • Structural lightweight concrete formulation with residues and low consumption of cement

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • JÚLIO CÉZAR DE OLIVEIRA FREITAS
  • KLEBER CAVALCANTI CABRAL
  • SANDRO MARDEN TORRES
  • ULISSES TARGINO BEZERRA
  • Data: 25-abr-2017


  • Resumen Espectáculo
  • The high-energy demand involved in the construction industry and the increasing consumption of concrete made this material an ideal option for the recycling of by-products from various industries such as: porcelain polishing residue (PPR); Tire rubber residue (TRR) and limestone residue (LSR). These residues often lack a treatment that will contribute to the degradation of the environment. Lightweight concrete (LWC) has been used in civil construction due to its benefits, which include: reducing the concrete's dead weight; increase of useful area; handling and less costly transport operations; Increased thermal and acoustic insulation and fire resistance. In the production of lightweight concrete, usually part or all of the aggregates are replaced by lightweight aggregates such as expanded clays (EC), TRR, pome stone, expanded vermiculite and others. LWC usually consume more cement because of the low strength of porous aggregates used in manufacturing. In this sense, the use of by-products that will increase the volume of the concrete without damaging the properties, can be a viable option in the production of low cost and sustainable LWC. The general objective of this work was to analyze the mechanical and thermal behavior of structural lightweight concrete (SLWC) produced with EC in replacement of the aggregate and with the addition of PPR, TRR and LSR to replace the small aggregate. And finally create a low-cost SLWC with good mechanical properties with minimal cement consumption. For this purpose, a 2³ factorial design was used for the choice of SLWC with the best performance in terms of consistency, mechanical properties and density. Subsequently, reductions of 10, 20 and 30% of cement were performed on SLWC that presented better performance and were characterized by mechanical tests. The best SLWC mix resulting from the combination of mechanical properties and cement consumption was characterized by: permeability tests; Flexural strength; TG/DTA; XRF; XRD; SEM; Thermal capacity; Thermal conductivity and thermal diffusivity. Finally, an economic analysis of the feasibility of the use of SLWC obtained with the reduction of cement was carried out. The results showed that residues contents around 21% presented better combination of properties. By maintaining the amount of residue at optimum levels it was possible to produce an economically viable CLE with good rheological, mechanical and thermal properties with a minimum cement consumption.

5
  • MICHELINE DAMIAO DIAS MOREIRA
  • ROUTES OF CHEMICAL SYNTHESES FOR OBTAINING NANOPARTICLES OF Ag/g-Al2O3 and Ag/ZnO WITH BACTERICIDAL PROPERTIES.

  • Líder : CARLOS ALBERTO PASKOCIMAS
  • MIEMBROS DE LA BANCA :
  • ANDRE LUIS CALADO ARAUJO
  • CARLA GRACY RIBEIRO MENEZES
  • CARLOS ALBERTO PASKOCIMAS
  • FABIANA VILLELA DA MOTTA
  • MAURICIO ROBERTO BOMIO DELMONTE
  • Data: 27-abr-2017


  • Resumen Espectáculo
  • The progressive demand for water has made the treatment and reuse of effluents a subject of worldwide relevance. Considering this situation, research has been carried out on the use of nanometric materials to obtain nanocomposites with antibacterial properties. In order to improve the obtaining of new materials, several methodologies and preparation techniques have been developed with the aim of controlling the shape and size of particles, which will consequently improve and optimize their properties. This work consists of obtaining, characterization and antibacterial evaluation of nanocomposites obtained by the impregnation of silver (Ag) in commercial alumina (g-Al2O3) and zinc oxide (ZnO) from different synthesis routes: hydrothermal method assisted by micro- Waves, sonoquímico and association of the sonoquímico and hidrotermal, destined to the disinfection of wastewater. A comparative study was performed between the nanoparticles g-Al2O3 and ZnO synthesized by sonochemical and hydrothermal microwave methods, investigating the influence of composition and distribution of particle size on the properties of these nanoparticles.Impregnations of 4%, 8%, 12% and 16% Ag in g-Al2O3 and ZnO were tested. The nanopó was applied in effluent coming from compact ETE (Sewage Treatment Station), after the secondary treatment step, and then, through bacteriological analyzes, the efficiency in the removal of the pathogenic indicators of contamination was evaluated. The results regarding the use of the ZnO nanocomposite impregnated with 8% Ag in the ratio of 0.3g/300 mL for a contact time of 30 minutes, indicated an efficiency of 100.00% in the removal of total coliforms, thermotolerant coliforms and Escherichia coli, reaching standards equal or superior to the already established disinfection techniques. The network parameters of the nanocomposites obtained through XRD, together with the FRX characterization techniques, particle size analysis and the micrographs from the SEM/FEG and EDS confirmed the adequate impregnation of the silver in the oxides. ICP-OES plasma optical emission spectrometry revealed that all samples analyzed had a silver content below the detection limit LD<0.50 mg/L, taking into account the maximum levels established by the current standards, as well as the toxicity to Health and the environment.

6
  • CÁSSIA CARVALHO DE ALMEIDA
  • CATALYTIC MATERIALS BASED ON NICKEL AND COBALT SUPPORTED IN SBA-15 TO USE IN THE STEAM REFORM OF THE ETHANOL AND IN THE  DRY REFORM OF NATURAL GAS

  • Líder : DULCE MARIA DE ARAUJO MELO
  • MIEMBROS DE LA BANCA :
  • DULCE MARIA DE ARAUJO MELO
  • ELEDIR VITOR SOBRINHO
  • RENATA MARTINS BRAGA
  • FLÁVIA DE MEDEIROS AQUINO
  • RAIMUNDO CRISOSTOMO RABELO NETO
  • Data: 26-may-2017


  • Resumen Espectáculo
  • In the last years, the processes of reform for the production of hydrogen as an energetic vector have been well studied because of the increase of the demand for alternative technologies of energy generation, showing a good relation cost/benefit when compared to other technologies of hydrogen production. In addition, they have advantages from an environmental point of view, not contributing to the increase of CO2 concentration in the atmosphere. However, hydrogen production through reform processes, while promising, still presents many technological bottlenecks, requiring advances in new materials with catalytic properties. In this proposal, the goal of this work is to obtain catalytic materials with high reactivity and selectivity for products in the face of reactions of steam reforming of ethanol (SRE) and dry reforming of methane (DRM). Catalysts based on nickel and cobalt supported on SBA-15 were prepared by wet impregnation method and characterized before and after the catalytic tests by several techniques: Thermogravimetric Analysis (TGA), Fourier Transformer Infrared Spectroscopy (FT- IR), X-ray diffraction (XRD), Temperature Programmed Reduction (TPR), Nitrogen Adsorption and Desorption, X-ray Diffraction in situ (XRD in situ), and Scanning Electron Microscopy (SEM) with Energy Spectroscopy (ES) to understanding the mechanisms involved in the reforming reactions and also responsible for the deposition of carbon on the catalysts. The catalysts tested against the steam reaction of ethanol for 6 hours at 500ºC presented an initial conversion around 80-100%, with H2 (65-70%), CO2 (18-23%) and only traces of CO (0.5-10%), but they suffered a rapid deactivation in the first hours of test, being more promising in the dry reforming reaction of methane, which showed good activity and stability during 10 hours of reaction at 700ºC with conversions (CH4 and CO2) and H2 yields above 80% and low carbon deposition.

7
  • GINEIDE CONCEIÇÃO DOS ANJOS
  • Use of diatomite as support of Ni and Co catalysts in the dry reforming reaction of methane.


  • Líder : DULCE MARIA DE ARAUJO MELO
  • MIEMBROS DE LA BANCA :
  • DULCE MARIA DE ARAUJO MELO
  • ELEDIR VITOR SOBRINHO
  • RENATA MARTINS BRAGA
  • JOANA MARIA DE FARIAS BARROS
  • RAIMUNDO CRISOSTOMO RABELO NETO
  • Data: 26-may-2017


  • Resumen Espectáculo
  • Due to the environmental demands in the past years, the search for more environmental-friendly fuels has intensified. The utilization of hydrogen gas as energetic vector has been highlighted in this scenario in a way that researches of its production have grown substantially. The main utilized routes for the hydrogen obtainment are the catalytic reform reactions, in which the development of adequate catalysts became an essential tool in these processes. However, the major difficulty in these reactions to produce H2 is to find stable catalysts for longer periods, that are resistant to the carbon accumulation and selective to the formation of hydrogen gas. The catalytic support present an important role in the reform reactions, proportionating a good dispersion and avoiding the active phase synthetization, influencing in a positive way the reactivity and stability of the catalyst. In this context, the diatomite, an amorphous sediment originated from frustules, unicellular algae skeletons, has been studied as a natural catalyst support. Because of that, this work utilized the diatomite as a catalyst support for the dispersing of Ni and/or Co metallic phases, and, posteriorly, evaluate the obtained catalysts in the dry reforming methane process. The mono and bimetallic catalysts with different concentrations were prepared by moist impregnation, with posterior calcination. The support and catalysts were submitted to the following characterizations: X-ray diffraction (XRD), adsorption and desorption of N2 isothermal analysis, thermogravimetric analysis (TGA/DTG), x-ray fluorescence (XRF), temperature programmed reduction (TPR), and scanning electron microscopy (SEM). The catalytic tests were performed in a quartz fixed-bed reactor coupled to a mass spectrophotometer. The results indicated that all the catalysts presented a good catalytic activity, with higher conversion rates and yields of CH4, CO2 and H2 superior to 80%. In all tests, the H2/CO ratio evolution was close to 1. However, the bimetallic catalyst NiCo/D showed the best stability and catalytic activity if compared to the other studied catalysts. Aiming to increase this efficiency, cerium and lanthanum promoters were added to these catalysts. The adding of cerium did not change the yields of the NiCo/D catalyst, while the lanthanum adding increased significantly the yield of H2 and in the H2/CO ratio, showing that the diatomite is a promissory for Nickel and/or Cobalt, and that the NiCo/D is a prominent catalyst for dry reform processes.

8
  • PATRICIA NEVES DE MEDEIROS
  • Synthesis of strontium-calcium indate (Sr0,9Ca0,1In2O4) codoped with rare earth ions for application in photoluminescence

  • Líder : FABIANA VILLELA DA MOTTA
  • MIEMBROS DE LA BANCA :
  • FABIANA VILLELA DA MOTTA
  • MAURICIO ROBERTO BOMIO DELMONTE
  • MICHELINE DAMIAO DIAS MOREIRA
  • MAXYMME MENDES DE MELO
  • VINÍCIUS DANTAS DE ARAÚJO
  • Data: 22-jun-2017


  • Resumen Espectáculo
  • Nanostructured ceramic materials have been extensively studied in recent years due to their great potential in areas such as photoluminescence, photocatalysis, electrochemistry. These materials allow the improvement of various properties due to their nanometric dimensions. The strontium indate (SrIn2O4) and the calcium indate (CaIn2O4) are oxides with structure of spinel type and orthorhombic crystalline system, being reported in the literature as host lattice for luminescent materials. The ultrasonic spray pyrolysis method allows continuous one-step production of particles with high purity. In this context, the synthesis of Sr(1-x)CaxIn2O4 was performed using the spray pyrolysis method, investigating the influence of the Ca2+ ion content on the photoluminescent properties of the solid solution. After analysis of the results it was verified that the composition Sr0,9Ca0,1In2O4 emitted higher intensity photoluminescent and was selected as host lattice for Rare Earth activator ions (RE3+). The indate Sr0.9Ca0.1In2O4: Eu3+, Tb3+, Tm3+, co-doped at different concentrations (%mol) were synthesized by spray pyrolysis. The obtained samples were characterized by X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (MEV-FEG), photoluminescence measurements (PL), UV-visible spectroscopy (UV-VIS) and photocatalytic activity by degradation of the methylene blue dye. The results of X-ray diffraction confirmed the formation of the strontium indate phase with orthorhombic structure. From the micrographs it can be observed the formation of microspheres composed of nanoparticles. The photoluminescence spectra of the Sr(1-x)CaxIn2O4 samples showed broadband emission and the Sr0,9Ca0,1In2O4 RE3+ (Eu3+, Tb3+, Tm3+) showed narrow and intense bands, characteristic emissions of RE3+ ions. The Sr(1-x)CaxIn2O4 samples showed low photocatalytic activity, with a maximum degradation of 45% of the dye. According to the results obtained, the strontium and calcium indate co-doped with RE3+ ions presents potential application in the area of photoluminescence.


9
  • ADRIANO LINCOLN ALBUQUERQUE MATTOS
  • ADDING VALUE TO LIGNOCELLULOSIC WASTE FROM REGIONAL BIOMASS BY POLYMER COMPOSITES

  • Líder : EDSON NORIYUKI ITO
  • MIEMBROS DE LA BANCA :
  • EDSON NORIYUKI ITO
  • JOSE HERIBERTO OLIVEIRA DO NASCIMENTO
  • ROSANGELA DE CARVALHO BALABAN
  • DIEGO LOMONACO VASCONCELOS OLIVEIRA
  • MEN DE SÁ MOREIRA DE SOUZA FILHO
  • Data: 28-jun-2017


  • Resumen Espectáculo
  • Lignocellulosic fibers have become an economical and ecological alternative for use as reinforcements and fillers in composites made of virgin or recycled polymers. The present work was subdivided in three papers that focus different aspects of the development of composites. The first one had involved the modification of lignocellulosic particles, using the cashew nut shell liquid (CNSL) as the source of cardanol. The objective was increasing in the degradability of polypropylene (PP) composites made of different types of lignocellulosic particles. Thermo-oxidation tests and analyzes of the mechanical behavior, chemical composition and physical properties of the samples allowed the verification that composites produced with CNSL-modified particles degraded in half the time of the conventional ones. The second article aimed at optimizing the methodology of chemical modification of lignocellulosic particles surface with CNSL that can also be used as an intermediary step in further functionalization of lignocellulosic particles, as it introduces upon its surface higher reactivity sites. The efficiency of the chemical modification methodologies was evaluated with the use of scanning electron microscopy (SEM), infrared spectroscopy (FTIR), thermogravimetry (TGA) and contact angle. The behavior of composites made of the modified particles in polypropylene matrix was also evaluated by mechanical tests and dynamic mechanical thermal analysis (DMTA). The third paper dealt with the production of PP composites made of cashew wood flour and carnauba leaf flour. The physical, mechanical and morphological properties were evaluated by TGA, differential scanning calorimetry, mechanical tensile and flexural tests, and SEM. Composites made of bulk fibers, mercerized and coupled with maleic anhydride were compared and the best performances were observed in the composites using maleic anhydride as coupling agent and carnauba fibers.

10
  • RAIMISON BEZERRA DE ASSIS
  • SYNTHESIS OF SODIUM AND POTASSIUM NIOBATE (K1-xNaxNbO3) WITH PHOTOCATALYTIC AND PHOTOLUMINESCENT PROPERTIES

  • Líder : FABIANA VILLELA DA MOTTA
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • FABIANA VILLELA DA MOTTA
  • MAURICIO ROBERTO BOMIO DELMONTE
  • MAXYMME MENDES DE MELO
  • NEFTALÍ LENIN VILLARREAL CARREÑO
  • Data: 29-jun-2017


  • Resumen Espectáculo
  • In recent years, photoluminescence and photocatalysis have proven to be a comprehensive field for the research and development of materials technology. The development of new materials has opened new perspectives for the production of devices with highly efficient photoluminescent and photocatalytic properties. Among the promising materials of technological interest are the semiconductors sodium and potassium niobates (KNN), which show good performance in optical and photocatalytic properties. In this work, perovskite structures of sodium and potassium niobate (K1-xNaxNbO3) for x = 0; 30; 50; 70; 100% (mol) were synthesized by the polymer precursor method and heat treated at 600°C, 700°C, 800°C and 900°C for the purpose of investigating their photocatalytic and photoluminescent properties. The samples were characterized by thermal analysis (TG/ DSC), X-ray diffraction (XRD), Raman spectroscopy, infrared absorption spectroscopy (FTIR), UV-vis optical absorption spectroscopy, scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS), photoluminescence (PL) and photocatalytic tests on the degradation of methylene blue dye. The results of X-ray diffraction confirmed the formation of the orthorhombic phase of the perovskite KNN, K1-xNaxNbO3 showing long-range organization. The FTIR spectra confirmed the X - ray diffraction data by presenting a reduction of bands related to short vibrations related to the double bonds of Nb = O. SEM images revealed that the KNN niobate samples presented morphology in the form of cubes with different particle sizes, with the presence of agglomerates and partially sintered regions. The optical absorption spectra by UV-vis characterized the niobates as semiconductors, indicating an optical gap between 2.59 eV and 3.35 eV, in addition to showing that the increase of the heat treatment temperature and the sodium concentration promoted an increase of the gap band. Photoluminescence spectra indicated a decrease in FL emission intensity with increasing sodium concentration in the KNbO3 matrix, exhibiting emission at room temperature in the region of violet (433 nm) in red (642 nm). Samples of niobates KN, KNN30, KNN50, KNN70 and NN showed satisfactory degradation rates, presenting excellent results for NaNbO3 (NN) thermally treated at 600°C with 95.95% degradation of the dye. The increase of the sodium concentration improved the photocatalytic performance of the KNN system, being efficient for photocatalytic applications. The results indicate the potential of sodium and potassium niobates in photocatalysis and photoluminescence.

11
  • MEYSAM MASHHADIKARIMI
  • OBTAINING TRIPLE LAYER POLYCRYSTALLINE DIAMOND COMPACT BY HPHT METHOD

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • UILAME UMBELINO GOMES
  • RUBENS MARIBONDO DO NASCIMENTO
  • FRANCINE ALVES DA COSTA
  • CLODOMIRO ALVES JUNIOR
  • MARCELLO FILGUEIRA
  • Data: 10-jul-2017


  • Resumen Espectáculo
  • The primary objective of this thesis is to obtain a polycrystalline diamond compact (PDC) with a WC- 10 wt% Co substrate and a sintered polycrystalline diamond top layer via high pressure high temperature (HPHT) sintering method. To achieve this objective, the project has been done in three different stages. The first stage was producing diamond sintered body with a suitable binder, for this reason four different binders was used to sinter diamond powder under HPHT condition. Binders were pure niobium (Nb) and three different mixture of niobium with Iron (Fe), Nickel (Ni) and Cobalt (Co). 10 wt% of binder was used and sintering was carried out at different temperature of 1600, 1700 and 1750°C under 5.5, 6.5 and 7.7 GPa of pressure for three successive holding time of 3 minutes (total 9 minutes). Obtained samples were studies according to relative density, microstructure, and hardness to find the optimum binder and sintering parameters. Studies at this stage showed that using pure niobium as binder and higher pressure and temperature have better results specially by avoiding graphitization during sintering. The second stage of project was done to study the hardmetal substrate at different sintering conditions. At this stage a powder mixture of WC-10 wt% Co was sintered via HPHT at 1500 to 1900°C under 7.7 GPa pressure for 2 and 3 minutes. Microstructural/structural analysis was performed by SEM/EDS and XRD. Hardness, Indentation Fracture Toughness (ITF) and compression tests were also carried out to understand effects of different sintering parameters. At this stage, it was found that full density can achieved for high sintering temperature along with abnormal grain growth. Undesirable ƞ phases were formed only in samples sintered at 1800 and 1900°C. High hardness was observed in range starting from 1250 up to 1650 HV. Third and last stage was done according to the results achieved from previous stages to obtain a triple layer polycrystalline diamond compact. A thin layer of WC 10 wt% Nb/Ni was used as an interface between diamond with pure Nb top layer and WC 10 wt% Co substrate. Sintering was done via HPHT method at 1750°C under 7.7 GPa of pressure. Two different holding time of 6 (three successive 2 minutes) and 9 (three successive 3 minutes) were used. Density, hardness and compression strength were measured and microstructural/structural studies were done via XRD and SEM/EDS. The overall results showed that a new kind of PDC can successfully produce using a new pure niobium binder for diamond without any graphitization. It was also found that using an interface having the resemblance to both substrate and sintered diamond body caused good adhesion between layers that can results in enhanced performance and improving durability of PDC.

12
  • MARIA JOSE SANTOS LIMA
  • Synthesis of Nanostructured composite powders (WC-Ni) by APT Carborreduction with Ni(NO3)2.6H2O and its Sintering in Vacuum Oven and by SPS.

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • UILAME UMBELINO GOMES
  • CARLSON PEREIRA DE SOUZA
  • FILIPE MARTEL DE MAGALHAES BORGES
  • MARCELLO FILGUEIRA
  • OSCAR OLIMPIO DE ARAÚJO FILHO
  • Data: 18-jul-2017


  • Resumen Espectáculo
  • In this work WC-Ni composite powders were synthesized by carborreduction of the hydrated ammonium paratungstate (APT) mixture with the nickel nitrate in proportions (5% p.Ni, 10% p.Ni and 15% p.Ni) a low temperature (800 ° C to 950 ° C) and small reaction time (90min to 150min) in a single synthesis process. The powders were characterized mainly by X-ray diffraction, Scanning Electron Microscopy (SEM), Dispersive Energy Spectroscopy (EDS), X-ray Fluorescence (FRX), Particle Size Analysis and (BET) and measures of magnetization, coercivity and remanence. The study of crystallite size was obtained from the X-ray diffractograms of post-composites, using the Scherrer equation. A factorial experimental design 23 with three central points was carried out to evaluate the influence of the synthesis conditions on the response variables (crystallite size). The synthesis parameters evaluated in this work were: reaction time (90min, 120min and 150min), synthesis temperature (800 ° C, 850 ° C and 900 ° C) and concentration of nickel by weight (5% p.Ni, 10 % P.Ni and 15% p.Ni). It was possible to produce nanometric WC-Ni composite powders in the desired proportions with the desired purity, with a mean crystallite size varying from 24.2 nm to 38 nm, with a surface area ranging from 24.6m²/g to 46.7 m²/g. The powders presented morphology with particles of varied sizes and shapes, quite agglomerated and also presented a good dispersion and homogenization of the phases. The specific characteristics of these nanometric materials provide their use for both the hard metal in catalytic reactions.Therefore, the composite powders obtained in this work were applied in the production of WC-Ni hard metal by solid and liquid phase sintering using conventional sintering and Spark Plasma Sintering techniques for comparison purposes. In the sintered samples the measurements of Vickers hardness and density by pycnometry were performed. We also performed XRD, SEM and EDS analyzes with mapping. The best results for the sintered WC-Ni were obtained for the sintered samples via SPS at 1350ºC, showing Vickers hardness (2322 HV) and density (97.67%) higher than the samples sintered by conventional sintering at higher temperatures.

13
  • ELANIA MARIA FERNANDES SILVA

  • STRUCTURED OXIDES OF PEROVSQUITA TYPE FOR GAS GENERATION OF SYNTHESIS VIA REFORMATION OF METANE DRY
  • Líder : DULCE MARIA DE ARAUJO MELO
  • MIEMBROS DE LA BANCA :
  • DULCE MARIA DE ARAUJO MELO
  • ELEDIR VITOR SOBRINHO
  • RENATA MARTINS BRAGA
  • ELSON LONGO DA SILVA
  • FLÁVIA DE MEDEIROS AQUINO
  • Data: 25-jul-2017


  • Resumen Espectáculo
  • High-performance catalysts have been widely researched in order to increase the yield in methane dry reforming processes (DRM). Some transition metals, especially nickel, are largely studied for this purpose. Due to its catalysts’ properties, thermal and chemical stability, perovskite-type oxides ABO3 are promising materials as catalytic precursors in DRM processes. In this work perovskite-type oxides ABO3 were synthesized by microwave assisted combustion using urea as fuel and calcinated at 900 ºC for 2h. After the calcination, all the prepared oxides were impregnated with 20% (w/w) of nickel and calcinated again at 600ºC for 2h. The samples were characterized by the following techniques: x-ray diffraction (XRD), temperature programmed reduction (TPR), and dispersive energy scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS). Methane reforming tests with CO2 were performed for evaluation of these materials as catalysts in the production of syngas. After the reforming tests, the catalysts were submitted once again to characterizations for the evaluation of the existence of carbon in the oxides’ surface. According to the X-ray diffractograms, secondary phases of nickel oxides were formed after the nickel impregnation in the powders. The SEM images showed that the impregnation methodology resulted in a homogeneous dispersion of the nickel oxide particles on the perovskite’s surface.

14
  • CLEONILSON MAFRA BARBOSA
  • SYNTHESIS AND CHARACTERIZATION OF MIXED NIOBIUM AND TANTALUM ELECTROCATALYSTS DOPED WITH Co, Cu AND Ni PRODUCED FROM COLUMBITE/TANTALITE.

  • Líder : CARLSON PEREIRA DE SOUZA
  • MIEMBROS DE LA BANCA :
  • ANA KARLA COSTA DE OLIVEIRA
  • ARIADNE DE SOUZA SILVA
  • CARLSON PEREIRA DE SOUZA
  • FABIO GARCIA PENHA
  • UILAME UMBELINO GOMES
  • Data: 31-jul-2017


  • Resumen Espectáculo
  • This paper proposes an alternative route for producing catalysts for methanol and ethanol oxidation reactions to be applied on fuel cells. Those catalysts are based on oxides and precursors of mixed niobium and tantalum nanostructured materials in their pure and doped (with Co, Cu or Ni) forms. These materials are obtained from columbite/tantalite, which is the base mineral for Nb, Ta, extracted from Rio Grande do Norte’s mineral resources. At first, an experimental planning for the complete purification of the mineral was performed. After purification, 10%wt. doping with each of the metals, and thermal treatment at three different temperatures (110,400 and 600°C) was carried out. Un-doped purified oxides were then subject to complexation process followed by metal addition (doping) and thermal treatment. Purified and thermally treated mineral was characterized by X-Ray Fluorescence (XRF) and X-Ray Diffraction and complete purification was attained. Complex precursors were evaluated on the basis of XRD, Infra-Red Spectroscopy (IR), thermal behavior (TG/DSC and DTA) and morphology (Scanning Electron Microscopy) and presented particle sizes under 0.2 µm, elevated weight loss (76.6%) and a porous structure of irregular shape. Pure and doped catalysts were characterized on XRD, XPS (X-Ray Excited Photon Spectroscopy), SEM and TEM (Transmission Electron Microscopy) basis, presenting indication of catalytic properties interesting for oxidation reactions, such as quick surface reduction. Electrical evaluation of the catalysts was performed according to Differentia Pulse Voltammetry (DPV) with the use of micro sensors during alcohol oxidation reactions. These analyses indicated the excellent conducting characteristics of the materials as electric current flow was increased in two orders of magnitudes in comparison to gold electrodes. The best catalytic behaviors were observed when dopping was performed with copper, followed by nickel, cobalt and without dopant addition. Therefore, the synthesized materials presented characteristics that indicate their suitability for use as fuel cells electrodes.

15
  • CIRO JOSÉ FERREIRA RODRIGUES
  • Hydrothermal synthesis and characterization of Ce-Al and Ce-Al composites 

     

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • DULCE MARIA DE ARAUJO MELO
  • RUBENS MARIBONDO DO NASCIMENTO
  • DANIEL ARAÚJO DE MACEDO
  • DANIEL ZANETTI DE FLORIO
  • Data: 17-ago-2017


  • Resumen Espectáculo
  • Solid Oxide Fuel Cells (SOFCs) are among modern devices that generate energy from hydrogen sources. SOFCs consist basically of three ceramic constituents acting as electrodes and electrolyte. Yttria-stabilized zirconia/NiO are traditional materials used as mixed anodes that operate with different sources of hydrogen. Although YSZ-NiO depicts high electrical energy conversion, it can only operate between 800 and 1000ºC. Alternative materials based on doped ceria show similarionic conductivity, lower ohmicloss and become operational between 500 and 800ºC. In a mixed anode composition, NiO acts as catalyst in the fuel reform, granting high electrical conductivity. On the downside, the costs of the material are relatively high, and the catalytic activity is decreased by the production of coke. The present study aimed at evaluating the synthesis of mixed ceria-doped anodes using different catalysts, i.e., Al2Oand SnO. NiO was also used as reference for the efficiency of electric conductivity. The following compositions were synthesized by the microwave assisted hydrothermal synthesis: Ce0.8Sm0.2O1.95-Al2O3 (SAL).Ce0.8Gd0.2O1.95-Al2O3(GAL).Ce0.8Sm0.2O1.95-SnO(SSN).Ce0.8Gd0.2O1.95-SnO(GSN).Ce0.8Sm0.2O1.95-NiO (SNI) and Ce0.8Gd0.2O1.95-NiO (GNI).The powders were characterized by SEM, thermal analysis and XRD. The electrical conductivity was evaluated by cyclic voltammetry. The method of synthesis was efficent in the preparation of all compositions studied. The crystallinity of the powders was compatible with that of other synthesis methods. SAL and GAL depicted high values of electrical conductivity, as a consequence of the relatively low densities of anodic and cathodic current. Measured peak currents were 1.01 x 10-5 A/mm² for SSN,6.17 x 10-5 A/mm² for GSN, 1.60 x 10-5 A/mm² for SNI and 1.81 x 10-4 A/mm² for GNI. These values suggest the occurrence of electrocatalytic reactions and low electrical conductivity for this kind of electrochemical analysis. 

16
  • EMANOELA PEREIRA DE MATTOS
  • HIGH TEMPERATURE BRAZING OF LEAN DUPLEX AND DUPLEX STAINLESS STEELS WITH AMORPHOUS NICKEL-BASED FOILS

  • Líder : AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • MIEMBROS DE LA BANCA :
  • AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • RUBENS MARIBONDO DO NASCIMENTO
  • NICOLAU APOENA CASTRO
  • ALOISIO NELMO KLEIN
  • WANDERSON SANTANA DA SILVA
  • Data: 25-ago-2017


  • Resumen Espectáculo
  • Duplex stainless steels, characterized by biphasic microstructure composed of similar fractions of ferrite and austenite, have been expanding their application in several fields, to the detriment of the use of traditional austenitic and ferritic stainless steels, in particular in the chemical and petrochemical industries where they can advantageously meet the requirements of mechanical resistance and corrosion in aggressive media. For fabrication of components with complex geometries and / or with reduced thickness sheets the most indicated processes are solid state diffusion welding and high temperature brazing (BAT) over conventional fusion welding methods. In this context, this work initially describes the results of BAT tests on austenitic stainless steel AISI 316L, exploring the applicability of this technology as an alternative manufacturing route for compact heat exchangers.. In addition, as main objective of the work were evaluated in more detail different brazing systems formed by 3 duplex stainless steels and 5 different nickel-based addition alloys. As base metals were used plates of duplex stainless steels UNS S32101 and UNS S32304 and duplex UNS S32205 and as addition metals, amorphous nickel-based foils with different amounts of alloying elements such as Cr, Fe and in particular the Si metalloids , B, P and C. The brazing process was carried out in a high vacuum atmosphere (10-4 mbar), under temperatures of 1020, 1100 and 1160 ° C for times of 30 minutes and 1 hour. A wedge brazing test at 1020 ° C with subsequent heat treatment (1000 and 1100 ° C for 60 and 120 minutes) was performed for the lean duplex UNS S32101 steel with addition alloy containing P in order to determine the behavior of intermetallics in the joint. The characterization of the brazed joints for the microstructural integrity of the steels, the presence of intermetallic phases in the melting zone and the base metal / metal addition interface was performed by optical microscopy, field emission scanning electron microscopy, dispersive energy spectroscopy, backscattered electron diffraction, X-ray diffraction and Vickers microhardness. The best-performing addition metal is the Si-B addition alloy, with continuous γ-Ni phase brazing and dispersed precipitation of borides and nitrides in the brazing zone. The lean duplex stainless steel UNS S32101 showed a phenomenon of high ferritic grain growth under vacuum at temperature over 1100 C, both on the free surface and at the brazing interface. The influence of the brazing atmosphere on the loss by sublimation of Mn and N, as well as the B content in the occurrence of this effect is discussed.

17
  • ERIK DOS SANTOS SILVA
  • EFFECT OF THE INCORPORATION OF TREATED SILICA WITH AMINOSILANE IN PMMA/SAN/SILICA NANOCOMPOSITES

  • Líder : EDSON NORIYUKI ITO
  • MIEMBROS DE LA BANCA :
  • AMANDA MELISSA DAMIAO LEITE
  • EDSON NORIYUKI ITO
  • MARCELO MASSAYOSHI UEKI
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • TOMÁS JEFERSON ALVES DE MELO
  • Data: 30-ago-2017


  • Resumen Espectáculo
  • Nanocomposites of polymers and silica have become the focus of many researchers in recent years because of their excellent properties when compared to individual components. In this work a surface modification treatment of the silica with 3-aminopropyltriethoxysilane (APTES) was carried out for incorporation in the poly(methyl methacrylate)/poly(styrene-co-acrylonitrile)(PMMA/SAN) blend by means of processing in double screw extruder. The effect of the addition of silica nanoparticles with and without surface modification on the structure and properties of PMMA/SAN blends was evaluated in order to promote better mechanical properties without compromising the transparency of the materials produced. The materials were characterized by flow index measures (MFI), mechanical tests of uniaxial traction, 3-point flexural, Rockwell M hardness (HRM) and Shore D, Izod impact, parallel plate rheometry, transmission electron microscopy (TEM), abrasion and scratch tests. The rheological results indicated that there was a reaction between the silica nanoparticles treated with the pure polymers and with the PMMA/SAN blend, proving a useful technique to evaluate possible reactions during the extrusion process. The nanocomposites presented a decrease in the properties of maximum tensile strength, impact strength and elongation at break when compared to PMMA/SAN blends, which showed synergism in the properties of maximum tensile strength and elongation at break. However, the properties of the nanocomposites with modified silica nanoparticles were superior to the nanocomposites without treatment. The addition of silica promoted an increase in the modulus of elasticity, hardness, abrasion and scratch of the nanocomposites produced.

18
  • MARIA DE FÁTIMA DANTAS E SILVA
  • PIGMENTS BASED ON SHALE AND IMPREGNATED WITH METALS FOR APPLICATION IN CERAMIC COATINGS.

  • Líder : MARCUS ANTONIO DE FREITAS MELO
  • MIEMBROS DE LA BANCA :
  • MARCUS ANTONIO DE FREITAS MELO
  • CARLOS ALBERTO PASKOCIMAS
  • ASENETE FRUTUOSO DA COSTA
  • JOANA MARIA DE FARIAS BARROS
  • PATRICIA MENDONCA PIMENTEL
  • Data: 01-sep-2017


  • Resumen Espectáculo
  • Most industries, the ceramic industry felt the need for the development of new pigments for the production of floors and coatings, in order to meet the demand of ceramics for the decoration of domestic and commercial environments. Given this, there is a great interest in developing new materials that are in accordance with environmental preservation and that are relatively low cost. Retried shale (XR) is a waste from the shale industry, which improperly stored or stored can cause damage to the environment and health. The objective of this study is to evaluate the viability of this material, pure retort shale and retorted shale impregnated with metals, in obtaining pigments that stably color several ceramic matrices; Trying to understand which parameters influence the pigmentation of the enamels. The XR-based pigments were prepared by impregnating the metals via wet and calcined at 700 and 900°C. These pigments were characterized by X-Ray Fluorescence (FRX), X-ray Diffraction (XRD), Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) spectroscopy in UV-Visible region and Colorimetry. The results confirm the feasibility of the use of shale as a pigment indicating that the use of XR and XR impregnated with iron and chromium nitrate have been favorable processes since they have the advantage of being simple, low cost and reduces the environmental impact caused for this waste. The pigments have light brown, red and shades of gray according to the impregnation and their calcination temperatures, which have become darker at higher temperature.

19
  • EDUARDO RIGOTI
  • DEVELOPMENT OF NEW CATALYTIC MATERIALS BASED MOLYBDENIUM SUPPORTED ON ORDERED MESOPOROUS SILICA AND CARBONS FOR HYDRODEOXYGENATION REACTIONS

  • Líder : SIBELE BERENICE CASTELLA PERGHER
  • MIEMBROS DE LA BANCA :
  • SIBELE BERENICE CASTELLA PERGHER
  • DULCE MARIA DE ARAUJO MELO
  • TIAGO PINHEIRO BRAGA
  • ANNE GABRIELLA DIAS SANTOS
  • CRISTIANE BARBIERI RODELLA
  • VICTOR LUIS DOS SANTOS TEIXEIRA DA SILVA
  • Data: 06-oct-2017


  • Resumen Espectáculo
  • The aim of this thesis was to develop new catalytic materials through the synthesis of mesoporous silica and carbon supports for Mo impregnation to study its catalytic performance in hydrodeoxygenation of gas-phase platform molecules, where it was tried to determine the influence of the catalyst, support and support/catalyst behavior under different reaction conditions. Mesoporous carbons were obtained using the silica materials as a template. The impregnation of molybdenum oxide (MoO3) was carried out by the incipient wetness impregnation to obtain an amount of 4 and 2 Mo atoms/nm² in the silica and carbon supports. Molybdenum carbides were obtained in situ and ex situ by means of Temperature Programmed Carburization (TPC). Characterization was performed using several techniques such as X-Ray Diffraction (XRD), N2 physisorption, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), by these techniques was possible to confirm the synthesis of the silica and carbon materials and the subsequent impregnation of the molybdenum oxide. The techniques of programmed temperature decomposition (TPD), programmed temperature reduction (TPR) and Raman spectroscopy allowed to evaluate the influences of the different reaction conditions on catalysts. The materials were evaluated in hydrodeoxygenation reactions phenol. The results showed an excellent selectivity in reactions with phenol indicating optimal conditions for the reaction at 500 °C. Among all the catalysts studied, the material supported on the CMK-3 carbon replica presented the best results.

20
  • ALESSANDRA AGNA ARAÚJO DOS SANTOS
  • STUDY OF THE SINTERING OF TUNGSTEN CARBIDE USING ALTERNATIVES BINDERS 316L AND FeNi WITH CROMIUM ADDED

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • UILAME UMBELINO GOMES
  • ANGELUS GIUSEPPE PEREIRA DA SILVA
  • ARIADNE DE SOUZA SILVA
  • GILSON GARCIA DA SILVA
  • JOAO BAPTISTA MANUEL
  • Data: 11-oct-2017


  • Resumen Espectáculo
  • Hard metal WC-Co is used in machining, drilling or in the manufacture of cutting tools. Nowadays, 70% of the cutting tools are WC-binder. In production numbers, approximately 40.000 MT tools of WC-binder have been produced worldwide since 2011. Today, more than 90% of all WC-binder uses cobalt as the main binder. The superiority of cobalt in relation to other binders is related to several factors, the main being the width of the carbon window. However, it has been studied for decades by alternative binders due to the scarcity and price of cobalt and mainly by the system WCCo be carcinogenic. The goal of this doctoral thesis was to analyze the sintering of the tungsten carbide with alternative binders (steel 316L, and FeNi with addition of chromium content) and verify if they are viable. Both systems WC-316L (binder content of 5, 7 and 20%) and WC-20%FeNi with addition of chromium (chromium content were added in 0, 5, 10 and 20%) were processed by the Powder Metallurgy, following the steps: preparing of the powders, milling (1h, 24h), isostatic compaction (200 MPa) and vacuum sintering (1400oC/1h). The characterization performed in all the sintered samples were: optical and electron microscopy, x-ray diffraction, magnetic saturation and coercivity, hardness, electrochemical etching, and calculation of the vertical sections of the phase diagrams for the system WC-FeNi with addition of chromium. The results obtained and discussed demonstrate that the binder 316L in hard metal is not a viable, because of the high chromium content in this alloy, that forming complex carbides which weaken the structure. The steel 316L binder in hard metal, regardless of the binder content or carbon content, precipitate eta phase (phase that must be avoided in hard metal). For the FeNi binder with addition of chromium, the results demonstrate that the maximum content of chromium that may be contained in solution is approximately 4% (for a binder content of 20%), FeNi with chromium content above 4% will be precipitated eta phase and other stable chromium carbides, the chromium content above 4% will still drastically reduces the carbon window of the composite, making it practically impossible to avoid eta phase or graphite precipitation.

21
  • PALOMA VINACHES MELGUIZO
  • Study of the organic cation 2-ethyl-1,3,4-trimethylimidazolium in synthesis of zeolites and zeotypes.

  • Líder : SIBELE BERENICE CASTELLA PERGHER
  • MIEMBROS DE LA BANCA :
  • DULCE MARIA DE ARAUJO MELO
  • ELEDIR VITOR SOBRINHO
  • FLORIAN EDOUARD PIERRE MENEAU
  • KATIA BERNARDO GUSMÃO
  • SIBELE BERENICE CASTELLA PERGHER
  • Data: 27-oct-2017


  • Resumen Espectáculo
  • In this PhD thesis the structure-directing agent 2-ethyl-1,3,4-trimethylimidazolium was studied in the context of zeolite and zeotype synthesis in hydrofluoric media. Initially, it was deepened into the study of the pure silica zeolite HPM-1 to understand the role of the cation in the nucleation and growth, explaining the helicoidal channels and the order of secondary building units formation. Subsequently, an alternative methodology of heteroatom introduction, never reported for the present material, was also presented to give HPM-1 catalytic properties. As a result of it, three different Al-HPM-1 samples were obtained, characterized and tested in ethanol dehydration reaction. Finally, an exploratory study of the organic cation in zeotype synthesis (with Si, Al and P) was performed, giving two main SAPO phases: CHA and LTA zeotypes. It was proven that the SAPO-CHA structure was directed not only by the use of the organic cation and the hydrofluoric media, but also its obtention was influenced by the temperature and a combination of dilution and time. In the case of the SAPO-LTA, the directing effect was mainly due to the organic cation.

22
  • JUCIKLÉCIA DA SILVA REINALDO
  • RHEOLOGICAL STUDY OF POLYMER BLENDS WITH POLY (METHYL METHACRYLATE) AND DIFFERENTS STYRENIC POLYMERS

  • Líder : EDSON NORIYUKI ITO
  • MIEMBROS DE LA BANCA :
  • EDSON NORIYUKI ITO
  • LUIZ ANTÔNIO PESSAN
  • MARCELO MASSAYOSHI UEKI
  • PANKAJ AGRAWAL
  • TOMÁS JEFERSON ALVES DE MELO
  • Data: 23-nov-2017


  • Resumen Espectáculo
  • The aim of this work was to investigate the influence of the effect of the chemical structures on the rheological behavior in the linear viscoelastic of polymer blends consisting of acrylic and styrene polymers, i.e., poly (methyl methacrylate) homopolymer (PMMAh), poly (methyl methacrylate) copolymer (PMMAe), polystyrene (PS), styrene-acrylonitrile copolymer (SAN) and acrylonitrile-butadiene-styrene copolymer (ABS) and methyl methacrylate-butadiene-styrene copolymer (MBS). Preliminary characterization of the pure polymers shows by Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) that the copolymers had different chemical structures based on acrylics, styrene, acrylonitrile, butadiene and other elastomer types present in the PMMAe copolymer. The results of the chemical compositions of the styrenic copolymers (SAN and ABS) presented percentage of AN that is within the window of miscibility for mixtures developed with the PMMA, i.e., of 25 and 21% respectively. The rheological results obtained at low shear rates in the region of linear viscoelasticity showed that there was a significant change in the rheological behavior in relation to the use of acrylic homopolymer in the development of the polymer blends, when compared to the use of acrylic copolymerized with elastomeric particles. It was possible to indicate the miscibility mixture of polymer blends with structural variation of the minority components (styrenic polymers) by means of the linear viscoelastic behavior of these polymer blends. The morphological results obtained by scanning electron microscopy (SEM) showed the immiscibility in the polymer blends with PS and a probability of miscibility between the SAN and the SAN phase of the ABS with the PMMAh forming a single phase, corroborating with the rheological results. However, polymer blends with PMMAe and ABS presented complex microrreological results, because both polymers presented elastomeric phases. The morphological results, obtained by transmission electron microscopy (TEM) together with the results of glass transition temperature (Tg) by DSC, led to the proposal in this work that the elastomeric domains of PMMAe are formed by the butyl acrylate-polystyrene copolymer (PBA-co-PS) in core-shell with PMMA.
23
  • ANA PAULA PEREIRA FULCO
  • DAMAGE MECHANISMS OF CARBON/EPOXY LAMINATES UNDER FATIGUE LOADING AND HIGROTHERMAL AGING

  • Líder : JOSE DANIEL DINIZ MELO
  • MIEMBROS DE LA BANCA :
  • ANA PAULA CYSNE BARBOSA
  • CARLOS ALBERTO CIMINI JUNIOR
  • FLAMINIO LEVY NETO
  • JOSE DANIEL DINIZ MELO
  • RAIMUNDO CARLOS SILVERIO FREIRE JUNIOR
  • Data: 30-nov-2017


  • Resumen Espectáculo
  • Carbon fiber reinforced polymer (CFRP) composites used in aeronautic and aerospace structures are often exposed to cyclic loading and environmental effects such as temperature and humidity, which can lead to degradation and failure of the component. The objective of this work was to study the effects of aging under exposure to high temperature and humidity on the damage mechanisms of carbon/epoxy composites subjected to cyclic loading. Initially, a preliminary accelerated aging study was conducted with unidirectional AS4/8552 samples using an exposure cycle of 8 h of UVA-340 at 80 °C followed by 4 h of condensation at 80 °C, for a total exposure period of 2,160 h.  The effects of aging were evidenced by weight loss, fiber exposure, chemical changes, increased crack density in interlaminar shear strength tests, and fiber buckling in fractured samples after compression tests, even though no significant changes mechanical properties were observed. Based on this preliminary work, a study was conducted on [02/902]s laminates of the same material, using an exposure cycle of 8 h at 160 °C followed by 4 h of 80% relative humidity at 70 °C, for a total exposure period of 2,880 h. Afterwards, stress-controlled tension-tension fatigue tests were conducted using a stress ratio R = 0.1 and frequency of 5 Hz. Composites were characterized using Fourier transform infrared spectroscopy (FTIR), Dynamic Mechanical Analysis (DMA), Scanning Electron Microscopy (SEM) and weight change, before and after hygrothermal exposure. Samples of plain epoxy 8552 were also exposed to the same aging conditions and characterized by optical microscopy (OM), FTIR spectroscopy and weight change. Based on the fatigue life diagrams, a shift function was proposed for the prediction of number of cycles to failure of aged composites based on data from unaged specimens. The study also showed that failure by fracture may not be the best parameter to evaluate the effect of hygrothermal aging on fatigue life of carbon fiber reinforced polymer composites. Other parameters such as delamination and crack saturation are also essential to assess durability of these composites.

24
  • ANA CLÁUDIA MEDEIROS DE CARVALHO
  • INFLUENCE OF SYNTHESIS PARAMETERS IN THE MORPHOLOGICAL CHARACTERISTICS OF POLY MICROCAPSULES (UREIA-FORMALDEHYDE) FOR USE IN SELF-TREATMENT SYSTEMS
  • Líder : MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • ANA PAULA CYSNE BARBOSA
  • JOSE DANIEL DINIZ MELO
  • EVANS PAIVA DA COSTA FERREIRA
  • AMELIA SEVERINO FERREIRA E SANTOS
  • JOSIANE DANTAS VIANA BARBOSA
  • Data: 13-dic-2017


  • Resumen Espectáculo
  • Self-healing materials are a class of smart materials with an inherent ability to repair damage, thus recovering their functionality. Urea-formaldehyde microcapsules have been studied to provide self-healing functionality to polymers and polymeric matrix composites. These microcapsules must be strong enough to remain intact during processing of the host polymer, and yet break when the polymer is damaged. A well-known self-healing system comprises an epoxy matrix with urea-based microcapsules containing dicyclopentadiene (DCPD). Upon release, DCPD can undergo ring-opening metathesis polymerization (ROMP) when in contact with a pre-embedded dispersed Grubbs’ catalyst. As the healing agent encounters the embedded catalyst, a polymerization reaction is initiated and proceeds until all released healing agent is consumed. The resulting polymer (poly(DCPD) serves as a bonding agent that bridges the crack, regaining much of the initial material properties. In this work, synthesis parameters of poly(urea-formaldehyde) microcapsules were evaluated and an experimental design 22 with three central points was assembled, with the objective of analyze the influence of agitation rate and pH in the size of microcapsules and thickness of capsules shell. The influence of agitation rate on microcapsules size and pH on shell thickness could be proven. From the experimental design results, microcapsules with different core materials such as, vegetable oil (soybean, olive, linseed and coconut), endo-dicyclopentadie and 5-etilidene 2-norbonene (ENB) were synthesized presenting same morphological characteristics and size. Capsules were characterized by Fourier infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Microcapsules filled with soybean, linseed oil and endo-DCPD were used in epoxy system with self-healing ability aiming delay corrosion in metallic substrate. Samples with capsules filled with soybean and linseed oils presented excellent anticorrosive results, with emphasis on the system containing capsules filled with soybean oil, which is an economical alternative to the other tested materials. Microcapsules filled with endo-DCPD were used in indentation tests to verify the self-healing effect, however, it was not possible to attest it, since the indentation did not generate a crack in the samples. Therewith, the behavior of the microcapsules obtained under the adjusted conditions of the experimental design was analyzed in epoxy samples by means of tests where cracks were produced using a blade, capsule rupture was verified as consequence of crack propagation. Capsules which presented adequate diameter and shell thicknesses for their use in the proposed self-healing system, were produced. However, due to the agglomeration and poor dispersion of the microcapsules in the epoxy matrix, in addition to the low amount of catalyst presented, the self-healing effect could not be proven in polymeric or polymeric composites samples.

25
  • LUCAS RICARDO FERNANDES FIGUEIREDO
  • ADHESIVE PROPERTIES OF BIODEGRADABLE POLYMERS WITH ADDITION OF CELLULOSE NANOWHISKERS

  • Líder : JOSE DANIEL DINIZ MELO
  • MIEMBROS DE LA BANCA :
  • JOSE DANIEL DINIZ MELO
  • ANA PAULA CYSNE BARBOSA
  • MARIA CAROLINA BURGOS COSTA DO NASCIMENTO
  • ELITON SOUTO DE MEDEIROS
  • HENRIETTE MONTEIRO CORDEIRO DE AZEREDO
  • JULIANO ELVIS DE OLIVEIRA
  • Data: 13-dic-2017


  • Resumen Espectáculo
  • Green adhesives are of great scientific and technological interest as an alternative to conventional commercial products, which often release toxic substances and take long time to degrade.  However, the poor mechanical properties and fast degradation of some biodegradable polymers limit their use in most practical applications.  In the present work, novel biodegradable composites were prepared using biodegradable polymers and cellulose nanowhiskers (CNW) for their use as wood adhesives.  The goal of the investigation was to study the effect of the addition of CNW on the mechanical properties and degradation of the polymers.  The biodegradable polymers synthesized by polycondensation based on glycerol and acids were poly(glycerol adipate) - PGA, poly(glycerol maleate) - PGM, poly(glycerol citrate) - PGC, poly(glycerol phthalate) - PGPh, poly(glycerol succinate) - PGSu and poly(glycerol sebacate) - PGS.  In addition, the copolymers synthesized were poly(glycerol succinate-co-maleate) - PGMSu, poly(glycerol succinate-co-adipate) – PGASu and poly(glycerol adipate-co-maleate) – PGMA.  Cellulose nanowhiskers (CNW) were added to the polymers as an approach for improving the mechanical properties and controlling the degradation rate.  Composites were produced with the addition of 0, 5, 10 and 20 wt.% of CNW.  The neat polymers and composites were analyzed by Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), X-ray diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR).  Adhesively bonded joints were produced in test specimens of slash pine (Pinus elliottii) and angelim (Vatairea heteroptera Ducke) and tested under shear by tensile loading and for accelerated aging degradation.  Bonded joints produced with polyvinyl acetate - PVAc and cyanoacrylate based adhesives were also tested under the same conditions for comparison purposes. Thermal analyses showed that most of the biodegradable glycerol-based polymers tested are stable up to about 260°C and the addition of CNW increased the thermal stability (Tonset) of some polymers by 26°C up to 48°C, while others were not affected.  Analyses of the fracture surface after the shear tests by Scanning Electron Microscopy (SEM) suggest less ductile fracture with the incorporation of CNW to the adhesive.  Adhesion measurements indicated that the green adhesives developed from glycerol polymers with 10 and 20% CNW addition showed shear strength superior to the commercial PVAc based adhesive and the best results were obtained for PGASu 20 wt.% CNW (2.57 ± 0.36 MPa) and PGM 20 wt.% CNW (2.33± 0.43), while the shear strength for polyvinyl acetate - PVAc is 1.58 ± 0,18 MPa.  Aging improved the shear strength of some adhesives. The best improvement was obtained for PGMA 20 wt.% CNW, which reached (3.89 ± 0.74 MPa) after 250h of aging, thus greater than the shear strength of cyanoacrylate (3.12 ± 0.53).  Ultimately, the results presented in this work suggest that the addition of cellulose nanowhiskers (CNW) is a viable approach to tailor mechanical properties and degradation rate of biodegradable polymers.
26
  • JULIANA ELIONARA BEZERRA COSTA
  • HZSM-5 ZEOLITES SYNTHESIZED FROM ALTERNATIVE SILICON AND ALUMINUM SOURCES FOR DEOXYGENATION OF COCONUT FIBER PRODUCTS FROM PYROLYSIS.

  • Líder : MARCUS ANTONIO DE FREITAS MELO
  • MIEMBROS DE LA BANCA :
  • CINTIA DE CASTRO COSTA
  • JOANA MARIA DE FARIAS BARROS
  • MARCUS ANTONIO DE FREITAS MELO
  • RAIMUNDO CRISOSTOMO RABELO NETO
  • RENATA MARTINS BRAGA
  • Data: 18-dic-2017


  • Resumen Espectáculo
  • Some residues from any kinds of activities can be reused so that the effect those impacts is decreased. The residues classified as lignocelluloses biomass can be converted to chemicals and fuels through the fast pyrolysis giving bio-oil as main product. This product usually shows some undesirable characteristics which are related to the biomass source and that lower its energetic efficiency. Using catalysts allows the reduction of those unwanted products and improves the final quality of the bio-oil. Thus, in the present thesis, ZSM-5 and HZSM-5 catalysts were synthesized using residues from granite powder. Glass powder diatomite and rice-husk ash as alternative sources of silica and aluminum; it was also synthesized a catalyst using a conventional silica and aluminum source as a standard. The goal of synthesizing those materials is to use them on the catalytic pyrolysis of the coconut fyber and to analyze the generated products. The used biomass was characterized through immediate constituent analysis (moist, ash, volatile and fixed carbon), specific density, elemental analysis, cellulose, hemicelulose and lignin percentage, calorific power, thermal analysis (TG/DTG), XRD, FT-IR and FRX in order to analyze its energetic potential. The silica and aluminum precursors were also put under FRX and XRD to see the behavior of the used materials. The catalysts were synthesized through the hidrothermic method and characterized by TG/DTG, XRD, FT-IR, SEM and BET. It was shown that the catalysts synthesized as alternative sources have ZSM-5/ HZSM-5-like characteristics and can be applied as catalysts on the coconut fyber pyrolisis.

27
  • HERCULANA TORRES DOS SANTOS
  • Effect of the addition of polyurethane on the permeability of light cement slurries containing air-entraining agent.

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • ERIKA PINTO MARINHO
  • JÚLIO CÉZAR DE OLIVEIRA FREITAS
  • ROSANGELA DE CARVALHO BALABAN
  • WENDELL ROSSINE MEDEIROS DE SOUZA
  • Data: 20-dic-2017


  • Resumen Espectáculo
  • The cementing is one of most important operations performed during the fase of construction of an oil well, because has the goal to seal permeable zones and provide support to the casing string. Depleted zones of interest or with low pressure of fracture requires slurries cementing of low density. Traditional methods to produce lightweight slurries cement including the formation of foam, the use of glass hollow microspheres or lightweight additives. The purpose this work is studying lightweight slurries cement by use of air incorporator. With the presence of the polyurethane increases the tenacity of the cement paste and thus, support thermomechanical cycles and improve the properties. In addition to present excellent results filtrate control, free water, porosity and permeability, contributing to reducing gas migration through cement sheath.The concentrations of incorporator chose was suggestion of providers. From of a density calculated 1.87 g/cm3 (15.6 lb/gal) to a pattern slurry, pastes with incorporator and polyurethane were prepared. An experimental planning was previously performed to improve the evaluation of effects of additives used. Tests of density, stability, mechanical strength and permeability were performed and attained the requirements of Petroleum Institute (API) and Brazilian Association of Technical Norm (BATN). Was observed a decreasing of density with increase of concentration of air incorporator. The compression strength increased with the incorporation ofair, in fact this event was waited due to the formation of bubbles, but the values are compatible with lightweight slurries. The tests of permeability were satisfactory, showing low values, that is a positive point. It was concluded that the use of air developer is viable with the polyurethane in lightweight cement pastes and oil well it is possible to obtain consistent results for conditions in formations with low fracture gradient.

28
  • MARIA VERONILDA MACÊDO SOUTO
  • Study of doping methods to obtain niobium oxide and niobium carbide with copper and its application in sintered composites (Cu-NbC).

  • Líder : CARLSON PEREIRA DE SOUZA
  • MIEMBROS DE LA BANCA :
  • CARLSON PEREIRA DE SOUZA
  • UILAME UMBELINO GOMES
  • ALESSANDRA AGNA ARAÚJO DOS SANTOS
  • ARIADNE DE SOUZA SILVA
  • CLEONILSON MAFRA BARBOSA
  • GILSON GARCIA DA SILVA
  • Data: 22-dic-2017


  • Resumen Espectáculo
  • In this work the doping method was carried out via humid and solid path to obtain niobium oxides and niobium carbides with copper (5% e 10% Cu mol/mol), from the hydrated ammonium trioxalate oxyniobate precursor, as well as an evaluation of the properties of copper-doped niobium (Cu-NbC) sintered carbide composite via SPS (Spark Plasma Sintering). Niobium oxide and copper (CuNb2O6) was obtained by solid-solid reaction at 660 ° C and duration of 120min. The niobium carbide was synthesized at low temperature (980ºC) and in short reaction time (60min) in a gas atmosphere of methane (CH4) and hydrogen (H2). For the sintering of the Cu-NbC composite, the following parameters were adopted: temperature 1200 ° C, compression pressure 30Mpa, reaction time 10min. The powders were characterized by X-ray diffraction, scanning electron microscopy, X-ray fluorescence (FRX), particle size analysis and nitrogen adsorption by the BET technique, as well as crystallite size measurements. The crystallite size was calculated by the Scherrer method using X-ray diffraction data. The reaction powders were obtained with nanometric particle sizes, ranging from ~ 20nm to 28nm, and in the desired proportions with the desired purity. The surface area ranged from ~ 38.0 m² / g to 48.0 m² / g. The moforlogy for both presents agglomerated particles of varied sizes and forms, prevailing the spherical format. The lowest composite deviations were obtained by the solid method, but by wet method the properties were improved, smaller sizes and particles and larger surface areas. The sintered composite was evaluated by XRD, Vickers hardness, density and crystallite size evaluation. Measurements of Vickers hardness, density by Archimedes, SEM and EDS with mapping were also performed, which identified good dispersion and homogenization of the phases. The best Cu-NbC results were obtained for the sintered samples via wet and 10% Cu, with Vickers hardness (84.1 HV) and density (79.3%).

2016
Disertaciones
1
  • HEYTOR VITOR SOUZA BEZERRA DE AZEVEDO
  • Efeito da adição de WC e Co na sinterização e propriedades mecânicas da alumina.

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • UILAME UMBELINO GOMES
  • FRANCINE ALVES DA COSTA
  • ARIADNE DE SOUZA SILVA
  • ELCIO CORREIA DE SOUZA TAVARES
  • Data: 29-ene-2016


  • Resumen Espectáculo
  • Compósitos à base de alumina (Al2O3), carbeto de tungstênio (WC) e cobalto (Co) apresentam propriedades específicas como baixa densidade, alta resistência à oxidação, alto ponto de fusão e elevada inércia química. Esse compósito revela ser um material promissor para ser aplicado em diversos campos da engenharia. Este trabalho tem como objetivo avaliar algumas propriedades mecânicas durante a confecção e, após a sinterização do compósito (Al2O– WC – Co). Pós compósitos com a composição de 80%.p de Al2O3, 18%.p de WC e 2%.p de Co foram processados pela rota de moagem de alta energia (MAE), em moinho planetário por 50 horas, bem como por mistura manual em um recipiente de vidro, seguindo a mesma proporção em peso. Amostras foram coletadas (2, 10, 20, 30, 40 e 50 horas) durante o processo de moagem. Em seguida, os pós foram prensados no formato de amostra circular com diâmetro de 5 mm em uma prensa uniaxial com pressões de 200 e 400 MPa. A sinterização ocorreu de duas maneiras: a primeira sinterização via fase sólida foi realizada à 1300 °C e à 1126 °C durante 1h com taxa de aquecimento de 10°C/min em forno resistivo sob atmosfera de argônio as pressões de compactação utilizadas foram de 200 e 400 MPa, a segunda sinterização foi realizada em dilatômetro via fase sólida à 1300 °C com pressão de compactação de 200 MPa, também foi realizada em dilatômetro outra sinterização, desta vez por fase líquida à 1550 °C com pressões de compactação de 200 e 400 MPa, obedecendo os mesmos parâmetros utilizados no forno resistivo. As matérias-primas foram caracterizadas por difração de raios X – (DRX), fluorescência de raios X – (FRX), microscopia eletrônica de varredura (MEV), espectroscopia por dispersão de energia (EDS) e particulometria a laser. As amostras sinterizadas foram submetidas a ensaios de microdureza. Os resultados mostraram que a moagem de alta energia atingiu os objetivos quanto ao tamanho de partícula e a densificação do compósito. Entretanto, a microdureza não alcançou resultados significativos, isso é um indício que o compósito possui baixa tenacidade à fratura.

2
  • KARINE FONSECA SOARES DE OLIVEIRA
  • INCORPORAÇÃO DO RESÍDUO PROVENIENTE DA ESTAÇÃO DE TRATAMENTO DE EFLUENTE DA INDUSTRIA TÊXTIL EM MASSA CERÂMICA

  • Líder : MARCUS ANTONIO DE FREITAS MELO
  • MIEMBROS DE LA BANCA :
  • MARCUS ANTONIO DE FREITAS MELO
  • GLAUBER JOSÉ TUROLLA FERNANDES
  • JOSE NILDO GALDINO
  • VÍTOR RODRIGO DE MELO E MELO
  • Data: 29-ene-2016


  • Resumen Espectáculo
  • A indústria de processamento têxtil desde 1949, agregou benefícios econômicos e sociais ao estado do Rio Grande do Norte. Entretanto, ao logo da cadeia produtiva deste segmento diversas operações levam a geração de resíduos sólidos, líquidos e gasosos, os quais apresentam grande potencial poluidor. Ao final dos processos de tratamento dos efluentes têxteis é obtido um resíduo sólidos denominado lodo, que é constituído basicamente por matéria orgânica e metais pesados. Nas últimas décadas, a preocupação acerca do destino final, tratamento e reciclagem desse resíduo tem instigado as empresas geradoras a contribuir para a diminuição do impacto que este material bem provocando ao meio ambiente. Neste contexto, este trabalho teve como objetivo estudar uma alternativa viável para a reciclagem do lodo gerado na estação de tratamento de efluentes de uma indústria têxtil por meio da incorporação à argila para a fabricação de tijolos utilizados na construção civil. As matérias primas, lodo e argila, foram caracterizadas por fluorescência de raios X (FRX), difratometria de raios X (DRX), termogravimetria (TG) e análise térmica diferencial (ATD). Posteriormente, o lodo foi incorporado à argila para a fabricação de blocos cerâmicos, barras e tijolos em escala reduzida, em percentuais de 0%, 10%, 20% e 30% em peso úmido. Os corpos de prova foram sinterizados nas seguintes temperaturas: 850, 900 e 950 °C. A barras cerâmicas foram avaliadas por meio de ensaios de resistência à flexão, absorção de água e retração linear de queima, constatou-se que poderão ter aplicação na indústria, sem causar danos ao meio ambiente, aqueles com limite máximo de incorporação de 20% do lodo em temperaturas de queima 850 e 900°C.  Para os tijolos em escala reduzida foram realizados os testes de resistência mecânica à compressão, absorção de água, retração linear de queima e cor, assim como para as barras, a incorporação de lodo no tijolo pode ser no máximo 20% sem comprometer as propriedades técnicas do produto. Em seguida, foi realizado uma análise estatística das propriedades técnicas obtidas para identificar qual parâmetro operacional contribuiu significativamente para o processo. A porcentagem de lodo contribui para o aumento da absorção de água e resistência mecânica à flexão nos corpos de prova produzidos, a temperatura também influencia porém com uma intensidade menor. Diante do exposto, pode-se concluir que é possível o reaproveitamento do lodo gerado na estação de tratamento da indústria têxtil para a produção de tijolos utilizados na construção civil.

3
  • JORGE DANIEL ARAUJO PINTO
  • Formulação e caracterização de misturas cimentícias secas para poços de petróleo onshore.

  • Líder : ANTONIO EDUARDO MARTINELLI
  • MIEMBROS DE LA BANCA :
  • ANTONIO EDUARDO MARTINELLI
  • FABIANA VILLELA DA MOTTA
  • ANDREZA KELLY COSTA NOBREGA
  • Data: 12-feb-2016


  • Resumen Espectáculo
  • Dry mixtures for oil wells cementing have generated enough interest by the mere fact of collaborating with the cementing operations, once it is only added water in the mixture for obtain the cement slurry. With the intention of verify if the dry mixture properties attend in an effective way the needs which are required in the field, this work aims to formulate dry cementitious mixtures and evaluate the behavior of the mixture when subjected to different times of vibration, and this application focused on onshore oil wells. For this it was designed a column in a cylindrical shape with PVC pipes which the dry mixture was packed, subsequently being vibrated at times of 30, 60 and 120 minutes. Then the column was divided in three sections, and subjected to API test (American Petrolleum Institute) as rheology, loss of filtrate, thickening time, mud balance and compressive strength by ultrasonic method (UCA) to see if there was a difference in the properties of the cementitious slurry after vibration. Slurries were formulated to attend the depths of 400, 800 and 1200 meters for onshore wells. The results demonstrated that the dry mixture had a satisfactory reproducibility, once that didn’t have significant migration of additives to the sections of the column after vibration. This possible migration was measured by the API tests which proved similarities of properties between the optimized slurry and from the column. The results of the granulometric analysis also reinforce the exposed above, since all the components introduced into the dry mixture showed averages values of particle size between two and eleven times greater than the cement. This factor contributed to obtain a homogeneous mixture after vibration, because the larger particle size difficulted a possible migration of additives to lower sections of the column under vibration.
     
4
  • IANE MAIARA SOARES DE SOUZA
  • DESENVOLVIMENTO DE CARREADORES AMBIENTALMENTE AMIGÁVEIS COM PROPRIEDADES DE LIBERAÇÃO LENTA DA UREIA FERTILIZANTE.

  • Líder : MAURICIO ROBERTO BOMIO DELMONTE
  • MIEMBROS DE LA BANCA :
  • CARLOS ALBERTO PASKOCIMAS
  • EVERALDO ZONTA
  • JUAN ALBERTO CHAVEZ RUIZ
  • MAURICIO ROBERTO BOMIO DELMONTE
  • Data: 09-mar-2016


  • Resumen Espectáculo
  • O nitrogênio é um macronutriente fundamental para o crescimento vegetal. Atualmente, devido os desgastes ao longo dos anos e a elevada demanda na produção de alimentos, o solo não consegue fornecer às plantas o nitrogênio necessário para seu crescimento. Por isso, o uso de fertilizantes nitrogenados é amplamente aplicado na agricultura, onde a ureia, por possuir elevado teor de nitrogênio, é o mais usado. Contudo, suas elevadas perdas acarretadas principalmente por volatilização de amônia e lixiviação de nitrato fazem com que seja necessário o desenvolvimento de sistemas que reduzam a velocidade de hidrólise da ureia. Neste trabalho foram desenvolvidos dois tipos de fertilizante a base de ureia e carreadores, um em que a ureia foi misturada com bentonita e outro onde a ureia foi misturada com a clinoptilolta, onde para cada argilomineral foram formulados três tipos de fertilizantes, variando as proporções carreador:ureia na forma: 1:4, 1:8 e 1:16. Ainda foi formulado um terceiro fertilizante constituído somente de ureia triturada e misturada com os aditivos utilizados nas formulações como talco e solução de PVP. Todas as composições propostas foram compactadas em cilindros com diâmetro de 7mm e altura de 4mm. Os fertilizantes foram caraterizados quanto a sua morfologia, análise química e mineralogia pelas técnicas de FRX, DRX, FTIR, TG/DSC e MEV. A eficiência agronômica foi avaliada quanto as perdas de  volatilizado, atingindo uma redução de 53% para Z1U16.

5
  • ANDREY JOSÉ MORAES DE LIMA
  • Síntese e caracterização de eletrólitos compósitos à base de céria e sais fundidos

  • Líder : RUBENS MARIBONDO DO NASCIMENTO
  • MIEMBROS DE LA BANCA :
  • RUBENS MARIBONDO DO NASCIMENTO
  • AURISTELA CARLA DE MIRANDA
  • DANIEL ARAÚJO DE MACEDO
  • FLÁVIA DE MEDEIROS AQUINO
  • Data: 31-mar-2016


  • Resumen Espectáculo
  • Solid electrolyte is the part of the fuel cell has three essential functions: separate
    reagents, blocking electronic current and have high ionic conductivity of the elements
    that compose it. Composite electrolytes consisting of a ceria (CeO2) or ceria-gadolinia
    (Ce0,9Gd0,1O2-, CGO) ceramic matrix and eutectic mixtures of Na2CO3/Li2CO3 or
    LiCl/KCl allow reducing the operating temperature of ceramic fuel cells from 600 -
    800°C to 400 – 600 °C. In this paper, composite electrolytes based on ceria and molten
    salts (eutectic mixtures of carbonates and chlorides) were obtained by the citrate
    method. The adopted chemical route enabled the simultaneous synthesis of the two
    phases, with precise control of composition and microstructure, providing substantial
    chemical interaction between phases. The study evaluated the effects of composition
    (carbonate or chloride content in the ceria based matrix) and processing (sintering
    temperature) on microstructure and transport properties of the composites. The
    structural characterization by X-ray diffraction showed that the carbonates and
    chlorides exist as amorphous phases. Despite the low relative densities (between 52
    and 75%), as a result of reduced sintering temperatures (ceria/carbonate at 690°C and
    ceria/chloride between 400 and 600°C), it was observed that the fusion of the
    amorphous phase acts as a seal that can prevent the flow of gases through the
    samples. The correlation between the composition and the electrical behavior, using
    the infrared spectroscopy techniques, scanning electron microscopy and impedance
    spectroscopy, has observed a homogeneous microstructural distribution between
    phases, indicating the formation of a ceramic skeleton based on ceria, surrounded by
    a mixture of amorphous salts, obtaining a conductivity of 0.079 S cm-1 and 0,058 cm-1
    S for the ceria composite and carbonates at 600 ° C and 0.0016 S cm-1 and 0.0011 S
    cm-1 for composites ceria and chlorides at 450 ° C.

6
  • JOAMIR HENRIQUE DA SILVA
  • INFLUÊNCIA DA ADIÇÃO DE SÍLICA ATIVA SOBRE A RESISTÊNCIA MECÂNICA E A TENACIDADE À FRATURA DE CONCRETOS DE CIMENTO PORTLAND PARA UTILIZAÇÃO EM PAVIMENTOS RÍGIDOS RODOVIÁRIOS

  • Líder : WANDERSON SANTANA DA SILVA
  • MIEMBROS DE LA BANCA :
  • WANDERSON SANTANA DA SILVA
  • JOSE HUMBERTO DE ARAUJO
  • PAULO ALYSSON BRILHANTE FAHEINA DE SOUZA
  • MARCOS ALYSSANDRO SOARES DOS ANJOS
  • Data: 31-mar-2016


  • Resumen Espectáculo
  • O concreto é um material compósito de matriz cerâmica e reforço também cerâmico, que se caracteriza por apresentar o chamado comportamento mecânico quase frágil. Suas propriedades são determinadas pela sua microestrutura, que pode ser controlada pela relação água/cimento, tamanhos dos agregados, pela adição de modificadores, como a sílica ativa, entre outros. Do ponto de vista do comportamento mecânico, o concreto é relativamente pouco estudado em relação à tenacidade à fratura. Neste trabalho é estudada a relação entre a adição de diferentes teores de sílica ativa e o comportamento mecânico (resistência à compressão axial e resistência à tração na flexão) e a tenacidade à fratura - utilizando corpos de prova do tipo “short-rod”, com entalhe Chevron (KICV) - de concreto aplicado em pavimentos rodoviários rígidos. Para tanto, foi produzido um total de 150 corpos de prova, sendo 45 cilindros de 15 x 30 cm, nos ensaios de compressão axial; 45 prismas de 15 x 15 x 50 cm, nos ensaios de tração na flexão; 45  do  tipo “short-rod” para  a determinação do KICV, a partir de um traço base (0%) e adições de 3, 6, 9 e 12% de adição de sílica ativa, em relção à massa de cimento. Os ensaios mecânicos foram realizados aos 7 e aos 28 dias de idade. Além disso, as diferentes composições foram avaliadas do ponto de vista das respectivas massas específicas, índice de absorção e índice de vazios, sendo, para tanto, moldados 15 cilindros de 15 x 30cm para os ensaios de massa específica, absorção e índice de vazios. Em relação à preparação das amostras, verifica-se que a adição de sílica ativa provocou uma queda no abatimento do concreto, revelando uma redução na  consistência  do  material, o que requereu um aumento na relação água/cimento, para manter este abatimento constante. Em relação à estrutrura do concreto, verifica-se um aumento na massa específica, seguida de uma redução no índice de absorção e no índice de vazios, com o incremento dos percentuais de sílica ativa. Em relação ao comportamento mecânico, verifica-se  que a resistência à compressão axial e a resistência à tração na flexão apresentaram tendência de crescimento com o aumento do percental de sílica ativa, tanto para as amostras com 7 e 28 dias de idade. No caso das amostras ensaiadas com  28 dias de idade, em ambas as situações, todos os resultados mínimos obtidos atenderam às especificações técnicas mínimas exigidas para a aplicação em pavimentos rígidos. Em relação à tenacidade à fratura, verifica-se valores coerentes com aqueles mostrados pela literatura e, a exemplo da resistência mecânica, verifica-se também uma tendência de crescimento dos valores obtidos, à medida que se aumenta os teores de sílica. A melhoria incremental do comportamento mecânioc, tenacidade à fratura e das propriedades físicas do concreto está associados aos efeitos físicos e químicos da sílica ativa, responsável pela redução de poros e pelo aumento da resistência na interface argamassa/aglomerado.

7
  • EDSON SILVA DO NASCIMENTO
  • Estudo da sinterização e oxidação anódica na produção de um capacitor eletrolítico de nióbio

  • Líder : UILAME UMBELINO GOMES
  • MIEMBROS DE LA BANCA :
  • ARIADNE DE SOUZA SILVA
  • ELCIO CORREIA DE SOUZA TAVARES
  • FRANCINE ALVES DA COSTA
  • UILAME UMBELINO GOMES
  • Data: 08-abr-2016


  • Resumen Espectáculo
  • Este trabalho tem como objetivo encontrar um material alternativo para os atuais capacitores de tântalo usados na indústria. O nióbio é um substituto em potencial por ser mais leve e barato que o tântalo. Eles pertencem ao mesmo grupo da tabela periódica e, desta forma, apresentam várias propriedades físicas e químicas semelhantes. O nióbio é usado em diversas aplicações tecnologicamente importantes, e o Brasil possui as maiores reservas mundiais, em torno de 96%. Esses capacitores eletrolíticos possuem alta capacitância especifica, ou seja, podem armazenar altas energias em volumes pequenos comparados a outros tipos de capacitores. A rota de produção do capacitor de nióbio foi realizada através das etapas de processamento da metalurgia do pó. Inicialmente, o pó de nióbio foi caracterizado através de DRX, MEV, granulometria a laser; e depois peneirado para apresentar uma granulometria de 400mesh. Posteriormente o pó foi compactado com uma matriz especial e então sinterizado em diferentes temperaturas e tempos de isoterma. Após a sinterização as amostras passaram por processo de oxidação anódica em diferentes tensões para a obtenção de uma camada óxida, a qual desempenha o papel do dielétrico do capacitor. Os resultados foram obtidos através de uma ponte de capacitância, mostrando a forte influência da sinterização e do processo de oxidação anódica na produção dos capacitores. Os melhores resultados foram obtidos para o pó sinterizado a 1400°C durante 60 minutos e anodizados a uma tensão de 10V. O processo apresentou valores significativos e com mais estudos pode-se melhorar ainda mais esses valores para competirem com o tântalo.

     


8
  • RAMIRO GOMES DE FREITAS NETO
  • Estudo da Recristalização do Aço Inoxidável Lean Duplex LDX2101 submetido a diferentes graus de redução por laminação a frio

  • Líder : WANDERSON SANTANA DA SILVA
  • MIEMBROS DE LA BANCA :
  • WANDERSON SANTANA DA SILVA
  • AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • NICOLAU APOENA CASTRO
  • MÁRCIO FERREIRA HUPALO
  • Data: 29-abr-2016


  • Resumen Espectáculo
  • Os aços inoxidáveis duplex são aços altamente ligados caracterizados por uma estrutura bifásica de ferrita-austenita obtida através de processos de conformação a quente ou tratamentos térmicos adequados após os processos de conformação a frio. A presença de frações volumétricas próximas de ferrita e austenita na estrutura dos aços duplex promove uma boa combinação entre as propriedades de resistência mecânica e resistência a corrosão. Uma das classes dos aços duplex que vem se desenvolvendo nos últimos anos é o Lean duplex, que apresentam teores mais baixos de Cr, Ni e Mo, o que os torna mais baratos em comparação com os austeníticos. Para compensar a redução de Ni e Mo, elementos como Mn e N são adicionados em maior quantidade para proporcionar uma boa resistência à corrosão e conferir a estabilidade da austenita no aço. Nos últimos anos o número de trabalhos relacionados ao aço Lean duplex cresceu bastante devido ao interesse em se conhecer, desenvolver e aplicar cada vez mais essa classe de aços. Uma das aplicações que está em alta é a soldagem por difusão no estado superplástico, e os aços inox duplex possuem o comportamento superplástico, que exige microestruturas com grãos pequenos e baixas taxas de deformação.  Sendo assim, um estudo de recristalização do aço inoxidável Lean duplex 2101 como método de refino de grão é proposto para este trabalho. Diferentes laminações a frio, sendo elas 70, 80 e 90% de redução, foram empregadas no material para fornecer potencial termodinâmico para a recristalização nos tratamentos térmicos em três temperaturas, 900°C, 1000°C e 1100°C por tempos de 20 minutos, 1 e 2 horas. Técnicas de microscopia óptica, eletrônica de varredura, EDS, medidas magnéticas, difração de raios-X, EBSD e microdureza foram empregadas para a caracterização. Os resultados de medidas magnéticas e microscopia ótica indicam que há acentuada ocorrência de transformação induzida por deformação da austenita para martensita CCC, além de indícios da ocorrência de outros mecanismos de deformação como maclação mecânica e deslizamento de discordâncias, bem como indícios de zonas de austenita não transformada, aparentemente isenta de encruamento, conforme indicado pelos valores de microdureza, mesmo para reduções de 90% na laminação a frio; aparentemente houve precipitações de fases indesejadas tanto na ferrita quanto na austenita durante os tratamentos térmicos e aparente recristalização total das amostras laminadas pós tratamento térmico mesmo para os tempos mais curtos. Nas amostras analisadas por EBSD foram observados indícios de refino do grão austenítico e uma tendência de crescimento secundário da ferrita. Nas amostras recristalizadas identificou-se que para temperaturas e tempos de tratamento mais baixo as frações de ferrita se mostraram levemente maiores, enquanto que para temperaturas e tempos de tratamentos maiores as frações de austenita foram maiores. 

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  • FELIPE FERNANDES CAVALCANTE
  • Comportamento Mecânico e Tenacidade à Fratura de Ligas de Alumínio 2024 e 7075 submetidas a diferentes tempos de envelhecimento

  • Líder : WANDERSON SANTANA DA SILVA
  • MIEMBROS DE LA BANCA :
  • WANDERSON SANTANA DA SILVA
  • AUGUSTO JOSE DE ALMEIDA BUSCHINELLI
  • MAURÍCIO MHIRDAUI PERES