Banca de QUALIFICAÇÃO: VIVIANE DA SILVA PINHEIRO DANTAS

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : VIVIANE DA SILVA PINHEIRO DANTAS
DATA : 09/12/2016
HORA: 09:00
LOCAL: Sala de aula do PPGCEM
TÍTULO:

Synthesis and characterization of nanometric particles of cerium oxide (CeO2) prepared by the Sol Gel method

PALAVRAS-CHAVES:

cerium oxide, x-ray diffraction, thermogravimetry, nanocrystalline powder

PÁGINAS: 58
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
ESPECIALIDADE: Cerâmicos
RESUMO:

Corrosion represents the major and most costly challenges facing the aviation industry across the globe. The wear of metallic parts in aircraft subjected to extreme environmental conditions, with chemically aggressive and reactive environments, justifies studies that allow the coating of metal components by films that protects corrosive processes and reduces the frequency of repairs. In this study, cerium oxide applied as an overlay of aluminum foil represents an alternative to be investigated from the point of view of technical and economic viability. This work was carried out with the main objective of synthesizing cerium oxide (CeO₂) in the form of nanometric particles with high surface area. The synthesis of the metal oxide occurred from the mixture of 50 ml of cerium nitrate aqueous solution hexahydrate (Ce (NO₃) 3.6H2O), prepared in a concentration of 117 mmol/L Ce^{+ 2} at 60 °C and mixed for 30 minutes with na organic solution containing ethylenediamine (C₂H₄(NH₂)₂), acetic anhydride ((CH₃CO)₂O) and acetylacetone (C₅H₈O₂) in proportions in which molar ratios of 2: 1, 3: 1 and 4: 1 organic load: cerium. After mixing, the final solution was kept at 80 °C for 3 hours before being subjected to the heat treatment in a muffle oven. Before being fed to the muffle furnace an aliquot of the resin was removed for thermal analysis (TG and DSC). The synthesis temperature of the oxide in a muffle furnace was studied at three different levels (250 °C, 350 °C and 450 °C) and, after synthesis, the material was characterized by X-ray diffractometry (XRD), infrared (FTIR) The BET method. In order to improve the interaction and dispersion of the pulverized material with the polymer base (dimethyl polysiloxane polymer (PDMS)) used for fixing the film to the aluminum foil, functionalization studies of cerium oxide in xylene solution and 3- (trimethoxysilyl methacrylate) Propyl (MEMO) were conducted. After the functionalization the material was applied as thin film to aluminum substrates and characterized. XRD analysis was used with treatment of the results conducted with the aid of MAUD software to observe phase formation, crystal structure, network parameters, mean crystallite size, microdeformation, density and volume of the unit cell. The product obtained from the calcination showed the light yellow CeO₂ phase with a cubic crystalline structure of the fluorite type. In the thermal analysis the thermal behavior of calcination of the resin resulting from the synthesis by sol gel from the ambient temperature up to 1000 °C was observed. The results showed that from the temperature of 190° C begins the formation of the cerium oxide with crystallization at the temperature of 250 ° C. The FTIR was used to investigate the behavior of the sample according to the chemical bonds before and after the functionalization procedure. The results indicated that there was occurrence of Si - O - Ce bond with wavelength close to 450 cm ^-1.

MEMBROS DA BANCA:
Presidente - 1883170 - MAURÍCIO ROBERTO BOMIO DELMONTE
Interno - 1300987 - CARLOS ALBERTO PASKOCIMAS
Interno - 1802888 - FABIANA VILLELA DA MOTTA
Externo à Instituição - VINÍCIUS DANTAS DE ARAÚJO - UFRPE