Banca de QUALIFICAÇÃO: ARTHUR GABRIEL FERREIRA DE OLIVEIRA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : ARTHUR GABRIEL FERREIRA DE OLIVEIRA
DATA : 10/06/2019
HORA: 08:00
LOCAL: Sala Anexa - LMCME
TÍTULO:

OBTANING OF Al₂O₃ – 5%Ni e Al₂O₃ COMPOSITES USING POWDER TECHNOLOGY AND MECHANICAL ALLOYING

PALAVRAS-CHAVES:

Alumina, Composites, Mechanical Alloying, Powder Technology

PÁGINAS: 104
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
ESPECIALIDADE: Cerâmicos
RESUMO:

Among the materials used in cutting tools, alumina-based ceramics play an important role, mainly because they have properties such as high hardness, chemical and thermal stability, high wear resistance and high refractoriness. However, they have low toughness, low bending strength, low thermal shock resistance and low thermal conductivity, which often compromises their application. In this way, it is necessary to develop studies in order to improve these properties. The addition of other materials, especially with greater ductility, can serve as a front to inhibit the crack propagation of these tools, greatly improving their toughness. In this context, this work aims to study the addition of nickel and niobium in alumina, using the route of the technology of the powders in the processing of the material. Compositions were prepared with 5% Nickel and 5% niobium in alumina. Subsequently, was performed the manual mixing of the powders and the Mechanical Alloying (MA) in a planetary ball mill for 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. Was analyzed the microstructure of the samples was analyzed by Scanning Electron Microscopy (SEM-FEG), the crystalline phases determined by X-ray Diffraction (XRD) and Dispersive Energy Spectroscopy (EDS). The density obtained by the Archimedes method, the hardness and fracture toughness by the critical length of crack. The results of the powders processing indicated the formation of composite powders in both compositions. Regarding the consolidation of the powders, there was a behavior difference between the added metals, especially considering the sintering. In the nickel composites, the best properties were obtained around the longest milling time, with density around 96%, hardness of 1480 HV and fracture toughness of 4.75 MPa.m^{1 / 2}. In the Alumina-Niobium composite, the optimum values were found in sintered powders ground in 5 hours MA, with a density around 95.5% hardness of 1329 HV and fracture toughness of 4.30 MPa.m^{1 / 2}. The properties of these composites when compared to the wide range of cutting tools used and literature, results in an indication of application mainly in AISI T15 (540 HV) fast steel machining and cutting speeds around 200m/min.

MEMBROS DA BANCA:
Externa à Instituição - ARIADNE DE SOUZA SILVA - UFRN
Externo ao Programa - 2613355 - FRANCINE ALVES DA COSTA
Externo ao Programa - 2414250 - MEYSAM MASHHADIKARIMI
Presidente - 345842 - UILAME UMBELINO GOMES