Banca de DEFESA: ARTHUR GABRIEL FERREIRA DE OLIVEIRA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : ARTHUR GABRIEL FERREIRA DE OLIVEIRA
DATA : 26/07/2019
HORA: 08:00
LOCAL: Auditório do DFTE
TÍTULO:

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

PALAVRAS-CHAVES:

Alumina, Composites, Mechanical Alloying, Powder Technology.

PÁGINAS: 102
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
SUBÁREA: Materiais Não-Metálicos
ESPECIALIDADE: Cerâmicos
RESUMO:

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.m^{1 / 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.m^{1 / 2} .

MEMBROS DA BANCA:
Externa à Instituição - ARIADNE DE SOUZA SILVA - UFRN
Externo à Instituição - CLODOMIRO ALVES JUNIOR - UFERSA
Externo ao Programa - 2613355 - FRANCINE ALVES DA COSTA
Externo à Instituição - MARCELLO FILGUEIRA - UENF
Presidente - 345842 - UILAME UMBELINO GOMES