Banca de DEFESA: MEYSAM MASHHADI KARIMI

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : MEYSAM MASHHADI KARIMI
DATA : 10/07/2017
HORA: 07:00
LOCAL: A definir
TÍTULO:

OBTAINING TRIPLE LAYER POLYCRYSTALLINE DIAMOND COMPACT BY HPHT METHOD

PALAVRAS-CHAVES:

Polycrystalline diamond compact, PDC, High pressure high temperature, Diamond, Interface, WC/Co substrate.

PÁGINAS: 129
GRANDE ÁREA: Engenharias
ÁREA: Engenharia de Materiais e Metalúrgica
RESUMO:

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.

MEMBROS DA BANCA:
Presidente - 345842 - UILAME UMBELINO GOMES
Interno - 1350249 - RUBENS MARIBONDO DO NASCIMENTO
Externo ao Programa - 2613355 - FRANCINE ALVES DA COSTA
Externo à Instituição - CLODOMIRO ALVES JUNIOR - UFERSA
Externo à Instituição - MARCELLO FILGUEIRA - UENF