In this study, the polycrystalline diamond compact(PDC) was manufactured by the high pressure, high temperature (HPHT) process. To improve the performance of PDC, the wear resistance and thermal shock properties were investigated in accordance with initial molding pressure, ratio of diamond particles, the diamond particles size.
First, the microstructure and wear properties of HPHT sintered PDC were investigated in accordance with initial molding pressure. After quantifying an identical amount of diamond powder, the powder was inserted in top of WC-Co sintered material, and molded under four different pressure conditions (50, 100, 150, 200 kg/cm2). The obtained diamond compact underwent sintering in high pressure, high temperature(HPHT) conditions. In the case of the 50 kg/cm2 initial molding pressure condition, cracks were formed on the surface of HPHT PDC. On the other hand, HPHT PDC obtained from 100~200 kg/cm2 initial molding pressure conditions showed a meticulous structure. As molding pressure increased, low Co composition within HPHT PDC were detected. A wear resistance test (VTL) was performed on the PDC, and the 200kg/cm2 condition PDC showed the highest wear resistance properties.
Second, the microstructure and thermal shock properties of PDC produced by the high pressure, high temperature (HPHT) were investigated . The diamond used for the investigation featured a 12~22 ㎛ and 8~16 ㎛ sized main particle, and 1~2 ㎛ sized filler particle. The filler particle ratio was adjusted up to 5~31% to produce a mixed powder, and then the tap density was measured. The measurement found that as the filler particle ratio increased, the tap density value continuously increased, but at 23% or greater, it reduced by a small margin. The mixed powder described above underwent an HPHT sintering process. Observation of PDC microstructures revealed that the filler particle ratio with high tap density value had increased direct bonding among diamond particles, Co distribution became even, and the Co and W fraction also decreased. The produced PDC underwent thermal shock tests with two temperature conditions of 820℃ and 830℃, and the results revealed that PDC with smaller filler particle content and low tap density value easily produced cracks, while PDC with high tap density value that contributed in increased direct bonding along with the higher diamond content resulted in improved thermal shock properties.
Third, the microstructure, wear resistance and thermal shock properties of HPHT sintered PDC were investigated in accordance with diamond particle size. Diamond particle sizes were (a) 12∼22 ㎛, (b) 10∼20 ㎛, (c) 8∼16 ㎛. In the results of XRD analysis on the PDC, diamond, WC, Co phase were observed. Observation of PDC microstructures revealed that PDC including large diamond particle size had increased Co fraction because of high surface area. A wear test (VTL) was performed on the PDC, and PDC including small diamond particle size showed the highest wear resistance properties. The produced PDC underwent thermal shock tests with two temperature conditions of 780℃ and 830℃, and the results revealed that diamond particle size small PDC easily produced cracks. The thermal shock properties of large diamond particle size PDC was improved.