Effect of pressure on sintering behavior of polycrystalline diamond

Polycrystalline diamond composites (PDC) have been used as a cutting material in a multitude of fields, from mechanical processing to oil and gas drilling. In this study, PDC samples were prepared under high pressure and high temperature (HPHT) conditions within a pressure interval of 5.5 to 10.5 GPa by sintering diamond powder (average grain size similar to 3 mu m) with WC-10 wt% Co substrate. Samples obtained with varying sintering pressures and temperatures were characterized using Vickers hardness tester, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results revealed that: (1) within a specified material system, each distinct sintering pressure condition corresponds to a unique optimal sintering temperature that yields the pinnacle of consolidation efficiency in samples. This optimal temperature exhibits a linearly increasing trend with rising sintering pressure; (2) at the intersection where the sintering pressure attains its optimal match with temperature, an increase in pressure fosters more intimate contact and stronger inter-grain bonding among diamond particles, thus amplifying the D-D bond formation effect, which consequently leads to a linear enhancement in the Vickers hardness values of PDC with increasing sintering pressure; (3) simultaneously, under conditions of optimal temperature matching, elevating the sintering pressure notably decreases the cobalt content within the polycrystalline diamond layer of PDC samples. These findings furnish crucial experimental evidence for optimizing PDC material properties, significantly contributing to the advancement of both theoretical exploration and technological innovation within the field, carrying profound academic value and practical guidance implications.