Polycrystalline diamond compact with enhanced thermal stability

Polycrystalline diamond compacts (PDC), which are composed of diamond and WC/Co substrate, and synthesized at high pressure and high temperature (HPHT), are widely applied as the tooth of drilling bit. However, the thermal stability of PDC will be reduced when diamond transforms into graphite due to cobalt in PDC acting as a catalyst during the drilling work. In this study, a new three-layer structured PDC with enhanced thermal stability has been successfully synthesized at pressures of 5.5-7.0 GPa and temperatures of 1650-1750 °C. In this structure, the diamond-SiC composite acts as the working layer, and the diamond-SiC-Co composite and WC/Co cements are as the intermediate layer and substrate, respectively. It is found that the initial oxidizing temperature of the three-layered PDC is enhanced up to 820 °C, which is significantly higher than that (∼780 °C) of the conventional PDC counterpart.