Mechanical properties and microstructures of HPHT sintered polycrystalline diamond compacts reinforced with SiC whiskers

Abstract

Polycrystalline diamond compact (PDC) cutters, the most widely used cutting tool in oil and gas drilling, often fail very quickly because of excessive wear and poor impact toughness in hard and complex formations. In this study, dense PDC samples doped with SiC whiskers (SiCw) were successfully synthesized under high pressure and high temperature (HPHT) conditions. The microstructures, elemental distributions, and phase compositions of the PDC samples were systematically investigated. The mechanical properties including the Vickers hardness, wear resistance, impact toughness and thermal stability, were tested. The introduction of SiCw reduced the Co content in the polycrystalline diamond layer. The testing results showed that the hardness of PDC doped with 0.5 wt% SiCw was 75.25 GPa, wear ratio was 145.6 × 104 and impact toughness reached 4020 J, which were 12.2%, 30.9%, and 142.2% higher than those of the control group (CG), respectively. The PDC-0.5 wt% SiCw had the lowest thermal expansion value, with a 57.5% reduction compared with the CG. In addition, the strengthening mechanism of SiCw was explored. SiCw partially replaced the weakening cobalt phase in the binder phase, thus improving the hardness, wear resistance, and thermal stability of the PDC. The introduction of SiCw inhibited the abnormal growth of WC at the interface of the cemented carbide substrate and changed the fracture mode from intergranular to transgranular, which were the main mechanisms responsible for the significant increase in the impact toughness of PDC.