Improving Heat Resistance Of Polycrystalline Diamond Compact Cutters For Rock Drilling

As a composite super hard materials,polycrystalline diamond compact(PDC),which is usually composed of diamond and WC-Co substrate,and synthesized at high pressure and high temperature(HPHT),are widely used as the tooth of drilling bits.Compared with other wear-resistant cutters such as polycrystalline diamond(PCD),PDC has better impact toughness and heat conductivity,which because PDC used the WC-Co metal materials as a substrate.PDC is now widely utilized in processing cutting tools,mine,oil and gas drilling,geological prospecting,deep drilling and so on.In this paper,the synthetic experimental studies about improving thermal stability of PDC had been done with hinge type domestic cubic presser.The synthetic method was infiltration process combined with mixed powder sintering in the condition of P=5.0~6.5GPa,T=1350℃~1650℃,t=5~7min.The influence factors about the synthesis and thermal stability improving including of the cubic assemble structure design,the conditions of temperature and pressure,the synthesis process curve and the place of catalyst metal disc,had been studied and the optimization design had been given,too.The different kinds of binder had been added to improve the thermal stability of PDC,which composition proportion had been designed,too.The scanning electron microscope(SEM),Energy Dispersive Spectrometer(EDS)and X-Ray Diffraction(XRD)had been utilized to analyze the microstructure,the composition and the thermal stability of the PDC samples.The thermogravimetry(TG)analysis had been done to test the thermal stability of PDC with adding different kinds of binder.The results showed that the conventional PDC initial oxidation temperature is 760℃,the improved PDC samples initial oxidation temperature are 840℃and 920℃,respectively,which are 80℃ and 120℃ higher than the conventional one.The synthesis mechanism about PDC with high thermal stability sintered by HPHT infiltration process had been studied.The mixed powder provide a gallery for the catalyst metal disc and the catalyst in the disc formed a pressure difference with the compound interface,which provide a driving force for synthesis.The addition formed the C-M-C bond with the diamond,which can improve the thermal stability of PDC.