金属含量对PDC齿微观结构及机械性能的影响OA

Objectives:At present,China's oil and gas exploration and development are gradually advancing towards deep and ultra-deep well fields,which have the characteristics of high environmental temperature,high rock strength,and complex formations.Therefore,higher requirements are put forward for the long-term and efficient performances of rock-breaking tools.Polycrystalline diamond compact(PDC)cutting cutter are formed by combining artificial diamond micro-powder with a tungsten carbide matrix through high-temperature and high-pressure sintering technology.They possess the high hardness,high wear resistance,and high thermal conductivity of diamond,as well as the high strength and good impact toughness of tungsten carbide,and are essential core materials and tools for oil and gas exploration and development.The content of metal phases such as Co and W in the polycrystalline diamond(PCD)layer has a decisive influence on the synthesis and performance of PDC cutting cutters.The study of metallic phases can provide an in-depth understanding of the performance,the microstructure and the failure mechanism of PDC cutting cutters.Methods:In the research and development of PDC cutting cutters,Co removal technology,composite doping technology,and structural design technology have been widely applied and have achieved excellent drilling results.For example,the wear resistance and thermal stability of PDC cutters can be enhanced by reducing the metal content in the PCD layer,and the impact toughness of PDC cutters can be enhanced by adding WC-Co metal.However,the research on the influence mechanism of metal content on the performance of PDC cutters is relatively scarce.Therefore,three types of PDC cutting cutters with different WC-Co contents were prepared using the high-temperature and high-pressure method and a uniform powder mixing process.The distribution of metallic phases and microscopic morphology characteristics in PDC are analyzed by X-ray diffraction(XRD)and scanning electron microscopy(SEM),and the wear resistance and impact resistance are compared and tested using a vertical turret lathe and a drop hammer impact tester.Meanwhile,the microstructure of the grinding section and impact fracture surface after performance testing of PDC cutting cutters are observed to further explore the influence of metal content in PCD on the mechanical properties and failure mechanism of PDC cutting cutters.Results:Three types of PDC cutters with different WC-Co contents,namely cutter#1,cutter#2,and cutter#3,are prepared using the uniform powder mixing method and cobalt removal treatment.The PCD layers are uniform,and the metal phase content gradually increases from cutter#1 to cutter#3.All three types of PDC cutters are well sintered,and the addition of WC-Co metal phase reduces the number of D-D bonds in the PCD layer.The removal of Co improves the wear resistance of PDC cutters,while the metal phase content is negatively correlated with the wear resistance of PDC cutters.As the WC-Co content increases,the roughness of the worn surfaces of PDC cutters increase,and the number of intergranular microcrack fractures at the grinding mouth increases.At the same time,the increase in metal phase content significantly improves the impact resistance of PDC cutters.The impact resistance of cutter#3 is much higher than that of cutter#1 and cutter#2.The reason is that the metallic phase in the PCD layer plays a key role in hindering the propagation of microcracks.Conclusions:An increase in the content of metallic phases will microscopically change the bonding degree of the diamond skeleton,the morphology of the ground surface and the fracture mode of microcracks,and will macroscopically directly affect the mechanical properties of PDC cutters.That is,changes in the microstructure of PDC cutters directly affect the quality of their macroscopic properties.