Synthesis And Properties Of New Ceramic Bonding Agent WC Cemented Carbide Materials

Conventional WC-based cemented carbides have limited performance of WC-based cemented carbides due to the presence of metal binder phases and hinder their use in high temperature,high speed and highly corrosive environments.The Ceramic bond WC cemented carbides has good high-temperature hardness and corrosion resistance and oxidation resistance because it does not contain a metal phase with a lower melting point.However,the research on the Ceramic bond WC cemented carbides have problems such as higher preparation temperature and lower fracture toughness.This topic uses high entropy compounds as a new ceramic binder.,which provides a new idea and method for the preparation of WC-based cemented carbide without metal binder.The TiC_0.4 of high-entropy compounds having a function of promoting sintering and accelerating atomic diffusion can solve the problem of high preparation temperature.The good mass transfer ability of the high entropy compound and WC during the sintering process makes the WC and the high entropy compound as the binder phase form a good interfacial bond,which has the effect of increasing the toughness of the sintered body.In this study,Firstly,the effect of C atom vacancies on the sinterability of composites in non-stoichiometric ratio TiC_0.4 was studied by TiC_0.4 and WC delamination and composite sintering.The effects of WC content,different temperatures and different sintering methods on the properties of TiC_0.4-WC composite sintered bodies were also studied.The test results show that the vacancies of TiC_0.4 have the effect of promoting sintering.Finally,when the content of TiC_0.4 is 15 vol.%and the content of WC is 85vol.%,the comprehensive performance of composite sintered body is best at plasma sintering temperature of 1600°C.It has a Vickers hardness of 22.2 GPa,a fracture toughness of 9.6 MPa·m ^1/2 and a flexural strength of 612 MPa.On the basis of the components TiC_0.4 and WC,VC,NbC and TaC were respectively added for composite sintering,and the molar ratio of the components was 1:1:1.The results show that the TiC_0.4-WC-VC sintered body has good comprehensive performance at 1600°C,Vickers hardness is 22.3 GPa,fracture toughness is 5.7 MPa·m^1/2,and flexural strength is 605 MPa.TiC_0.4-WC-NbC sintered body has good comprehensive performance at 1600°C,Vickers hardness is 19.8 GPa,fracture toughness is 6.21 MPa·m^1/2,and flexural strength is 563 MPa.The TiC_0.4-WC-TaC sintered body has good comprehensive performance at 1700°C,Vickers hardness of 19.9 GPa,fracture toughness of 6.12MPa·m^1/2,and flexural strength of 532 MPa.The composite sintering experiments of TiC_0.4 and various transition metal carbides show that the equimolar ratios of TiC_0.4,NbC,VC and WC can form a single face-centered cubic?fcc?structure under the action of a large number of C atom vacancies.The single-phase covalent bond compound has the best performance at a sintering temperature of 1500°C,and has a Vickers hardness of 23.53 GPa and a fracture toughness of 6.41MPa·m ^1/2.