Research On Preparation Technology And Mechanical Properties Of TiC_0.7N_0.3-WC-TaC-Mo-（Ni,Co） Cermets

Ti(C,N)-based cermet is a kind of interesting composites with unique combination of properties such as high hardness, wearing and high-temperature hardness, and chemical stability. It has been widely used in high-speed cutting and accurate machining.Developing high performance cutting tools of Ti(C,N)-based cermet is significant to promote the technologies and the industries level of high-speed cutting and accurate machining.The cermet of TiC0.7N0.3-WC-TaC-Mo-(Ni,Co) material was prepared with the component of TiC0.7N0.3、WC、TaC、Mo、Ni and Co powders and submicron Si C particle or Si3N4 whisker by the process route of ball-milled, dried and sifted, Die pressing and vacuum sintering. The density determinator, Rockwell hardness tester, mechanical universal testing machine, x-ray diffusion equipment(XRD), scanning electronic microscope(SEM), EDX equipment were used to measure respectively the density,hardness, flexural strength, phase structure, microstructure and component of the cermet.And the effect of sintering temperature, Mo content, submicron SiC particles and Si3N4 whisker on the microstructure and mechanical properties of TiC0.7N0.3-WC-TaC-Mo-(Ni,Co) cermet were anlysed and discussed in detail.The effect of sintering temperature on the microstructure and properties of the cermet has been studied. The results show that: the core-rime microstructures is formed in the boundary of hard ceramic phase and binding metallic component by the process of dissolution and precipitation of different component, and varies with the sintering temperature, which plays significant roll to the cermet mechanical properties. The cermet get optimized microstructure and mechanical properties when sintered at 1450℃.The investigation of the effect of Mo content on microstructure and properties of the cermet were conducted in this paper too. The results show that: Element Mo is good to the formation of core-rime microstructure and grain refinement and uniformity when its content is less than 9%. The transverse rupture strength of the cermet increased with the Mo content. But there is an inverse relationship between the Mo and the properties of cermet when Mo content lager than 9%.The effect of submicron SiC particle and Si3N4 whisker on microstructure and mechanical properties of the cermet were studied respectively. The results show that: SiC particles and Si3N4 whisker have similar effect on the cermet. The grain size becomesmaller and rime phase increase in the cermet with the increase of the content of SiC particle and Si3N4 whisker, which improve the material strength. The density and TRS of the material are the best when the content of SiC particle are 1%. The toughness and HV are best when the content of SiC particle is 2% and 3% respectively. When the content of and Si3N4 whisker is 1% and 3%,the TRS and HV of the material are the best.When the content of and Si3N4 whisker is 2%,the density and toughness of the material are the best.The material strength decrease with the increase of SiC particle and Si3N4 whisker,because them can reduce the cermet density and rime phase.