| Because of the excellent properties: high hardness, abrasion resistance, corrosion resistance, high temperature resistance etc. Ti(C,N) cermet received special attention in the industry application, such as metalworking and high temperature parts, but its widely using were limited by its brittleness. The mechanical properties of Multiwalled Carbon Nano-Tubes(MWCNTs) were higher than another fiber materials. Therefore, it is an important theoretical significance and practical value to investigate the prepartion and properties of MWCNTs/Ti(C,N) cermet composites.In this investigation, MWCNTs/Ti(C, N) cermet composites were prepared by purified, dispersed and vacuum hot pressing sintering, with TiC,TiN as raw materials, WC, Mo2C, TaC, Cr3C2 as hard addition phases, Ni and Co as binder phases, and MWCNTs as fiber reinforcing agent, the effects of MWCNTs addition on the microstructure and mechanical properties of Ti(C, N) cermet were investigated. The optimum content of MWCNTs and sintering system were finded, the high temperature oxidation resistance was characterized and the toughening mechanisms of composites were studied.The MWCNTs with lower chemical activities were acidified and purified by concentrated nitric acid, and nano-TiO2 were supported on its surface by reacted with tetrabutyl titanate, to improve its dispersibility and compatibility in Ti(C, N) cermet, the results showed that: the impurities in MWCNTs were rapidly and effectively removed by concentrated nitric acid at 80℃holding 1h, the issues of winding and adhesion were reduced, the dispersity of disperse liquid were improved in ethanol with MWCNTs purified and supported TiO2.The typical core-rim microstructure existed in acidified MWCNTs/Ti(C,N) cermet composites: black core-gray rim structure and white core-gray rim structure, the volume fraction of white core structure and the size of core structure were increased as MWCNTs addition increased, but the black core were incompleted as its increased, and the densities of cermet were decreased slowly then sharply until MWCNTs addition reached 2.5wt%. The bending strength, hardness and fracture toughness of cermet were trended to increase and then decrease as MWCNTs increasing. bending strength, Vickers hardness and fracture toughness of composites was respectively reached 1224.46MPa, 20.96GPa and 9.85MPa?m1/2,when MWCNTs addition is 1wt%, and respectively 11.33%, 10.26% and 16.71% improved comparing with the mechanism properties (respectively 1090.87MPa, 19.01GPa, 8.44MPa·m1/2) of Ti(C,N) cermet without MWCNTs contented. The best comprehensive mechanical properties of sample S10 were reached by adding 1wt% MWCNTs supported TiO2, sintering in 1440℃holding 20min and the molding pressure is 25MPa, which obtained by orthogonal test, the bending strength, Vickers hardness and fracture toughness of S10 was 1275.14MPa,22.27GPa and 10.60MPa·m1/2, was respectively 16.89%,17.15% and 25.59% improved comparing with the properties of Ti(C,N) cermet without MWCNTs contented. Bridging and pulling out of MWCNTs, crack deflection, residual stress toughening and micro-voids toughening attributed to fracture toughness of composites.High temperature oxidation resistance of S10 were studied, in the section SEM photograph of sample,the sample which put in 1100℃holding 2h with compact surface and content oxide layer and transition layer, the thickness respectively is 56.3μm and 11.12μm, this dense layer of protection were effectly prevent further oxidation of the sample, showed the excellent oxidation resistance.
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