Study On Synthesis And Propenies Of Ti₃SiC₂/Ti （C, N） Composite Material

(Titanium silicon carbide) attracts increasing interest owing to their unique properties. Ti3SiC2combines unusual properties of both metals and ceramics. Like metals, it is a good thermal and electrical high temperature mechanical property. It is resistant to thermal shock and unusually damage tolerant and exhibit machined by using conventional tools without lubricant, which is of great exceptional solid lubricant with an ultra-friction. But the bad wear ability because of easy cleavage character and relatively low hardness limits the project application.Owing to the high hardness, high modulus, excellent chemical stability and approximate thermal expansion coefficient, Ti (C, N) herein is chosen to produce Ti3SiC2/Ti (C, N) composites in order to increase the hardness and strength of Ti3SiC2.In this study, Ti3SiC2powder is synthesized by vacuum-sintering with composition of4Ti/2SiC/lTiC/0.2Al in molar ratio. And then Ti3SiC2/Ti (C, N) composites added with the Ti (C, N) quality content is5wt%,10wt%,15wt%and20wt%could be sintered in the temperature range of1250-1400℃. The phase composition, the microstructures and the physical properties of the Ti3SiC2/Ti (C, N) materials were investigated, as following respectively:(1) The bulk Ti3SiC2/Ti (C, N) materials is synthesized by vacuum-sintering. Analyzing its component through XRD, in indicates that the material principal constituent is Ti3SiC2and Ti (C, N), but also includes few impurities, like SiC and TiC. The results of SEM of sample surface indicated that the Ti3SiC2grains are well developed and plate-shape. The second phase of Ti (C, N) possessed the characteristic of isometric crystal, Ti (C, N) can distribute uniformly in the composites. The particles reinforced of Ti (C, N) improved the density and hardness of the composites.(2) The added of the Ti (C, N) improved the composites hardness which enhanced the material ability of resistance to plough and advanced the efficiency of the material friction and wear properties. But in higher load and speed, the hard phase in the material will be stripped to form pits and will reduce the materials friction and wear properties. The materials friction and wear properties are related with the formation of oxide film during the process of friction.(3) The oxidized dynamics research indicates:the cyclic-oxidation kinetic of Ti3SiC2in the temperature range of800-1000℃for40cycles follows the parabolic raw, at1200℃for40cycles could divide into two parabolic processes. The principal oxidized product at800℃is TiO2and SiO2, the principal oxidized product at1000℃and1200℃is TiO2and a few SiO2. compact oxides layer on the surface of Ti3SiC2/Ti(C, N) prevents the further oxidiation from the inner layer material, thus it enables the Ti3SiC2/Ti (C, N) material to have a good oxidization resistance performance.