Research On Synthesis, Micro-structure And Mechanical Properties Of Ti-Al-N,Ti-Al-V-N Composite Coatings And Ti-Al-N/VN Multilayers Coatings

Ti-Al-N composite films, Ti-Al-V-N composite films and Ti-Al-N/VN multilayer films were prepared by reactive magnetron sputtering technique. The effect of Al content on the microstructure, mechanical properties and friction and wear properties of Ti-Al-N composite films were investigated. The effect of V content on the microstructure properties of Ti-Al-V-N composite films investigated. Ti-Al-N/VN multilayer films microstructure and mechanical properties influenced by modulation periods, the mechanisms of hardening were investigated. The main conclusions in this work are summarized as follows:Ti-Al-N composite films always grew in c-Ti-Al-N(111). As the Al content increased up to 57.92at.%, the h-AlN(100) phase was formed. With the content of Al is 49.97at.% the films got a maximum microhardness of 27.05GPa, solid solution hardening derived from the Al dissolution into the TiN. The temperature of oxidation resistance of Ti-Al-N composite films was between 900℃-950℃. The minimum friction coefficients of Ti-Al-N composite films are 0.7723 at room temperature with the content of Al is 49.97at.% and 0.3792 at high temperature with the. content of Al is 39.51at.%. The reasons are the change of microhardness and toughness at room temperature and Al2O3 as lubricating layer at high temperature.Ti-Al-V-N composite films always grew in c-Ti-Al-N(111). With the content of V is 16.95at.% the films got a maximum microhardness of 31.67GPa, solid solution hardening derived from the V dissolution into the Ti-Al-N. With the V content increases, the temperature of oxidation resistance of Ti-Al-V-N composite films was decline. The minimum friction coefficient of Ti-Al-V-N composite films at room temperature is 0.3864 while the content of V is 16.95at.%, the possible reasons are the reduce of TiO2 which from chemical reactions in the friction test and microhardness. The minimum friction coefficient of Ti-Al-V-N composite films at high temperature is 0.2197 while the content of V is 26.72at.%. The low friction was attributed to the formation of a V2O5 glaze layer on the oxide surface.Ti-Al-N/VN multilayer films with different modulation periods always grew in (111). The multilayer film got a maximum microhardness of 33.12GPa while the modulation period is 6nm. It was analyzed that Hall-Petch mechanism did not play role in the multilayer films, modulus difference mechanism was not main reason and the hardness enhancement was due to coherence stress through theoretical calculation.