Mechanical Property Ang Oxidation Behavior Under High Temperature Of TiAlN/Mo₂N Nano-multilayer Films

Cutting tools with hard films are a new kind of material in recent decades.which have effectively solved the contradiction between tools hardness and toughness.However.whith the rapid development of green manufacturing industry,high-speed dry cutting technology adapting to the requirements of energy saving and environmental protection has gradually become an important development trend of the mechanical processing industry,which with harsh working conditions puts forward higher requirements for the high temperature stability of films for.TiAIN CrAIN and other hard films have high hardness,but their higher COF is not good to reduce the generation of friction heat in the condition of high-speed dry cutting,resulting in rapid oxidation failure of the films.Therefore,the key to improve tool life is to further reduce the COF of the films while maintaining its high hardness.Study shows that,TiAlN/Mo2 nano-multilayer film has higher hardness and lower friction coefficient,but the high temperature mechanical properties and high temperature oxidation behavior of the film are rarely reported.Therefore,TiAIN/Mo2N nano-multilayer films with different Mo or Al content were deposited by Closed-Field Unbalanced Magnetron Sputtering technique in this article.The microhardness of the TiAlN/Mo2N nano-multilayer films with the increase of the annealing temperature was discussed and the hardening mechanism of the film?and hardness,toughness.H/E associated with the tribological properties of the films;In addition,the high-temperature oxidation behavior and oxidation mechanism of TiAlN/Mo2N nano-multilayer films were analyzed.It was found that TiAIN/MO2N nano-multilayer films of different Mo or Al content were composed of TiAIN phase and Mo2N phase,and the superlattice structures was obtained by TiAIN layer and Mo2N layer.The changes of Mo or Al content had significant effect tribolosgical properties and oxidation behavior of TiAlN/Mo2N nano-multilayer films.The studies about high temperature mechanical properties and high temperature oxidation behavior of TiAlN/Mo2N nano-multilayer films showed that:with the increase of annealing temperature,The microhardness of TiAlN/Mo2N-20at%Mo nano-multilayer film increased furstly and then decreased,exhibiting super hardness(41.8 GPa)in 600?,which is associated resistance of TiAlN/Mo2N nano-multilayer films gradually becomes worse.At high temperature,oxygen diffusion was mainly carried out along the boundaries of mo-rich regions and columnar crystals with more defects,leading to non-uniform oxidation of the film.In addition,with the increase of Al content,the COF and specific wear rate of Ti1-xAlxN/Mo2N nano-multilayer films decreased gradually,which was related to the formation easily of Mo Magneli oxides with higher A1 content under dry friction conditions.Under the condition of high temperature oxidation,with the increase of Al content,the Al2O3 formed on the surface of the film gradually changed from loose and porous structure to continuous and compact,thus improving the oxidation resistance of the film.