Preparation And Properties Of AlCrTiSiN/AlCrTiSiON Multilayer Composite Coating

As one of the most effective methods to improve the surface properties of materials,PVD coating plays an important role in cutting.As a kind of hard protective coating,AlTiN coating has been widely used in the field of cutting tools.With the rapid development of machining industry,high-speed and high-precision machining needs and the wide use of difficult to machine materials put forward higher requirements for tool coating.However,doping Cr,Si and other elements into the AlTiN coating can effectively improve the microstructure of the coating,improve the mechanical and wear resistance of the coating.Based on the above,the AlCrTiSiN multicomponent composite coatings were prepared by arc ion plating technology in this paper.The effects of deposition temperature and preoxidation time on the structure and properties of the coatings were systematically studied,AlCrTiSiN was annealed in vacuum to investigate the effect of heat resistance and annealing temperature on structure and properties of coating.In addition,cutting experiments were carried out to compare the cutting performance of uncoated milling cutter,AlTiN coated milling cutter,as well as the original and annealed coatings.The results are as follows:In the process of coating deposition,the movement state of evaporated ions is closely related to the deposition temperature,which directly determines the performance of the coating.The results show that the AlCrTiSiN coating is mainly composed of fcc-TiN and hcp-AlN phases,which grow preferentially along the(220)crystal face of fcc-TiN phase.With the increase of deposition temperature,the diffraction peak intensity of the coating increases slightly,and the mechanical and wear resistance increase first and then decrease.When the deposition temperature is 450?,the hardness,critical load,friction coefficient and wear rate of the coating are 23.7 GPa,82.1 N,0.66,3.86×10^-3?m³/N·?m^-1 respectively.The heat resistance of AlCrTiSiN coating was further investigated,and the mechanism of coating performance change under different annealing temperature was analyzed.The AlCrTiSiN coating was annealed in vacuum.The results show that with the increase of annealing temperature,the diffraction peak intensity of the coating increases gradually;the surface of the coating tends to be smooth;the hardness increases first and then decreases;the critical load of the coating decreases and the wear resistance improves.In addition,the high temperature friction experiment of AlCrTiSiN coating shows that when the temperature is 800?,the wear resistance of the coating is significantly improved,and the friction coefficient and wear rate are reduced to the lowest,which are 0.72 and 1.49×10^-3?m³/N·?m^-1,respectively.In order to further improve the high temperature oxidation resistance of AlCrTiSiN coating,AlCrTiSiON surface protective layer was prepared on the surface of AlCrTiSiN by pre oxidation experiment.The results show that the coating is mainly composed of Al₂O₃,AlN,(Al,Cr)₂O₃,and grows preferentially along the(115)crystal face of Al₂O₃phase;The mechanical properties and friction and wear properties of the coating decrease slightly after oxygenation.In addition,the cutting test shows that AlCrTiSiN coating has good protection ability for cemented carbide tool matrix due to its compact structure and excellent wear resistance.After annealing,the grain size of AlCrTiSiN coating increases and the protective ability of coating decreases.After preoxidation,the mechanical and wear resistance of the coating decrease,and the cutting performance decreases.