| With the rapid development of processing and manufacturing,the number of difficult-to-machine materials is increasing,and binary coatings such as Ti N and Cr N have been unable to meet the requirements of modern industrialization.In recent years,coatings such as Al Cr N and Al Ti N have attracted widespread attention due to their high hardness,wear resistance and high temperature oxidation resistance.The Al Cr N coating can form a dense Cr2O3 and Al2O3mixed oxide film under high temperature conditions,which can effectively prevent the diffusion of O into the coating,reduce the oxidation rate,and enhance the high temperature oxidation resistance of the coating.However,too high Al content will cause the phase transition of Cr N?Cr2N?Cr in the coating at high temperature,which will reduce the red hardness of the coating.Ti Al N coating has high hardness and wear resistance,but under high temperature atmospheric conditions,Ti element in the coating is easily oxidized to form loose and porous Ti O2,which has poor oxidation resistance.In this paper,the advantages of Al Cr N and Al Ti N coatings are comprehensively used to prepare Al Cr N/Al Ti N nano-multilayer coatings under different deposition parameters,and their properties are studied.The research results are as follows:Two kinds of Al Cr N/Al Ti N nano-multilayer coatings were prepared by changing the deposition temperature(300°C and 400°C).Crystalline preferential growth.As the deposition temperature increases,the large particles on the coating surface decrease and the deposition rate increases.When the deposition temperature is 400?,the coating has higher hardness,elastic modulus,lower residual compressive stress,friction coefficient(0.586)and wear rate(9.59×10-7mm3/(N·m)),showing better wear resistance.After being kept at 700°C for 1 h,the hardness and bonding force of the two coatings were greatly improved.For H13 die steel cutting,both Al Cr N/Al Ti N nano-multilayer coating milling cutters can greatly extend the cutting life of the tool.Four kinds of Al Cr N/Al Ti N nano-multilayer coatings were prepared by changing the bias voltage.The main phase structures of the coatings are fcc-(Al,Cr,Ti)N phase,which grows preferentially along the(111)crystal plane.Using TEM to observe the high-resolution image of the Al Cr N/Al Ti N nano-multilayer coating prepared when the bias voltage is-150V,it is found that the coating is alternately grown by Al Cr N and Al Ti N with a modulation period of 2.66nm.As the bias voltage increases,the deposition rate first increases and then decreases,and the surface roughness is low.When the bias voltage is-180V,the hardness and elastic modulus reach the maximum value of 33.01GPa and 597.63GPa,respectively.When the bias voltage is-150V,the lowest wear rate of the coating is 1.391×10-7mm3/(N·m),which shows the best anti-friction and wear performance.Three kinds of Al Cr N/Al Ti N nano-multilayer coatings were prepared by changing the N2/Ar ratio,and the phase structures of the coatings were all fcc-(Al,Ti,Cr)N phases.With the increase of N2/Ar,the hardness and elastic modulus of the coating first increased and then decreased.When the N2/Ar ratio is 4/1,the hardness(H)and elastic modulus(E*)of the coating obtain the maximum values of 36.77GPa and 668.92GPa,respectively,and have the maximum H/E*(0.055),H3/E*2(0.111),We(65.28%)values;and the lowest wear rate of 5×10-8mm3/(N·m),showing the best anti-friction and wear performance.The microstructure and properties of Al Cr N,Al Ti N single-layer coatings and Al Cr N/Al Ti N nano-multilayer coatings were compared.The results show that the three coatings are all composed of solid solution phase and grow preferentially along the(111)crystal plane.The hardness,elastic modulus and H3/E*2 value of Al Cr N/Al Ti N nano-multilayer coatings are higher than those of Al Cr N and Al Ti N single-layer coatings,and they have the lowest friction coefficient(0.286)and wear rate(5.04×10-7mm3/(N·m)),showing the best anti-friction and wear performance.After high temperature annealing at 800??1000?,the Al Cr N/Al Ti N nano-multilayer coating still has the highest hardness. |
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