Study On Hardness And Toughness Modulation And Erosion Resistance Of Cr/CrN/Cr/CrAlN Multilayer Film

Erosion wear is one of many kinds of wear,which is widely used in aerospace,machinery and energy industries.Serious erosion wear will lead to parts failure and reduce the service life of equipment.At present,surface treatment technology is commonly used to prepare protective film to protect the surface of materials and reduce the damage caused by erosion wear.In this paper,a series of Cr/CrN/Cr/CrAl N multilayers were designed and prepared on the surface of TC4 titanium alloy based on the vacuum cathode arc ion plating technology.Through the mechanical properties test,erosion wear experiment,friction wear experiment and tensile experiment,combined with scanning electron microscopy and other analysis means,the effects of modulation ratio,modulation period and film thickness on the structure and performance of Cr/CrN/Cr/CrAl N multilayers were studied,and the following conclusions were drawn:（1）With the increase of the modulation ratio L_Cr/CrN:L_Cr/CrAlN（thickness ratio of Cr/CrN to Cr/CrAl N）,the surface quality of Cr/CrN/Cr/CrAl N multilayers improves,and the preferred growth orientation of Cr/CrN/Cr/CrAl N multilayers changes from（111）crystal plane to（200）crystal plane.The hardness decreases,while the binding force,toughness and friction and wear properties increase first and then decrease.When the modulation ratio L_Cr/CrN:L_{Cr/CrAl N}is 1:2,the multilayer film has the best comprehensive performance:the erosion rate is 1.1μm/g at 90°erosion angle,0.366μm/g at 30°erosion angle,and the wear rate is 1.477×10^-6mm³/（N·m）.（2）When the modulation ratio L_Cr/CrN:L_Cr/CrAlNis 1:2,the proportion of large particles on the surface of Cr/CrN/Cr/CrAl N multilayers decreases first and then increases with the decrease of the modulation period,and the hardness,bonding force,toughness,friction and wear resistance and erosion resistance of Cr/CrN multilayers increase first and then decrease,while the residual stress decreases first and then increases.When the modulation period is 200 nm,the comprehensive performance of the multilayer film is the best:the adhesion force is 50.0N,the crack growth resistance is 483,the wear rate is 1.465×10^-6mm³/（N·m）,the preferred growth orientation is（200）,the erosion rate is 1.177μm/g at90°erosion angle and 0.283μm/g at 30°erosion angle.（3）When the optimal modulation ratio L_Cr/CrN:L_Cr/CrAlNis 1:2,the modulation period is 200 nm,with the increase of Cr/CrN/Cr/CrAl N multilayer thickness,the surface quality of the film has little change,the multilayer structure becomes better first and then worse,the preferred growth orientation changes from（200）crystal plane to（111）crystal plane,and the hardness gradually increases to a constant value.The bonding force,toughness,friction and wear resistance and erosion resistance all increase first and then decrease,while the residual stress increases gradually（reaching-3.851 GPa at 15μm）.When the film thickness is 12μm,the comprehensive performance of Cr/CrN/Cr/CrAl N multilayers is the best:the hardness is 3303HV,the bonding force is 58.6N,the crack propagation resistance is 758,and the wear rate is 1.29×10^-6mm³/（N·m）.The erosion rate is 0.694μm/g at 90°erosion angle,and the erosion rate is 0.479μm/g at 30°erosion angle.The tensile properties of 4μm to 12μm multilayers have no negative effect,and the elongation of 15μm multilayers is 30%lower than that of titanium alloy matrix.