Study On Preparation And Properties Of TiCN Films By Arc Ion Plating And Composite Technology On Cr12MoV Steel

Auto parts mainly rely on stamping die forming,however the failure of stamping molds often originally appear on the surface.Therefore the surface performance directly affects the use and service life of the die.PVD is an economical and effective method to improve the surface hardness and wear resistance of stamping die.To satisfy the demands of high-end molds with high strength,high quality and long service life,the films should provide high hardness and wear resistance,especially have good adhesion strength between the films and the substrate.In this paper,a series of TiCN hard films,Ti/TiCN multilayer films and nitrided composite films were obtained by arc ion plating and plasma nitriding.The effects of process parameters,such as bias and modulation period,and nitriding pretreatment techniques on the microstructure and mechanical properties of TiCN films and Ti/TiCN multilayer films were studied.The main results were as follows:Arc ion plating was used to deposit TiCN monolayer films based on orthogonal experiments.The influence of deposition process parameters,like bias,total gas and gas flow ratio on the microstructure and mechanical properties of TiCN films were initially explored.The experimental results show that the bias is a dominant influence factor for the hardness and bonding strength of the TiCN films.In addition,the total amount of gas has the greatest influence on the films thickness.The optimal process for orthogonal experiments is total gas:300 sccm,gas ratio:Q?CH₄?:Q?N₂?=2:1,bias:-200 V.A series of TiCN films were deposited under different bias voltages to optimize the bias parameter.The results show that the bias can change the existence of carbon in the TiCN films.The hardness of the TiCN films is greatly increased with the increase of bias.The adhesive strength of the TiCN films first increases and then decreases.The wear resistance of the TiCN films is improved,and the main friction and wear mechanism is changed from adhesive wear to abrasive wear.The best overall performance of TiCN films can be obtained at a bias voltage of-250 V.In this case,the hardness value,bonding force,average friction coefficient and wear rate of the films are 4017 HV_0.025,51.06 N,0.3221 and 2.9×10^-77 mm³·N^-1·m^-1,respectively.For Ti/TiCN multilayer,the effect of modulation cycles on the microstructure and mechanical properties of the multilayer films was studied.The results show that the cross-section of the multilayer films is columnar crystal.With the decrease of the modulation period,smaller grain size and fewer surface droplets of the Ti/TiCN multilayer films were obtained,while the growth of TiC_0.7N_0.3 in the?200?and?220?directions is promoted.In terms of mechanical properties,as the modulation period decreases,the hardness of the multilayer films increases monotonously,and the highest hardness value is 4010 HV_0.025.The adhesion strength of the films and the substrate first increases and then decreases.Both the friction coefficient and the wear rate show a similar tendency to increase first and then decrease,and the main wear mechanism is abrasive wear.Ti/TiCN multilayer films show the best overall performance when the modulation period is 188 nm.At this time,the hardness is 3601 HV_0.025,and the adhesion strength is 52.91 N.The average friction coefficient and the wear rate of the films are 0.4328and 4.66×10^-77 mm³·N^-1·m^-1,respectively.The surface composite strengthening treatment of Cr12MoV steel was carried out by plasma nitriding technology and arc ion plating technology.The results show that the nitriding pretreatment will improve the hardness and bonding strength of the composite films,and the composite films have better wear resistance.The nitriding pretreatment and TiCN composite films have the best performance,delivering the hardness of 4257 HV_0.025,the adhesion strength of 60.61 N,the average friction coefficient of 0.3014 and the wear rate of 2.41×10^-7 mm³·N^-1·m^-1.