Effect of Substrate Heating Temperature on Structure and Frictional Properties of WC-DLC Coatings

By intermediate frequency magnetron sputtering and arc ion plating technology,WC doped diamond-like coatings were prepared on 316L stainless steel substrates,which were heated to 150℃,250℃,350℃and 450℃,respectively.The influence of the heating temperature on the structure and tribological performance of diamond-like films was studied through phase structure analysis,hardness test,and friction and wear test.The results show that the doping element amount of W in DLC films increases slightly with the increase of substrate temperature,and the maximum doping amount is 3.45%.There are mainly two crystal phases,WC_1-x and W₂C,and the crystal structure changes from WC_1-xto W₂C as the temperature increases.At 150℃,the content of sp³C bond in the film is the highest,and the nano-hardness value is up to 7.4 GPa.The increase of substrate temperature changes the structure of the film,and the mechanical properties become worse.Under 2 N load of dry friction test,the friction coefficient decreases first and then increases with the increase of temperature.At 350℃,the friction coefficient is 0.2,which is the minimum one,while the wear rate increases gradually with the heating temperature.At 150℃,the minimum is 3.45×10^-11m³/N·m,and the wear mode is abrasive wear.