Role of deposition temperature on the mechanical and tribological properties of Cu and Cr co-doped diamond-like carbon films

Abstract In this study, Cu and Cr co-doped diamond-like carbon (Cu/Cr-DLC) films were synthesized using a hybrid ion beam deposition system. The effects of deposition temperature on the metal content, hardness and wear behavior of Cu/Cr-DLC films were investigated. Particularly, an optical emission spectroscopy was applied to characterize the plasma at different deposition temperatures. Results showed that the intensities of Cu and Cr spectral lines decreased dramatically as the temperature increased from 60 to 250 °C. The concentrations of Cu and Cr decreased from 18.1 to 2.7 at.% and 10.5 to 2.2 at.%, respectively. Meanwhile, high temperature promoted the formation of the Cr carbide phase, which was beneficial to achieve high hardness of the film. Although the residual stress increased with the rise of deposition temperature, the Cu/Cr-DLC film showed a better adhesive strength in comparison with pure amorphous carbon film. The wear resistance was also significantly improved at high deposition temperature, and only faint wear was observed when the temperature was above 150 °C. The excellent tribological performance of Cu/Cr-DLC film was mainly attributed to good mechanical properties and the formation of continuously compacted graphitized transfer film under dry sliding conditions.