Effects of Cr concentrations on the microstructure, hardness, and temperature-dependent tribological properties of Cr-DLC coatings

Cr doped diamond like carbon (Cr-DLC) coatings were deposited by using a combined system consisting of middle frequency (MF) magnetron sputtering and ion plating. The structure and properties of the undoped and Cr-doped DLC coatings were analyzed by various testing, such as Raman, XPS, hardness and temperature-dependent frictional wear testing. The results showed that Cr-DLC coatings with low Cr concentration was a effective protective coating containing Cr-C nanometer grains, whose mechanical properties were obviously improved, such as, residual stress and cohesive strength, and still kept good wear resistance at the ambient temperature of 400 °C.