Microstructure, electrochemical and tribocorrosion behaviors of CrCN nanocomposite coating with various carbon content

Abstract The CrCN nanocomposite coatings with various carbon content were firstly synthesized via mid-frequency magnetron sputtering to seek the possibility of application in marine corrosion environment. The microstructure of the CrCN coatings were characterized systematically. In particular, the mechanical, electrochemical as well as tribocorrosion performances of the resulting coatings were evaluated in detail. The results showed that the CrCN coatings were polycrystalline structures composed of CrN phase, Cr7C3 phase and amorphous carbon. The carbon content of the CrCN coating significantly influenced its mechanical, electrochemical and tribocorrosion properties. The hardness and elastic modulus of the CrCN coating increased initially and then gradually decreased as the raising of the carbon content in the coating. And the CrCN coating with 20.3% carbon content exhibited maximum hardness of 14.7 GPa and the highest elastic modulus of 197.7 GPa among all coatings. However, the adhesion strength of the prepared coatings gradually deteriorated as the carbon element doping into CrN coating. The CrN coating with many defects exhibited poor electrochemical performances compared with the dense CrCN coatings. The CrCN coating with 20.3% carbon content presented the lowest wear rate of 3.85 × 10−7 mm3(Nm)−1 and minimum OCP value of −0.19 V, revealing its excellent tribocorrosion properties. This could ascribe to its high hardness and the obvious graphitization of the wear surface. Finally, the possible tribocorrosion mechanisms of the as-prepared coatings were proposed according to the analyzed results of their microstructure, electrochemical behaviors and wear surfaces.