Chromium arc plasma characterization, structure and properties of CrN coatings prepared by vacuum arc evaporation

Plasma is one of the most important factors affecting the structure and properties of coatings deposited by vacuum arc evaporation, while its specific characteristics are rarely analyzed. In this study, the effects of working pressure and arc current on plasma characteristics, microstructure and intrinsic properties of CrN coatings deposited by vacuum arc evaporation were investigated. The plasma characteristics were characterized by optical emission spectroscopy, and the electron density and plasma temperature were calculated. It was found that the calculated plasma temperatures were in the range of 7000 K–9000 K under the assumption of local thermodynamic equilibrium conditions. The arc burning condition of 4.0Pa/90A corresponds to the highest plasma density and the highest temperature. The interaction between plasma and macro-particles affects the structure and intrinsic properties of the coating. When working pressure and arc current are at a low level, the number of macro-particles is small, and the coating properties match well with the change of plasma state. When working pressure and arc current are too high, the number and size of macro-particles increase explosively, which increases the influence on the structure and properties, thus weakening the influence of the plasma state on the coating. It can provide guidance for preparation of CrN coatings with high properties by vacuum arc evaporation.