Effects of carbon content on the microstructure and mechanical property of cathodic arc evaporation deposited CrCN thin films

Chromium nitride coating is characterized for its adequate mechanical properties, corrosion and oxidation resistance. The addition of carbon into the chromium nitride coating can improve the hardness and tribological properties effectively. In this study, a series of higher nitrogen contained CrCN thin films with different carbon contents were grown by the cathodic arc evaporation (CAE) deposition method using different flow ratios of N2 and C2H2 gas mixture. The crystalline structure, surface roughness, microstructures, hardness, adhesion and tribological properties were evaluated. It was observed that the surface roughness and grain size decreased with increasing C content. A nanolaminated structure was obtained when the C2H2 gas flow rate was 17.5 sccm. The CrCN coating containing 3.5 at.% C showed the optimal hardness, adhesion and tribological properties in this work.