Influences of bias voltage on the microstructures and tribological performances of Cr–C–N coatings in seawater

Abstract

CrCN coatings were deposited on single crystal silicon and 316L stainless steel substrates using the cathodic arc ion plating technique with different substrate bias voltages that ranged from −10 to −160V. The relationships between substrate bias voltage and the coating characterization such as nanohardness, modulus, adhesion of the coatings and tribological behavior in ambient air, distilled water and seawater were investigated. Results showed that the hardness and modulus increased significantly with the increase of bias voltages from −10 to −160V. Both the friction coefficients and wear rates of CrCN coatings in ambient air, distilled water and seawater decreased with the increase of bias voltages in the lower range, whereas, they were constant when the bias voltage increased to the high level. In addition, the friction coefficients and wear rates of CrCN coatings under aqueous solution were significantly lower than those under ambient air. Excellent friction and wear behaviors of the CrCN coatings deposited with bias voltages in the range of −100 to −130V may be attributed to low roughness, excellent adhesion strength, high hardness and planar (2D) graphite-like structure.