Corrosion and tribological behaviour in a 3.5% NaCl solution of vacuum arc deposited ZrCN and Zr–Cr–Si–C–N coatings

Abstract

ZrCN and Zr–Cr–Si–C–N coatings were deposited on Si (100) and 316L stainless steel substrates using the cathodic vacuum arc technique in a mixed atmosphere of C2H2 and N2. The coatings were grown keeping almost constant the ratio of the C2H2 and N2 mass flow rates, substrate bias and deposition temperature at ∼0.81, −200 V and 320 ℃, respectively. The investigation carried out aimed to determine the corrosion and tribological performance of the novel Zr–Cr–Si–C–N coating obtained by Cr and Si addition to the ZrCN reference coating. The films were characterized in terms of elemental and phase composition, crystalline structure, hardness, reduced elastic modulus and adhesion. Particular attention was devoted to the investigation of coatings' corrosion resistance and tribological performance carried out in a 3.5% NaCl solution. Cr and Si addition to ZrCN coating leads to reduction in film crystallinity, finer microstructure, enhanced corrosion resistance and better tribological performance under corrosive testing conditions. In this paper, we discuss the measured mechanical and tribological properties of the two coatings in terms of various ratios of hardness and reduced elastic modulus. The coated samples exhibited high corrosion protection efficiency, reaching 97.8% for the Zr–Cr–Si–C–N coating. Both coatings improved the tribological performance of 316L steel in the saline solution. Specifically, the addition of Cr and Si into ZrCN coating results in a decrease of the wear rate of about 60%.