Corrosion and tribological behavior of Ni–Cr alloy coatings electrodeposited on low carbon steel in Cr (III)–Ni (II) bath

Abstract

Despite great corrosion and tribological properties of Cr (VI), the utilization chromium (VI) is extremely restricted due to its hazards for environment. Therefore, the objective of this study was to replace Cr (VI) with less hazardous coating such as Cr (III) and Ni (II). In this study, Ni–Cr alloy coatings were electrodeposited in Cr (III)–Ni (II) bath using various current densities. The effects of current density on deposition rate, morphology and chemical composition of the coatings were investigated. Potentiodynamic polarization and EIS (electrochemical impedance spectroscopy) tests in 3.5% NaCl solution were used to evaluate corrosion properties of the coatings. Tribological behaviors of the coatings were also studied by means of ball-on-disk method. The results showed an optimum range of current densities, in which the deposition rate was low. Ni–Cr alloy surface roughness along with Cr content was optimized by increasing the current density. The alloy coating containing 39.8wt.% Cr, had the best corrosion and wear resistance among all the samples. The corrosion current density and volume loss of this coating were about 9 and 52 times lower than those of the steel substrate, respectively.