Corrosion-Wear Mechanism of Si-DLC Films in Nitric Acid Solution

In this study, tribocorrosion behaviors of DLC and Si-DLC films in deionized water and nitric acid environment were investigated by the electrochemical workstation and tribometer. The potentiodynamic polarization and electrochemical impedance spectroscopy tests were performed to evaluate the electrochemical property of the two films. The wear volumes in different environments were used to investigate the corrosion-wear mechanism of DLC and Si-DLC films in nitric acid solution. The results indicate that doping of Si element in DLC films decreased the friction coefficient, while it also led to deterioration of corrosion protection property, due to the increasing corrosion current density of films in nitric acid solution. Corrosion-wear of films was determined mainly by mechanical wear and affected scarcely by electrochemical corrosion. The synergistic effect between mechanical action and electrochemical corrosion was also a significant factor during tribocorrosion, and accounted for nearly 4% of the total wear volume of DLC and Si-DLC films.