Corrosion and Tribocorrosion Properties of Duplex Surface Treatments Consisting of Plasma Nitriding and DLC Coating

Abstract

In this study, a comprehensive analysis was performed to investigate the corrosion and tribocorrosion behaviour of untreated and duplex ceramic coated AISI 4140 steel. Therefore, samples were plasma nitrided in a glow discharge environment and then, they were coated with diamond-like carbon (DLC) film. Electrochemical impedance spectroscopy, potentiodynamic polarization and tribocorrosion tests were performed in fourteen different parameters. Nitriding treatment increased the surface roughness compared to the base material. The negative effect of roughness on corrosion and tribocorrosion performance has disappeared with the ceramic film thickness increasing with temperature and time. Harder surfaces compared to the base material contributed to the wear resistance. Compound, diffusion layers and DLC film have a barrier effect, delaying the arrival of the corrosive liquid to the base material.