Wear-corrosion behavior of ion plated thin films

Abstract

The combined action of wear and corrosion processes was investigated on Cr and TiN thin films ion plated onto 304 stainless steel and M 50 steel, respectively. A new laboratory technique was used to study the simultaneous effects of mechanical and electrochemical parameters during a sliding wear process in a corrosive environment. The wear-corrosion studies were conducted in 0.1M NaCl using potentiodynamic polarization scans. The wear process was found to affect the materials’ corrosion behavior by lowering the corrosion potential, extending the activation polarization region, and increasing the passive current density. The degree to which these changes occur is a primary function of the oxide stability and the repassivation kinetics. The wear process produced a smaller effect in both ion plated films when compared to their steel substrates. The TiN film in particular remained intact after wear-corrosion testing and showed a current density three to six orders of magnitude less than M 50 steel. The TiO2 stability, adherence to the ion plated film, and high rate of formation, together with low film roughness, are the main parameters producing the high wear-corrosion resistance in this system.