TiCxOy thin films for decorative applications : tribocorrosion mechanisms and synergism

Abstract

Recently, tribocorrosion is widely accepted as an interdisciplinary area of research and such studies on the various materials is gaining more attention by the scientist and engineers due to its practical and economical significances. Hence the main objective of present work was to investigate the tribocorrosion behavior of single layered titanium oxycarbide, TiCxOy, thin films on a reciprocating sliding tribo-meter, and in the presence of artificial sweat solution at room temperature. Such films can be used as a decorative coating on various components. The films were produced by dc reactive magnetron sputtering, using C pellets incrusted in the Ti target erosion area. A gas atmosphere composed of Ar and O2 was used. The Ar flow was kept constant, and the oxygen gas flow varied from 0 to 10 sccm. During the wear tests both the open circuit potential and the corrosion current were monitored. Also, Electrochemical Impedance Spectroscopy (EIS) tests were performed before and after sliding in order to evaluate, in detail, the modification of the protective character of the coating introduced by the joint action of wear and corrosion. The modifications of the coating microstructure and/or chemical composition induced by the variation of the deposition parameters were also evaluated and correlated with the wear-corrosion mechanisms occurring in each system. The effect of hardness, film thickness and structure of the films on the tribocorrosion performance of the coating, as a function of oxygen fraction was studied and an attempt was made to classify them. Further, individual and synergistic effects of wear and corrosion on total wear loss were estimated and correlated with tribocorrosion mechanisms.