Self‐Lubrication of Chlorine‐Implanted Titanium Nitride Coating

Abstract

Chlorine implantation into TiN coatings decreases the wear loss and the friction coefficient. Even by low‐dose chlorine implantation, the wear volume is decreased by three orders of magnitude or more, and the friction coefficient becomes <0.1. This self‐lubrication mechanism is related to the presence and mobility of implanted chlorine atoms inside the columnar TiN microstructure. According to observations of chlorine‐implanted TiN coatings using high‐resolution transmission electron microscopy, the chlorine atoms are present in the damaged region, where TiN is composed of nanosized grains. From these data, a self‐lubrication mechanism is proposed with chlorine catalyzing the oxidation of titanium and leading to the formation of some tribological reaction product.