Formation mechanisms of low-friction tribo-layers on arc-evaporated TiC1-xNx hard coatings

A detailed correlation of the tribological performance of arc-evaporated TiC1-xNx coatings with testing temperature, atmosphere as well as variation in load and sliding velocity is presented in this paper. The low-friction behavior in combination with its mechanical integrity are the reasons for the extensive industrial application of TiC1-xNx over the last decades. Still the tribo-mechanisms behind this performance are not yet completely understood. The present study adds further understanding, as the low-friction behavior degrades at elevated temperatures and dry or inert environments, which is related to the different constitution of the tribo-layer formed as investigated by Raman spectroscopy. Surprisingly, the wear rate of the coatings does not correlate with the coefficient of friction indicating the presence of different wear regimes. (C) 2007 Elsevier B.V. All rights reserved.