Comparison of tribological behaviour of TiN, TiCN and CrN at elevated temperatures

PVD-coated instruments are often used at elevated temperatures. However, the friction and wear data of these coatings at temperatures exceeding room temperature are still lacking. In order to help remedy this lack, three coatings widely spread in industrial applications, TiN, TiCN and CrN, taken from standard production of customer's coating centre were comparatively measured up to 500 °C. The coatings were deposited on hardened steel substrates either by unbalanced magnetron sputtering or arc evaporation deposition. The measurements were done using a high-temperature tribometer (pin-on-disc, CSM Instruments). The evolution of friction coefficient with sliding distance (number of cycles) was measured at different temperatures and the wear rate of the ball and coating were evaluated. 100Cr6 balls and the Si 3N 4 ceramic balls were used as counterparts. The wear tracks were examined optically and by SEM. The surface oxidation at elevated temperatures and chemical composition inside and outside the wear track was also measured by EDX analysis.