Characterization of tribological behavior and wear mechanisms of novel oxynitride PVD coatings designed for applications at high temperatures

This paper focuses on high-temperature tribotests of nanostructured Al-Cr-based oxynitride and oxide coatings. Pin-on-disk tribological tests were performed at temperatures in between room temperature and 800 °C, and the results compared to a conventional AlTiN coating. The AlCrN and AlCrON coatings showed good to acceptable wear resistance up to 600 °C while at 800 °C, both coating types failed. The new corundum-structured (Al,Cr)2O3 oxide showed excellent wear performance up to 800 °C. Imaging and chemical analysis of the high-temperature wear tracks allowed for explaining the differences in the wear mechanisms. The ability of a coating to resist oxidation and to delay substrate oxidation, together with an excellent abrasional wear resistance, were identified as the major factors influencing wear rates under severe high-temperature conditions.