Effect of Elevated Temperature on Tribological Properties of PVD Layers

The present study investigated tribological properties of multilayer TiAlN and nanocomposite (nc-Ti1-xAlxN)/a-Si3N4) coatings. Tested coatings were deposited by two PVD methods on the high speed steel Böhler S 600 Isorapid substrate. The coatings demonstrated good adhesion to the substrate and high hardness (2090 - 2510 HV0.5). Tribological properties of the coated specimens were evaluated by the Ball-on-Disc test and by metallographical analysis of the tribological track after testing at room temperature and at 450°C. The specimens with multilayer TiAlN coatings showed slightly better tribological properties, as regards the course of friction coefficient. Although the values of friction coefficient of multilayer coatings were comparable to the values determined for nanocomposite, the course of friction coefficient and analysis of tribo-tracks showed that the failure of the multilayer TiAlN coating was less pronounced compared to the nanocomposite coating.