Tribological aspects related to the morphology of PVD hard coatings

In this work the running-in behavior of different hard coatings was evaluated with respect to the type of substrate material, the substrate surface topography and the type of surrounding environment. The coatings with different topographies show different friction development during the running-in period and also a different level of friction in the steady-state period. We showed that post-polishing of the coating surface has a significant influence on both the coating wear and friction. The composition of tribofilm and roll-like debris formed in the wear track during sliding test were analyzed by nano-AES spectrometry and we found that both have similar composition. We also found that the highest friction coefficient and wear rate of all coatings were obtained in an oxygen atmosphere, while they are the lowest in nitrogen.