The role of the tribofilm and roll-like debris in the wear of nanoscale nitride PVD coatings

Reciprocating (ball on flat) dry sliding wear tests of TiAlN/VN and CrN/NbN multilayer coatings were undertaken under ambient conditions with either an alumina or tungsten carbide counterface. Wear rates were found to be in the mild wear regime. Worn surfaces and wear debris were examined by using scanning electron microscopy (SEM) and Fourier transformed infrared (FTIR) microscopy. Surface smoothing by the wear process was associated with wear debris with a roll shape, which adhered to the worn surface. Analysis of wear debris suggests they are probably hydrated. The properties of the tribofilm and rolls are correlated with the friction.