Composition effect on dry sliding weak behaviors of Ti-B-N thin films

Friction and sliding wear behaviour of Ti-B-N coatings against AISI440C steel ball and WC-6wt%Co ball were studied by using pin-on-disk tribometer along with microstructure characterization using optical microscopy (OM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). It is shown that the wear resistance of film depended on the wear mechanism. In the case of AISI440C steel, adhesive wear were pre-dominant and the wear rate increased sharply to a maximum when N content reach -38at.%. This might be related to the change of film microstructure and phase configuration, so the least adhesive transfer of tribo-film was observed. If WC-6wt%Co ball was used, less deformation wear debris was observed, this was responsible for the rise of wear rate. Despite of different wear modes, friction coefficients in both cases were found to depend mainly on the formation and the amount of h-BN phase. Elemental analysis by energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) revealed that oxygen participated in the wear behavior by reacting with films to form the debris comprised of various types of Ti oxide including TiO, TiO₂ and Ti₂O₃, which increased wear resistance.