Tribological behaviour of monolayer and multilayer Ti-based thin solid films deposited on alloy steel

The fretting wear and adhesive wear resistance of Ti-based thin solid films deposited on MDN121 steel substrate are evaluated. Plasma-assisted cathodic arc evaporation technique is used to develop the TiC-C monolayer coating and Ti/TiN/TiCN/TiN/TiCN multilayer coatings used in the study. FESEM-EDS, nanoindentation, Raman spectroscopy, optical profiler, and confocal microscope are used to characterise the coatings and wear tracks. Diamond-like carbon is observed in the microstructure of both the coatings. During the fretting analysis, the coefficient of friction (COF) is reduced by 68.49% in the case of the TiC-C monolayer coating and 42.46% in the Ti multilayer coatings as compared to the substrate. The volumetric wear loss of the TiC-C monolayer coating is lower than the multilayer coating. The wear surface morphology reveals the abrasive form of the fretting wear mechanism in both the monolayer and multilayer coatings whereas the galling failure in the substrate. During adhesive wear, the COF is reduced by 71.73% in the monolayer coating and 59.33% in the multilayer coatings compared to the substrate. The monolayer coating exhibits low friction and low wear rate as compared to the multilayer coating.