Tribological Investigation of W-Ti-N Thin Film on Plasma Nitrided Stainless-Steel Multilayer Coating

Duplex treatment consisting of plasma nitriding and tungsten titanium nitride thin film (W-Ti-N) was applied to 304L stainless steel multilayer coatings to enhance their mechanical and tribological properties compared to nitrided and the non-nitrided multilayer coatings. The 304L stainless-steel coating was formed by four layers deposited by twin-wire arc spraying (TWAS) and then post-annealed in vacuum conditions. The coating was nitrided using plasma immersion ion implantation (PIII). W-Ti-N thin film was deposited by physical vapour deposition (PVD) magnetron sputtering using a W + 30 wt.% Ti target. Characterization results showed important mechanical and tribological properties for the duplex-treated stainless-steel multilayer coating, reaching a hardness of 22.3 GPa and a low friction coefficient that was about four times lower than that of the stainless-steel multilayer. Furthermore, the wear rate was three orders of magnitude lower than that of the multilayer. Nitrided stainless-steel multilayers also combined good performance in terms of hardness, friction coefficient, and wear rate.