Effect of Hybrid Surface Treatment Composed of Plasma Nitriding and W-Cr-Ti-Al-N Coating on Tribological Behavior of AISI 316L Steel

The aim of this study is to investigate the effect of plasma nitriding pre-treatment on hardness and tribological behavior of the hard coatings produced by Physical Vapor Deposition (PVD). AISI 316L austenitic stainless steel were subjected to surface modifications by plasma nitriding. W-Cr-Ti-Al-N coatings were prepared by multi-arc ion plating equipment in a modified commercial system. The surface morphology and microstructure analysis showed that a duplex surface layer structure consisting of the 2.4 µm W-Cr-Ti-Al-N coating with supported by nitrogen expanded austenite phase and CrN precipitation + ferrite phase diffusion case was generated by the plasma nitriding. The reciprocating friction tests were performed against bearing steel counterparts on a UMT-3 tribometer at room temperature. The friction and wear tests demonstrated that the difference of hardness between the hybrid specimens and those only nitrided specimens, and the former specimens showed a significant amount of wear resistance with decrease in the coefficient of friction in comparison to the latter ones.