Tribological properties of CrSiN-coated 301 stainless steel under wet and dry conditions

The tribological properties of CrSiN coatings were investigated under dry and wet conditions. CrSiN films (2 μm thick) were deposited on 301 stainless steel substrates by dual magnetron sputtering, using a chromium interface layer (500 nm thick) on the top of plasma nitrided surface. The morphology and microstructure of the CrSiN films were examined by SEM, EDS and X-ray diffractometry. Dry and wet wear tests were performed using a linear reciprocating ball-on-flat tribometer. In wet condition, the contact was immersed in NaCl 1 wt.%, and the sliding wear tests were performed at open circuit potential (OCP), and under cathodic and anodic conditions.

CrSiN films were found to exhibit excellent wear resistance under dry condition: the films had no tendency to delaminate after 1800 cycles of sliding wear under 1.6 GPa Hertzian stress. However, under wet condition, the wear resistance was rather poor: the films detached from the substrate at smaller contact pressures (1.2 GPa). It was demonstrated that the corrosion reactions at the electrode/electrolyte interface were the reason for the degradation of the tribological properties of these films; in the absence of corrosion reactions (under cathodic polarization), CrSiN coatings were found to resist much better sliding wear.