<i>In-vitro</i> corrosion and mechanical properties of titanium oxynitride coatings deposited by (RF) magnetron sputtering

Abstract TiOxNy coatings were deposited on 316 L stainless steel substrates by reactive magnetron sputtering, with varying negative bias voltages applied during the deposition process (0, −25, −50, −75, and −100 Volts). Raman spectroscopic analysis of the coatings confirmed the formation of the TiOxNy phase, characterized by distinctive TiN and TiO2 bands. Surface analyses revealed alternating needle-like and mountain-like morphologies corresponding to different bias voltages, while crystallite dimensions and coating thickness demonstrated voltage-dependent variations. Electrochemical analyses in Ringer’s solution indicated superior corrosion resistance for coatings deposited at −50 V, exhibiting minimal corrosion current density and porosity (0.008%), with maximum protective efficiency (55.812%). The H/E ratio, which is indicative of elastic strain to failure, and the H 3 /E 2 ratio, which reflects resistance to plastic deformation, were also determined. The highest H/E ratio of 0.06 was obtained for the coating deposited at a substrate bias voltage of 50 V. Meanwhile, the maximum H 3 /E 2 ratio recorded was 0.012 GPa, corresponding to the coating deposited at 0 V bias voltage. Related ratios, reached their peak values at −50 V bias, coinciding with improved adhesion and scratch resistance