Formation of Titanium Oxynitride Films by Reactive Magnetron Sputtering, Their Structural Features and Properties

TiOxNy coatings are known for their good biocompatibility and corrosion resistance and have been previously explored for biomedical applications, including cardiovascular stents. In this work, emphasis is placed on a systematic investigation of the effect of substrate bias voltage on the structural, morphological, and mechanical properties of TiOxNy films deposited by reactive magnetron sputtering. TiOxNy coatings were deposited on 316L stainless steel substrates using a pure titanium target (99.99%) in an Ar–N2–O2 gas mixture at various substrate bias voltages (0 to −150 V). The influence of substrate bias on the deposition rate, structure, and mechanical properties of the films was investigated. X-ray diffraction (XRD) analysis revealed the sequential phase evolution from cubic TiN to oxynitride TiON and further to TiO2 (anatase/rutile) with increasing negative substrate bias, indicating that ion bombardment energy plays a decisive role in determining the crystallinity and phase composition of the coatings. The coating deposited at −50 V exhibited the highest hardness (~430 HV) and good adhesion strength (critical load 20–25 N). Contact angle measurements confirmed the hydrophilic behavior of the coatings, which is favorable for biomedical applications.