A comparative study of the corrosion performance of titanium (Ti), titanium nitride (TiN), titanium dioxide (TiO2) and nitrogen-doped titanium oxides (N–TiO2), as coatings for biomedical applications

The performance of four titanium coatings, namely, Ti, TiN, TiO2, and N–TiO2 was assessed in terms of their surface properties and electrochemical corrosion in simulated body fluid in relation to their medical applications. Ti, TiN, TiO2, and N–TiO2 coatings were deposited onto stainless steel substrates by a plasma surface alloying technique. Morphology, composition, and structure were investigated by SEM, GDOES, and XRD. Corrosion resistance results indicated that Ti, TiN, TiO2, and N–TiO2 coatings could achieve higher corrosion polarization resistance and a more stable corrosion potential in the SBF environment than the uncoated stainless steel substrate SS316L. In comparison with the Ti, TiN, and TiO2 coatings, the N–TiO2 coating exhibited superior corrosion resistance. This resistance may be attributed to the multilayered structure of the coating (an outer oxidative layer and an inner diffusion zone of Ti and N), which can hinder the diffusion of reactive ions.