Deposition of Adherent and Biocompatible Zirconia Layer on Ti6Al4V Alloy Using Plasma Electrolytic Oxidation to Enhance Biological Performance

Titanium and its alloy, particularly Ti6Al4V, have been extensively utilized in biomedical applications due to their excellent mechanical properties, corrosion resistance and biocompatibility. However, their potential drawbacks are their vulnerability to fluoride-induced corrosion and the release of potentially toxic metal ions, which poses challenges in long-term medical applications. Plasma electrolytic oxidation (PEO) is an effective surface modification process that improves corrosion resistance, wear resistance, and biocompatibility by creating a porous ceramic oxide layer on the metal surface. In this study, Ti6Al4V alloys processed with PEO in a phosphate-based electrolyte containing suspended zirconia (ZrO2) microparticles. The findings substantiated the integration of zirconia into oxide layer as a homogeneously porous structure. Corrosion analysis showed a dramatic enhancement in corrosion resistance of the zirconia-modified Ti6Al4V over Ti6Al4V without zirconia coatings. Microstructural characterization through SEM and EDS showed a uniform distribution of zirconia, which is responsible for improved surface stability. The coating thickness increased up to 27.6 µm with 6 g/L ZrO2, improving protective properties but also leading to excessive porosity at higher concentrations. Wettability and biofilm adhesion tests revealed enhanced antibacterial efficacy, especially against E. coli and S. epidermidis. Roughness tests also validated enhanced osseointegration potential. All these findings support that PEO-based zirconia addition is a promising solution for enhancing the longevity and efficacy of titanium alloys in biomedical fields.