Preparation, Characterization and Biocompatibility of Bioactive Coating on Titanium by Plasma Electrolytic Oxidation

Owing to high specific strength, biocompatibility, and corrosion resistance, titanium (Ti) and its alloys are considered the best materials for bone repair and replacement. However, Ti-based metals have low surface bioactivity and low bond strength with bone tissues, restricting their clinical application. Therefore, surface modification of Ti-based implants is important for improving surface bioactivity and biocompatibility. In this study, we prepared a ceramic coating containing calcium (Ca) and phosphorus (P) on Ti by plasma electrolytic oxidation (PEO). The coating was characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, and atomic force microscopy to study its surface morphology, Ca and P contents, and surface topography. The hydrophilicity of the coating was evaluated by measuring the static contact angle. Nanoindentation testing was performed to determine the microelastic modulus and microhardness. Characterization revealed the formation of a coating that was dense inside but porous and rough outside by PEO on the Ti surface. The coating consisted of Ti, Ca, P, and O. The microelastic modulus and microhardness of the coating were (39.08+8.23) GPa and (2.36 +/- 0.85) GPa. To conclude, PEO formed a loose and porous TiO2 coating containing Ca and P on the Ti surface, which exhibited good bioactivity and mechanical performance and has application potential.