Fabrication and induced mineralization of bio-piezoelectric ceramic coating on titanium alloys

The application of piezoelectric materials in bone repair is a hot topic because both positive and negative charge can promote the cells growth. However, the deposition process of apatite induced by piezoelectric materials with periodic loading is still not clear. In this work, TiO2–BaTiO3 coatings were prepared on medical titanium alloys by microarc oxidation and hydrothermal reactions. The TiO2 layer obtained by micro-arc oxidation participated in hydrothermal reaction to generate BaTiO3 on the surface of TiO2 layer. After electric field polarization, the coating was endowed with bioelectric activity similar to that of natural bone. Periodic mechanical loading was applied to the coatings using a cyclic stress loading device. It was found that the negative charge could attract Ca2+ to be gathered on the coating surface, thus obtaining a high deposition of apatite, increasing the Ca/P ratio and promoting the crystallinity of the apatite. In addition, the negative charge also changed the type of apatite growth units near the coating, resulting in the deposition of apatite in hexagonal flake shapes perpendicular to the coating.