Hydroxyapatite formation on oxide films containing Ca and P by hydrothermal treatment

Oxide films were formed on titanium by means of microarc oxidation (MAO) using a direct current power supply. The oxide films containing Ca and P were obtained in an electrolyte containing β-glycerophosphate sodium salt pentahydrate (β-GP) and calcium acetate (CA). The surfaces of the oxide films were rough and porous, and the concentration of Ca and P were 7.3 mol% and 6.4 mol%, respectively, when MAO was performed in an electrolyte containing 0.04 M β-GP and 0.10 M CA at 200 A/m2 current density and 430 V final voltage. The oxide film consists of anatase, rutile and an amorphous phase. After hydrothermal treatment at 190 °C, the hydroxyapatite crystals were precipitated on the oxide film surfaces. The amount of hydroxyapatite crystals increased by increasing the hydrothermal treatment time and the Ca/P ratio in the oxide film.