One-step synthesis of petal-like apatite/titania composite coating on a titanium by micro-arc oxidation

Petal-like apatite/titania (TiO2) coating was prepared on commercially pure titanium (Ti) by micro-arc oxidation in electrolyte containing calcium and phosphate for the first time. The surface morphology, crystalline structure, chemical composition and binding state of the apatite/TiO2 composite coating were characterized. The coating consists of a double-layer (apatite layer and TiO2 layer) structure. The average thickness of the inner TiO2 layer and the outer apatite layer is about 6 μm and 16 μm respectively. The outer apatite layer is porous and exhibits petal-like pattern. The apatite layer consists of hydroxyapatite (HA) and carbonate–apatite and the inner TiO2 layer consists of anatase and rutile.