Biomimetic deposition of apatite coatings on biomedical NiTi alloy coated with amorphous titanium oxide by microarc oxidation

The biomedical NiTi alloy was treated by microarc oxidation (MAO) in H ₃PO₄ electrolyte using DC power supply. The amorphous titanium oxide coating with porous and rough structure was formed on NiTi alloy. The MAO treated NiTi was soaked in a simulated body fluid (1·0SBF) to investigate the biomimetic deposition of apatite on the surface of titanium oxide coated NiTi alloy. It was found that titanium oxide coated NiTi alloy shows an excellent apatite forming ability after soaking in a simulated body fluid (1·0SBF) for 28 days, while no apatite forming ability was observed on bared NiTi alloy, even though soaking time is up to 28 days. The Fourier transformed infrared and X-ray photoelectron spectroscopy results showed that apatite deposited on MAO treated NiTi is a kind of CO₃^2- incorporated and Ca deficient apatite.