Formation mechanism of biomedical apatite coatings on porous titania layer

A titania containing calcium and phosphate with rough and porous structure was prepared by microarc oxidation. The in vitro bioactivity was examined by immersing the samples into the simulated body fluid (SBF). And the mechanism was also discussed. The results show that only 3 days of immersion in SBF, apatite was formed on the surface, and after 6 days, nearly all the surface covered by apatite. This indicates that the layer can induce the formation of apatite in simulated body fluid. It is analyzed that the key factors of the apatite formation are the hydrolysis of the CaTiO₃ and special structure.