Porous titania layer of containing calcium and phosphate and its mechanism of bioactivity

A porous layer of TiO₂ film containing calcium and phosphate was prepared by microarc oxidation on titanium at different voltages. The bioactivity of the sample was examined by measuring the formation of apatite through in vitro soaking in simulated body fluid. It is found that apatite are formed only on the surfaces of samples prepared at the voltages of 400 V and 450 V. It indicates that there is bioactivity only on the sample prepared at the higher voltages. However there is nothing deposited on the surface of the samples prepared under 240 V and 300 V after soaking in simulated body fluid for even more than 50 d, indicating that there is no bioactivity. It can be concluded that the hydrolysis of CaTiO₃ appeared at higher voltages results in the deposition of calcium and phosphate. It is the main reason for the formation of apatite, although the rough and porous layer is beneficial to the nucleation of apatite.