In vitro bioactivity of plasma-sprayed TiO2 coating after sodium hydroxide treatment

TiO2 coatings were deposited on titanium alloy substrates by atmospheric plasma spraying using commercial TiO2 powders. A chemical treatment method was employed to induce bioactivity on the TiO2 surface. The as-sprayed TiO2 coatings were immersed in 10M sodium hydroxide solutions at 60 °C for 24 h and then soaked in simulated body fluids (SBF) for a period of time to investigate the formation of apatite on the sample surface. Field-emission scanning electron microscopy was used to observe the surface morphologies and the phase composition of the as-sprayed coating and apatite were analyzed by X-ray diffraction and Fourier transform infrared spectroscopy. Our results show that the as-sprayed coatings are composed of rutile, anatase and a small quantity of Ti3O5. After the NaOH treatment, carbonate-containing hydroxyapatite can be induced to form on the surface during the SBF immersion test.