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 Ti₃ O₅. After the NaOH treatment, carbonate-containing hydroxyapatite can be induced to form on the surface during the SBF immersion test. © 2005 Elsevier B.V. All rights reserved.