C. Ding, Chinese Academy of Sciences, Shanghai Institute of Ceramics, Shanghai, China; X. Zhao, Department of Materials Science and technology, Jiangsu Polytechnic University, changzhou, China; X. Liu, Shanghai Institute of Ceramics, Chinese Academy of Science, Shanghai, China; Z. Chen, Department of Materials Science and technology,, Changzhou, China

Summary: In this paper, nano-structured TiO2 coatings have been successfully deposited onto titanium alloy substrates by atmospheric plasma spraying technology using optimized plasma parameters. A chemical treatment method was employed to induce bioactivity on the TiO2 surface. The bioactivity of as-sprayed and chemical treated TiO2 coatings were evaluated by investigating the formation of apatite on their surface after they were soaked in simulated body fluids (SBF) for a period of time. Microstructure and the phase composition of the as-sprayed coating and apatite were analyzed by Field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy-dispersive X-ray spectrometry (EDS). The results obtained indicate that as-sprayed TiO2 coating consists of rutile, anatase and suboxide such as Ti3O5. The surface of nano-TiO2 coating is covered by nano particles of about 50nm in size. The bonding strength of TiO2 coating with Ti alloy substrate is as high as 40Mpa. The anti-corrosion performance of nano-coating in SBF is better than that of Ti-6Al-4V alloy. The surface of as-sprayed TiO2 coating can not induce bone-like apatite formation. Chemical treatment, such as acid and alkali, can improve bioactivity of TiO2 coating surface.. Keywords: plasma-sprayed TiO2 coating, nano-structure, bioactivity, chemical treatment