Characterization of Electrolytic TiO[sub 2] Coating on Ti for Biomedical Applications

Abstract

The cathodic reactions of electrolytic nanocrystalline coating on pure titanium were investigated by polarization tests in alcoholic and HCl aqueous solutions, respectively. Three major reactions which belong to various applied voltage ranges were identified: (i) from −0.1 to −0.3 V (Ag/AgCl), from −0.3 to −0.9 V, and from −0.9 to −2.5 V. Excellent deposition was located at the third stage, because ions were depleted and many more ions were provided to form on the cathodic surface. The coated films were further characterized by thermogravimetric differential thermal analysis, X-ray diffraction, X-ray photoelectron spectrometer, scanning electron microscopy, atomic force microscopy, dynamic cyclic polarization, and cell bioactivity assay. After being annealed at 300°C for 1 h, the coated films were further condensed into anatase and gradually transformed into rutile at 500°C. From cross section, the coated film ∼1.2 μm thick revealed excellent adhesion with substrate. Compared with thermally grown oxide film, much better bioactivity and more corrosion resistance were found on the electrolytic coated specimens. © 2004 The Electrochemical Society. All rights reserved.