Incorporation of Ca and P on anodized titanium surface: Effect of high current density

This study systematically evaluated the surface and corrosion characteristics of commercially pure titanium (grade 2) modified by plasma electrolytic oxidation (PEO) with high current density. The anodization process was carried out galvanostatically (constant current density) using a solution containing calcium glycerophosphate (0.02 mol/L), and calcium acetate (0.15 mol/L). The current densities applied were 400, 700, 1000 and 1200 mA/cm(2) for a period of 15 s. Composition, crystalline structure, morphology, roughness, wettability and "in-vitro" bioactivity test in SBF of the anodized layer were evaluated by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, profilometry and contact angle measurements. Corrosion properties were evaluated by open circuit potential, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The results show that the TiO2 oxide layers present an increase of thickness, porosity, roughness, wettability, Ca/P ratio, and bioactivity, with the applied current density up to 1000 mA/cm(2). Corrosion resistance also increases with applied current density. It is observed that for 1200 mA/cm(2), there is a degradation of the oxide layer. In general, the results suggest that the anodized TiO2 layer with better properties is formed with an applied current of 1000 mA/cm(2). (C) 2014 Elsevier B.V. All rights reserved.