Effect of anodic oxidation on the corrosion behavior of Ti-based materials in simulated physiological solution

Abstract

Anodic oxidation in acetic acid was investigated as a means of improving the corrosion resistance, in simulated physiologic solution, of titanium and two titanium-based alloys, Ti–6Al–7Nb and Nitinol. The composition and the thickness of the surface layers formed by anodization were analyzed using X-ray photoelectron spectroscopy. The electrochemical characteristics were investigated by linear polarization, cyclic polarization, and electrochemical impedance spectroscopy at the open circuit potential. Anodization of all these three metals resulted in the formation of TiO2 as the main oxide. These layers improved the corrosion behavior in simulated physiological solution, as evidenced by significant increase in polarization resistance and decrease in corrosion current density. Electrochemical impedance results were interpreted based on the two-layer structure of the passive film. Anodization has thus been shown to provide a simple and effective means of improving the corrosion behavior of titanium-based alloys in simulated physiological solution.