Effect of electropolishing on electrochemical behaviours of titanium alloy Ti-10V-2Fe-3Al

Abstract

The electrochemical behaviours of titanium alloy Ti-10V-2Fe-3Al after electropolishing in a self-developed electrolyte in comparison with conventional grinding were studied by electrochemical impedance spectroscopy (EIS). Optical microscopy (OM), scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to evaluate the surface characteristics of the alloy. It was found from the EIS experiments that the polarization resistance (R _p) was increased, the double layer capacitance (Q _c) was decreased and the electrochemical impedance of the alloy was enhanced by electropolishing. The electropolished surface was flat, smooth and bright and its roughness was 3.310 nm. To underline the advantage of electropolishing process against grinding to provide the anodic oxidation process with a higher quality substrate, the ground and electropolished titanium alloys were anodized in parallel under the same conditions. The corrosion behaviours of the two kinds of anodized titanium alloys were compared. It was revealed that electropolishing generated a high quality substrate and improved the corrosion resistance of anodic oxide film formed on titanium alloy Ti-10V-2Fe-3Al. Furthermore, the mechanism of electropolishing improving the corrosion resistance of the anodic oxide film was proposed.

Keywords

titanium alloy / electropolishing / electrochemical impedance spectroscopy / X-ray photoelectron spectroscopy / atomic force microscopy

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