Influence of Working Frequency on Structure and Corrosion Resistance of the Anodic Oxide Film on Ti–6Al–4V Alloy

To evaluate influence of working frequency on the structure and corrosion resistance of oxide film on Ti–6Al–4V alloy, an anodic oxidation is conducted employing direct-current (DC) pulse power source in an environmental friendly electrolyte. Scanning electron microscopy (SEM), Raman spectroscopy, and electrochemical techniques are employed to characterize the oxide film. It shows that the oxide film presents a uniform petaloid drum and micro-cracks morphology. Additionally, the micro-cracks dramatically swell with the enhancing of frequency, as well as the thickness increase of the oxide film. The Raman analysis result illustrates a close similarity in the crystal structure of the obtained Ti–6Al– 4V oxide films with the increasing frequency. And the higher the working frequency, the more crystalline oxides (anatase and rutile) are. Furthermore, at the frequency of 120freq/min, a most positive corrosion potential and minimum corrosion current density are observed, demonstrating an appropriate working frequency for fabrication of the corrosion-resistant anodic oxide film