Electrochemical properties of the anodic films formed on titanium and its Ti-6Al-4V alloy in HBr solution

The electrochemical properties of anodic oxide films formed on titanium were compared with those on its Ti-6Al-4V alloy. Under potentiostatic anodization in HBr solution over the range 0.20-1.2 V, the current density recorded in the case of Ti was always lower than that for its alloy. The electrochemical impedance spectroscopy results indicate that anodization stimulates higher oxide formation efficiencies, with Ti exhibiting stronger propensity to form thicker passivating oxide layers. The thickness of galvanostatically formed oxide films on Ti up to a definite voltage decreases linearly with prolonged immersion in HBr solution of various concentrations. The dissolution rates (k(1) and k(2)) for the two oxide layers comprising the anodic films on Ti were found to increase with the concentration of the test HBr solution, where the value of k(1) (of the outer layer) is always much higher than that of k(2) (of the inner layer). Copyright (C) 2010 John Wiley & Sons, Ltd.