Analysis of repassivation kinetics of Ti based on the point defect model

Abstract

Repassivation kinetics of Ti in deaerated pH 8.5 buffer solution were investigated using a rapid scratching electrode technique. The repassivation kinetics were analyzed in terms of the current density (i) flowing from the scratch as a function of the time (t). The rate of repassivation was evaluated by the repassivation time (t(r)) that has been passed to achieve the predetermined current density (i(r)) from scratching, where the shorter t(r) the faster the repassivation rate. The repassivation rate increased as the applied potential and solution temperature increased, which was attributed to the corresponding increase in the rate of oxygen vacancy (V-o) generation reaction at the metal/passive film interface according to the point defect model. The increase in the rate of oxygen vacancy generation reaction was then explained by the change in the fundamental film parameters including transfer coefficient for oxygen vacancy generation and electric field strength in the film with applied potential and temperature. (c) 2006 The Electrochemical Society.