Repassivation kinetics of zirconium alloys investigated by a scratching electrode technique

The repassivation behavior of zirconium alloys in a solution containing 0.1 M H₃BO₃ and 0.1 M LiOH was examined by means of a rapid scratching electrode technique. The repassivation behavior of the scratched surface of the alloys varied with time. The place exchange model reveals that at the initial stage of repassivation (within 10 ms) log i (t) is linearly proportional to q (t) with a slope of 1/K. The high field ion conduction model reveals that after 25 ms log i (t) is linearly proportional to 1/q(t) with a slope of cBV. The cBV value, in particular, which is a measure of the protectiveness and erosion resistance of an alloy, increases when there is an increase in the Nb content of the alloys, as well as in the applied potential and the solution temperature. This result suggests that these parameters can affect the repassivation rate of zirconium alloy.