Repassivation behavior of alloy 690TT in simulated primary water at different temperatures

摘要

The repassivation behavior of Alloy 690 T T in simulated primary water at different temperatures was investigated by the rapid scratching electrode technique together with electrochemical measurements.The results showed that the repassivation process had three stages: the initial stage conformed to the place exchange model, the final stage conformed to the high field ion conduction model and in between there was a transition stage. At the initial stage, when the repassivation process of alloys was controlled by the place exchange model, anodic dissolution of substrate was dominated;after the film coverage rate was more than 0.99, the repassivation process of alloys was controlled by high field ion conduction model. Increasing the temperature resulted in a reduction of the repassivation rate and protectiveness of the passive film. The correlations among several mechanisms describing the repassivation behavior of alloys were discussed.