科研之友
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摘要
Alloy 800 is an important steam generator material used in nuclear power plants, and so there is significant interest in the properties of passive films of this alloy under service conditions. In this work, the semiconductivity of Alloy 800 in sulfate and chloride solutions was investigated using Mott-Schottky analysis, electrochemistry impedance spectroscopy (EIS), scanning electron microscopy (SEM), and scanning electrochemical microscopy (SECM). The Mott-Schottky results show that the semiconductivity is affected by the sulfate to chloride concentration ratio; p-type semiconductivity is exhibited at high concentration ratios but transitions to n-type when the concentration ratio is low. EIS, SEM, and SECM results indicate that the degradation form of the passive film changes from transpassive dissolution to pitting as the concentration ratio decreases while the film's surface reactivity increases, an effect that is related to the semiconductivity conversion. The observed variation in semiconductivity results from the competitive adsorption of sulfate and chloride, a process that modifies the potential drop at the film/solution interface, changes the vacancy types and ultimately determines the semiconductivity.
- 出版日期2014-8
- 单位天津大学; 中国地质大学（北京）
