304不锈钢在模拟压水堆一回路水中高温电化学腐蚀行为

通过模拟压水堆一回路水环境,研究了氯离子浓度和溶解氧对304不锈钢高温电化学腐蚀行为的影响.动电位极化曲线结果表明,氯离子浓度主要影响高电位下的二次钝化效应,低电位下影响效果不明显,结合X射线光电子能谱对氧化膜元素成分的分析发现二次钝化效应与氧化膜中Fe/Cr元素含量比密切相关.电化学阻抗谱和扫描电镜结果表明,随着氯离子浓度增加,氧化膜阻抗逐渐降低,表面外层氧化物颗粒和间隙逐渐增大,耐腐蚀性能降低.随着溶解氧含量的升高,304自腐蚀电位逐渐升高,钝化电流密度降低,钝化区间缩小,表面氧化膜阻抗逐渐增加.

Electrochemical corrosion behavior of 304 stainless steel in simulated pressurized water reactor primary water

The effects of chloride concentration and dissolved oxygen on the high-temperature electrochemical corrosion behaviors of 304 stainless steel sheets were investigated in simulated pressurized water reactor ( PWR) primary water. The results of potentiody-namic polarization measurements reveal that the chloride ion mainly affects the second passivation region under high potential, but little effect under low potential. Oxide film chemical content analysis by X-ray photoelectron spectroscopy ( XPS) shows that the second pas-sivation properties are closely related to the Fe/Cr ratio of the oxide film. Electrochemical impedance spectroscopy ( EIS) and scan-ning electron microscopy ( SEM) results show that, when the chloride ion concentration increases, the oxide film resistance decreases, the size of oxide particles and the gap between oxide particles on the outer layer increases and the corrosion resistance decreases. Besides, with the increase of dissolved oxygen, the corrosion potential increases, the passive current density decreases, the passive potential region shrinks, and the oxide film resistance gradually increases.