核电蒸汽发生器690合金管在高温高压水中的腐蚀电化学行为

Electrochemical Corrosion Behaviors of Alloy 690in High-Temperature and High-pressure Water

通过模拟压水堆一回路水环境,研究了溶液温度（25~285°C）和溶解氧（DO）（20μg/L,2.1mg/L,8.4mg/L）对690合金电化学腐蚀行为的影响,及690合金在一回路水环境中的均匀腐蚀行为.极化曲线和光电子能谱的结果分析表明：随着溶液温度的升高,690合金的自腐蚀电位下降,自腐蚀电流密度增大,钝化区缩小;随着DO的升高,690合金的自腐蚀电位升高,自腐蚀电流密度降低,钝化区缩小;690合金在一回路水环境中的均匀腐蚀速率为0.244mg/（dm2·h1/2）,形成了外层富Fe、Cr和Ni的氢氧化物和内层富Fe、Cr和Ni的金属氧化物的氧化膜.

The effects of temperature（25to 285°C）and dissolved oxygen（20μg/L,2.1mg/L,8.4mg/L）on high-temperature electrochemical corrosion behaviors of Alloy 690,and the uniform corrosion behaviors of Alloy 690 were investigated in stimulated pressurized water reactor（PWR）primary water.The results of potentionamic polarization measurements and X-ray photoelectron spectroscopy（XPS）reveal that the corrosion potential（Ecorr）decreases,the corrosion current density（Icorr）increases,and the passive potential region shrinks with the increase of temperature while the corrosion potential increases,the corrosion current density decreases,and the passive potential region shrinks with the increase of DO.The uniform corrosion rate of Alloy 690 exposed in investigated conditions is 0.244 mg/（dm2·h1/2）,and the oxide,of which the outer layer is rich in Fe-Cr-Ni hydroxide and the inner layer is rich in Fe-Cr-Ni oxide,is formed on Alloy 690.