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用扫描电化学显微镜(SECM)和电化学阻抗谱(EIS)原位表征了溶液pH值对核电蒸汽发生器800合金溶液中的腐蚀行为的影响.实验结果表明:在酸性氯化钠溶液中,SECM探针渐进曲线为正反馈,表明800合金为活化阳极溶解,腐蚀电位下的EIS图呈现完整的单容抗弧特征;而在中性或者碱性溶液中,SECM探针渐进曲线为负反馈,表明800合金为自钝化,不同阳极电位下的EIS图均呈现不完整的容抗弧特征,但随着阳极极化电位的增加,EIS谱容抗弧半径减小,表明钝化膜的耐蚀性下降;SECM二维扫描图像结果显示探针电流增加,表明电极表面活性增加,即钝化膜的溶解速度增加.而在中性或者碱性溶液中的SECM二维图像中均可观察到若干活性点,这可能与晶界或者金属夹杂物等有关.
The effect of solution pH value on the corrosion behavior in the alloy 800 nuclear steam generator was characterized by scanning electron microscopy (SECM) and electrochemical impedance spectroscopy (EIS). The experimental results show that in acidic sodium chloride solution, SECM probe asymptotic curve is positive feedback, indicating that the 800 alloy is activated anode dissolution, corrosion potential EIS showed a complete single capacitive arc characteristics; and in neutral or alkaline solution, SECM probe asymptotic curve of negative feedback , Indicating that the 800 alloy is self-passivated and the EIS curves at different anode potentials show incomplete capacitive arc characteristics. However, as the anodic polarization potential increases, the arc radius of EIS decreases, indicating that the passivation film Corrosion resistance decreased; SECM two-dimensional scanning image results showed that the probe current increased, indicating that the electrode surface activity increased, the passive film dissolution rate increased in the neutral or alkaline solution SECM two-dimensional images can be observed To a number of active points, which may be related to grain boundaries or metal inclusions.