THE ELECTROCHEMICAL IMPEDANCE RESPONSE OF TRANSPASSIVE DISSOLUTION OF CHROMIUM IN NEUTRAL SOLUTIONS CONTAINING SODIUM-CHLORIDE AND SODIUM-FLUORIDE
THE ELECTROCHEMICAL IMPEDANCE RESPONSE OF TRANSPASSIVE DISSOLUTION OF CHROMIUM IN NEUTRAL SOLUTIONS CONTAINING SODIUM-CHLORIDE AND SODIUM-FLUORIDE
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DOI：
10.1016/0010-938x(95)00092-x
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发表时间：
1995-11-01
影响因子：
8.3
通讯作者：
WATANABE, K
中科院分区：
文献类型：
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作者：
ITAGAKI, M;MATSUZAKI, A;WATANABE, K
用电化学阻抗谱(EIS)研究了铬的过钝化溶解动力学。与铬在含氯和氟离子的中性溶液中的过钝化溶解相对应的电化学阻抗响应的奈奎斯特曲线在0.7V(SSE)附近显示了电容和电感行为，在贵金属电位下显示出明显的Warburg阻抗。提出了一个考虑电极表面电化学过程和生成的铬酸盐离子扩散过程的理论模型。在此基础上，对电化学阻抗和极化曲线的实验结果进行了模拟。计算结果与模拟结果吻合较好。在氟离子存在下，铬的过钝化溶解速率大于在氯离子中的溶解速率。用模拟得到的反应速率常数解释了这种差异。
The kinetics of transpassive dissolution of chromium have been investigated using electrochemical impedance spectroscopy (EIS). Nyquist plots of electrochemical impedance responses corresponding to transpassive dissolution of chromium in neutral solutions containing chloride and fluoride ions show capacitive and inductive behaviour at around 0.7V(SSE) and an apparent Warburg impedance at noble potentials. A theoretical model which takes into account the electrochemical processes at the electrode surface and the diffusion process of generated chromate ion is proposed. Experimental results of electrochemical impedances and polarization curves were simulated on the basis of the proposed model. They are in good agreement with the simulated results. Transpassive dissolution rate of chromium in the presence of fluoride ion is larger than in chloride ion. This discrepancy was explained using the reaction rate constants obtained by the simulation.