混合控制下腐蚀过程的电化学动力学参数测定

通过恒电量脉冲技术测定Q235碳钢在天然海水中腐蚀过程的电化学动力学参数. 分别利用不同极化幅度的恒电量瞬态响应分析获得极化电阻和Tafel斜率, 进而计算腐蚀电流icorr. 并对比了恒电量方法和考虑扩散影响的稳态极化曲线方法的测量结果. 结果表明, 采用恒电量强极化积分算法(CPSI)获得的Tafel斜率与极化曲线方法有很好的相关性. 同时, CPSI测定的阴极Tafel斜率符合氧还原反应的理论Tafel斜率值. 因此, 采用恒电量瞬态响应测量大大减小了浓差极化的影响, 有利于快速测定电荷传递和扩散传质混合控制下腐蚀过程的电化学动力学参数.

Determination of Electrochemical Kinetic Parameters in a Mixture Controlled Corrosion System

A transient analysis method, based on the coulostatic impulse technique, is developed. This method can compute the polarization resistance and Tafel slopes by analyzing the coulostatically-induced transients with different amplitude over-potential decay and, on the ground of their knowledge, evaluate the corrosion current, icorr. The experimental application concerns the behavior of carbon steel in natural seawater. Experimental results for carbon steel exposed to natural seawater show good agreement between the proposed method and the steady-state polarization curves method with concentration polarization consideration. Additionally, the cathodic Tafel slopes obtained by the coulostatic strong polarization integral(CSPI) method are closer to the theoretical values associated with the oxygen reduction reaction. Therefore, the coulostatic method is very useful in evaluation of the electrochemical corrosion parameters in mixture controlled systems, which enable us to minimize the effect of concentration polarization.