pH值和氯离子浓度对铁在酸溶液中的腐蚀电化学行为的影响

发展了一种根据弱极化区的单支极化曲线确定腐蚀电流密度Ⅰ_(corr)和阳极反应与阴极反应的Tafel斜率b_a与b_c的方法。利用这种方法研究了溶液pH值与Cl~-浓度对铁在酸溶液中的腐蚀电化学行为的影响,并用强极化区的实验数据进行了校验。结果表明,OH~-和Cl~-都参与了铁的阳极溶解过程,反应级数分别为1和0.5;b_a和b_c分别为40mV和120mV。提出了一个铁在含Cl~-的酸中阳极溶解反应的动力学模型。实验结果还证明,在pH值与Cl~-浓度两者对E_(corr)和Ⅰ_(corr)的影响之间并无交互效应。

THE INFLUENCE OF pH VALUE AND Cl~--CONCENTRATION ON THE ELECTROCHEMICAL BEHAVIOR OF Fe CORROSION PROCESS IN ACID SOLUTIONS

A technique for determining corrosion current density Ⅰ_(corr) and anodic and cathodic Tafel coefficient b_a and b_c based on the data on cathodic polarization curve in weak polarization region was suggested. The influence of pH value and Cl~--eoncentration on the electrochemical behavior of Fe te corrosion process in acid solutions was studied by using this technique, and the results obtained were verified, by the data in strong polarization region. It is shown that OH~- and Cl~- both take part in the anodie dissolution process Of Fe with reaction orders of 1 and 0.5 respectively, and the values of b_a and b_c are 40 mV/decade and 120 mV/deeade respectively. A kinetic model for the anodic dissolution reaction of Fe in Cl~--containing acid solutions was suggested. It is also demonstrated that there is no significant interaction between the influence of pH value and Cl~--concentration on E_(corr) and Ⅰ_(corr).