304不锈钢在FeCl_3溶液中腐蚀行为的电化学研究

Electrochemical Study of Corrosion Behavior of 304 Stainless Steel in FeCl_3 Solution

采用开路电位、电化学阻抗谱(EIS)、循环极化曲线三种电化学测试方法和扫描电镜(SEM),研究304不锈钢在Fe^(3+)浓度为0.001mol·L^(-1)时,Cl^-浓度对其腐蚀行为的影响.结果表明,随着溶液中Cl^-浓度的增加,48h的E_(OCP)值由0.07V减小到-0.036 6V.EIS和循环极化曲线试验结果表明:随Cl^-浓度的增加,304不锈钢钝化膜稳定性降低,耐点蚀能力下降;304不锈钢在0.001mol·L^(-1)Fe^(3+)+0.2mol·L^(-1 )Cl^-溶液中浸泡48h时,不锈钢耐点蚀性经历了先变大后变小的过程,在浸泡至6h时耐点蚀性能最好;随浸泡时间增加,样品表面腐蚀形貌点蚀坑深度加深,在浸泡48h时发展为均匀腐蚀.

The influence of Cl^- concentration on corrosion behavior of 304 stainless steel at Fe：3＋ concentration of 0. 001 mol·L^-1 was studied by using three electrochemical test methods, opencircuit potential, electrochemical impedance spectroscopy and cyclic polarization curve, and scanning electron microscope（SEM）. The results show that the Eocp value of 48 h decreases from 0. 07 V to -0. 036 6 V with the increase of C1- concentration in solution. The test results of EIS and cyclic polarization curve show that, with the increase of C1- concentration, the stability of 304 stainless steel passivation film decreases, and the corrosion resistance decreases. When the stainless steel was soaked for 48 h at Fe3＋ 0. 001 mol·L-1＋C1- 0.2 mol·L-1 , the corrosion resistance of stainless steel had undergone a process of getting higher then lower. Especially the corrosion resistance was the best when it was soaked for 6h. As the soaking time increases, the corrosion pit depth of the corrosion morphology of the sample surface deepens, and the corrosion becomes even when soaked for 48 h.