表面状态对Q235钢在不同氯离子浓度溶液中电化学腐蚀行为的影响

Effect of surface state of Q235 steel on its electrochemical corrosion behavior in solutions with different concentrations of chloride ions

采用电化学法结合失重法,研究了Q235碳钢电极在质量分数分别为2.0%、3.5%和5.0%的NaCl溶液中的腐蚀行为与腐蚀速率的变化规律。结果表明:碳钢电极表面的腐蚀产物会对电化学实验结果的准确性产生较大的影响。在进行电化学测试前,采用−30μA/cm^(2)恒定电流对碳钢电极进行极化预处理后测得的腐蚀电流密度随Cl^(-)质量分数的增大而表现出先减小后逐渐趋于稳定的变化趋势,修正后的电化学测试结果与失重实验结果能较好地吻合,两者之间的平均误差为5%~9%。通过对腐蚀电极进行阴极极化预处理,令金属表面腐蚀产物进行充分还原,能够有效降低金属表面腐蚀产物对电化学实验结果造成的偏差。

The corrosion behavior of Q235 carbon steel electrode and the variation of its corrosion rate with immersion time in 2.0%,3.5%,and 5.0%NaCl solutions respectively were studied by electrochemical method in combination with weight loss method.The results showed that the corrosion products on the carbon steel electrode surface have a great effect on the accuracy of electrochemical testing results.If the carbon steel electrode was subjected to polarization with a constant current density of−30μA/cm^(2) prior to the electrochemical testing,the corrosion current density of carbon steel electrode measured was decreased initially and then gradually became stable with the increasing of Cl^(-)concentration.The corrected electrochemical testing results are in good agreement with the weight loss values with an average error ranging from 5%to 9%.By performing cathodic polarization as a pretreatment on the corroded electrode,the corrosion products on the metal surface can be reduced completely,and the deviation of electrochemical testing results caused by the existence of corrosion products on the metal surface can be effectively reduced.