The Effect of Surface State on Electrochemical Behaviors of Iron in Slightly Alkaline Solutions

摘要

The effect of prior cathodic polarization (PCP) treatment on the nature of the surface state and electrochemical behavior of iron in dilute bicarbonate solutions were studied. PCP treatment could cause a transition of open circuit state of iron from passive state to active dissolution state. The electrochemical impedance spectroscopy for iron in test solutions at open circuit state was significantly lower after the PCP treatment. Without PCP treatment, iron was in passive state and no obvious active-passive transition could be observed on anodic polarization curves in bicarbonate solutions with sulfate ion concentration less than 0.5 mol/L. After the PCP treatment, iron was in active dissolution state, and all anodic polarization curves exhibited active-passive transition characteristics.