Magnetic Field Effect on Anodic Dissolution Behavior of Iron in Sodium Perchlorate Solution

Abstract

It has been reported that magnetic field affects the anodic dissolution and passivation behavior of iron in acidic, neutral, slightly alkaline solutions. Perchlorate solution has been used in the mechanistic study of anodic dissolution mechanism of iron. In this study, the effects of 0.4T magnetic field on the electrochemical behavior and corrosion morphologies of iron in sodium perchlorate solution were studied by optical microscope (OM), scanning electron microscope (SEM) and several electrochemical methods such as potentiodynamic polarization curve and potentiostatic polarization. Magnetic field was placed horizontally and parallel to the working electrode. The anodic polarization curves show that magnetic field did not have strong effect on anodic current at the potential before the transpassivation potential. In the transpassivation range, magnetic field increased the anodic current, increased the slope of the i/E curve. After the potentiodynamic polarization curve measurements up to 2.0V(SCE), severe electrode thinning was observed under both 0T and 0.4T. Macroscopically uniform dissolution was observed on the electrode after measurements under 0T, while locally accelerated thinning was found on the iron electrode after the measurements under 0.4T, showing the accelerating effect of magnetic field on the anodic dissolution at the edges of the electrode along the horizontal direction, as the result of uneven distribution of the actual magnetic field flux density. Potentiostatic polarization measurements show that magnetic field decreased the anodic current density in the passive range, where the electrode was not significantly affected by magnetic field due to low current density. The accelerating or inhibiting effect of magnetic field can be interpreted based on the magnetohydynamic driving force and the magnetic field gradient driving force theory. Figure 1