Effect of Magnetic Field on Anodic Dissolution of Nickel in an Alkaline Solution with Chloride Ions

Abstract

Localized corrosion is a kind of serious failure that happens frequently in natural and industrial metallic structures. There are some reports on the influence of magnetic fields on pitting corrosion. In this study, the effects of magnetic field on anodic dissolution of nickel in 0.05 mol/L NaOH+0.2 mol/L NaCl system was investigated by potentiodynamic polarization, potentiostatic polarization and morphology observation. The potentiodynamic polarization curves with or without a 0.4 T magnetic field were shown in Fig. 1. The magnetic field has no obvious influence on the polarization curve at low potentials, and the anodic current density increased with the magnetic field at potentials higher than 0.9V(SCE). The results of potentiostatic polarization at 0.1V (SCE) show that the current density decreased rapidly with time starting from the beginning of polarization, and Imposing 0.4T magnetic field at 200s and removing the magnetic field at 400s did not change the current density. The morphological observations results show that the sample surfaces were bright without showing pitting, showing that the applied magnetic field has no obvious influence on the anodic dissolution at 0.1V(SCE). When polarized at 0.6V (SCE) and 0.8V (SCE) potential, current density suddenly increased within a short period of time and then increased gradually. Imposing a 0.4T magnetic field increased the anodic current while withdrawing the magnetic field decreased the anodic current, as shown in Figs. 2 and 3. More small pits were found the electrode surface after polarized at 0.6V (SCE) under 0.4T than that under 0T, implying that magnetic field would promote the pitting initiation at this potential. More large pits were found the electrode surface after polarized at 0.8V (SCE) under 0.4T than that under 0T, showing that the magnetic field would affect the pit growth period. Figure 1