Application of AC resistmetry to monitoring of localized corrosion of iron

Abstract The electric resistance of an iron wire electrode was traced during a potential sweep in a neutral borate buffer solution. The dissolution depth calculated from resistance change due to iron dissolution in the active potential region was in a good agreement with that calculated from the electric charge. Using a wire electrode with a diameter of 100 μm, the resolution of the dissolution depth was in the order of nm. When Cl − ions were added to induce pitting, resistance increased more rapidly than that predicted from uniform dissolution. From comparison of resistance change, electric charge of iron dissolution, and surface observations using an scanning electron microscope and optical microscope, the degree of nonuniform dissolution was evaluated.