Self-Healing Ability of Zinc-Plated Steel Coated with Magnesium Electrodeposited from a Molten Salt

Abstract

In order to clarify the reason for the excellent corrosion resistance of zinc-plated steel coated with magnesium which was electrodeposited from a molten salt, corrosion products in a 5 mass%NaCl aqueous solution were investigated by X-ray diffraction analysis and EPMA. It was found that thin MgO layer was rapidly formed on the surface and acted as a protective film. It was also found that thin MgO layers were formed along the cracks in the zinc-plated layer, and stopped up the cracks and prevented corrosion from proceeding through the cracks. The latter fact means that the magnesium-containing zinc-plated layer has a self-healing ability.