Effect of Metal Cations in Fresh Water on Surface Film Structure and Initial Corrosion of Mild Steel

摘要

Effect of metal cations on the corrosion of mild steel in model fresh water was investigated by immersion corrosion tests with surface observations, mass changes, and surface analysis by X-ray photoelectron spectroscopy (XPS). XPS analysis showed that hard metal cations precipitate on the mild steel and form hydroxides on the steel. The results of corrosion test suggested that corrosion rate of mild steel in fresh water has a correlation with protective ability of hydroxide layer precipitated on the steel. A novel corrosion indicator, that consists of hardness of cation, X, and molar volume ratio, ΔV, is proposed, and it is shown that the indicator is useful for explaining the corrosion changes by metal cations in fresh water.