アミン類を主剤とする防食剤の研究 (第48報)

KCl-H₂SO₄水溶液中のステンレス鋼のアミン類による防食

抄録

Corrosion inhibition of Type 304 stainless steel was investigated in aqueous solution of KCl and H₂SO₄ with primary and tertiary amines by means of measuring time to breakdown of its passive film. The primary amine can be adsorbed by two ways such as protonation and electron-donation, while the tertiary amine can be adsorbed only by electron-donation. Prim. -n-octylamine could extend the time to film-breakdown, perhaps because of its adsorption by protonation on the oxide film, while tert. -N, N-dimethyl n-octylamine could not. In their dried carbon tetrachloride solution, the primary amine could be adsorbed on the stainless steel by displacing adsorbed water, while the tertiary amine could not be adsorbed. Stainless steel test pieces, which had been treated with the primary amine in its carbon tetrachloride solution, were dipped in the KCl-H₂SO₄ solution, resulting in no delay in the time to film-breakdown. This phenomenon cannot be clearly understood yet and more detailed study should be needed, but it may be partly true that the primary amine can penetrate into the passive film to breakdown the oxide layer by pulling off the bonding water.