Investigations of Corrosion Inhibitors for Past 70 Years

―Some Reviews Related to the Hard and Soft Acids and Bases Principle―

Abstract

Inhibition mechanisms of corrosion Inhibitors for metals are closely related to the hard and soft acids and bases （HSAB） principle. Markedly high inhibition efficiency of decamethyleneimine （CH₂）₁₀ NH was explained by the formation of a stable chemisorption bond between iron and nitrogen atoms caused by a high strain in the ring using this principle. The anodic processes of iron corrosion in the presence of inhibitive or stimulative anions were discussed on the basis of the HSAB principle.