3 - Corrosion inhibition with rare earth metal compounds in aqueous solutions

Abstract

Inhibitors are probably the oldest method of corrosion protection. In the late 1980s, legislation forced research into environmentally friendly corrosion inhibitors combining low toxicity with high efficiency. Rare earth metal (REM) compounds are a promising type of environmentally friendly inhibitors. The mechanism of action of the lanthanide salts for different materials is a consequence of blocking the cathodic areas by precipitation of a film of lanthanide oxide/hydroxide. The trivalent ions of rare earths in an aqueous solution undergo progressive hydrolysis to form complex hydroxylated ions. The composition depends on the lanthanide cation and the particular anion of the solution.