Inhibitors for Armco iron and ASTM A106 plain steel in hydrofluoric acid

Abstract

Different classes of organic substances (acetylenic derivatives, N-containing and/or S-containing additives) wre tested as inhibitors for corrosion of ASTM a106 plain steel and Armco iron in hot diluted HF solutions. The additives interacting with the metal surface by chemisorption through available lone pairs were the most efficient substances. The best results were obtained with S-containing additives: these markedly inhibit the acid attack both on pure iron and plain steel. Though very efficient, some S-containing additives (e.g. phenylthiourea) act as promoters of hydrogen entry into the metal lattice in HF corrosion; however, others (e.g. dibenzylsulphoxide) can be safely used as inhibitors in this acid solution.