Effect of nitrogen-containing inhibitors on the corrosion inhibition of low-carbon steel in solutions of mineral acids with various anionic compositions

Abstract

The corrosion of low-carbon steel in 2 M HCl, 2 M H2SO4 and 2 M H3PO4 (25°C) inhibited by a triazole derivative − IFKhAN-92 – and quaternary ammonium salts was studied by the mass loss of metal samples and by voltammetry of the steel electrode. The inhibition of electrode reactions on steel in these environments is due to the formation of polymolecular protective layers by the molecules of these nitrogen-containing compounds on the steel surface. This is a versatile mechanism of inhibitor action since it slows down the electrode reactions on steel, regardless of the acid composition of the corrosive environment. The strongest hindrance of electrode reactions on steel in all the environments studied and, hence, the strongest corrosion inhibition is provided by the IFKhAN-92 additive. This effect results from the ability of the molecules of this compound to form protective layers whose molecules are interconnected with each other in the layer bulk and with the surface of the metal being protected by chemical interactions owing to the presence of a triazole ring in their structure.