Thin 1,2,4-Triazole Films for the Inhibition of Carbon Steel Corrosion in Sulfuric Acid Solution

Abstract

Etching of steel items in sulfuric acid solution is used in various human activities (oil and gas industry, metal production, utilities, transport, etc.). This operation is associated with significant material costs due to corrosion losses of the metal. It has been found that an efficient way to prevent corrosion of steel in sulfuric acid solution involves the formation of thin protective films consisting of corrosion inhibitor molecules of triazole class on its surface. It has been shown that the protection of steels with a 3-substituted 1,2,4-triazole (3ST) in H2SO4 solution is accompanied by the formation of a polymolecular layer up to 4 nm thick. The 3ST layer immediately adjacent to the steel surface is chemisorbed on it. The efficiency of this compound as an inhibitor of corrosion and hydrogen absorption by steel is determined by its ability to form a protective organic layer, as experimentally confirmed by XPS and AFM data. The kinetic constants of the main stages of hydrogen evolution and permeation into steel in the H2SO4 solution were determined. A significant decrease in both the reaction rate of cathodic hydrogen evolution and the rate of hydrogen permeation into steel by the triazole in question was noted. It has been shown that the preservation of the metal plasticity in the acid medium containing the triazole under study is due to a decrease in the hydrogen concentration in the metal bulk.