Protective afteraction of inhibitor IFKhAN-92 during chromium-nickel stainless steel corrosion in sulfuric acid

Abstract

The protective polymolecular layers formed on the surface of 12Kh18N10T chromium-nickel stainless steel in a solution of sulfuric acid with IFKhAN-92 (a triazole derivative) added is shown to have the protective afteraction in the same acid. The effectiveness of the protective afteraction of mixtures containing IFKhAN-92 is determined by the time of preliminary adsorption of the inhibitor, its concentration in the solution of preliminary adsorption, the temperatures of the solution of preliminary adsorption of the inhibitor and the background acid solution. The layers formed on steel by the IFKhAN-92 + KNCS and IFKhAN-92 + KI compositions have the highest protective afteraction. These layers protect steel at 80 °С in the background 2 M H2SO4. An increase in temperature of the solutions of preliminary adsorption of inhibitors enhances their protective afteraction, which indicates chemical nature of the interaction of the inhibitor molecules with the steel surface. The composition and the structure of the protective layers formed on the steel surface was studied by XPS analysis. The protective layer is chemically bonded to the phase of hydroxides and oxides of Fe, Cr and Ni, adjacent to the metallic phase. The lower part of the protective polymolecular layer of the organic inhibitor consists of a polymer complex formed by molecules of IFKhAN-92 and metal cations (Fe, Cr and Ni). The outer part of the protective organic layer consists of physically adsorbed molecules IFKhAN-92, easily removed from the metal surface during ultrasonic washing of samples.