Surface Modification of Low-Carbon Steel with 4-Amino-4H-1,2,4-triazole-3,5-dithiol for Corrosion Inhibition in a 0.5 M Solution of Sulfuric Acid

Abstract

Organic corrosion inhibitors based on heterocyclic compounds provide significant coverage of a metal surface and protect it from corrosion by adsorption. The adsorption of 4-amino-4H-1,2,4-triazole-3,5-dithiol (ATD) on the surface of low-carbon steel in a 1 M solution of sulfuric acid is studied by a set of physicochemical methods including polarization measurements, electric impedance spectroscopy, contact angle method, and optical microscopy. The redistribution of the components of free energy of the surface and its hydrophobization support the existence of a protective film of ATD. The calculation of the activation energy of the corrosion process based on polarization measurements shows a change in the character of adsorption with increasing temperature from mixed to chemical. It is found based on the data of electrochemical impedance spectroscopy and contact angles that multilayer filling occurs at a concentration of 100 mg/L. ATD predominantly inhibits the cathodic partial electrochemical reaction, forming adsorption layers on the energetically heterogeneous surface in accordance with the Redlich–Peterson isotherm model.