Corrosion Inhibition of Carbon Steel by Lepidine in HCl Solution

摘要

Carbon steel is an important metal for structure and machines, and it is easily corroded in acidic media.In this paper, lepidine was used as a corrosion inhibitor for carbon steel in 1 mol/L HCl solution. Aweight loss test and electrochemical methods were used to study the inhibition performance at differenttemperatures; surface analysis and a thermodynamic method were used to clarify the corrosion inhibitionmechanism. In the weight loss test, when the corrosion inhibitor was added, the corrosion rate wasdecreased from 12.54 mg cm-2 h-1 to 0.113 mg cm-2 h-1, and the rate of corrosion inhibition was 99.1%.Furthermore, the corrosion inhibition efficiency decreased with an increase in temperature. From thepolarization curve test, the corrosion potential of the corrosion inhibitor was moving forward to cathodeas concentration increased, and the cathode current density decreased obviously. From EIS, the radiusof the resistance of the corrosion inhibitor was found to increase gradually with an increase inconcentration. With an increase in concentration, Rct increased and Cdl decreased, showing that thecorrosion inhibitors replaced water and adsorbed onto the film. Adsorption of the corrosion inhibitorobeyed the Langmuir isothermal adsorption equation, and SEM and XPS proved this hypothesis.Adsorption of the inhibitor on the surface of carbon steel is a spontaneous exothermic process.