P280GH carbon steel pipe is widely used in the main feedwater system of Hualong One unit, and octadecylamine (ODA) is applied to form a corrosion inhibition film by adsorption on the inner wall of the pipe. ODA can effectively inhibit corrosion and avoid pipe failure and serious scaling of steam generator (SG). However, the mechanism of adsorption and film formation of ODA on carbon steel surface is still unclear, which seriously restricts the performance optimization, optimization and application of ODA. In order to solve this problem, molecular dynamics (MD) simulation method is used to carry out the study. The results show that the nitrogen atoms at the head of the ODA molecule form coordination bonds with the iron atoms on the carbon steel surface, which promotes the adsorption and anchoring of the ODA molecule. The microscopic configuration of the corrosion inhibition film formed is dependent on the concentration of ODA. At low concentration, the corrosion inhibition film has a poorly interwoven single-layer configuration between ODA molecular tail chains, and as the concentration increases, the corrosion inhibition film evolves into a tightly interwoven complex bilayer configuration between ODA molecular tail chains. After the concentration of ODA exceeds a certain threshold, the configuration of the corrosion inhibition film no longer changes significantly, and the ODA molecules that are not adsorbed to form the film eventually accumulate to form colloidal micelles. © 2023 Yuan Zi Neng Chuban She. All rights reserved.
