Understanding of ammonium salts under-deposit corrosion: Electrochemical and AIMD investigations

Abstract

In-situ electrochemical experiments and ab initio molecular dynamics (AIMD) simulations are combined to investigate the under-deposit corrosion and hygroscopicity of ammonium salts on SAE 1020 steel interdigital electrodes. The findings indicate that the hygroscopicity of ammonium salts influences the evolution of the interface and the accumulation of the product film. The corresponding simulations reveal that the hydrolysis of NH4+ leads to the generation of a proton transfer chain, resulting in an elevation of H+ concentration. This hydrolysis behavior is effectively catalyzed on the Fe(1 0 0) surface, promoting the occurrence of anodic adsorption and cathodic hydrogen evolution reaction, thereby inducing corrosion.