Corrosion and oxidation on iron surfaces in chloride contaminated electrolytes: Insights from ReaxFF molecular dynamic simulations

A reactive force field for the Fe/Cl system has been developed and the force field was applied to analyze the corrosion process of iron (Fe) in solutions containing chloride ions, aiming to uncover the mechanisms underlying chloride-induced corrosion and oxidation reactions on the Fe surface. Through reactive molecular dynamics simulations, it was found that the corrosion behavior of Fe(100) surface began with the enrichment of chloride ions on the surface, and then the dissolution of iron on the surface was induced under the action of chloride ions to form an effect similar to pitting corrosion, and at the same time, the surface of the iron substrate generated an iron oxide film similar to iron rust at the same time. As the simulation progressed, the thickness of the iron oxide film gradually increased. Concurrently, the corrosion state on the iron surface evolved from localized pitting to extensive corrosion, with the corroded area demonstrating a linear relationship with the progression of simulation time. These results can provide insights into the formation of oxide films and localized initiation of corrosion nucleation on Fe surfaces at the atomic level.