Coupling Process between Droplet and Iron Investigated by Reactive Molecular Dynamics Simulations

The droplet-to-iron electrochemical reaction is common in nature and industrial production, and it causes damage to the economy, safety, and the environment. The electrochemical reaction of droplet-to-iron is a coupling process of wetting and corrosion. Presently, investigations into electrochemical reactions mainly focus on the corrosions caused by a solution, and wetting is rarely considered. However, for the droplet-to-iron electrochemical reaction, the mechanism of charge transfer in the process is still unclear. In this paper, a reactive molecular dynamics simulation model for the droplet-to-iron electrochemical reaction is developed for the first time. The electrochemical reaction of droplet-to-iron is studied, and the interaction between droplet wetting and corrosion on iron is investigated. The effects of temperature, electric field strength, and salt concentration on the electrochemical reaction are explored. Results show that droplet wetting on the iron surface and the formation of a single-molecular-layer ordered structure are prerequisites for corrosion. The hydroxyl radicals that penetrate the ordered structure acquire electrons from iron atoms on the substrate surface under the action of Coulomb forces and form iron-containing oxides with these iron atoms. The corrosion products and craters lead to a reduced droplet height, which promotes droplet wetting on iron and further intensifies the droplet-to-iron electrochemical reaction.