Electrochemical corrosion is the deterioration of a material, usually a metal, caused by electrochemical reactions between the material and its surrounding environment. It occurs when a metal is exposed to an electrolyte such as water, moisture, soil, or an aqueous chemical solution, allowing electrical and chemical processes to occur simultaneously. The corrosion process converts the metal from its metallic state into more chemically stable compounds such as oxides, hydroxides, or salts. Rusting of iron in the presence of water and oxygen is one of the most common and well-known examples of electrochemical corrosion.
The process is based on the formation of electrochemical cells on the metal surface. In these cells, different regions of the metal act as anodes and cathodes. At the anodic region, oxidation occurs and metal atoms lose electrons and enter solution as ions. At the cathodic region, reduction reactions consume the electrons released at the anode. The movement of electrons through the metal and ions through the electrolyte completes the electrochemical circuit. Because metal dissolution occurs at the anodic sites, those regions experience material loss and structural degradation.
