14.3. What is electrochemical corrosion?

Electrochemical corrosion refers to the corrosion that occurs when metals interact with electrolytes through electrochemical reactions. During this process, an electric current is generated. As one of the most widespread corrosion types, it manifests in various forms such as atmospheric corrosion and soil corrosion. This phenomenon primarily arises from microscopic cells formed when trace impurities (like carbon and other metal particles) on the metal surface combine with an electrolyte film. If the base metal is more reactive than the impurities, it will dissolve and corrode. When steel pipes are exposed to humid air, water vapor condenses on their surfaces while absorbing carbon dioxide from the atmosphere, creating microcell phenomena that lead to electrochemical corrosion.