What is electrochemical corrosion

Electro-chemical corrosion is metal material contact with electrolyte solution and get rusted through electrode reaction.

During the action, metal lose electron and get oxidized. The action processing is called anode reaction and reaction product is metallic ion in medium and metal oxide cover on metal surface. The matter in solution get electron from metal and get deoxidated, this action is called cathodic reaction. In cathodic reaction, the matter get electron and deoxidated is called polarization. In average corrosion, the probability of anode and cathodic reaction on whole metal surface with no obvious difference. And the positions with the two reactions exchange randomly. If some area mainly with anode reaction, the rest with cathodic reaction. The first is called anode region and later one is called cathodic region. The two regions combine corrosion element. The one make metal get rusted is anode reaction, so usually use external power source, or connect another metal with lower electrode voltage to make the corrosion present on other metal.