Corrosion is defined as an alteration of a material by chemical reaction with an oxidant. Corrosion can be combined with the mechanical effects and give corrosion under stress and corrosion fatigue; Similarly, it is involved in some forms of surface wear for which the causes are both chemical and mechanical.
The best-known examples are the chemical alterations of metals in air or water, such iron and steel rust or the formation of gray-green on copper and its alloys (bronze, brass). However, corrosion is a vast area, affecting all kinds of materials (metals, ceramics, polymers) in various environments (aqueous, atmosphere, high temperatures).