Oxidation of Metals

the reaction in which a metal and oxygen combine to form an oxide. In a more general sense, oxidation of a metal is a reaction in which atoms lose electrons to yield various compounds, such as chlorides and sulfides.

With very few exceptions, metals occur naturally in oxidized form and are called ores. Consequently, metallurgical processes involve the reduction of various compounds. With use, metals and alloys undergo gradual oxidation, or corrosion, owing to environmental effects. The course of the oxidation of a metal is determined by a thermodynamic factor—the change in free energy during the reaction—and by a kinetic factor—the reaction rate—that is largely dependent on both the nature of the oxidation products and the interaction between the products and the metal. Oxidation of metals during metallurgical production may cause the formation of scales, resulting in the loss of valuable alloying elements and steel. In many cases, metals are intentionally oxidized for protective or decorative purposes.