Oxide Coating

an intentionally applied protective film that is obtained by oxidation of the surface layer of metal products. Oxide coatings protect metal from corrosion and are used for decorative purposes and as electrical insulation. They also serve as undercoatings for such protective products as varnishes paints, and greasepaints. Oxide coatings are applied by chemical methods, for example, in air or liquid mediums using alkalis or acids, and by electrochemical methods, such as anodizing. Oxide films vary in thickness from fractions of a micron (μ) to 500–600 μ, depending on the oxidizing conditions and alloy composition. Oxide coatings are applied to steel and cast iron, as well as to alloys of aluminum, copper, and zinc.