A chromate conversion coating is a type of chemical conversion coating that is typically applied to aluminum alloys. Other types of chemical conversion coatings include iron phosphate and zinc phosphate coatings, typically applied to steel.
A chromate conversion coating protects the underlying aluminum against corrosion, serves as a base for paint adhesion, and can allow for electrical conductivity when applied as a thin coat.
Chromate conversion coatings for aluminum are widely used in the aerospace industry, as well as with everyday hardware such as nuts and bolts.