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 are widely used in the aerospace industry, as well as with everyday hardware such as nuts and bolts.
Learn more about chromate conversion coatings in our page covering the topic in depth at What is Alodine / Chem film / Chromate Conversion Coating?