Chromate Coating

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. 

It’s important to keep in mind that anodizing differs from chromate plating because no metal is added to create the protective layer. 

Plating is a conversion coating, meaning that the process changes the chemical character of the surface, turning it into aluminum oxide.