6. Metallic coatings

Metallic coatings on aluminum alloys are mainly used to improve mechanical surface properties, such as friction resistance, and to enhance the optical properties of parts, such as brightness.

For this type of application, the anti-corrosion properties of coatings are a second function sought after the improvement of mechanical and/or aesthetic properties. Few metals have a lower potential than aluminum for sacrificial anode corrosion protection. Metallic coatings are therefore often more noble than the underlying aluminum substrate. These coatings must be produced with a minimum of defects, otherwise premature pitting of the aluminum alloy may occur.

Coatings are mainly produced by electroplating, a process that can be adapted to many types of parts. Compared to the steel electroplating process, aluminum alloys require special pre-treatment...