Plasma treatment of metals

Plasma treatment is usually associated with the cleaning and activation of polymers. I would like to highlight the fact that plasma is also a very effective way to clean and activate metallic surfaces.
When an adhesive or paint is applied to an aluminum surface, the bond actually happens between the adhesive and the oxide layer that is present on the aluminum. Naturally forming aluminum oxide is an unstable, and non-uniform, surface to bond to.
By using atmospheric plasma as a pre-treatment to aluminum, not only will the contaminants be removed in exactly the same way as they are on polymer surfaces, but the density and stability of aluminum oxide layer as well as its associated hydroxyl group concentration will be increased.
This resulting new layer will allow for the formation of covalent bonding of the adhesive to the aluminum.