CHROMATE CONVERSION

What is Chromate Conversion?
To achieve their full protective properties on Aluminium alloys, most organic coatings require the metal surface to be pre-treated to provide a surface film, which becomes an integral part of the metal surface involving virtually no dimensional change. These conversion coatings form an ideal substrate for paints and precious metals, providing a clean, essentially inert surface, which gives optimum adhesion.

Most organic coatings applied directly to Aluminium surfaces will not adhere well, and if subjected to any deformation, they will tend to flake off exposing the bare Aluminium. Scratching off the paint surface would also provide a nucleation site for Aluminium corrosion and further undercutting of the coating.

The answer!
A pre-treatment is therefore required which can be applied to Aluminium to provide a suitable basis for subsequent coatings. Conversion coatings have been developed which can be used on Aluminium alloys and which are compatible with most paint systems. These coatings are so named because surface film is formed by a chemical reaction. As a result of this reaction and conversion the film becomes an integral part of the metal surface, exhibiting excellent adhesion properties.

Applications
The application of Chromated Aluminium can cover a wide range of functions.
Conversion coating can provide mild wear resistance, better drawing or forming characteristics and may be used to provide as a decorative finish and is also ideal for pre-treatment prior to Powder Coating.

The Process
The successful application of this conversion process requires the Aluminium to be clean and free from organic soils, oxides and corrosion products. We can clean or degrease the component as an additional service at Slough.