The coating process applied to protect aluminum surfaces is called Chromating. It is named according to the color of the coating or the ion charge of the applied Cr coating. It has varieties such as yellow (Cr+6), green (Cr+3), and Chromium-free (Transparent)
Yellow Chromate Coating provides good adhesion of paint on aluminum surfaces. It provides a long resistance to rust in products where dyeing is not desired. As in other coating applications, the application starts with degreasing and degreasing the products. It is then dipped into yellow chromate baths made of stainless or plastic. If the operation is spraying, the contact areas of the chemical should be stainless or polypropylene. The more intense the yellow color, the thicker the coating. The unused bath must be disposed of by transforming it into cr+3.
Green chromate creates a light green variegated coating on aluminum. However, the corrosion and paint adhesion ability of this coating on the aluminum surface is very high. Although the product itself is Cr+6, the coating it creates is Cr+3. In other words, it does not contain heavy metals under the paint.
Its application can be the same as yellow and green. It is a method used to protect the environment and human health. Disposal is also not a problem. Rust resistance is lower than chromate coating. In addition, it is relatively difficult to follow, as it does not make a visible coating.