Chromating is a type of conversion coating used to passivate steel, aluminum, zinc, cadmium, copper, silver, magnesium, and tin alloys. It is primarily used as a corrosion inhibitor, primer, decorative finish, or to retain electrical conductivity. Chromating is used to reduce the reactivity and to improve durability and surface finish of metals such as aluminum and zinc alloys.
Anodizing is an electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide finish. Aluminum is ideally suited to anodizing, although other nonferrous metals, such as magnesium and titanium, also can be anodized.
Chromating is a cost-effective corrosion inhibitor, protecting vital components from material degradation. It acts as a primer, it provides a decorative finish, and it also improves electrical conductivity.
In aluminum, an anodic oxide finish is fully integrated with the substrate, so it cannot chip or peel. It has a highly ordered, porous structure that allows for secondary processes such as coloring and sealing.
The need for electrical conductivity of the finishes of your work piece will be the deciding factor for either chromating or anodizing.