Anodization generally occurs on aluminium substrates, but can also be done on magnesium and titanium. Anodization is an electrochemical conversion process that can increase the hardness of the substrate, provide electrical insulation, resist corrosion and add colour as a decorative feature.
There are three common types of anodization processes:
- Type I – Chromic – using chromic acid in a very thin coating, primarily in the aerospace industry.
- Type II – Regular – using sulphuric acid at room temperature, this relatively inexpensive process provides a harder finish than chromic anodization.
- Type III – Hardcoat – again using sulphuric acid but at lower temperatures and in thicker coatings to provide extreme durability and corrosion resistance.