Anodizing (Sulfuric)

MIL-A-8625/MIL-PRF-8625F Type II is a sulfuric anodizing process for aluminum and its alloys, which provides a thicker coating compared to Type I. The Type II anodizing process is further classified into two classes: Class 1 and Class 2.

Type II, Class 1 involves anodizing aluminum parts to produce a relatively thin coating with a minimum thickness of 0.0001 inches. The process involves immersing the aluminum parts in a sulfuric acid solution and passing an electric current through the solution to produce a layer of anodic oxide on the surface of the aluminum. Class 1 coatings are used primarily for general purposes, such as providing a base for painting or bonding, and improving wear resistance.

Type II, Class 2 involves anodizing aluminum parts to produce a thicker coating with a minimum thickness of 0.0002 inches. This process provides improved wear resistance and is often used for parts that will be subjected to more severe environments. The process is similar to Type II, Class 1 anodizing, but with longer processing times and higher current densities.

Both Type II, Class 1 and Class 2 coatings provide good corrosion resistance, electrical insulation, and improve the adhesion of subsequent coatings or adhesives. These coatings are commonly used in aerospace and defense applications, as well as in the automotive, electronics, and architectural industries.