Anodizing

Anodizing is an electrolytic passivation process that enhances the natural oxide layer's thickness on the surface of metal parts. The part to be treated forms the anode electrode of an electrical circuit, enabling the process to occur.

Anodizing provides numerous advantages, including increased resistance to corrosion and wear, improved adhesion for paint primers and glues, and aesthetic benefits. Thick porous coatings can absorb dyes, while thin transparent coatings can add interference effects to reflected light.

Sulfuric acid anodizing (Type II & III)
Sulfuric acid is the most commonly used solution for producing anodized coatings. According to MIL-A-8625, coatings of moderate thickness ranging from 1.8 μm to 25 μm (0.00007" to 0.001") are known as Type II, whereas

Type III, hardcoat, hard anodizing, or engineered anodizing refer to thick coatings that require more process control. Such coatings are produced in a refrigerated tank and with higher voltages. Hard anodizing can be made between 13 and 150 μm (0.0005" to 0.006") thick, increasing wear resistance, corrosion resistance, and ability to retain lubricants.