Hardcoat Anodizing

MIL-A-8625F Type III, Class 1 or 2

hard coatHardcoat Anodizing is different than conventional anodizing. Lowering the temperature and increasing the current density produces a thicker and more compact layer on the surface of the metal. This process is ideal for parts that need extra protection under extreme conditions.

Hardcoat Anodizing penetrates the metal as much as it builds up on the surface. The term “thickness” includes penetration and build up. A typical hard anodized application will increase in diameter by .002” (50 microns) – .001 penetration and .001 build up – and produce a hardness of 60 to 65 Rockwell on the C scale.

Wear resistance is the most frequent reason for specifying Hardcoat Anodizing.  However, because Hardcoat is also highly dielectric, it is often used to insulate assembly components.  Corrosion resistance is a third reason for using Hardcoat.  At normal thickness of 0.002″, the coating offers corrosion protection superior to that of other anodic coatings, especially when it is sealed.

Hardcoat can cost more than sulfuric acid anodize but is usually less than chromic acid anodize.  In comparison to other wear-resistant coatings applied to aluminum, it is generally much more economical.

Note: The Hardcoat Anodize process is not compatible with Aluminum Alloy 2024.