Hard anodizing and hard coating

What is hard anodizing, or hard coating?

Hard anodizing, also known as hard coating, is a thick and protective metal treatment used in various industrial areas due to its particular strength. Compared to normal, thin anodizing, hard anodizing is used when particularly high wear resistance, corrosion protection and slide are required. This treatment is regulated by UNI EN ISO 7796 certification and has an appearance that varies — depending on the metal compounds in the alloys — from pale bronze to dark grey, with the possibility of a black, green, red or orange finish under certain conditions.

How hard anodizing works

The hard anodic oxidation process relies on a current flowing through a tank at sub-zero temperatures, which forms a hard oxide present in nature as corundum. Anodizing is not a coating, but rather a process that transforms the very surface to which the treatment is applied, with half of the newly formed layer remaining on the outside and half penetrating the surface with even distribution. Because of this, one aspect of the design stage concerns differences in height associated with the desired treatment thicknesses. The layers range from 20 to 50 microns, but 100 microns are even possible in special cases.

Applications of hard anodizing

Because this treatment is nontoxic, it is used in both the food and pharmaceutical sectors, but the main areas of use are the automotive industry (for brake parts, from Formula 1 to MotoGP), the aeronautics sector, the chemical/pharmaceutical industry, the oil & gas industry and many other sectors where metalwork is required.

In general, hard anodizing is used whenever moving parts must have the highest wear and corrosion resistance.