Hard Anodizing

Through electrolytic oxidation, a thick and dense oxide layer is formed that is significantly harder than the natural oxide layer that spontaneously develops on aluminum. The result is a surface with very high wear resistance, excellent corrosion protection, electrical insulation, and strong resistance to chemical attack. The layer achieves a hardness of up to 400–600 HV, comparable to hardened steel, making it highly resistant to abrasion and mechanical stress.

A hard-anodized layer can be customized in thickness between 25 and 150 µm, depending on the alloy and the specific requirements of the component in terms of protection, insulation, dimensions, or friction properties. Common thicknesses are typically in the range of 50 to 70 µm. The surface normally develops a matte appearance but can also be dyed or post-treated to achieve specific technical or aesthetic properties.

Unlike conventional anodizing, which is mainly used for decorative purposes and corrosion protection and produces a thinner layer of about 5–25 µm, hard anodizing provides significantly greater hardness, corrosion resistance, and wear resistance. This makes the process particularly suitable for components exposed to severe mechanical or chemical stress.

Thanks to these properties, hard anodizing is used in a wide range of demanding applications. In the aerospace industry, it ensures low weight combined with high wear resistance. In the automotive and engineering industries, it is applied to components subject to heavy mechanical loads, such as cylinders, valves, tools, and machine parts. Additionally, its electrically insulating properties are utilized in electronic applications where aluminum must be protected from electrical currents.

Provexa offers the option to take advantage of the insulating effects of hard anodizing while still ensuring electrical conductivity in selected areas when required. This is achieved by anodizing the component first, then machining away the oxide layer in the areas where conductivity is needed. The part is subsequently passivated with Surtec 650, a treatment that provides corrosion resistance in combination with electrically conductive properties.

In summary, hard anodizing is an effective method of combining aluminum’s low weight with a surface capable of withstanding extreme stresses, making it indispensable in many high-tech and industrial applications.

Facts

Base material:
Aluminium

Size constraints:
(Length x Width x Depth) mm
L2500 x W500 x D1150

Standards

ISO 10074:2021

ASTM B580