Zink different. Siegener Verzinkerei Gruppe - Oberflächenveredlung
Anodic oxidation in general
Anodic oxidation is an accelerated electrochemical oxidation process, which is intensified by the natural oxide skin on aluminium. As a result of the process, the transparent oxide layer becomes considerably thicker than the natural oxide layer. Significant advantages of the process are a strong resistance to corrosion and long-term protection. And thanks to the transparent layer, the character of the metal remains intact.
How does anodic oxidation work?
Aluminium parts are connected with a positive pole (anode) in a bath containing diluted sulphuric acid. The electrochemical process generates oxygen (O₂), which combines directly with the aluminium and produces aluminium oxide (Al₂O₃). The newly formed aluminium oxide can accept pigments and other substances immediately after anodizing, resulting in the individual metallic colouring. As a result of the sealing process, in which the pores of the layer are packed tight, the surface transforms into a sealed layer. This is not only resistant to corrosion, but also remains clean and retains its colour. Anodized aluminium is easy to recycle because the aluminium is protected by a metallic layer.
Corrosion protection with a wide range of characteristics
A variety of anodizing processes exist, such as electrolytic oxidation, hard anodization, Nituff®, CompCote® and coloured electrolytic oxidation. The various processes result in anodized layers with a range of characteristics – for example certain layer thicknesses, certain colours or levels of hardness, certain wear resistances and strongly anti-corrosive or antifriction characteristics.
Technical features:
• Layer thicknesses of up to 100 micrometers (µm)
• Hardness up to 600 Micro-Vickers
• Greater wear resistance than tempered steel
• Break-down voltage at approx. 40 Volt/µm
• The aluminium is free of black streaks after the process
• Resistance to the majority of chemicals and solvents
• The layer thicknesses can be achieved with extremely high precision