Anodized layer
An anodized coating is an artificially created oxide protective layer on aluminum, formed by electrochemical conversion. It protects against corrosion and wear and insulates electrically.
Physical-chemical mechanism of action
The anodized coating forms through an electrochemical conversion of aluminum in a sulfuric acid bath. The aluminum reacts with the acid to form a thin protective oxide film of aluminum oxide (Al2O3).
Metallurgical relevance & risks in welding
The anodized coating protects aluminum from corrosion and wear by forming a barrier. If handled incorrectly during welding, the coating can be damaged, leading to increased corrosion susceptibility. It is important to remove or protect the coating before welding.
Workshop practice & instructions for use
Before welding aluminum, the anodized coating should be removed by cleaning the metal with a fine abrasive. This prevents the coating from being damaged during welding and impairing corrosion resistance.