Anodising
Anodising is an electrochemical process that converts a metal surface into a decorative and often protective anodic oxide finish. The anodic oxide structure is made up of a layer of metal oxide on the surface which slightly increases the thickness of the metal. The oxide is not attached to the surface like a paint or plate but is fully integrated with the underlying substrate, which helps to stop chipping or peeling. It also has a porous structure which allows for further processing such as colouring and sealing.
Aluminium is ideally suited to anodizing, although other nonferrous metals, such as magnesium and titanium, also can be anodized. The anodic oxide structure originates from the aluminium substrate and is composed entirely of aluminium oxide
Anodising is a process of controlled oxidation (in effect the same process as rusting). It involves a tank where aluminium is immersed into an acid electrolyte bath, a cathode is mounted to the inside of the tank and an electric current is passed through the aluminium. As this happens the aluminium acts as an anode, causing oxygen ions to be released from the electrolyte and combine with the aluminium atoms at the surface of the part being anodized, this creates a thickened, protective, integrated layer.
[edit] Related articles on Designing Buildings
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- Crevice corrosion.
- Deterioration.
- Electrochemistry.
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- Galvanised steel.
- Galvanic corrosion.
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