Surface properties (Topic 11033)

The corrosion resistance of aluminium is very much dependent on the aluminium oxide layer. Therefore, the surface quality of a profile maybe the most important parameter with regards to corrosion performance in natural environments.

Any irregularities both on micro and macro scale should be avoided as far as possible. This includes:

ñ Cathodic particles both as alloying elements and as deposits (e.g. copper, iron, graphite)

ñ Aggressive salts (e.g. chlorides, bromides, fluorides)

ñ Dirt and fingerprints

ñ Rough or scratched surface(unless it is intended as a pre-treatment for increased adhesion)

ñ Remains from etching or anodising baths

ñ Particles from machining or welding

ñ Holidays in applied surface treatment

A homogeneous surface will in most cases give the best corrosion performance, because there will be no localisation of the anodic and cathodic reactions.