Though aluminium generally presents good corrosion resistance to the atmosphere, finishing technologies are applied for its protection and decoration in a wide range of applications. These technologies basically consist of anodizing and painting. This paper summarizes the results obtained in Working Group No. 5 “Coatings on Aluminium” in the framework of the PATINA project, a four-year iberoamerican research programme on atmospheric corrosion.
The reported information includes gravimetric and electrochemical impedance spectroscopy determinations for bare and anodized aluminium, and undercutting at the scribe, filiform corrosion, fungal attack and changes in decorative properties (loss of gloss, colour changes and chalking) for the painted specimens. The anodizing and sealing of aluminium avoids the risk of localized corrosion. The degradation of organic coatings refers mainly to their decorative properties: soiling, staining by fungi, colour changes, chalking and loss of gloss; with the last two types of deterioration being dependent upon the intensity of solar radiation at the exposure site.