Long-term Outdoor Exposure Research Articles

Longterm Outdoor Exposure of Anodic Coatings Coloured by Precipitation of Inorganic Pigments

SUMMARYBetween 1954 and 1958 the authors undertook a large scale investigation into methods of colouring anodic coatings without the use of water soluble dyestuffs. Part of this work involved colouring by precipitating inorganic pigments into the pores of anodic coatings produced by sulphuric acid or oxalic acid anodizing, and the techniques employed were reported1 at the time. Following the recent closure of the laboratories where the work was originally undertaken, the results are summarised for up to 21 years of outdoor exposure. The following new colours can be recommended for architectural use: a green, a Prussian blue, a yellow-bronze, and a Chromate yellow. After exposure for 21 years in an industrial environment the anodized surfaces are in good condition despite considerable loss of film thickness due to erosion.

Surface composition of copper alloys: Influence of outdoor exposure

The surface composition of some copper alloys was studied after exposure indoors (for reference) and outdoors in urban, rural and marine atmospheres. The duration of exposure ranged from two months to 16 years. The investigations were performed partly using Auger electron spectroscopy and scanning electron microscopy and partly by conventional techniques including X-ray and metallographic studies. The effects of outdoor exposure under cover are similar to those of high temperature oxidation. Long-term outdoor exposure shows the combined effect of alloying elements and specific atmospheric constituents on the composition of the copper alloy surface.