Failure mode and interface chemistry of localized coatings on brass

The behaviour of partly coated aluminium brass has been examined under accelerated laboratory and under natural conditions. Acrylic (Incralac) coatings are found to have a good life and to provide a long-term protection of brass surfaces. Analysis of failed interfaces by photoelectron spectroscopy showed that acidic conditions developed beneath the coating and contributed to a partial weakening of the bond strength. Eventually the crevice conditions drift back towards neutral and there is little further loss of strength.