Pitting corrosion of aluminium in the tropical climate of Mauritius

Abstract

ABSTRACTAluminium is a commonly used metal in Mauritius. However, the tropical Mauritian atmosphere is quite corrosive with the highest measured corrosivity, according to ISO 9223, falling in the category C4. Hence, this study was performed to investigate the atmospheric corrosion behaviour of aluminium AA1050 in the island. The aluminium samples were exposed outdoors at three sites, according to ISO 8565. Upon removal after specific time intervals over a 1½ years period, pit depth, pit diameter and pit density of the samples were determined. The maximum pit depth varied with the time of exposure, according to the power law function. Pit diameter increased linearly with the time of exposure. Chart rating, according to ISO 11463, was also performed. It was found that the corrosivity of the Mauritian atmosphere falls in categories A4-B1-C1 and A5-B1-C1. Application of extreme value statistics showed that Gumbel type 1 distribution fits maximum pit depth data at the three sites.