Corrosion resistance of aluminum alloys

img27Corrosion resistance of aluminum alloys

Corrosion resistance of aluminum alloys. The main products of aluminum corrosion in industrial atmospheres are aluminum sulphate, which as a white deposit is almost invisible; podobnie jak wodorotlenekglinu często występujący jako produkt korozji tego metalu. Corrosion resistance of individual aluminum alloys, it depends on the type of atmosphere, to which they are exposed. Aluminum alloys, resistant to industrial atmospheres, they may perform poorly in a marine atmosphere and vice versa. We can assume, that corrosion of aluminum takes place in both environments: acidic and alkaline due to the dissolution of the metal in both alkalis and acids (an amphoteric element). Acidic or alkaline reaction of a thin film (layers) moisture covering the aluminum during storage or transport causes damage to the oxide layer that protects against corrosion. The corrosion of aluminum castings in the atmosphere depends, apart from the composition, also on the method of casting and heat treatment due to the influence of the heterogeneity of the structure on corrosion. Heat treatment combined with rapid tempering increases the corrosion resistance of copper-containing castings, while quenching reduces corrosion resistance. In general, you can say, that each heat treatment aimed at homogenizing the structure of aluminum alloys allows for obtaining an alloy with a higher resistance to atmospheric corrosion.