Abstract
The galvanic corrosion behaviour of aluminium 3004 - 70/30 brass and aluminium 3 004 - copper have been studied in the tropical marine environment of Mandapam, over a period of 436 days, under different area ratios. The area ratios, viz. AAl : Abrass and AAl : Acopper, studied are 0.125, 0.25, 0.5, 1,2,4 and 8. The galvanic corrosion behaviour of the metals are studied in terms of the relative increase in the corrosion rate of Al due to galvanic coupling with brass and copper, the relative decrease in the corrosion rates of brass and copper due to galvanic coupling with aluminium, and the susceptibility of aluminium to pitting owing to galvanic coupling with brass and copper. The galvanic potential and galvanic current of the systems are monitored. Pits of different dimensions ranging from mild etchings to perforations are experienced on the borders and the surfaces of the interface of aluminium in contact with copper and brass. The weathering parameters and the environmental pollutants have a major role in influencing the galvanic corrosion of metals are also been monitored. The corrosion products resulting from galvanic corrosion are analysed with XRD and the pitting on aluminium resulting from galvanic corrosion is highlighted in terms of pit depth, size and density of pit, using a high resolution microscope.
