CORROSION CHARACTERISTICS OF SOME ALUMINUM-ALLOYS IN OXALIC-ACID

The corrosion behaviour of 1060 and 1100 aluminium alloys in different concentrations (0.1, 0.25, 0.5, 0.75, 1.0, 2.0 and 5.0%) of oxalic ac id solutions has been investigated by weight loss and potentiostatic p olarisation techniques, at 25 degrees C. The data indicate that 1100 a luminium is less corrosion resistant than 1060 aluminium. The corrosio n rates of these alloys are a function of the concentration of electro lyte in a narrow range of concentration only. The anodic polarisation curves of both the alloys exhibit active behaviour at each concentrati on of oxalic acid and in the whole range of the applied potential. The cathodic polarisation curves are almost linear in both the cases, res embling that for hydrogen evolution reaction. The corrosion behaviour of aluminium alloys in oxalic acid has been explained in terms of the acidity of the solution and self inhibition due to the adsorption of o xalate ions.