Effect Of Copper And Zinc Additives On The Corrosion Rate Of Aluminium alloys In Aqueous Solutions

Document Type : Original Article

Authors

1 Chem. Eng. Branch, Military Technical College, Cairo, Egypt.

2 Armament Authority, Cairo, Egypt.

Abstract

The corrosion behavior of five Al alloyscontaining different amounts of copper (0-4%) or zinc (0-6%) was investigated in aqueous solutions of ammonium chloride, ammonium nitrate, sodium chloride, sodium hydroxide, and sodium silicate using weight loss measurements and eletrochemical methods, namely corrosion potential, polarization and cyclic polarization techniques. The results show that copper (or zinc) has an accelerating effect on the corrosion rate of the investigated alloys in all previous solutions except sodium hydroxide solution , where it has an inhibiting effect. The accelerating effect is explained by an anodic (in sodium chloride, sodium silicate, and ammonium chloride solutions) and cathodic (in ammonium nitrate solution) depolarization mechanism.The inhibiting effect is explained by an anodic polarization mechanism .

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