Dissolution and Corrosion Inhibition of Copper, Zinc, and Their Alloys

The corrosion behavior of copper, zinc, and their alloys in sulfuric acid (H2SO4) solutions with oxygen and ferric ions (Fe3+) was studied using a potentiostat. Oxygen and Fe3+ ions were shown to play an important role in corrosion of copper and copper-zinc alloys. Cathodic reduction of oxygen mainly was controlled by chemical reaction, and that of Fe3+ ions was controlled by diffusion. The overall cathodic process was the summation of the reduction of oxygen and Fe3+ ions. Corrosion of zinc was controlled mainly by reduction of water. Corrosion inhibition using benzotriazole (BTAH) also was investigated in aerated and deaerated solutions. BTAH was found to be a useful inhibitor, and the inhibition layer was shown to be stable and persistent. Morphology of the surface of copper, zinc, and brasses after corrosion in the presence and absence of BTAH was examined by scanning electron microscopy. BTAH formed a protective layer on the surface, thereby inhibiting corrosion. Solution analysis of the dissolution of brasses showed that zinc dissolved preferentially in the initial stages, followed by simultaneous dissolution of copper and zinc.