Effects of Cu and Sb on Corrosion Resistance of ZnAl27 Alloy

The corrosion behavior of ZnAl27 alloys in 35g/L NaCl solution has been studied by electrochemical and immersion corrosion tests. The effects of Cu and Sb on the Tafel curves, electrochemical parameters of free corrosion potential, linear polarisation resistance (LPR) and free corrosion current, of the ZnAl27 alloy have been investigated. The surface morphologies of the alloy after immersion corrosion tests have been observed through SEM. The results indicate that addition of proper Cu can improve its corrosion resistance of the alloy, or the free corrosion potential the corrosion current shift towards the positive and negative,respectively. However, excessive addition of Cu can deteriorate the corrosion resistance of the alloy. On the other hand, the corrosion resistance of the ZnAl27 alloy decreases with the increasing of Sb content.