ELECTROCHEMICAL STUDIES ON A ZINC LEAD CADMIUM ALLOY IN AQUEOUS AMMONIUM-CHLORIDE SOLUTION

Studies are reported of the anodic polarization behaviour of a zinc-lead-cadmium alloy in aqueous ammonium chloride solution over a wide range of current densities between 5 and 1000 mA cm-2 . A casting method is employed to prepare the electrode; the alloying constituents are analysed by atomic absorption spectroscopy (AAS). It is found that both the internal resistance and the anodic potential of the systems are at a minimum in 5.5 N NH4Cl. The data has been compared with those obtained for pure zinc and it is concluded that the present alloy is a better electrode throughout the polarization range of this investigation. A conventional weight-loss method shows that the corrosion rate is greater than that exhibited by pure zinc. Scanning electron micrographs of the post-immersed surface are compared with those for the pre-immersed surface. Supplementary investigations of linear polarization have been conducted in order to gain an understanding of the system for a narrow perturbation range of potential.