A STUDY ON ZINC-IRON ALLOY ELECTRODEPOSITION FROM A CHLORIDE-ELECTROLYTE

The electrodeposition of zinc-iron alloys from a chloride-based electr olyte has been studied using electrochemical polarisation techniques, Ager Electron Spectroscopy (AES), Scanning Electron Il Microscopy (SEM ), Energy Dispersive X-ray Analysis (EDXA) and Computer Assisted Pulse Plating (CAPP). A change in the electrodeposition mechanism from equi librium codeposition to anomalous codeposition with a change in cathod ic current density has been observed. Zn-Fe alloys with compositions r anging from less than 5 wt-% to more than 75 wt-% Fe have been electro deposited from a single electrolyte, making this system ideal for prod uction of compositional modulated alloy (CMA) electrodeposits. Chlorid e content, pH and agitation of the electrolyte have been observed to h ave a strong influence on the reaction at the cathode surface, just as the use of pulse reversal current during electrodeposition. A theory on the electrodeposition mechanism, accounting for the above observati ons, is presented.