Corrosion properties of mild steel surface modified by bright Zn-Co alloy electrodeposit from acetate electrolytic bath

The zinc-cobalt (Zn-Co) alloy coatings were electrodeposited on mild steel using acetate electrolytic bath at various current densities. The corrosion behaviour of the Zn-Co alloys was determined in a 3.5% sodium chloride solution. Highest corrosion protection efficiency with corrosion rate of 7.33 mpy was obtained at Current density 4.0 A.dm⁻². The effect of current density with temperature, throwing power, corrosion behaviour and surface morphology of the deposits were discussed. The surface texture and hardness of the deposit were investigated by scanning electron microscopy (SEM) and Vickers hardness tester. The surface morphology of an alloy deposit depends mostly on the presence of cobalt in the alloy deposit. The XRD pattern has shown the η-phase orientation of (110) plane and the peak intensity were hugely increased with Co content in the deposit. (paper)