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Electrodeposition of Bright Zn–Co–Fe Alloy Coatings on Mild Steel and Their Characterization

Ramesh S. Bhat, A. Chitharanjan Hegde


Sulphate bath having ZnSO4. 7H2O, CoSO4. 7H2O, FeSO4.7H2O and thiamine hydrochloride (THC) and citric acid (CA) in combination, was optimized for deposition of bright Zn–Co–Fe alloy coating on mild steel. Bath constituents and operating parameters were optimized by Hull cell method, for highest corrosion performance against coating. The effect of current density on deposit characters viz., corrosion resistance, hardness, thickness, CCE were evaluated. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) methods were used for the corrosion behaviours measurements. The composition of deposits was determined by colorimetric method. Surface morphology of the deposits was examined using scanning electron microscopy (SEM). A new sulphate bath, for bright Zn–Co–Fe alloy coating on mild steel has been proposed, and results were discussed.

Keywords: corrosion resistance, cyclic polarisation, electrodeposition, surface morphology, ternary Zn–Co–Fe alloy

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