Electroplating and Corrosion Properties of Binary and Ternary Zinc Alloys with Nickel, Cobalt and Iron

Ramesh S. Bhat; Venkatakrishna K; A. Chitharanjan Hegde

Abstract

The anti-corrosive three binary (Zn-Ni, Zn-Co, Zn-Fe) and two ternary (Zn-Ni-Co, Zn-Co-Fe) alloy coating films on mild steel from acid chloride bath using sulphanilic acid and gelatin as additives for the electroplating technique. The normal Hull cell method was used to optimize the bath compositions, temperature and pH of the bath solutions for coating performance against corrosion. The cause of current density (CD) on metal weight percentage (M = Ni, Co, Fe), thickness (t), hardness (VH), and throwing power (TP) has been investigated. The corrosion resistance of binary and ternary alloy coating films was determined using the potentiodynamic polarization technique. The metal content in the coatings were determined by colorimetric method. Under optimal conditions, the corrosion rate of Zn-Ni-Co was approximately ~8 times, ~10 times higher than Zn-Ni, and Zn-Co coating films. Also Zn-Co-Fe coating film was approximately ~8 times, and ~13 times higher than Zn-Co and Zn-Fe coating films. Thus ternary zinc-nickel-cobalt and zinc-cobalt-iron coatings can replace usual binary alloy deposits for many industrial applications such as automobile, machinery items like tools, bolts, and nuts, etc.

Abstract

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