Corrosion resistant electrodeposited zinc coating from zinc dross

Abstract

Electrodeposition of metals from aqueous solution produces a variety of metal alloy coatings. Zincalloy coatings are obtained by electrogalvanising of pure zinc. Properties of electrogalvanised steellike corrosion resistance spot weldability and adhesion are superior to hot-dip galvanisedsteel.Inthe present investigation, an attempt has been made to study electrodeposition of zinc from solidzinc drossas ananodic material on steel sheet acting as cathode and an aqueous bath containingdifferent concentration of Cl- ions, ammoniumsaltsandconducting substances at roomtemperature. An acid chloride bath was mainly used at different pH values. Very thin adherentand impervious coating was obtained on steel sheet. The zinc coating so obtained byelectrodepositionwas finally passivated to minimize white rust. X- ray diffraction, coatingthickness, atmospheric exposure test, electrochemical test, microhardness and cathodic efficiencyof zinc coated substrates were carried out. Salt -spray test on the coating was performed for 15days. Polarization experiments were carried out in 3.5 %NaCl solutionusingEG&G PARC-273Amodel Potentiostat Galvanostat. Open circuit potential (OCP) and corrosion potential (Ecorr) wererecorded. The process developed is very simple, economically viable and eco-friendly.