Electrodeposition and characterization of Zn‐Mn coatings for corrosion protection

Zn–Mn alloys were electrodeposited from an acidic chloride bath. The influence of bath composition and deposition parameters on the alloysʹ composition, cathodic current efficiency and physical and electrochemical properties was studied. It was found that the composition of the plating bath and deposition potential have significant influence on the manganese content, morphology and corrosion property of the Zn–Mn alloys. Data obtained from linear polarization, Tafel analysis and impedance studies revealed higher corrosion resistance for the Zn–Mn alloy deposits when compared to bare Zn deposit. The Ecorr vs. time curves for Zn–Mn and Zn showed that the bare Zn deposit reached the steel potential after 40 h while the Zn–Mn reached the steel potential after 30 days. In addition, the results obtained from anodic passivation studies indicated that Zn–Mn alloys possess passivation behavior in NaCl solution.