Zn-Ni compositionally modulated multilayered alloy coatings for improved corrosion resistance

Zinc-Nickel monolayer (single layer) and compositionally modulated multilayer alloy coatings were developed on to mild steel from acidic sulphate bath; and their corrosion performance were studied using potentiodynamic polarization and electrochemical impedance spectroscopy methods. The coating layers were formed galvanostatically by single bath technique, using square current pulses and triangular current pulses. For the best efficiency of the deposits against corrosion, the switched cathode current density and the number of layers were optimized. Under optimized conditions, Zn-Ni multilayer alloy coatings were produced at the current density 3.0/5.0 A dm(-2)having 300 layers were similar to 65 (square) and similar to 48 (triangular) times more corrosion resistant respectively than the single layer alloy coating of the same thickness. Scanning electron microscopy has been employed to investigate, the formation of multilayer alloy coatings as well as the morphology of the surface before and after corrosion studies.

Automated summary

The corrosion performance of Zinc-Nickel monolayer and compositionally modulated multilayer alloy coatings on mild steel was studied, and the efficiency of the deposits against corrosion was optimized by adjusting the switched cathode current density and the number of layers. Under optimized conditions, the Zn-Ni multilayer alloy coatings showed significantly higher corrosion resistance compared to single layer alloy coatings of the same thickness, and scanning electron microscopy was used to investigate coating formation and surface morphology before and after corrosion studies.