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

• Published in: Surface engineering Vol. 37; no. 6; pp. 755 - 763
• Main Authors: Bhat, Ramesh S., Nagaraj, P., Priyadarshini, Sharada
• Format: Journal Article
• Language: English
• Published: London, England Taylor & Francis 03.06.2021; SAGE Publications
• Subjects: CMMA coating; corrosion resistance; monolayer; SEM; square pulse; triangular pulse; square pulse; triangular pulse; monolayer; SEM; CMMA coating; corrosion resistance
• ISSN: 0267-0844; 1743-2944
• DOI: 10.1080/02670844.2020.1812479

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 ∼65 (square) and ∼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.