INFLUENCE OF NICKEL CONCENTRATION ON THE CHARACTERISTICS OF THE ELECTROPLATING Zn-Ni ALLOY

Bui Thi Thanh Huyen

Abstract


Zn-Ni alloy electroplating behaves as anodic coating but has better mechanical properties in comparison with pure Zn coatings. Hence, Zn-Ni coating is accepted as an environmentally friendly alternative to cadmium coatings which is very toxic during producing and use. In this paper, Zn-Ni alloys were electrodeposited from sulfate electrolyte baths at various ratios of Ni2+/Zn2+. Influences of nickel concentration on the plating process were investigated. The composition, morphology and structural properties of the thin films were analyzed by scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) measurements. Electrochemical behaviour of the plated thin films was characterized by open circuit potential and potentiodynamic polarization curves. It was seen that the optimum condition for Zn-Ni electroplating was at temperature of 50 °C, current density of 5 A/dm2, anode - cathode distance of 2.5 cm with stirring. Current efficiency of the plating process and characteristics of the Zn-Ni alloy coatings depended much on the nickel concentration in the plating bath. The best properties were found for the electroplated alloy coating with nickel content in the range of 12 - 14 %.

 


Keywords


Zn-Ni coating, Zn-Ni alloy, electroplating, cadmium coating substitution.

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DOI: https://doi.org/10.15625/2525-2518/55/5B/12225

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Bioteknologi Agrikultur

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Published by Vietnam Academy of Science and Technology