Electrodeposition behavior of Zn-Ni alloys from an alkaline zincate solution containing ethylenediamine

Hiroaki Nakano, Shingo Arakawa, Satoshi Oue, Shigeo Kobayashi

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    15 Citations (Scopus)

    Abstract

    Electrodeposition behavior of Zn-Ni alloys was investigated at current densities of 5-500 A·m-2 and a charge of 5×10 4 C·m-2 at 308 K in an unagitated zincate solution containing ethylenediamine (EDA), which forms a stable complex with Ni 2+ ions. In the case of the TEA solution, the Zn-Ni alloy exhibited normal codeposition at low current densities, wherein electrochemically more noble Ni deposited preferentially, while it exhibited anomalous codeposition at high current densities, wherein less noble Zn deposited preferentially. In the EDA solution, the alloy exhibited anomalous codeposition at high current densities; on the other hand, even at low current densities, the Ni content in the deposit was almost identical with the composition reference line, showing a behavior similar to anomalous codeposition. In the EDA solution, Ni deposition and H2 evolution were significantly suppressed over a larger region of current densities, showing the formation of an inhibitor for deposition, which results from Zn2+ ions in the cathode layer. The dependence of the current efficiency for alloy deposition on the current density was smaller in the EDA solution than in that containing TEA. In the TEA solution, the underpotential deposition of Zn apparently occurred with Ni, while in the EDA solution, the underpotential deposition of Zn never occurred, because Ni deposition was suppressed by the coexistence of Zn2+ ions even at low current densities. The throwing power of Zn-Ni alloys in the EDA solution was better than that in the TEA solution.

    Original languageEnglish
    Pages (from-to)1864-1870
    Number of pages7
    Journalisij international
    Volume53
    Issue number10
    DOIs
    Publication statusPublished - 2013

    All Science Journal Classification (ASJC) codes

    • Mechanics of Materials
    • Mechanical Engineering
    • Metals and Alloys
    • Materials Chemistry

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