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

Hiroaki Nakano, Shingo Arakawa, Satoshi Oue, Shigeo Kobayashi

Research output: Contribution to journalArticle

Abstract

Electrodeposition behavior of Zn-Ni alloys was investigated at current densities of 5-500 A·m-2 and a charge of 5×104 C·m-2 in an unagitated zincate solution containing ethylenediamine, which forms a stable complex with Ni2+ ions at 308 K, and was compared with that from the solution containing triethanolamine. In a solution containing triethanolamine, the Zn-Ni alloy exhibited normal codeposition at low current densities, wherein electrochemically more noble Ni deposited preferentially and it exhibited anomalous codeposition at high current densities, wherein less noble Zn deposited preferentially, while in a solution containing ethylenediamine, it exhibited anomalous codeposition at high current densities, however, even at low current densities, the Ni content in deposit was almost identical with the composition reference line, showing the behavior close to anomalous codeposition. In a solution containing ethylenediamine, Ni deposition and H2 evolution were significantly suppressed in the 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 current efficiency for alloy deposition on the current density was smaller in a solution containing ethylenediamine than triethanolamine. In a solution containing triethanolamine, the underpotential deposition of Zn apparently occurred with Ni, while in a solution containing ethylenediamine, 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 alloy was better in a solution containing ethylenediamine than triethanolamine.

Original languageEnglish
Pages (from-to)35-41
Number of pages7
JournalTetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
Volume99
Issue number6
DOIs
Publication statusPublished - Jun 18 2013

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Metals and Alloys
  • Materials Chemistry

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