Structure and codeposition behavior of Ni-W alloys electrodeposited from ammoniacal citrate solutions

Satoshi Oue, Hiroaki Nakano, Shigeo Kobayashi, Hisaaki Fukushima

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26 Citations (Scopus)

Abstract

The microstructure of Ni-W alloys electrodeposited at 1000 A m2 from ammoniacal citrate solutions was discussed in terms of their codeposition behavior. When the W content in the alloys was increased, the partial current efficiency of W first increased toward a maximum value and then decreased. This showed the existence of two characteristic alloy compositions, i.e., a W content at a maximum partial current efficiency of W and an upper limiting content of W. The deposition behavior of Ni-W alloys was explained by the multistep mechanism of the reduction of the electrochemically reduced W(IV) oxide to W by atomic hydrogen adsorbed using the unpaired 3d electrons of the freshly deposited Ni. X-ray diffraction (XRD) analysis revealed that alloys with a low W content consisted of a Ni solid solution, and the diffraction peaks became broader with an increase in W content. Ni-W alloys with high W contents showed a smooth surface composed of fine grains. Transmission electron microscopy studies revealed that the major phase in Ni-W alloys was the Ni solid solution, and the XRD pattern of the Ni-53.9 mass % W alloy revealed a halo pattern characteristic of an amorphous structure. This alloy consisted of crystal grains smaller than 10 nm in diameter.

Original languageEnglish
Pages (from-to)D17-D22
JournalJournal of the Electrochemical Society
Volume156
Issue number1
DOIs
Publication statusPublished - Jan 1 2009

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Renewable Energy, Sustainability and the Environment
  • Surfaces, Coatings and Films
  • Electrochemistry
  • Materials Chemistry

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