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

Satoshi Oue, Hiroaki Nakano, Shigeo Kobayashi, Hisaaki Fukushima

Research output: Contribution to journalArticle

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
JournalJournal of the Electrochemical Society
Volume156
Issue number1
DOIs
Publication statusPublished - Jan 1 2009

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Citric Acid
Solid solutions
Oxides
X ray diffraction analysis
Diffraction patterns
Hydrogen
Diffraction
Transmission electron microscopy
X ray diffraction
Crystals
Microstructure
Electrons
Chemical analysis

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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Structure and codeposition behavior of Ni-W alloys electrodeposited from ammoniacal citrate solutions. / Oue, Satoshi; Nakano, Hiroaki; Kobayashi, Shigeo; Fukushima, Hisaaki.

In: Journal of the Electrochemical Society, Vol. 156, No. 1, 01.01.2009.

Research output: Contribution to journalArticle

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