Effects of electrolyte composition and additives on the formation of invar Fe-Ni alloys with low thermal expansion electrodeposited from sulfate bath

Yuki Kashiwa, Nobuaki Nagano, Tomio Takasu, Shigeo Kobayashi, Keisuke Fukuda, Hiroaki Nakano

Research output: Contribution to journalArticlepeer-review

Abstract

The effects of solution composition and additives on the formation of electrodeposited invar Fe-Ni alloys with low thermal expansion was investigated. In all the solutions, with increasing the current density from 10 A·m-2, the Ni content in deposits significantly decreased and showed the anomalous codeposition in which electrochemically less noble Fe deposits preferentially. With increasing current density further, Fe deposition reached the diffusion limitation of Fe2+ ions, as a result, the Ni content in deposits increased with current density. The current density for initiating to increase the Ni content in deposits shifted to higher value with increasing the concentration of Fe2+ ions because of increase in diffusion-limited current density of Fe. With increasing the concentration of malonic acid, the current density region in which the Ni deposition was suppressed, extended and the potential which Fe deposition reached to the diffusion limitation of Fe2+ ions shifted to the less noble direction. As a result, the curve which showed the relationship between the Ni content in deposits and current density, shifted to higher current density region with increasing the malonic acid. The current efficiency for alloy deposition greatly decreased due to promotion of hydrogen evolution with the concentration of malonic acid above 0.05 mol·dm-3. The Ni content in deposits significantly increased with thiourea. With boric acid, the Ni content in deposits somewhat increased in the lower current density region. With both boric acid and saccharin, the invar alloy of Fe-36 mass% Ni was obtained in the wider current density region.

Original languageEnglish
Pages (from-to)585-593
Number of pages9
JournalTetsu-To-Hagane/Journal of the Iron and Steel Institute of Japan
Volume104
Issue number10
DOIs
Publication statusPublished - Oct 2018

All Science Journal Classification (ASJC) codes

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

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