Electrodeposition of Iron-Nickel Alloys in Presence of Magnetic Field.

Research Project

Project/Area Number	01550522
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	金属精錬・金属化学
Research Institution	Kyushu University
Principal Investigator	FUKUSHIMA Hisaaki Kyushu University, Engineering, Professor, 工学部, 教授 (50038113)
Co-Investigator(Kenkyū-buntansha)	AKIYAMA Tetsuya Kyushu University, Engineering, Associate Professor, 工学部, 助教授 (10136517)
Project Period (FY)	1989 – 1990
Project Status	Completed (Fiscal Year 1990)
Budget Amount *help	¥2,200,000 (Direct Cost: ¥2,200,000) Fiscal Year 1990: ¥500,000 (Direct Cost: ¥500,000) Fiscal Year 1989: ¥1,700,000 (Direct Cost: ¥1,700,000)
Keywords	Electroplating / Alloy Deposition / Iron-Nickel System / Anomalous Codeposition / Deposition Mechanism / Composition Gradient / Magnetic Field / 磁場効果 / 鉄合金 / ニッケル合金
Research Abstract	The electrodepstion of Fe-Ni alloys which was classified into anomalous type was carried out using sulrate solutions to make the codeposition mechanism clear. All phenomena inherent to the electrodeposition of Fe-Ni alloys were not able to be explained by the hydroxide suppression mechanism based on the ferrous hydroxide precipitated on the cathode due to a rise in pH in the vicinity of cathode, because the partial polarization curve of Ni as well as Fe did not change with the variation of bulk pH and the anomaly appearing in Fe-Ni system was not brought about by the polarization of Ni but depolarization of Fe. And other mechanisms based on ferric hydroxide and deposition overpotential of Ni were not justified. Then, the extent of polarization of Fe due to a decrease in the activity of Fe in the alloys was estimated. Any stable intermetallic compounds were not formed in the deposited alloys. However, since the Fe deposition was significantly depolarized in the codeposition of Fe with more noble Cu, the decrease in the activity of Fe was involved in the appearance of the anomaly in Fe-Ni system to some extent. The composition gradient in the electrodeposited Fe-Ni alloys was investigated by IMA and EPMA. It was indicated that Ni was preferentially deposited at the first stage of the electrodeposition and this phenomenon was able to be explained by the hydroxide supression mechanism. The enrichment of Fe near the deposit surface was also observed and might be caused by the preferential oxidation of Fe. Finally, the effect of magnetic field on the electrodeposition behavior of the alloys was evaluated. It was found that the presence of magnetic field resulted in not only the polarization of the alloy deposition but also the changes in the magnetic properties of the deposits.