日本金属学会誌

J. Japan Inst. Metals, Vol. 32, No. 6 (1968),
pp. 543-549

Formation of Iron Particles by Electrodeposition into Mercury and their Thermal Growth

Yoshimichi Masuda1, Sadao Kikuta2 and Ryuzo Watanabe1

1Department of Metal Processing, Faculty of Engineering, Tohoku University, Sendai
2Miyagi Technical College, Natori

Abstract:

Dendritic iron particles were prepared by electrodeposition into a mercury cathode. Effects of the electrolytic conditions and successive heat treatments on the shapes of the particles were examined by electron-microscopic observations and the measurement of the average magnetic coercive force.
The formation of dendritic particles in molten mercury may be explained in the same way as the crystal growth in a supersaturated solution.
The selected area electron diffraction patterns indicated that the direction of the long axis of the dendritic particles coincided with the [111] direction of alpha iron.
By the proper heat treatment necklace-like particles were obtained, but the orientation of the long axis was unchanged. Further heat treatment changed these particles to be of spheroidal form, and no definite crystal orientation was observed.
The changes in average magnetic coercive force of the particles with their thermal growth followed a simple isothermal equation.
In concidering the increased solubility of fine iron particles in mercury, it was concluded that the mechanism of thermal growth of iron particles in mercury might be a solution-diffusion-precipitation process controlled by a simple rate-determining step.


(Received 1967/12/13)

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