To elucidate the effects of the electrolysis conditions on the formation of electrodeposited invar Fe-Ni alloys with low thermal expansion, Fe-Ni electrodeposition was performed at 10-5 000 A·m−2 and 5 × 105 C·m−2 in an agitated solution containing NiSO4, NiCl2, FeSO4, H3BO3, C7H4NNaO3S, and C3H4O4 at 40°C-60°C. In the low-current-density region, the Ni content in the deposits significantly decreased with increasing current density, reached a minimum, and then increased after reaching the diffusion-limiting current density for Fe deposition. With the increasing concentration of FeSO4 in the solution, the Ni content in the deposits decreased in the lower-current-density region, reached a constant at a moderate current density, and then began to increase at higher current density. As a result, the current density range in which the Ni content in the deposits reached a minimum and remained constant became wider with increasing FeSO4 concentration. With the decreasing pH of the solution, since the partial polarization curve for H2 evolution and the total polarization curve shifted to a higher-current-density region, the curve of the Ni content in the deposits as a function of the current density shifted toward a higher current density. The change in the composition of the Fe-Ni alloy deposits because of the electrolysis conditions can be explained by the changes in the total polarization curve and the partial polarization curves for Fe and Ni deposition and H2 evolution.
|出版ステータス||出版済み - 2019|
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