1986 Fiscal Year Final Research Report Summary
Study on the Control of Morphology of Electrodeposited Metal
| Project/Area Number |
60430018
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
金属精錬・金属化学
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| Research Institution | Kyoto University |
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Principal Investigator |
KONDO Yoshio Kyoto University, Department of Metallurgy, Professor, 工学部, 教授 (10025778)
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| Project Period (FY) |
1985 – 1986
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| Keywords | Morphology / Electrodeposition / Ionic Mass Transfer / Holographic Interferometry / Dendritic Growth / Concentration Overpotential / Surface Overpotential |
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| Research Abstract |
Morphology of copper electrodeposited from Cu <SO_4> and Cu <SO_4> - <H_2> <SO_4> solution under the particular overpotential was examined by the scanning electromicroscopy. It was found that the morphology of electrodeposited copper could be classified into three groups depending on the total overpotential; faceted structure, columnar dendrite or spheroidal and spongy dendrite. The transition overpotential among them is not influenced by Cu <SO_4> concentration, but by the presence of <H_2> <SO_4> . Moreover, the concentration profiles of <Cu^(2+)> and <H^+> ion near the cathode surface were measured by the two-wavelength holographic interferometry and the concentration overpotential at the cathode surface immersed in various kinds of electrolyte was calculated. The ratio of concentration overpotential to the total overpotential in electrolyte acidified with an excess amount of <H_2> <SO_4> was negligibly small in comparision with the ratio obtained in Cu <SO_4> solution. The larger m
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agnitude of surface overpotential, the difference between the total and the concentration overpotentials may introduce a number of three dimensional nucleus to form many spheroidal precipitated particles and the ionic mass transfer around the spheroidal particle is associated with the formation of columnar dendrite or spongy dendrite.
Another example on this subject is the electrodeposition of silver whose exchange current density is much higher than that of copper, and the dendritic precitation is easily formed. The concentration profile of <Ag^+> ion formed near a dendrite tip of 60 <micro> m in thickness was measured by the holographic interferometry and the growth rate was nicely correlated with the concentration gradient of <Ag^+> ion. This dendritic formation could be controlled by the pulse electrolysis. It was found that the optimal averaged current density is attained at 60 mA/ <cm^2> for 0.5 MAg <NO_3> - 0.5 MH <NO_3> and the effect is improved with smaller value of the duty cycle. Less
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