1994 Fiscal Year Final Research Report Summary
FUNDAMENTAL RESEARCH OF PHYSICAL AND ELECTROCHEMICAL PROPERTIES OF ELECTROLYTES IN INDUSTRIAL PROCESS.
| Project/Area Number |
05650732
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Metal making engineering
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| Research Institution | Kyushu University |
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Principal Investigator |
FUKUSHIMA Hisaaki Kyushu University, Engineering, Professor, 工学部, 教授 (50038113)
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| Co-Investigator(Kenkyū-buntansha) |
AKIYAMA Tetsuya Kyushu University, Engineering, Associate Professor, 工学部, 助教授 (10136517)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Industrial electrolysis / Zinc / Silver / Electric conductivity / Density / Viscosity / Energy efficiency / Productivity |
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| Research Abstract |
The selection of the instruments for the measurements of the physical properties such as electric conductivity, density and viscosity of electrolytes was made on a basis of their price and measurement accuracy. Using these instruments, the physical properties of industrial Zn electrowinning and Zn electroplating baths employed for the surface finishing of steel sheets for automobile body were measured to compare the properties between both electrolytes. As a result, the conductivity of the electrowinning bath is extremely higher than that of electroplating bath, while density and viscosity of electroplating bath show the higer values than the electrowinning bath. This indicates that the composition of electrowinning bath is determined from the viewpoint of high energy efficiency. In the Zn electroplating of steel sheets, since the applied current density is increased by the enhancement of the limiting current density due to vigorous agitation and high concentration of Zn ion in bath, the main emphasis is placed on the productivity of Zn plating.
These physical properties were also measured in electrorefining and electroplating baths of Ag. The conductivity of electrorefining bath(nitrate type)is not so high because of a small amount of free nitric acid in bath. This indicates that re-dissolution of the deposited Ag can occur in the bath having high concentration of nitric acid. In the electroplating of Ag from cyanide bath, the discharge of Ag ion from cyanide complex takes place a significant cathodic overvoltage to improve the surface appearance of deposited Ag.
Finally, the physical properties of the electrolytes were compared between the synthesized and industrial sulfate baths of Zn. The small differences in their values are observed between both electrolytes because of the presence in various metallic ions and organic additives in industrial bath.
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