| Project/Area Number |
09555217
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Material processing/treatments
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| Research Institution | Kyushu University |
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Principal Investigator |
FUKUSHIMA Hisaaki Kyushu University, Engineering, Professor, 工学研究科, 教授 (50038113)
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| Co-Investigator(Kenkyū-buntansha) |
NAKAKOJI Hisatada Kawasaki Steel Co., Research Lab., Senior Researcher, 技術研究所・表面処理研究部, 課長
OHGAI Takeshi Kyushu University, Engineering, Research Associate, 工学研究科, 助手 (60253481)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥12,700,000 (Direct Cost: ¥12,700,000)
Fiscal Year 1999: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1998: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1997: ¥10,700,000 (Direct Cost: ¥10,700,000)
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| Keywords | Steel Sheet / Zinc / Chromium / PEG / pH / Hydroxide / polarization / Electrodeposition / メタノール |
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| Research Abstract |
We have been investigated the electrodeposition behaviors of Zn-Cr allots from sulfate baths, which is expected as the surface finishing method of steel in the next generation. The results are as follows :
Cr was codeposited with Zn at highly current density in both PEG-free and PEG containing baths. However, PEG made it possible to reduce CrィイD13+ィエD1 to metallic state, and Cr existed in the state of CrィイD13+ィエD1 hydroxide in the deposits obtained from PEG-free bath. The chromium content in the deposits increased with an increase in the concentration and the molecular weight of PEG. The addition of PEG with molecular weight higher than #1540 permitted the deposition of zinc-chromium alloys of smooth and lustrous surfaces, while no deposits containing metallic chromium were obtained in the PEG-free baths and the baths containing PEG with lower molecular weight.
Cathode potential of polarization curve shifted to less-noble direction by adding PEG to bath. The cathode potential was shifted to less positive direction with an increase in the concentration and molecular weight of PEG. Therefore, PEG inhibits the zinc deposition by absorbing on the cathode, and thus making it possible to attain the deposition potential of metallic chromium.
The pH at cathode surface increased up to about pH4 during electrolysis. By identification of the hydrolysis products, it was expected that the hydroxides of Cr and Zn formed simultaneously in this cathode region. In Zn-Cr alloy baths containing PEG, the alloys were produced by discharging from the composite oxide of Zn and Cr formed by pH rising at cathode surface. Therefore, it seemed that PEG acts as a polarizer, which makes the cathode potential shift enough to discharge Cr Oxide to metallic state.
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