1999 Fiscal Year Final Research Report Summary
Original Preparation of High Temperature Environment-resistant Surface by Electrodeposition Using Molten Salt as Medium
| Project/Area Number |
10650702
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Material processing/treatments
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| Research Institution | AKITA UNIVERSITY |
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Principal Investigator |
HARA Motoki Faculty of Engineering and Resource Science, Akita University, Professor, 工学資源学部, 教授 (50156494)
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| Project Period (FY) |
1998 – 1999
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| Keywords | Electrodeposition / Molten salt / Rare earth element / Lanthanum / High temperature oxidation / Cyclic oxidation |
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| Research Abstract |
The object of this study was that a high temperature environment-resistant surface was prepare by the implantation of rare earth elements into the heat-resistant stainless alloy surface using the molten salt electrodepostion and interdiffusion with the substrate metal. First, the behavior of cathodic reduction of La ion was examined in the molten NaCl-KCl. On the basis of this result, the electrodeposition of La on Fe-Cr and Fe-Cr-Al alloys was carried out.
Thereafter, the behavior of cyclic oxidation of these deposited alloys was examined. The results were summarized as follows :
1. Behavior of cathodic reduction of La ion
The cathodic polarization curves of Ni electrode in molten NaCl-KCl containing 4 mo1% LaィイD22ィエD2OィイD23ィエD2 and 12〜24 mol% NHィイD24ィエD2Cl at 1023 K were measured. It was found that the reduction reaction of LaィイD13+ィエD1 was generated in the potential region lower than -1.6V (vs. Ag/AgCl(0.1)).
2. Electrodeposition of La on Fe-Cr and Fe-Cr-Al alloys
La was deposited on Fe-Cr and Fe-Cr-Al alloys by the potentiostatic polarization at -1.6 and -2.0 V in the molten NaCl-KC1 containing 4 mol% LaィイD22ィエD2OィイD23ィエD2 and 24 mol% NHィイD24ィエD2Cl at 1023 K. It was found that about 1 mass% of La was contained in the surface layer of the alloys.
3. Behavior of cyclic oxidation of La-deposited Fe-Cr and Fe-Cr-Al Alloys
The cyclic oxidation tests for the La-deposited alloys were carried out at 1273 and 1373 K. For Fe-17mass%Cr alloy, the mass gain due to the oxidation was independent of the practice of the electrodeposition, whereas for Fe-23mass %Cr alloy, the mass gain largely decreased by the La deposition. For Fe-10mass %Cr-2mass% Al alloy, conversely, the mass gain increased by the La deposition.
Consequently, the implantation of La into Fe-Cr system alloy surfaces was succeeded by the electrodeposition using molten salt. By this implantation, the cyclic oxidation resistance for the CrィイD22ィエD2OィイD23ィエD2-formed alloy was improved remarkably.
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