| Project/Area Number |
12555194
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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 | TOHOKU UNIVERSITY |
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Principal Investigator |
LI Jing-feng Tohoku Univ., Graduate School of Engineering, Associate Professor, 大学院・工学研究科, 助教授 (50241542)
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| Co-Investigator(Kenkyū-buntansha) |
WATANABE Ryuzo Tohoku Univ., Graduate School of Engineering, Professor, 大学院・工学研究科, 教授 (20005341)
ESASHI Masayoshi Tohoku Univ., New Industry Creation Hatchery Center (NICHe), Professor, 未来科学技術共同研究センター, 教授 (20108468)
TANAKA Shuji Tohoku Univ., Graduate School of Engineering, Assistant Professor, 大学院・工学研究科, 講師 (00312611)
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| Project Period (FY) |
2000 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥10,700,000 (Direct Cost: ¥10,700,000)
Fiscal Year 2001: ¥4,600,000 (Direct Cost: ¥4,600,000)
Fiscal Year 2000: ¥6,100,000 (Direct Cost: ¥6,100,000)
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| Keywords | thermoelectric material / micro-module / micromachining / microfabrication / materials micro-processing / glass-encapsulating process / BiTe / micro-casting / 熱間等方圧成形 / PbTe |
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| Research Abstract |
Thermoelectric materials can be used as solid-state devices that convert thermal energy from a temperature gradient into electrical energy, known as the "Seebeck effect", or generate a temperature gradient by the "Peltier effect" when electrons pass through the materials. Thermoelectric devices that work without any moving parts are virtually maintenance-free, and are environment-friendly because they do not use or generate gases of any kind. Thermoelectric devices can be used either in the Peltier mode for refrigeration or in the Seebeck mode for electrical power generation. The most effective method to increase the performance of TE devices made of state-of-the-art materials is to multiply the numbers of P-N TE leg couples in a fixed area, and this approach has led to the miniaturization of TE modules. However, conventional cutting and assembling techniques have some difficulties to reduce the dimensions of thermoelectric elements to the micrometer order because of the weakness of th
… More
e thermoelectric materials.
We have developed a novel micro fabrication process that uses a micromachined silicon wafer as a mold to fabricate microstructures of non-silicon materials, by which alternately aligned P-type and N-type TE elements with micrometer diameter and high aspect ratio can be built in a single micromachined silicon mold. Our process consists of the following major steps: (1) micromachining a silicon mold; (2) filling the mold with thermoelectric materials; (3) connecting P- and N-type elements and assembling the whole module. This process combines MEMS technology and materials processing into a novel process for manufacturing thermoelectric devices with densely aligned microscale cross-section and high-aspect-ratio thermoelectric elements. The Si mold was made from a 20 mm square piece of 400 μm-thick Si wafer, whose central portion of 10 mm square was machined to contain 10,000 holes of 300 μm deep and 40 μm square in cross section on each side. The two surfaces of such a mold are covered respectively with P- and N-type of thermoelectric alloy powders and vacuum-encapsulated into a glass tube, and the materials are squeezed into the microholes by pressurized casting or hot-isostatic pressing. At present, the study has been concentrated on the micro fabrication of Bi-Sb-Te alloy, which is the state-of-the-art TE materials used in many TE applications, and its element arrays with dimensions equal to the holes were successfully fabricated using the micromachined Si mold. The results obtained in the present study as the first step to the whole project indicate that the present process will lead to remarkable miniaturization of TE microdevices. Less
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