2023 Fiscal Year Final Research Report
Establishment of HHP sintering technology for enabling densification of heat-unstable cobalt compounds and applications to thermoelectric materials
| Project/Area Number |
21K04715
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Multi-year Fund |
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| Section | 一般 |
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| Review Section |
Basic Section 26050:Material processing and microstructure control-related
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| Research Institution | Kanagawa Institute of Technology (2022-2023)
Ube National College of Technology (2021) |
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Principal Investigator |
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| Co-Investigator(Kenkyū-buntansha) |
山崎 友紀 法政大学, 経済学部, 教授 (50311048)
相馬 岳 香川高等専門学校, 機械電子工学科, 教授 (60508266)
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| Project Period (FY) |
2021-04-01 – 2024-03-31
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| Keywords | 熱電材料 / コバルト層状化合物 / セラミックス / 酸化剤 / 水熱ホットプレス / コールドシンタリング |
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| Outline of Final Research Achievements |
Starting with NCO (NaxCoO2) powder, a Co-layered compound with the highest level of thermoelectric performance among oxides, we synthesized compound powders with a wide interlayer distance using a simple redox method. However, these compounds had problems with thermal stability. We, therefore, discovered that the HHP (hydrothermal hot pressing) method, in which a small amount of aqueous solution is added to the powder and pressure is applied, followed by heat treatment at less than 300 °C, and the CSP (cold sintering process) method, which is essentially equivalent to HHP, have a densification effect. When high pressure was applied and heat-treated at 150 °C or higher, densification to a relative density of approximately 80% or more was promoted. The thermoelectric properties of the compounds with a wide interlayer distance surpass those of the starting material NCO when sintered by the above method.
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| Free Research Field |
材料工学
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| Academic Significance and Societal Importance of the Research Achievements |
本研究成果における学術的意義は、本研究で用いたCo層状化合物など機能性材料としてのポテンシャルはあるが熱安定性のない物質を緻密化する手法の1つとして水熱ホットプレス法の可能性を見出すことができた点にある。今後、低温での緻密化メカニズム解明を行ううえでの基礎となるデータが得られたものと考えられる。
本研究成果における社会的意義は、本手法が省エネルギー化に直接貢献するとともに、今後における焼成条件や助剤の改良により、高性能な機能性材料の開発が期待される点にある。
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