2005 Fiscal Year Final Research Report Summary
Synthesis of refractory silicon nitride using liquid phase with high nitrogen content
| Project/Area Number |
15360355
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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 | 一般 |
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| Research Field |
Inorganic materials/Physical properties
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| Research Institution | National Institute for Materials Science |
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Principal Investigator |
HIROSAKI Naoto National Institute for Materials Science, AML, Senior Researcher, 物質研究所, 主席研究員 (80343838)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIMURA Toshiyuki National Institute for Materials Science, AML, Senior Researcher, 物質研究所, 主幹研究員 (50354428)
TANAKA Hidehiko National Institute for Materials Science, AML, Director, 物質研究所, ディレクター (40343868)
TAKAHASHI Junichi Tohoku University, Institute of Multidisciilinary research for Advanced Materials, Assistant Researcher, 多元物質科学研究所, 助手 (20261472)
YAMANE Hisanori Tohoku University, Center for Interdisciplinary Research, Professor, 学際科学国際高等研究センター, 教授 (20191364)
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| Project Period (FY) |
2003 – 2005
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| Keywords | gas turbine / silicon nitride / grain-boundary base / high-temperature strength / oxidation / creep / high-temperature deformation / rare earth |
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| Research Abstract |
Silicon nitride sintered material in which the grain boundary phase crystallized as Lu-containing oxynitride found to have the excellent high-temperature properties. By reduction and crystallization of the intergranular glassy phase, further improvement is expected. As a result of examining the phase relationships in detail, we found that the grain boundary composition was controlled as Lu_4Si_2O_7N_2 using the liquid phase with high nitrogen content. New silicon nitride was fabricated using high nitrogen content liquid phase in the Si_3N_4-LuN-Lu_2O_3 system.
Pure lutetium nitride LuN), indispensable for high nitrogen content liquid phases, was synthesized. Lu metal was directly nitrided by gas-pressure sintering. Using this LuN, Si_3N_4-Lu_2O_3-LuN reaction root was designed for a new high-nitrogen content phase in Lu-Si-O-N quaternary system, and the phase relationship and the crystal structure was refined by X-ray analysis. Finally, we fabricate the silicon nitride ceramics with Lu-oxynitride grain boundary phase by the addition of small amount of Lu_2O_3 and by gas-pressure hot-pressing. This material showed excellent strength, oxidation resistance, high-fracture toughness and creep resistance at 1500 ℃ during 1400 h under 137 MPa tensile stress.
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