| Project/Area Number |
04650706
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
無機工業化学・無機材料工学
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| Research Institution | Nagasaki University |
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Principal Investigator |
UCHIYAMA Yasuo Nagasaki University, Department of Materials Science and Engineering, Associate Prof., 工学部, 助教授 (50039690)
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| Co-Investigator(Kenkyū-buntansha) |
KOBAYASHI Kazuo Nagasaki University, Department of Materials Science and Engineering, Prof., 工学部, 教授 (30225495)
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| Project Period (FY) |
1992 – 1993
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| Project Status |
Completed (Fiscal Year 1993)
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| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1993: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1992: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Keywords | Silicon Carbide / Contact stress / Round Indenter / Deformation / Contact Damage / Microstructure / Radial Crack / Hertzian Crack |
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| Research Abstract |
Four kinds of silicon nitride ceramics with different grain sizes and different amounts of the boundary phase were prepared, and the polished surface of the samples was indented with a round diamond indenter. The morphology of the surface deformation, cracks and the structure under the indented surface were investigated. After indentation, a round impression was formed on the surface and the swelling was found around the impression. The diameter and the maximum depth of the impression were larger in the samples with a large grain size and a large amount of the boundary phase. Two types of cracks were observed, namely a radial crack and a Hertzian crack. The radial crack propagated from the impression above the indentation load of 147 N, and its length was larger in the samples with a coarse grain size. The Hertzian crack was found inside the impression of the samples with a fine grain size. After etching in a NaOH melt a ring shape area was corroded away from the indented samples. The area of the corroded region depended on the grain size and the amount of the boundary phase. Load-depth curve during loading and unloading depended on the amount of the boundary phase.
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