2002 Fiscal Year Final Research Report Summary
Study on crack-healing behavior of structural ceramics -Crack-healing behavior at service temperature and resultant strength at temperature of healing-
| Project/Area Number |
13650076
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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 |
Materials/Mechanics of materials
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| Research Institution | Yokohama National University |
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Principal Investigator |
ANDO Kotoji Yokohama National University, Faculty of Engineering, Professor, 大学院・工学研究院, 教授 (40017992)
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| Co-Investigator(Kenkyū-buntansha) |
TAKAHASHI Koji Yokohama National University, Faculty of Engineering, Lecturer, 大学院・工学研究院, 講師 (90334630)
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| Project Period (FY) |
2001 – 2002
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| Keywords | Crack-healing / Structural ceramics / In-situ crack-healing / Proof test / Bending strength / Fatigue strength / High temperature strength / Self-repair material |
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| Research Abstract |
The object of this study is to investigate the following four topics. (1) Crack-healing behavior at service temperature and resultant strength at temperature of healing of mullite/SiC composite sintered by the authors. (2) Crack-healing behavior at service temperature and resultant strength at temperature of healing of Si_3N_4/SiC composite sintered by the authors. (3) Development of alumina (Al_2O_3) having quite high crack-healing ability. (4) Development of silicon carbide (SiC) having quite high crack-healing ability. The results obtained for each object are as follows :
(A) It was found that the mullite/SiC has quite high in-situ crack-healing ability, that is, the material can heal a crack even at service temperature and, moreover, crack-healed zone had quite high strength at the temperate of healing. A pre-crack of considerable length, which reduced the bending strength by 70%, can be healed completely at temperatures between 1273K and 1473K even under quite high static and cyclic bending stress. The bending strength of the crack-healed specimens is similar to that of the smooth specimens.
(B) It was found that the Si_3N_4/SiC has quite high in-situ crack-healing ability. A pre-crack of considerable length, which reduced the bending strength by 50%, can be healed completely at temperatures between 1173K and 1473K even under quite high static and cyclic bending stress. The bending strength of the crack-healed specimens is similar to that of the smooth specimens.
(C) An alumina having quite high crack-healing ability and high temperature strength has been developed. The basic crack-healing behavior of the alumina was investigated.
(D) The limit temperature of the crack-healed zone of SiC ceramics was increased from 873K to 1473K.
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