1995 Fiscal Year Final Research Report Summary
Development of Hybrid-Type Ceramic Matrix Composites Based on Fail-Safe Concept
| Project/Area Number |
05302049
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| Research Category |
Grant-in-Aid for Co-operative Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Composite materials/Physical properties
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| Research Institution | The University of Tokyo |
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Principal Investigator |
KISHI Teruo Professor, Research Center for Advanced Science and Technology, The University of Tokyo, 先端科学技術研究センター, 教授 (40011085)
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| Co-Investigator(Kenkyū-buntansha) |
YOKOBORI Toshimitsu Asso.Professor, Fac.Engr.Tohoku University, 工学部, 助教授 (00124636)
TAKAHASHI Kiyoshi Professor, Res.Inst.Appl.Mech., Kyushu University, 応用力学研究所, 教授 (10010795)
HIGO Yakichi Professor, Inst.Precision Engr., Tokyo Institute for Technology, 精密工学研究所, 教授 (30016802)
ENOKI Manabu Asso, Professor, RCAST,The University of Tokyo, 先端科学技術研究センター, 助教授 (70201960)
NIIHARA Kouichi Professor, Inst.Ind.Sci., Osaka University, 産業科学研究所, 教授 (40005939)
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| Project Period (FY) |
1993 – 1995
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| Keywords | Ceramics / Strength / Fracture Toughness / Hybrid-Type Composites / Microstructure / Nano-Size Particles |
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| Research Abstract |
Fracture toughness of high-strength ceramics can be improved through the microstructure control and composite reinforcement. Nano-size-particle-dispersed composites are most promising among other candidate materials. The following three types of alumina based hybrid-type nano-composites were investigated through this study, in order to demonstrate the fundamental mechanism of nano-size intragranular dispersion and the contollability of the micructure by intergranular dispersion.
(1) Al_2O_3/5vol% Nano-Size SiC Dispersed Composites : Although very small SiC particles tended to exist within alumina grains, larger ones are dispersed at grain boundaries. The dispersion process of nano-size particles was closely related with the degree of alumina matrix densification. The grain size of alumina could be contolled by carefully selecting the size of reinforcing particles.Both strength and toughness were improved through nano-size particle dispesion.
(2) Al_2O_3/SiC/YAG Hybrid Composites : Micron-size YAG and nano-size SiC particles were successfully dispersed to fabricate Al_2O_3/SiC/YAG Hybrid Composites. Since the grain growth of alumina was controlled and homogeneous microstrucure was accomplished, the mechanical properties were much improved through hybritization.
(2) Al_2O_3/LaAl_<11>O_<18> Composites : Alumina matrix composites with elongated fiber-like reinforcing phases were sucessfully fabricated. Both strength and fracture toughness increased as the volume fraction increased. In particular, the fracture toughness was much improved through the increase in the aspect ratio of reinforcement. Bridging and crack deflection contributed the toughness improvement to a large extent.
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