1994 Fiscal Year Final Research Report Summary
Development of toughened zirconia laminate materials
| Project/Area Number |
05452281
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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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 |
ENOKI Manabu RCAST,The University of Tokyo, Associate Professor, 先端科学技術研究センター, 助教授 (70201960)
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| Co-Investigator(Kenkyū-buntansha) |
KISHI Teruo RCAST,The University of Tokyo, Professor, 先端科学技術研究センター, 教授 (40011085)
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| Project Period (FY) |
1993 – 1994
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| Keywords | zirconia / laminate / fracture toughness / micro fracture / acoustic emission |
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| Research Abstract |
Cermics are expected to be high-temperature use materials or high wear resistance materials, but their essential brittleness interfere the pratical application of ceramics. In this research, we have developed the high-toughened zirconia laminates to improve the brittleness of ceramics. It is well known that the fracture toughness of partially stabilized zirconia materials are enhanced to due the stress induced transformation. However, an increase of toughness is limited by the saturation of transformation quantity. We have developed the toughened zirconia laminates with high crack propagation resistance by stacking non-transformed and transformed layrs and by controlling the thickness of layrs.
The thin layrs of ZrO_2-6mol%Y_2O_3, ZrO_2-3mol%Y_2O_3 and ZrO_2-2mol%Y_2O_3 were produced. The pawder was mixed with liquid. Layrs with a constant thickness were obtained by controlling viscosity of slury. The obtained layrs were stacked and hot-pressed. Three types of specimens with different direction of load were prepared by changing the stacking direction.
The four-point bending strength and fracture foughness were measured. Acoustic emission signals during these tests were also measured. The maximum fracture toughness was9MPam^<1/2>. The effect of thickness and composition on mechanical properties was investigated. The ratio of transformation near main crack was measured by X-ray diffraction analysis system. The role of transformation near main crack was analyzed by the acoustic emission characteristics during crack propation and the observation of crasks, and the mechanism of toughening was evaluated.
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