1996 Fiscal Year Final Research Report Summary
BRITTLENESS,TOUGHNESS AND DUCTILITY OF CERAMICS -THE MICROSCOPIC PROCESSES AND CHARACTERIZATION.
| Project/Area Number |
07555194
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 試験 |
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| Research Field |
Inorganic materials/Physical properties
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| Research Institution | TOYOHASHI UNIVERSITY OF TECHNOLOGY |
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Principal Investigator |
SAKAI Mototsugu TOYOHASHI UNIVERSITY OF TECHNOLOGY,FUCULTY OF ENGINEERING,PROFESSOR, 工学部, 教授 (50124730)
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| Co-Investigator(Kenkyū-buntansha) |
SUGANUMA Motohiro AICHI INDUSTRIAL RESEARCH INSTITUTE,SENIOR RESEARCHER, 材料部, 主任研究員
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| Project Period (FY) |
1995 – 1996
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| Keywords | CERAMICS / BRITTLENESS / TOUGHNESS / DOUCTILIGY / CHARACTERIZATION,ANALYSIS |
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| Research Abstract |
1) The brittleness and the ductility as characteristic material parameters were defind and derived based on an energry principle of indentation contact mechanics. The brittleness/ductility parameter gives a quantitative measure for characterizing the machinability of brittle materials.
2) An apparatus was designed for characterizing the brittleness/ductility parameter and the degree of indentation-induced damage in a wide range of temperatures ranging from room temperature to 1,400ﾟC.
3) Conducted were the theoretical consideration and experimental work of viscoelatic indentation contact deformation of brittle materials at elevated temperatures. The indentation hysteresis energy was successfully utilized to characterize the viscoelastic behavior of surface deformation.
4) An acoustic microscopy was applied to the surface damage introduced by indentation contact. An analytical method for characterizing the damage evolution has been established.
5) A nonlinear rheological constitutive equation was proposed based on considerations of the grain-boundary sliding and grain interlocking of polycrystalline ceramics with grain-boundary melt at elevated temperatures.
6) An experimental apparatus was designed for examining viscoelastic behavior of polycrystalline materials at elevated temperatures up to 1600ﾟC.A novel test specimen geometry (double shear geometry) under compressive loading mode makes possible to conduct rheological testing under simple shear deformation. An experimental scrutiny confirmed that the constituteve equation proposed in Item 5) quantitatively predicts the nonlinear viscoelastic behavior associated with grain-boundary sliding and grain interlocking.
7) Toughening processes and mechanisms have been examined via experimental as well as theoretical studies on the mixed-mode fracture and R-curve behavior of several types of ceramics. A novel test technique and a fracture mechanics-based size-effect law were proposed to estimate process zone/wake zone sizes.
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