• Title/Summary/Keyword: Fibrous monolithic

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Microstructures and Fracture Characteristic of Pressureless-Sintered DyNbO4 body (상압소경에 의해 제조된 DyNbO4 소결체의 미세조직과 파괴특성)

  • 김기만;안종관;이병택
    • Journal of Powder Materials
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    • v.9 no.3
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    • pp.148-152
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    • 2002
  • The microstructures and indentation fracture of pressureless-sintered $DyNbO_4$ crystalline were investigated as a basic study for the application of weak phase of fibrous monolithic composites. They were comprised with many lamella twins as well as micro-cracks at the grain boundaries. The hardness at room temperature was remarkably low value(575 Hv) due to the low relative density and existence of microcracks at grain boundaries. The main fracture mode was a typical intergranular fracture, and showed remarkable micro-cracking effect. The heavy plastic deformation was observed around the site of indentation. In addition, the $DyNbO_4$ was expected to apply as a weak phase in the fibrous monolithic composites because of the low hardness and easily plastic deformation that could be led the preferable pulled-out and microcracking toughening under the failure.

Microstructure Control of Fibrous Monolithic Al2O3-ZrO2 Composites (섬유단상 Al2O3-ZrO2 세라믹 복합재료의 미세조직제어)

  • Kim, Ki-Hyun;Kim, Taek-Soo;Lee, Byong-Taek
    • Korean Journal of Materials Research
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    • v.13 no.4
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    • pp.213-218
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    • 2003
  • Fibrous monolithic control of$ Al_2$$O_3$ -$ZrO_2$composite was investigated by multi-pass extrusion process. To obtain sound $Al_2$$O_3$-X $O_2$sintered bodies, burning out and sintering process were carefully carried out. The sintered bodies showed continuous, fibrous monolithic microstructure without any swelling. Many microcracks were observed at the $Al_2$$O_3$-$ZrO_2$interfaces due to the mismatching of thermal expansion coefficient between $Al_2$$O_3$ and $ZrO_2$phase. Most of m- $ZrO_2$grains included twin defects such as (001), (010) and (011) type to accommodate the phase transformation induced stress.