Effects of the Residual Stress on Fracture Toughness in ZTA

ZTA에서 잔류응력이 파괴인성 증진에 미치는 영향

  • Lee, Young-Min (Department of Materials Science & Engineering, KAIST) ;
  • Yu, Jin (Department of Materials Science & Engineering, KAIST)
  • 이영민 (한국과학기술원 재료공학과) ;
  • 유진 (한국과학기술원 재료공학과)
  • Published : 1990.03.01

Abstract

In this investigation, bar-shaped specimens which consisted of three layers are prepared to study the effects of residual compressive stress on the mechanical properties in ZTA. The outer layers contained Al2O3 and unstabilized ZrO2 and the central layer contained Al2O3 and stabilized ZrO2(with 5.10wt% Y2O3). When cooled from the sintering temperature, some of zirconia in the outer layers transformed to the monoclinic form while zirconia in the central layer was retained in the tetragonal form. The transformation which induces to dilatational expansion led to the estabilishmenet of compressive stress in the outer layers and balances tensile stress in the central layer. Decrease of outer layer thickness(for a fixed total thickness)increases residual compressive stress. Because of residual compressive stress in the outer layers, the fracture toughness of outer layers of 3-layers composite is 10.21 Mpam1/2, which is increased to 25% above in comparison with 1-layer specimens in ZTA. Also, the 3-layers composite is believed to exhibite greater fracture resistance in contact damage environment from thermal shock test.

Keywords

References

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