Journal of the Korean Ceramic Society (한국세라믹학회지)

The Korean Ceramic Society (한국세라믹학회)
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Effect of Tetragonal $ZrO_2$ Addition on the Mechanical Properties of $\alpha$-Alumina/La-\beta-Aluminate $Composite

정방정 $ZrO_2$의 첨가가 $\alpha$-Alumina/La-\beta-Aluminate $ 복합체의 기계적 성질에 미치는 영향

  • Suk-Won Kang (Ceramic Materials Lab., Korea Institute of Machinery & Metals) ;
  • Hai-Doo Kim (Ceramic Materials Lab., Korea Institute of Machinery & Metals) ;
  • Shin Kim (Ceramic Materials Lab., Korea Institute of Machinery & Metals) ;
  • Soo-Young Lee (Ceramic Materials Lab., Korea Institute of Machinery & Metals) ;
  • Dong-Soo Park (Ceramic Materials Lab., Korea Institute of Machinery & Metals)
  • 강석원 (한국기계연구원 재료기술연구부) ;
  • 김해두 (한국기계연구원 재료기술연구부) ;
  • 김신 (한국기계연구원 재료기술연구부) ;
  • 이수영 (한국기계연구원 재료기술연구부) ;
  • 박동수 (한국기계연구원 재료기술연구부)
  • Published : 1994.05.01
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Abstract

Alumina composite was fabricated by introducing tetragonal ZrO2 in alumina composite of $\alpha$-alumina reinforced with in-situ formed La-$\beta$-aluminate (LaAl11O18). The powder mixture of composition (100-x)[88 Al2O3+(La2O3+11 Al2O3)]+x vol% ZrO2 was prepared with x from 0 to 40. Dense composites fabricated by hot-pressing exhibited bending strength up to 1200 MPa. The gain growth inhibiting effect of ZrO2 grains and La-$\beta$-aluminate platelets, and possibly the stress-induced phase transformation of ZrO2 have resulted in the high bending strength. The fracture toughness of the composite also increased up to 8.5 MPa.m1/2. The enhancement in toughness can be explained by transformation and microcrack toughening of ZrO2 and by crack deflection and bridging of La-$\beta$-aluminate platelets and ZrO2.

In-situ 반응에 의하여 형성된 La-$\beta$-aluminate (LaAl11O18)로 강화된 알루미나 복합체에 정방정 ZrO2를 첨가하여 알루미나 복합체를 제조하였다. 사용된 분말 혼합체의 조성은 (100-x)[88 Al2O3+(La2O3+11 Al2O3)]+x vol% ZrO2였으며, x는 0부터 40까지 변화시켰다. 열간가압형성에 의하여 얻어진 치밀한 소결체는 1200MPa의 곡강도값을 나타내었다. 이러한 높은 곡강도값은 첨가한 ZrO2 입자와 기존의 La-$\beta$-aluminate platelets의 기지 입자에 대한 입성장 억제 효과와 ZrO2의 응력유기 상변태 효과로부터 기인하였다. 상기 복합체의 파괴 인성도 역시 8.58.5 MPa.m1/2까지 증가하였는데, 이러한 파괴인성의 증가는 ZrO2의 상변태 강화와 미세균열 강화, 그리고 La-$\beta$-aluminate와 ZrO2 입자의 균열 deflection과 bridging의 효과로 설명되어질 수 있다.

Keywords

References

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