정방정 $ZrO_2$의 첨가가 $alpha$-Alumina/La-beta-Aluminate $ 복합체의 기계적 성질에 미치는 영향 |
강석원, 김해두, 김신, 이수영, 박동수 |
한국기계연구원 재료기술연구부 |
Effect of Tetragonal $ZrO_2$ Addition on the Mechanical Properties of $alpha$-Alumina/La-beta-Aluminate $Composite |
Suk-Won Kang , Hai-Doo Kim , Shin Kim , Soo-Young Lee , Dong-Soo Park |
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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. |
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