Thermal Shock Behavior of <TEX>$Al_2O_3$</TEX>-<TEX>$ZrO_2$</TEX> Ceramics Prepared by a Precipitation Method

,; ,; ,; ,

J. Korean Ceram. Soc. > Volume 28(1); 1991 > Article

Journal of the Korean Ceramic Society 1991;28(1): 11.

침전법으로 제조한 $Al_2O_3$-$ZrO_2$계 세라믹스의 열충격 거동

홍기곤, 이홍림¹

산업과학기술연구소 에너지 연구부
¹연세대학교 공과대학 요업공학과

Thermal Shock Behavior of $Al_2O_3$-$ZrO_2$ Ceramics Prepared by a Precipitation Method

ABSTRACT

A precipitation method, one of the most effective liquid phase reaction methods, was adopted in order to prepare high-tech Al2O3/ZrO2 composite ceramics, and the effects of stress-induced phase transformation of ZrO2 on thermal shock behavior of Al2O3-ZrO2 ceramics were investigated. Al2(SO4)3.18H2O, ZrOCl2.8H2O and YCl3.6H2O were used as starting materials and NH4OH as a precipitation agent. Metal hydroxides were obtained by single precipitation(process A) and co-precipitation(process B) method at the condition of pH=7, and the composition of Al2O3-ZrO2 composites was fixed as Al2O3-15v/o ZrO2(+3m/o Y2O3). Critical temperature difference showing rapid strength degradation by thermal shock showed higher value in Al2O3/ZrO2 composites(process A : 20$0^{circ}C$, process B : 215$^{circ}C$) than in Al2O3(175$^{circ}C$). The improvement of thermal shock property for Al2O3/ZrO2 composites was mainly due to the increase of strength at room temperature by adding ZrO2. The strength degradation was more severe for the sample with higher strength at room temperature. Crack initiation energies by thermal shock showed higher values in Al2O3/ZrO2 composites than in Al2O3 ceramics due to increase of fracture toughness by ZrO2.