Effects of <TEX>$alpha-AI_2O_3$</TEX> Seeding on Phase Formation and Densification Characteristics of Alumina-Mullite-Zirconia Composites

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J. Korean Ceram. Soc. > Volume 31(12); 1994 > Article

Journal of the Korean Ceramic Society 1994;31(12): 1475.

Alumina-Zirconia-Mullite 복합체의 상생성 및 치밀화 특성에 미치는 $alpha-AI_2O_3$ Seeding 효과

조성목, 장현명

포항공과대학 재료공학과 정밀세라믹스 공정과학연구실

Effects of $alpha-AI_2O_3$ Seeding on Phase Formation and Densification Characteristics of Alumina-Mullite-Zirconia Composites

ABSTRACT

Compositionally triphasic boehmite-silica-zirconia composite gels were prepared by a multiphasic sol-gel route. Phase-formation characteristics and densification behavior of the gel compacts were examined with and without $alpha$-Al2O3 seeding. In the unseeded triphasic gels, both $alpha$-Al2O3 and mullite crystallize simultaneously at 130$0^{circ}C$. On the other hand, the $alpha$-Al2O3 seeding selectively induces the formation of corundum phase ($alpha$-Al2O3) at a significantly lower temperature (~110$0^{circ}C$) and facilitates an epitaxial growth of $alpha$-Al2O3 between 1100~130$0^{circ}C$. The densification of alumina-mullite-zirconia composite (derived from the triphasic gels) was also enhanced by the $alpha$-Al2O3 seeding, and this was attributed to the delayed crystallization of mullite in the $alpha$-Al2O3 seeded gel.