J. Korean Ceram. Soc. > Volume 34(6); 1997 > Article
 Journal of the Korean Ceramic Society 1997;34(6): 553.
 $Al_2O_3$의 상전이 및 그에 따른 미세구조 제어에 관한 연구 신상현, 오창섭1, 최성철 한양대학교 공과대학 무기재료공학과1만도기계중앙연구소 A Study on Phase Transformation and Microstructure Control of $Al_2O_3$ ABSTRACT A fine $alpha$-Al2O3 powder was prepared by sol-gel process for membrane application. And it was carried out by adding 1.5wt% $alpha$-Al2O3 powders(mean size : 87 nm) as seeds to the prepared sols and by controlling the heating schedule (the heating rate and the soaking time) to prevent the microstructural change, which occured during $theta$-to $alpha$Al2O3 phase transformation. The seeded $alpha$-Al2O3 particles acted as the heterogeneous nucleation sites for the $alpha$-Al2O3 nucleation during the transformation of $theta$- to $alpha$-Al2O3 and resulted in increasing the driving force of phase transformation to activate the formation of $alpha$-Al2O3 phase at 82$0^{circ}C$. By $alpha$-Al2O3 seeding and controlling of heating condition the phase transformation of $theta$- to $alpha$-Al2O3 was accomplished at low temperature and the grain growth process was depressed. Therefore, the unsupported membrane could be fabricated in $alpha$-Al2O3 . The average diameter of pores in the fabricated membrane was 7 nm and the porosity was 47%. Key words: $\alpha-Al_2O_3$, Seeds, Heating schedule, Phase transformation, Heterogeneous nucleation and grain growth
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