Effects of Oxide Additions on Mechanical Properties and Microstructures of AlN Ceramics Prepared from Al-isopropoxide

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J. Korean Ceram. Soc. > Volume 27(6); 1990 > Article

Journal of the Korean Ceramic Society 1990;27(6): 799.

Al-isopropoxide로부터 제조한 AlN 세라믹스의 기계적 성질과 미세구조에 미치는 산화물 첨가제의 영향

이홍림, 황해진

연세대학교 공과대학 요업공학과

Effects of Oxide Additions on Mechanical Properties and Microstructures of AlN Ceramics Prepared from Al-isopropoxide

ABSTRACT

In this study, effects of oxide additives on mechanical properties and microstructure of A1N and A1N polytype ceramics were investigated. Fine A1N powder was synthesized by nitriding alumiuim hydroxide prepared from Al-isopropoxide, at 1350$^{circ}C$ for 10h in N2 atmosphere. By adding 3w/o Y2O3, 0.56w/o CaO, and 10w/o SiO2 to AlN powder, AlN and AlN polytype ceramics were prepared by hot-pressing under the pressure of 30 MPa at 1800$^{circ}C$ for 1h. AlN ceramics with no additives formed considerable amount of AlON phase, while AlN ceramics doped with Y2O3 or CaO decreased AlON phase and formed Y-Al or Ca-Al oxide compound. AlN＋10w/o SiO2(＋3w/o Y2O3) composition produced AlON and AlN polytype compound having 21R as a major phase. Room temperature flexural strength of AlN ceramics with no additive was 246MPa, and room temperature flexural strength and critical temperature difference by thermal shock(ΔTc) of AlN ceramics dooped with Y2O3 or CaO were 532MPa/340$^{circ}C$ and 423MPa/300$^{circ}C$, respectively. Y2O3 and CaO used as sintering agent played roles of densification and oxygen removal of AlN ceramics, and affected grain growth/grain morphologies of AlN ceramics.