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Journal of the Korean Ceramic Society 1990;27(2): 201. |
알콕사이드로부터 Mullite 분말의 합성 및 Mullite-Zirconia 복합체의 특성 |
함종근, 이홍림 |
연세대학교 공과대학 요업공학과 |
Synthesis of Mullite Powder from Alkoxides and the Properties of the Mullite-Zircocnia Composites |
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ABSTRACT |
The mullite-15v/o ZrO2 composites were prepared by dispersing ZrO2-3m/o Y2O3 powders into the mullite matrix in order to improve the mechanical properties of the mullite. The densification and retention of t-ZrO2 in the matrix of synthetic mullite were also investigated. From IR spectroscopic analysis, the obtained amorphous SiO2-Al2O3 powder was observed to have Si-O-Al chemical bond in its structure which might result in the homogeneous mullite composition. The lattice parameter of the mullite powder calcined above 130$0^{circ}C$ (a0=7.5468$AA$) is nearly close to the value of stoichiometric mullite (71.8wt% Al2O3, a0=7.5456$AA$). The sintering behavior, microstructure, flexural strength and fracture toughness of the mullite and mullite-15v/o ZrO2 composites have been studied. The mullite-15v/o ZrO2(+3m/o Y2O3) ceramics with relative densities of 96% were obtained when sintered at 1$600^{circ}C$. The flexural strength and fractrue toughness of the composites sintered at 1$600^{circ}C$(calcination temperature of mullite powders ; 125$0^{circ}C$) had maximum values of 307MPa and 2.50MPa.m1/2, respectively. The fracture toughness improvement in the mullite-ZrO2 cmoposite is assumed to be resulted from the combined effect of the stress-induced phase transformation of tetragonal ZrO2 and the crack deflection due to microcracking by the monoclinic ZrO2 formation. |
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