Effect of heating rate on microstructure and properties of spark plasma sintered Li-α-sialon |
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Authors: | Zhangfu Yang Hao Wang Xinmin Min Weimin Wang Zhengyi Fu Soo Wohn Lee Koichi Niihara |
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Affiliation: | aState Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070, China;bDepartment of Environmental Engineering, Sun Moon University, Chungnam 336-708, Republic of Korea;cExtreme Energy-Density Research Institute, Nagaoka University of Technology, 1603-1 Kamitomioka, Nagaoka, Niigata 940-2188, Japan |
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Abstract: | Li-α-sialon ceramics with low oxygen content were prepared by spark plasma sintering at 1750 °C, using three heating rates of 100 °C/min, 200 °C/min and 300 °C/min. In all cases, the densification of Li-α-sialon ceramics is effectively promoted. The rapidly anisotropic growth of grains, either α-sialon or β-sialon, is significantly enhanced with a heating rate above 200 °C/min. This could be attributed to a large amount of low viscosity oxygen-rich liquid formed at elevated temperatures, which gives rise to a so-called dynamic ripening mechanism at the early stage of sintering. Furthermore, for the composition near α-sialon boundary, the oxygen-rich liquid results in the formation of β-sialon together with a large amount of intergranular glassy phase. Only the Li-doped sialon with low lithium and oxygen content possesses relatively high infrared transmittance when sintered at a rate of 100 °C/min. |
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Keywords: | A Sintering B Microstructure-final C Optical properties D Sialon |
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