Effect of agarose content on microstructures and mechanical properties of porous silicon nitride ceramics produced by gelcasting
Porous Si3N4 self-reinforce ceramics were prepared by gelcasting using agarose solutions. By changing the agarose content in the slurries, the porous silicon nitride ceramics with different porosities, α→β-Si3N4 phase transformation, and mechanical properties were obtained. When the agarose content...
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Published in | Journal of Zhejiang University. A. Science Vol. 11; no. 10; pp. 771 - 775 |
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Main Authors | , |
Format | Journal Article |
Language | English |
Published |
Hangzhou
Zhejiang University Press
01.10.2010
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Subjects | |
Online Access | Get full text |
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Summary: | Porous Si3N4 self-reinforce ceramics were prepared by gelcasting using agarose solutions. By changing the agarose content in the slurries, the porous silicon nitride ceramics with different porosities, α→β-Si3N4 phase transformation, and mechanical properties were obtained. When the agarose content changed from 0.2% to 0.8% (w/w, based on powder), the porosities increased from 10.3% to 21.4%, while the fracture strength decreased from 455 to 316 MPa and the fracture toughness decreased from 6.6 to 5.5 MPa·m1/2. Many fibrous β-Si3N4 grains grown from the internal wall of the round pores is the typical microstructure of the gelcasting porous silicon nitride ceramic. Both elongated β-Si3N4 grains and suitable interfacial bonding strength contributes to high fracture toughness by favoring crack deflection and bridging. The growth mechanisms of fibrous grains resulted from the synergy of solution-diffusion-reprecipitation and vapor-liquid-solid (VLS). |
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Bibliography: | TQ174.62 Porous Si3N4 ceramics, Gelcasting, Microstructure, Mechanical properties 33-1236/O4 TQ174.758 |
ISSN: | 1673-565X 1862-1775 |
DOI: | 10.1631/jzus.A1000125 |