Silicon carbide ceramics through temperature-induced gelation and pressureless sintering


Temperature-induced gelation is a novel near-net-shape method for forming ceramic green bodies from homogeneous high-solids-loaded suspensions. It is based on the change of the solubility of dispersant in solvent with changing temperature. Stable and low-viscosity suspensions of SiC, Y(2)O(3) and Al(2)O(3) powder mixtures were prepared in methyl ethyl keton (MEK)/ ethanol (E) solvent with solid loading as high as 60 vol.% using hypermer KD1 (a polyester/polyamine condensation polymer) as dispersant. The solubility of the dispersant in MEK/E decreased dramatically on cooling. Thus, the suspension displayed a reversible temperature-induced gelation process, being a stable and free flowing fluid at 20 degreesC, and being completely solidified at 5 degreesC. The obtained green body showed uniform microstructure, and it was possible to obtain almost theoretical density (greater than or equal to0.98) upon pressureless sintering without special dispersant burn-out procedure. The possibilities of fabricating homogeneous and complex SiC green parts that can achieve high sintered densities by pressureless sintering are demonstrated. (C) 2004 Elsevier B.V. All rights reserved.



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Science & Technology - Other Topics; Materials Science; Metallurgy & Metallurgical Engineering


Xu, X; Mei, S; Ferreira, JMF; Nishimura, T; Hirosaki, N

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