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.




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


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

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