Processing of High Performance Silicon Carbide

Abstract:

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Liquid phase sintering based on the dissolution-precipitation mechanism was applied to densify a 0.8 μm SiC powder with alumina (1.2 vol%)-yttria (0.9-3.3 vol%) additives. To uniformly distribute the sintering additives around the SiC particles, a heterocoagulated particle network was formed among negatively charged SiC particles, positively charged 0.2 μm alumina and yttrium ions in an aqueous suspension at pH 5. Yttrium ions were electrostatically adsorbed on the negatively charged SiC surfaces. The consolidated green compacts were highly sintered to 97-99 % of theoretical density by hot-pressing at 1950 °C. Four-point strength, fracture toughness and Weibull modulus were highly enhanced when a bimodal particle size system of SiC (75 vol% 0.8 micrometer-25 vol% 30 nanometer SiC) was sintered. The maximum strength reached 1.1 GPa. The fracture toughness was about 6 MPa•m1/2 and the Weibull modulus was 5.9. When a small amount of SiC precursor polymer was infiltrated in the green compact, the strength and Weibull modulus were further improved.

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Periodical:

Edited by:

Katsutoshi Komeya, Yi-Bing Cheng, Junichi Tatami and Mamoru Mitomo

Pages:

165-168

DOI:

10.4028/www.scientific.net/KEM.403.165

Citation:

Y. Hirata et al., "Processing of High Performance Silicon Carbide", Key Engineering Materials, Vol. 403, pp. 165-168, 2009

Online since:

December 2008

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$35.00

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