Low-Temperature Fabrication of Porous -SiC Ceramics in Sodium Vapor
-silicon carbide (SiC) porous ceramics were synthesized from pelletized powder mixtures of silicon (Si) and fullerene or Si and amorphous carbon (carbon black) at 1000 K for 24 h in sodium (Na) vapor. The relative density of the ceramics was 29%–34% of the theoretical density of SiC. Scanning electron microscopic observation of the fracture surface showed that the ceramics prepared with fullerene were agglomerates of submicrometer-sized SiC particles and open spaces. The samples prepared with carbon black had a smooth fracture surface with cavities and voids. Using transmission electron microscopy, grains of over 250 nm and a diffuse electron diffraction ring pattern of -SiC were observed for the sample prepared with fullerene, and grains of 10–20 nm with a -SiC spot ring pattern for the sample prepared with carbon black. A surface area of 11–17 m2/g and a mesopore size distribution in the range of 2–10 nm were shown by a nitrogen adsorption technique. Energy-dispersive X-ray analysis detected 1–5 at.% of Na against Si on the fracture surface of the ceramics.
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Document Type: Research Article
Affiliations: Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai 980-8577, Japan
Publication date: January 1, 2008