Formation of Silica-Coated Carbon Powder and Conversion to Spherical β-Silicon Carbide by Carbothermal Reduction

Autor:	Seung M. Oh, Ou Jung Kwon, Yoon Seok Jung
Rok vydání:	2002
Předmět:	Materials science Scanning electron microscope Mineralogy chemistry.chemical_element Microstructure Surface energy Carbide chemistry.chemical_compound chemistry Chemical engineering Carbothermic reaction Materials Chemistry Ceramics and Composites Silicon carbide Carbon Fumed silica
Zdroj:	Journal of the American Ceramic Society. 85:2134-2136
ISSN:	1551-2916 0002-7820
DOI:	10.1111/j.1151-2916.2002.tb00421.x
Popis:	Spherical β-SiC powders that are a few micrometers in size have been prepared by heating a mixture of phenolic resin powder and fine-grained fumed silica at 1600°C in argon. The overall process is composed of two consecutive steps: (i) the formation of silica-coated spherical carbon powder and (ii) carbothermal reduction. The irregularly shaped resin powder transforms to a spherical-shaped morphology in the first step, and the resulting silica-coated spherical carbon powder is converted to β-SiC in the second step. The key factor in the first step is the utilization of fumed silica that has hydrophobic surface functional groups. Hydrophobic interactions at the point of intimate contact between the resin powder and the silica likely reduce the surface energy of the resin powder, thereby discouraging interparticle coalescence. The resulting β-SiC powder exhibits a radially developed columnar microstructure. Hollow β-SiC spheres also can be prepared by controlling the reaction conditions in the carbothermal reduction step.
Databáze:	OpenAIRE
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