Carbothermal Synthesis, Properties, and Structure of Ultrafine SiC Fibers
А. С. Лебедев, А. V. Suzdaltsev, В. Н. Анфилогов, А. С. Фарленков, Н. М. Поротникова, Э. Г. Вовкотруб, L. A. Akashev
Abstract
This paper briefly reports the results of the carbothermal synthesis of SiC from natural graphite and quartz in a reactor with a self-organizing protective CO–SiO atmosphere and in argon at a temperature between 1600 and 1650°C. The chemical and phase compositions of the synthesized SiC have been determined using chemical analysis, X-ray diffraction, and Raman spectroscopy. We have found conditions for obtaining the 6H-SiC or 3C-SiC polytype with a total impurity concentration within 0.3 ppm (with no allowance for the SiO2 film). The structural properties and particle size of the SiC powder obtained in a reactor with a CO–SiO atmosphere have been studied using scanning electron microscopy, laser diffraction, ellipsometry, and mathematical description of physical adsorption. The SiC powder has been shown to consist of platelike agglomerates in which the average particle size (40 to 60 μm) and shape have been inherited from the graphite used in the synthesis process and which have a specific surface area of 10.4 m2/g. The agglomerates have a fibrous structure, with fiber diameters from 100 to 300 nm (the thickness of the forming SiO2 film is 53 ± 2 nm).