Silicon Carbide Modified Carbon Materials. Formation of Nanocrystalline SiC from Thermochemical Processes in the System Coal Tar Pitch/Poly(carbosilane) |
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Authors: | Cezary Czosnek Jerzy F. Janik Zbigniew Olejniczak |
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Affiliation: | (1) University of Mining and Metallurgy–AGH, Al. Mickiewicza 30, 30-059 Kraków, Poland;(2) Institute of Nuclear Physics–IFJ, ul. Radzikowskiego 152, 31-342 Kraków, Poland |
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Abstract: | Poly(carbosilane) or PCS, {–CH2–SiH(CH3)–}n, is used as a Si-bearing precursor in combination with a coal tar pitch to study thermally induced transformations toward SiC-modified carbon composites. Following mixing of the components in the molten pitch at 160°C, the mixture is heated under argon atmosphere at 500°C yielding a solid carbonizate that is further subjected to separate pyrolysis experiments at 1300°C or 1650°C. At temperatures up to 500°C, the PCS reacts with suitable pitch components as well as undergoing decomposition reactions. At higher temperatures, clusters of prevailingly nanocrystalline -SiC are confirmed after the 1650°C pyrolysis step with indications that the formation of the compound starts at 1300°C. 29Si MAS NMR, XRD, FT-IR, XPS, and elemental analysis are used to characterize each pyrolysis step, especially, from the viewpoint of transformation of silicon species to silicon carbide in the carbon matrix evolved from the pitch. |
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Keywords: | poly(carbosilane) nanocrystalline silicon carbide SiC carbonizate carbon composites carbon materials 29Si MAS NMR |
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