Reaction Mechanisms of Silicon Carbide Fiber Synthesis by Heat Treatment of Polycarbosilane Fibers Cured by Radiation: II, Free Radical Reaction |
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| Authors: | Masaki Sugimoto Toshio Shimoo † Kiyohito Okamura † Tadao Seguchi |
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| Affiliation: | Japan Atomic Energy Research Institute, Takasaki Radiation Chemistry Research Establishment, Takasaki, Gunma 370–12, Japan |
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| Abstract: | Silicon carbide (SiC) fibers were synthesized by the pyrolysis of radiation-cured polycarbosilane (PCS) fibers. The pyrolytic reaction was analyzed through free radicals by electron spin resonance (ESR). Free radicals on Si and C atoms were produced in the pyrolysis, and their yield as a function of reaction temperature depended on the oxygen content in the cured PCS fibers. There were two temperature ranges for the reactions related to Si and C atoms in PCS fibers. The radical concentration reflects the rate differences between the radical formation by the cleavage of Si-H and C-H bonds and the decay by recombination of radicals. The reaction of Si-H was strongly influenced by the oxygen content in the cured PCS fibers, and the decay rate of radicals decreased with an increase of the oxygen content in PCS fibers introduced in the curing process. |
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