Si-Ti-C-O系繊維の熱分解に及ぼす酸素の影響

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The mechanism of pyrolysis of two types of amorphous Si-Ti-C-O fibers (Tyranno fiber T-1 containing 17.8% O and T-2 containing 13.3%O) was studied in an argon atmosphere at temperatures from 1673 K to 1973 K. The pyrolysis rate was measured with a thermobalance, and the pyrolysis products were investigated by X-ray diffraction and TEM observation. The amorphous fiber T-1, in which the atomic arrangement was disordered in comparison with that in T-2, evolved both SiO and CO to crystallize to β-SiC and TiC rapidly. TEM observation showed three-dimensional growth of SiC crystallites. At the same fractional decomposition of the fiber, the crystallite of T-1 was smaller than that of T-2. The pyrolysis rate was described with an Avrami-Erofeev equation. The exponent m of this equation was 1.4 for both fibers. The rate constant k for T-1 was larger than that for T-2. The activation energies were 413 kJ/mol for T-1 and 368 kJ/mol for T-2. The pyrolysis rate was determined by the crystal growth of SiC controlled by the diffusion of carbon in the fiber.
社団法人日本セラミックス協会の論文
1991-05-01