化学量論的炭化ケイ素繊維(Hi-Nicalon-S)の酸化速度と機械的特性

概要

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The oxidation behavior of stoichiometric SiC fiber (Hi-Nicalon-S) was investigated and compared with those of Nicalon and Hi-Nicalon fibers. Hi-Nicalon-S fiber was oxidized in Ar-O_2 gas mixtures with 25-100%O_2 at 1273-1773 K. The oxidation rates were measured with thermobalance experiments. The thickening in SiO_2 film produced a large decrease in the strength of the as-oxidized fiber. The SiO_2 film-removed fiber (unoxidized core) retained high strength independent of the SiO_2 film thickness. The oxidation rate obeyed the diffusion-controlled contracting-disc formula. The rate constant was proportional to the oxygen partial pressure of Ar-O_2 gas mixture. The activation energy was 79 kJ/mol. The oxidation rate was considered to be controlled by the diffusion of oxygen molecule through the micropores in SiO_2 film. Compared to Nicalon and Hi-Nicalon, Hi-Nicalon-S is resistant to oxidation and has good strength in the oxidized state.
社団法人日本セラミックス協会の論文
2000-12-01