低酸素Si-Ti-C-O系繊維の酸化挙動

The oxidation behavior of a Si-Ti-C-O fiber with a low oxygen content of 6 mass% has been investigated. The kinetic data of the fiber were expressed by the contracting-cylinder formula. The activation energies were calculated to be 72 and 430 kJ/mol at the low-temperature (T<1473 K) and the high-temperature (T>1473 K) regions, respectively. An oxide film consisted of SiO_2 and TiO_2 ; and the former was amorphous during the low-temperature oxidation process tending to be crystallized into cristobalite at higher temperatures. When the fiber was oxidized at 1773 K, the interface between the oxide film and the unoxidized core fiber contained many microcracks ; moreover, the core fiber lost 75% of its original strength at room temperature