Evaluation of oxidation resistance of thin continuous silicon oxycarbide fiber derived from silicone resin with low carbon content

Si–O–C ceramic fiber was synthesized from a kind of silicone resin with low carbon content. The melt-spun resin fiber was exposed to SiCl₄ vapor under a nitrogen gas flow, and the fiber was heated at 373 K for 2 h to complete the curing process. The cured fiber was pyrolyzed at 1273 K in an inert atmosphere to be converted to Si–O–C fiber. The entire chemical composition of the pyrolyzed fiber was almost identical to that of a previously reported resin which was pyrolyzed without curing. Auger spectrum analysis indicated an increase in silicon content near the fiber surface. The Si–O–C fiber thus obtained was heat-treated at 1511 or 1603 K in an air flow to evaluate oxidation resistance. Elemental analysis, XRD measurement, and SEM image observations were carried out on the oxidized Si–O–C fibers. Even with such thin fiber diameters, the oxidation process under these conditions was slow and the formation of a thin oxide layer on the fiber surface was confirmed. The existence of a residual Si–O–C core surrounded by a crystallized silica layer was observed in fractured fiber cross-sections after severe treatment conditions of 24 h oxidation at 1511 K or 3 h oxidation at 1603 K.