Formation of silicon carbide on carbon fibers by carbothermal reduction of silica

Abstract

Both PAN- and pitch-based carbon fibers were reacted at different temperature by carbothermal reduction of silica with the objectives of understanding texture and oxidation behavior changes of both carbon fibers, and the role of carbon precursor and reaction temperature. The reduction at 1800 °C resulted in the SiC coating on the fibers as expected, but the microtextures were different with carbon precursors. Unexpectedly, both carbon fibers were completely converted into SiC fibers at 1500 °C but with different microtextures: PAN-based carbon fibers were composed of approximately 1-μm size of grains; in contrast, pitch-based carbon fibers consisted of 100-nm size of particles. Oxidation resistance of the fibers increased as the reduction temperature increased, but it was overturned at 1800 °C due to the remaining unreacted carbon.