Fabrication of Alumina and Silicon Carbide Fibers from Carbon Fibers

Abstract:

Carbon fibers of ~9 μ m in diameter were used as templates to fabricate alumina and silicon carbide fibers. The carbon fibers were placed in a vacuum furnace with aluminum and heated at 1100°C for 8 h to form aluminum carbide. Then, the aluminum carbide fibers were oxidized in air at 1500°C. The resulted fibers were hollow and the alumina layer was porous in the interior. To fabricate silicon carbide fiber, carbon fibers were reacted with Si at 1300°C -1500°C in Ar. The thickness of silicon carbide layers increased with reaction temperature and reaction time. Solid fibers could be obtained after reaction at 1400°C for 4 h. In contrast to porous alumina layer, the silicon carbide layer/fibers were dense. The porous alumina hollow fibers were fragile while the solid silicon carbide fibers were flexible. BET surface area measurements revealed that the porous alumina had surface area as high as ~100 m2/g.