SILICON CARBIDE FIBERS MADE FROM NANO-POWDERS

Silicon carbide exhibits high strength, thermal shock resistance, chemical and thermal stability, relatively good radiation resistance and high hardness. Its use is hence expected in numerous applications, such as aeronautics, nuclear or wear resistant components. Silicon carbide fibers are used in the most demanding applications of ceramic matrix composite materials. We undertook to develop new silicon carbide fibers starting from slurries including SiC nano-powders. These slurries were extruded and further pressureless sintered. The preparation process was optimized according to the main following parameters: the type of thermal treatment, the sintering parameters and the composition of the initial mixture: SiC, sintering additives and carbon. The best parameters were selected to obtain a density reaching 97% of the theoretical density for SiC. The sintering procedure was carried out under pure argon. A temperature step of 800 degrees C was first applied to pyrolyse the binder. A second one at 1500 degrees C was used for the carbo-reduction of the silicon oxide. The sintering eventually took place at 2000 degrees C. Ongoing work is carried out to optimize the environmental conditions for pressureless sintering of pure silicon carbide fiber.