Web-type silicon carbide fibers prepared by the electrospinning of polycarbosilanes

Silicon carbide web was prepared by the electrospinning of polycarbosilane (PCS) solution and the pyrolysis of the electrospun web at 1000-1400°C after a thermal curing process. The optimum spinning conditions for obtaining a uniform SiC web were a 1.3 g/ml PCS solution with 30% DMF/70% toluene composition and a spinning voltage higher than 20 kV. A uniform SiC web with fibers ranging from 1 to 3 μm was obtained. This was characterized by FE-SEM, infrared spectroscopy, thermogravimetric analysis, X-ray diffraction and transmission electron microscopy. A large amount of oxygen was introduced during the thermal curing of the as-spun web due to its large specific surface area; this resulted in an increased ceramic yield as the mixed phases of amorphous oxycarbide, SiC nanocrystallites, and amorphous silica. By increasing the pyrolysis temperature, this mixed phase underwent decomposition that made the fiber structure nanoporous.