Preparation of SiC Nanofibers by Using the Polymer Blend Technique

SiC nanofibers were prepared by using polymer blend and melt-spinning techniques. Polycarbosilane (PCS) as a SiC precursor polymer was dispersed finely in novolac-phenolic resin (PF) as a carbon precursor polymer with a ratio of PCS/PF=3/7. The polymer blend was melt-spun continuously. The fibers were then soaked in an acid solution in order to stabilize them (to convert into an infusible state) and finally heat-treated at 1000°C. The resulting fibers consisted of PF-derived carbon matrix including elongated nanofibers derived from PCS. Finally, the fibers were oxidized with nitric acid to remove the carbon matrix, and the released nanofibers were collected with a membrane filter. The resulting nanofibers were several 100 nm in diameter and 100 μm or more in length. They were amorphous and contained a large amount of oxygen. A part of the nanofibers was further heated to 1500°C in a graphite tube resistance furnace, resulting in crystallization into β-SiC. The behaviors were quite similar to those of a commercially available SiC fibers derived from PCS. In order to obtain optimum conditions, the processes were examined.