Preparation of in situ grown silicon carbide nanofibers radially onto carbon fibers and their effects on the microstructure and flexural properties of carbon/carbon composites

Silicon carbide nanofibers (SiCNFs) used as the second reinforcements of carbon/carbon composites were grown radially on the carbon fiber surface. The microstructure of SiCNFs and their effects on the microstructure and flexural properties of C/C composites were investigated. Results show that there are many defects such as twin crystals and stacking faults in SiCNFs which were grown by catalytic chemical vapor deposition. During the same process, the skin region of carbon fiber has changed. Several SiC layers are formed and the arrangement of the graphite layers around SiC layers is more orderly. In the next chemical vapor infiltration, due to the induction of SiCNFs, the middle textural pyrocarbon were formed firstly and then is the high textural pyrocarbon. The existence of SiCNFs also contributes to the three-phase interface between pyrocarbon, SiCNFs and carbon fibers, resulting in a good bond between carbon fiber and matrix. Those structural changes lead the better flexural properties of SiCNF–C/C composites compared with C/C composites.