Morphologies evolution and mechanical behaviors of SiC nanowires reinforced C/(PyC-SiC)_n multilayered matrix composites

SiC nanowires reinforced C/(PyC-SiC)_n multilayered matrix composites (SM-CS for short) were prepared by combined with sol-gel and chemical vapor infiltration (CVI) method. Firstly, (PyC-SiOC)_n multilayered structure was formed by cycles of impregnation and deposition. Then SiOC was transformed into SiC by heat-treatment, and (PyC-SiC)_n multilayered structure would be obtained. At the same time, the PyC layer which was designed as the outmost layer could decrease gas supersaturation to form in-situ tubular SiC nanowires on the surface of multilayered structure. The results of three-point bending test showed that the maximum force of SM-CS composites was increased by the number of cycles of the preparation process, which were up to enhanced by 74.38% compared with C/C composite materials. The fracture surface showed that the improvement was due to the multiscale reinforcing system of (PyC-SiC)_n multilayered structure and SiC nanowires. Multilayered structure can protect carbon fibers and release stress concentration by induction of cracks. And the mechanical interlocking effect of SiC nanowires could reinforce bonding force of the remaining matrix.