Multiscale Reinforcement of Multi-layer Ceramic Composites with Micrometer-scale Carbon Fibers and In-Situ Formed Nanometer-scale SiC Nanowires

In this study, the multi-layer ceramic composites were reinforced by carbon fibers and SiC nanowires at the micrometer- and nanometer-scales, respectively. The reinforcement and failure mechanism of carbon fibers and the growth mechanism of SiC nanowires were investigated by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results showed that the surface of carbon fibers and the microcracks of fused SiO2 were the main regions for in-situ forming SiC nanowires. The concentration of C atoms was the main reason for the various morphologies of the nanowires and the propensity of the growth positions. Hence, the thread-shaped SiC nanowires coated by an amorphous carbon coating with a thickness of 13 nm eventually grew into a rod-shape with a diameter of 41 nm. In addition, the maximum strength of the samples was raised by 14.72 MPa when the carbon fiber content and sintering temperature were 0.4 wt% and 1500 °C, respectively, over the samples without carbon fibers. In conclusion, the synergistic effect of micrometer-scale carbon fibers and the nanometer-scale SiC nanowires dramatically promoted the enhancement of ceramic matrix.