Silicon carbide nano-fibers in-situ grown on carbon fibers for enhanced microwave absorption properties

Abstract

Silicon carbide nano-fibers (SiCNFs) were in-situ grown on the surface of carbon fibers by catalysis chemical vapor deposition (CCVD) with Ni nano-particles as catalyst at 1000°C. The phase composition, microstructures, oxidation resistance and microwave absorption properties of the SiCNFs coated carbon fibers were investigated by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Thermal gravity analysis (TGA) and Vector network analyzer, respectively. The results show that the as-grown nano-fibers which are mainly composed of β-SiC, present a withe-like morphology with diameter of 20–50nm and aspect ratio of 100–150. Additionally, the TGA curves indicate that the oxidation resistance of the SiCNFs coated carbon fibers is significantly improved in comparison to the pure carbon fibers. Moreover, the investigation reveals that the microwave absorption properties of the SiCNFs coated carbon fibers are effectively enhanced. The reflectivity of the SiCNFs coated carbon fibers is less than −10dB within the frequency ranging from 9.2 to 11.7GHz and the lowest value of reflectivity can approach −19.9dB when the thickness of specimen is 2mm. While the reflection loss of the pure carbon fibers is higher than −2.1dB within the whole band ranging from 2 and 18GHz. The superior microwave absorbing performance of the SiCNFs coated carbon fibers is mainly attributed to the improved impedance matching as well as dissipation resulted from hopping migration. In conclusion, this study provides an effective modification approach to improve the microwave absorption properties of carbon fibers. Finally, the SiCNFs coated carbon fibers could be considered as a promising candidate in light-weight microwave absorbing materials.