Carbon fiber/Si3N4 composites with SiC nanofiber interphase for enhanced microwave absorption properties

In this paper, SiC nanofibers (SiCNFs) as multifunctional interphase were prepared on carbon fibers via catalysis chemical vapor deposition (CCVD) in order to improve the microwave absorption for carbon fiber reinforced silicon nitride (CFs/Si3N4) composites. Experimental results indicated that the chemical compatibility between CFs and Si3N4 matrix under high temperature could be effectively improved by incorporating SiCNFs interphase. Additionally, the dielectric responses and microwave absorbing performance of CFs/Si3N4 composites are significantly influenced by the mass fraction of SiCNFs on CFs. An optimal reflection loss (RL) of -14 dB and 96% absorbing bandwidth (BW) of X-band could be achieved in the CFs/Si3N4 composites with 8 wt % of SiCNFs. Furthermore, experimental points of permittivity in Cole-Cole plane are inclined to distribute on distinguishing circular arcs, corresponding to three types of electric polarization modes. It is concluded that the hopping relaxation of electrons between SiCNFs plays more pronounced contribution to the superior microwave attenuation capability of CFs/Si3N4 composites with SiCNFs interphase than the relaxation loss of free electrons inside short CFs.