Dielectric response and microwave absorption properties of SiC whisker-coated carbon fibers

SiC whisker-coated carbon fibers with improved microwave absorption properties were synthesized by catalysis chemical vapor deposition. Dielectric response and microwave absorption properties of SiC whisker-coated carbon fibers were investigated at the frequency range of 2-18 GHz. 8 and 18 wt% SiC whiskers were grown on carbon fibers after depositing for 2 and 3 h, respectively, and the whiskers grew thicker and more compact with prolonged deposition time. Many stacking faults formed during the growth of SiC whiskers. Moreover, carbon fibers coated with 8 and 18 wt% SiC whiskers both presented decreased complex permittivity. Although their electromagnetic wave attenuation capability slightly decreased, impedance matching clearly improved. The minimum reflection loss of carbon fibers significantly increased from around - 2 to - 19.8 dB after coating with 18 wt% SiC whiskers at a thickness of 2.0 mm. Carbon fibers coated with 18 wt% SiC whiskers also exhibited remarkably enhanced microwave absorbing properties of - 44.53 dB at 7.4 GHz at a thickness of 3.0 mm.