Electromagnetic wave absorption property of SiC whiskers regulated by stacking faults and SiC@SiO2 core-sheath microstructure

In this study, SiC whiskers were prepared by chemical vapor deposition using graphite powder mixed with resin powder and silicon powder as raw materials. The crystal structure, morphology, surface chemical state and electromagnetic wave absorption properties were studied. The density and number of stacking faults inside the SiC whiskers can be controlled by changing the proportion of nitrogen atmosphere during the preparation of SiC whiskers which in turn affects the wave absorption properties. We found that the whiskers prepared in a nitrogen-free atmosphere with a large number of stacking faults 'have better electromagnetic wave absorption performance. This is mainly due to the large number of stacking faults inside the SiC whiskers that can act as polarization and scattering centers to enhance dielectric losses under alternating electromagnetic fields. The minimum reflection loss (RL) can reach −20 dB near 17 GHz, and an effective absorption (RL ≤ −10 dB) bandwidth of 1.1 GHz (16.9–18) at the absorber layer thickness of 5 mm. In addition, after proving that a large number of stacking faults are beneficial, a SiO2 shell was designed outside the SiC whiskers through a simple oxidation process. The minimum RL can reach −35 dB near 17 GHz, and an effective absorption (RL ≤ −10 dB) bandwidth of 2.5 GHz (15.5–18) at the absorber layer thickness of 5 mm.