Dielectric, electromagnetic absorption and interference shielding properties of porous yttria-stabilized zirconia/silicon carbide composites

SiC was infiltrated into porous yttria-stabilized zirconia (YSZ) felt by chemical vapor infiltration (CVI), and continuous SiC matrix layer was formed around YSZ fibre. When 86.9 wt.% SiC is introduced into the porous YSZ felt, the mean values of the real part of the permittivity and dielectric loss tangent of porous YSZ felt increase from 1.16 and 0.007 to 8.2 and 1.31, respectively. The electromagnetic interference (EMI) shielding efficiency (SE) increases from 0.069 dB to 16.2 dB over the frequencies ranging from 8.2 GHz to 12.4 GHz. The reflection loss of the composites with a thickness of 5 mm at 8-18 GHz is smaller than -6.5 dB, and the bandwidth below -10 dB is 5 GHz at room temperature, which increases to 5.9 GHz at 800°C. The considerable increases in EMI SE and microwave absorption properties are attributed to the formation of continuous SiC matrix layer composed of SiC nanocrystals in the porous YSZ felt, which is beneficial for the production of induced electric current and the enhancement of dielectric loss.