Fe-doped SiC/SiO₂ composites with ordered inter-filled structure for effective high-temperature microwave attenuation

Fe-SiC/SiO₂ monolithic composites with ordered inter-filled structure and high crystallinity were successfully prepared by nanocasting and cold-pressing at 1200°C, using polycarbosilane as a precursor and ordered mesoporous silica SBA-15 as a template. In the composites, SiC particles can be endowed with high crystallinity by a trace of Fe-doping and incorporated into nanochannels of the SBA-15 to form the ordered rodlike arrays. Their high-temperature microwave absorbing properties were investigated from 25 to 500°C in X-band (8.2-12.4GHz), in which SiC particles acted as electromagnetic (EM) wave absorbers and SiO₂ as EM wave transparent matrix. Both of the complex permittivity and dielectric loss gradually enhanced with the rising temperatures. A minimum reflection loss (RL) value of -32dB and a broader absorption band (RL<-10dB) over the whole X-band (4.2GHz) were obtained for the Fe-SiC/SiO₂ at 500°C. These good properties were attributed to the enhanced dielectric loss resulting from the intrinsic physical properties and special structures. Such monolithic composite exhibited a promising prospect as a high-temperature microwave absorbing material.