Mesporous 2H/3C-SiC heterojunction fibers for microwave-absorbing properties

Silicon carbide (SiC), recognized as a high-quality dielectric material, stands out as a promising candidate for wave-absorbing applications. Nevertheless, at room temperature, SiC often suffers from suboptimal impedance matching and loss coefficients, resulting in inferior wave-absorbing performance. In response to this challenge, we synthesized polymer-derived ceramics (PDCs)-SiC fibers rich in heterojunctions and turbostratic carbon. This was achieved by incorporating cobalt (Co) catalysts into the organopolysilazane spinning precursor, followed by high-temperature pyrolysis. We systematically investigated the influence of Co catalyst content and pyrolysis temperature on the electromagnetic absorption (EMA) properties of PDCs-SiC and elucidated the underlying wave-absorption mechanism. Our findings reveal that the introduction of an appropriate quantity of Co catalyst not only effectively reduces the temperature required for the conversion of organopolysilazanes into SiC but also facilitates the growth of 2H-SiC and a substantial amount of turbostratic carbon within the fibers. This unique structure serves to enhance the conductivity loss and simultaneously generates an abundance of interfaces and dipole polarization. The fabricated mesoporous 2H/3C-SiC heterojunction fibers exhibit outstanding wave-absorbing capabilities. Specifically, at a thickness of 1.4 mm, they achieve a minimum reflection loss (RL min ) of −53.93 dB, and at a thickness of 1.6 mm, they possess an effective absorption bandwidth (EAB) of 3.21 GHz. Moreover, the EAB can be precisely regulated by adjusting the Co content. This work offers innovative perspectives for the subsequent design of novel wave-absorbing materials with enhanced absorption capacity.