Optimization of Ti with modified SiC ceramics for electromagnetic absorption properties

The high conductivity of SiC ceramics by polymer-derived ceramics (PDCs) technology hampers their application in electromagnetic (EM) wave absorption. The current study reports SiCTi ceramics by PDCs technology with Ti modified polycarbosilane (PCS), which effectively increases the polarization loss and reveals the composition evolution among carbon, SiC and TiC, achieving adjustable dielectric and EM wave absorption properties. The addition of Ti not only reduces the free carbon and induces the growth of SiCnws for a three-dimensional (3D) network structure but also enriches multiple loss media of TiC, SiC, SiCnws, and carbon. According to the first-principles calculation, the electronic interaction in the two types of hetero-interfaces (TiC/C, SiC/TiC) is significantly lower than that of the C/SiC hetero-interface, which reduces the electrical conductivity. The results exhibit that SiCTi ceramics (3 wt% Ti, at 1300 °C) have a minimum reflection coefficient (RC_min) of −16 dB at 8.9 GHz, and the effective absorption bandwidth (EAB) is 4.2 GHz (in the whole X band) when the thickness varies from 1.7 to 2.4 mm because of the adjustable polarization loss, conduction loss and multiple reflections and scattering. This work points out the direction for high conduction loss materials to achieve effective EM wave absorption by constructing a hetero-interface and optimizing the composition for high temperature applications.