Structure and microwave absorbing property of polycarbosilane derived silicon carbide ceramic

SiC ceramic was fabricated through pyrolyzing polycarbosilane (PCS) at 800~1200 °C. The morphology, crystal phase and micro structure of free carbon were characterized by SEM, XRD and Raman spectrum, respectively. The DC conductivity of samples was tested. The complex permittivity of SiC ceramics derived from PCS (PCS-SiC) were measured by the method of rectangular waveguide using vector network analyzer in the frequency range of 8.2~12.4 GHz (X band). Based on transmission-line theory, the microwave absorbing properties of samples were calculated. The results show that DC conductivity, real and imaginary parts of permittivity increase with the evolution of pyrolysis temperature due to graphitization of free carbon in PCS-SiC ceramic. And, the microwave absorbing properties were improved due to enhancement of polarization and loss.