The effect of Ag nanoparticles content on dielectric and microwave absorption properties of β-SiC

In the present work, high purity cubic silicon carbide (beta-SiC) was synthesized by using resorcinol-formaldehyde aerogel coated silica as precursor at high temperature. Subsequently, beta-SiC was coated with various concentrations of silver nanoparticles (Ag NPs) by tin sensitization electroless plating. Thereafter, the effect of various Ag NPs contents on the dielectric and microwave absorption properties of beta-SiC was investigated in detailed. It is found that the Ag NPs can significantly increase the overall complex permittivity, reduce the thickness of the absorber and increase the absorption bandwidth to some extent. Despite, the improvement of the attenuation ability of electromagnetic wave with increasing contents of Ag NPs also has an adverse effect on impedance matching. The improvement in the microwave absorption of beta-SiC coated with Ag NPs mainly comes from the enhancement of dipole polarization, interface polarization and conductivity loss. In the 2-18 GHz band, Ag@SiC (1.0 g/L) can achieve an effective bandwidth of 4.99 GHz at a thickness of 1.6 mm, and it is a kind of lightweight, high-temperature microwave absorbent with excellent performance.