Microwave absorption properties of polymer-derived SiCN(CNTs) composite ceramics

With advantages of light weight, good thermal stability and strong oxidation resistance, SiCN ceramic is a promising material for application related to dielectric and microwave absorption function. Precisely, SiCN ceramic, as a good absorbing material, is able to enhance the microwave absorption properties when coupled with other absorbers as the matrix. The present study aims to fabricate SiCN(CNTs) composite ceramics by dispersing carbon nanotubes (CNTs) into SiCN ceramic matrix, in order to improve the electrical conductivity and strengthen the microwave absorption effect in alternating electric field of SiCN based composite ceramics. The phase composition, microstructure, chemical composition, electromagnetic parameters and microwave ab-sorption properties of SiCN (CNTs) pyrolyzed at different temperatures were analyzed. The results show that the optimum RL-38.40 dB at 18 GHz was obtained in the sample with a thickness of 4.4 mm, where the effective absorption bandwidth (EAB) was 1.3 GHz, when the pyrolysis temperature was fixed at 1100 degrees C. By further increasing the sample thickness to 4.7 mm, a wider EAB of 2.16 GHz was revealed. Overall, the microwave absorption properties of SiCN(CNTs) shows significant enhancement compared to SiCN ceramics, demonstrating that with excellent absorbing properties, thin thickness, light weight and wide EAB, SiCN (CNTs) has huge potential as a competitive absorbing material.