Fabrication and electromagnetic absorbing properties of CNTs modified PDCs-SiOC

To enhance dielectric properties and electromagnetic (EM) absorption performances of polysiloxane (PSO) derived SiOC ceramics, carbon nanotubes (CNTs) as modifiers were introduced by the pyrolysis of CNTs/PSO mixtures. Effects of CNTs content and heat treatment temperature on the microstructure evolution and dielectric properties of CNTs/SiOC composites are studied. Results show that CNTs can accelerate the crystallization of SiOC and such a role becomes more significant with CNTs content and heat treatment temperature increasing, inducing the formation of large-sized SiC nanocrystals and SiC nanowires. Foreign CNTs, crystalline SiC phases, and amorphous SiOC matrix construct a typical A/B/C EM absorption structure, which endows CNTs/SiOC with greatly improved reflection losses. When the CNTs content is 2 wt%, CNTs/SiOC with a thickness of 2.9 mm treated at 1400 degrees C reaches a minimum reflection coefficient of -59 dB at 9.6 GHz and has an effective EM absorption bandwidth of 3.5 GHz in the X-band.

Automated summary

Carbon nanotubes (CNTs) were introduced as modifiers to improve the dielectric properties and electromagnetic (EM) absorption performances of polysiloxane (PSO) derived SiOC ceramics. The effects of CNTs content and heat treatment temperature on the microstructure evolution and dielectric properties of CNTs/SiOC composites were studied. Results showed that CNTs can accelerate the crystallization of SiOC, leading to the formation of large-sized SiC nanocrystals and SiC nanowires. The CNTs/SiOC composites exhibited significantly improved reflection losses due to the A/B/C EM absorption structure formed by foreign CNTs, crystalline SiC phases, and amorphous SiOC matrix. The optimized CNTs/SiOC composite had a minimum reflection coefficient of -59 dB at 9.6 GHz and an effective EM absorption bandwidth of 3.5 GHz in the X-band, with a CNTs content of 2 wt% and treated at 1400 degrees C with a thickness of 2.9 mm.