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 °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.