Microstructure evolution and microwave absorbing properties of novel double-layered SiC reinforced SiO2 aerogel

Abstract

In this paper, a novel double-layered SiC reinforced SiO2 aerogel (SSA) was successfully synthesized by a facile route. The porous double-layered SiC microstructure was constructed by chemical vapor deposition (CVD) technology, and SiO2 aerogel was introduced by sol-gel method to adjust the dielectric properties. The microstructures of the interconnected double-layered SiC structure remained intact after SSA formation. The porous SiO2 aerogel particles were filled between the double-layered SiC structure, and the stem segments of the double-layered SiC structure were wrapped by SiO2 aerogel. In addition, SiO2 aerogel spread into the hollow pores of the double-layered SiC, forming a large number of interfaces. As expected, SSA could be used as an absorber. The minimum reflection loss (RL) value of SSA achieved − 22.80 dB at 15.77 GHz at the thickness of 3.57 mm. The optimal effective absorption bandwidth (fE) of 6.8 GHz was recorded at a 4.0 mm absorber thickness. The absorber thickness of 3.5–5.0 mm was easy to obtain wider fE and smaller RL, which provided practical guidance for the application of SSA. Finally, the microwave absorbing mechanism of SSA was studied deeply. The importance of attenuation constant (α) was more significant than the impedance matching ratio (Zr) for the microwave absorption performance of SSA. The higher Zr ascertained that a large proportion of the electromagnetic waves entered the SSA absorber, and then the α supported the microwave absorbing mechanisms.