WANG Xiaomeng, MA Xin, WANG Lin, QIU Haipeng, LIANG Yanyuan, ZHAO Yuliang,LUO Wendong, JIA Wei

(Composite Technology Center, AVIC Manufacturing Technology Institute, Beijing 101300, China)

Abstract:  In order to address of limitation of the absorption performance of structural microwave-absorbing ceramic matrix composites through fiber design, multi-walled carbon nanotubes (MWCNT) were used as fillers that were dispersed uniformly in liquid polycarbosilane precursor. Silicon carbide (SiC)-based microwave absorbing ceramic matrix composites were prepared through precursor infiltration and pyrolysis (PIP). The influence of the nano-fillers on dielectric properties of the matrix and microwave absorbing properties of the composites was studied. It was found that 3 wt.% MWCNT could effectively increase dielectric constant of the SiC matrix and lead to strong microwave loss ability. However, the impedance matching between the composite material and the free space was reduced, resulting in an increase in the reflection of the incident wave on the surface. This problem was effectively solved by using an intermediate layer. Specifically, excellent absorbing performance, with reflection loss of <-6 dB in 8 GHz -18 GHz was achieved at room temperature.

Key words:  carbon nanotubes; SiC/SiC ceramic matrix composites; electrical properties; precursor infiltration and pyrolysis