Electromagnetic shielding and thermal conductive properties of SiC nanowires reinforced C/(PyC-SiC)n composites

Abstract

SiC was introduced as nanowires and multilayered structure matrix to modify C/C composites, then SiC nanowires reinforced C/(PyC-SiC)n (SM-CS) composites were prepared. The electromagnetic shielding and thermal conductive properties were investigated and the further relationship between these properties and the number of cycles of preparation (N) was also studied. The results showed that total shielding effectiveness (SET) values of modified composites were all higher than 30 dB which meant more than 99.9% electromagnetic wave was shielded. And the SET values increased with the rising of N (SM-CS4--47.6 dB > SM-CS3--42.7 dB > SM-CS2--37.1 dB). With the rising of N, not only the conductivity of SM-CSN composite increased, but also the interfaces inside the matrix increased, leading to a continuous increase in reflection and absorption of electromagnetic waves. Meanwhile, the thermal diffusivities and conductivities of the SM-CS composites in the temperature range from 25 to 1500 °C were all higher than those of pure C/C composites, and they were also almost increased by N. That was because the improvement of SiC nanowires in heat transport was very large, and even exceeded the reducing of multilayered structure. Due to these good functional properties, the modified composites would exhibit excellent potential in aerospace field.