Simultaneously improving the mechanical strength and electromagnetic interference shielding of carbon/carbon composites by electrophoretic deposition of SiC nanowires

Abstract

C/C composites with both high specific strength and excellent electromagnetic shielding efficiency are required for advanced space applications. For this purpose, SiC nanowires (SiCNWs) were introduced in C/C composites by electrophoretic deposition. The presence of SiCNWs in C/C induces the formation of a SiCNW/pyrocarbon coaxial structure, which refines the matrix and decreases the stress concentration of the matrix. The average flexural strength of C/C composites increases by ∼100% after adding SiC nanowires due to enhanced interlaminar bonding after introducing the nanowires. Meanwhile, the average electromagnetic shielding efficiency in the X band (8.2–12.4 GHz) increases from 35.6 dB to 60.5 dB with an optimized nanowire content. Reflection is the predominant mechanism for electromagnetic shielding while introducing SiC nanowires also enhances the electromagnetic absorption within the composites. As pyrocarbon in the SiCNW–pyrocarbon coaxial structure shows a higher degree of crystallization, the coaxial structure increases the electron loops in the matrix and greatly improves reflection at high frequency. Also, the absorption of electromagnetic waves inside the composites is enhanced by introducing SiCNWs due to the increase of electron hopping among interfaces. This work proves that introducing SiC nanowires is promising in fabricating lightweight C/C composites with excellent mechanical and electromagnetic properties.