Regulating synergistic micro-nano pore structure of CNT sponge to control EMI shielding performance

The aggregation in high-content carbon nanotube reinforced silica carbide composites (CNT/SiC) imposed constraints for further large-scale industrial applications. This study established a synergistic micro-nano pore structure by assembling CNT bundles to fabricate the CNT sponge preform, and then the SiC matrix was in-situ deposited by chemical vapor infiltration method, which facilitates composites with high density and exceptional properties. The pore size distribution and pore area can be regulated by simply adjusting the compression ratios (CRs) of the as-assembled CNT sponge. Samples with CR of 50 % exhibited noteworthy densification, significantly reduced porosity, and a remarkable 163.54 % extra increase in compression strength compared to uncompressed ones. Additionally, the CNT/SiC composites displayed excellent oxidation resistance and demonstrated improved electromagnetic interference (EMI) shielding performance, which exhibited a substantial increase with higher CRs. These findings underscore the significance of employing appropriate multi-level porosity in CNT preforms to fabricate advanced ceramic matrix composites with superior EMI shielding capabilities.