Microstructures and EMI shielding properties of composite ceramics reinforced with carbon nanowires and nanowires-nanotubes hybrid

Carbon/ceramic composites are promising candidates as electromagnetic interference (EMI) shielding materials used at various harsh environments. The aim of present work is to prepare and investigate two kinds of composite ceramics reinforced with carbon nanowires (CNWs) and nanowires-nanotubes (CNWs-CNTs) hybrid, respectively. Results indicate that CNWs is highly curved and multi-defected, and CNWs-CNTs hybrid shows the best crystal structure at an optimal catalyst concentration of 5 wt%. When CNWs accounts for 5.15 wt%, the total shielding effectiveness (SE) of CNWs/Si3N4 reaches 25.0 dB with absorbed SE of 21.3 dB, meaning that 99.7% incident signal can be blocked, while it reaches 25.4 dB for CNWs-CNTs/Si3N4 as the carbon loading only increasing to 3.91 wt%. By contrast, CNWs/Si3N4 exhibits better electromagnetic attenuation capability with stronger absorption, mainly due to the unique microstructure of CNWs. Both of two composite ceramics have great potential to be designed as structural and multi-functional materials.