Effect of carbon nanotubes on the electromagnetic shielding properties of SiCf/SiC composites.

Carbon nanotube (CNT)-reinforced SiC f /SiC composites were prepared through in-situ growth of CNTs on SiC fiber via catalytic chemical vapor deposition (CCVD) and subsequent densification by precursor infiltration and pyrolysis (PIP) to optimize electromagnetic interference (EMI) shielding performance in the frequency range of 8.2–12.4 GHz. The influence of CNTs on the dielectric properties and EMI shielding properties of the SiC f /SiC composite were studied. The SEM/TEM morphology showed that the CNT network was formed on the surface of SiC fibers. The electrical conductivity of composites increased owing to the introduction of CNTs, leading to markedly increased conductive loss. Elevated CNT concentration was found to enhance complex permittivity and tan δ. Experimental results exhibited that absorption shielding effectiveness was the dominant EMI shielding mechanism. With the increase in CNT amount, the EMI total shielding effectiveness of the composite increased and reached a maximum of 39 dB with Co loading of 8%, an increase of 60% over that of plain SiC f /SiC composites. The achieved EMI shielding properties suggested the potential of CNT-reinforced SiC f /SiC composites as new-generation EMI shielding materials. [ABSTRACT FROM AUTHOR]