Influence of porosity on the electromagnetic shielding properties of 3D C/C composites

3D carbon/carbon (C/C) composite materials with different porosities and bulk densities were fabricated by repeated precursor infiltration and pyrolysis (PIP) process, and the electromagnetic interference shielding (EMI) effectiveness of C/C composites at 8.2-12.4 GHz (X band) with different porosities were studied. The results indicate that both EMI absorption shielding effectiveness and the total EMI shielding effectiveness of C/C composites could be improved by reducing the porosity appropriately. When the open porosity is 33.4%, the C/C composite material shows a maximum shielding effectiveness of 40 dB, and the EIM apsorption shielding effectiveness (30 dB) is much higher than EMI reflection shielding effectiveness (12 dB)). Porous C/C composite is one kind of excellent EMI shielding materials with high absorption and low reflection.