Electromagnetic interference shielding performance and mechanism of Fe/Al modified SiC /SiC composites

• The electromagnetic performance of the composites has been significantly improved after being modified by Fe(NO) 3 . • Compared with the twill weave composites, the plain weave composites exhibit better EMI shielding performance. • The plain weave structure composites modified by Fe(NO) 3 possess the maximum SE T and SE A , up to 39.29 dB and 32.36 dB. The pyrolysis of two kinds of inorganic salts Fe(NO 3 ) 3 and NH 4 Al(SO 4 ) 2 were respectively used to enhance electromagnetic interference (EMI) shielding performance of SiC f /SiC composites via improving electrical conductivity and electromagnetic performance. The results show that after the modification by Fe and Al elements, the EMI shielding effectiveness of SiC f /SiC composites have been significantly increased in the X-band (8.2–12.4 GHz). In particular, the composites with the plain weave cloth layer structure modified by Fe element possess the maximum SE T and SE A values of 39.28 dB and 32.36 dB. Compared with the composites reinforced by the twill cloth, the composites with the plain cloth structure exhibit better electromagnetic shielding performance, which can be attributed to the fabric structure difference that the more buckled yarns in the plain weave provide more reflection and absorption channels for electromagnetic waves in the material, and generate more attenuation. The shielding mechanism can be concluded that the superior shielding effect of SiC f /SiC composites is mainly based on the dissipation of electromagnetic waves caused by the multiple reflection and absorption inside the composites.