Cf@BN/(CrZrHfNbTa)C-SiC High-Entropy Ceramic Matrix Composites with Outstanding Electromagnetic Interference Shielding and High-Temperature Resistance

Electromagnetic interference (EMI) shielding materials with excellent load-bearing and high-temperature resistance have attracted much attention for both civil and military applications. In this regard, mechanically robust (bending strength of 246 ± 15 MPa) Cf@BN/(CrZrHfNbTa)C-SiC high-entropy ceramic matrix composite with BN interphase was designed and fabricated in this work for highly EMI shielding performance and high-temperature resistance. As a result of the synergistic effect of multi-components, mean total EMI shielding efficiency (SET) of the composite with 3 mm thickness is up to 32.5 dB (higher than 99.9% EMI shielding) in Ku-band. This indicates that thickness of the BN interphase has a remarkable effect on EMI shielding performance, indicating that the absorption coefficient (A) increases gradually with increasing BN thickness. The EMI shielding performance exhibit excellent high-temperature stability in an oxidation environment. Even after multiple high temperature oxidations in the temperature range of 400-800 °C, the composite remains outstanding EMI shielding performance. This study provides a structural and functional integrated EMI shielding material with a potential long service life at high temperatures.