High-temperature electromagnetic wave absorption and structural reliability of SiC/Si₃N₄ composites with integrated load-bearing capability

In this study, we synthesized SiC/Si₃N₄ composite ceramics with varying SiC contents using spark plasma sintering (SPS) to achieve a balance between mechanical integrity and electromagnetic wave (EMW) absorption efficiency. A systematic investigation was conducted to assess the impact of SiC content on the microstructure, dielectric properties, and reflection loss (RL). The composite ceramic containing 30 wt% SiC (SCN30) demonstrated optimal impedance matching and EMW absorption, achieving the lowest RL value of –57.6 dB and an effective absorption bandwidth (EAB) of 2.0 GHz at a minimum thickness of 1.19 mm. Effective absorption was sustained up to 500 °C, whereas performance degradation at higher temperatures was primarily due to conductivity-induced impedance mismatch. This exceptional EMW absorption capability is attributed to the synergistic effects of conductive loss, interfacial polarization, and impedance matching. Moreover, the fracture toughness of this composite material was maintained at a high level of 7.91 ± 0.24 MPa·m^1/2, highlighting its dual attributes of structural and functional integration.