Study on the High-Temperature Microwave Absorption Performance and Mechanism of SiC Nanowire-Reinforced Porous Si3N4 Ceramics

SiC nanowires (SiCnw), due to their excellent dielectric properties, are promising high-temperature absorbing materials. However, the mechanism of their high-temperature absorption still requires further research. Therefore, porous SiCnw/Si3N4and SiC/Si3N4ceramics with different SiC phase morphologies were fabricated using a simple precursor impregnation and pyrolysis method. The Fe impurity content of the Si3N4powder raw material significantly affects the generation of SiC nanowires. When SiC exists in the form of nanowires, the excellent conductivity brought by the conductive network of the nanowires causes a significant response of the material’s permittivity to temperature. When the test temperature is room temperature, SiCnw/Si3N4has excellent absorption performance with a minimum reflection loss of −29.75 dB at 2.16 mm and an effective absorption bandwidth of 3.72 GHz at 2.54 mm. As the test temperature increases to 300 °C, the effective absorption bandwidth of SiCnw/Si3N4covers the entire X-band. The porous SiCnw/Si3N4ceramics exhibit excellent electromagnetic wave absorption performance, demonstrating significant application potential for high-temperature environments.