Microstructure, microwave absorbing and mechanical properties of SiC_f/Si₃N₄composites containing frequency selective surface (FSS)-type fiber cloth

In order to obtain superior microwave absorption and mechanical qualities of SiC_f/Si₃N₄ composites, two types of SiC fibers with high strength and distinct dielectric characteristics were chosen in this work. First, SiC_f/Si₃N₄ composites with frequency selective surface-type fiber cloth (FSS-SiC_f/Si₃N₄) were designed. Through the use of a multi-scale absorbing structure, the electromagnetic wave absorption ratio can surpass 60 % in the 8–18 GHz frequency range. At the same time, the uniform distribution of the BN interface and Si₃N₄ matrix in the FSS-SiC_f/Si₃N₄ composites can effectively transfer stress, which further improves the mechanical stability of the material, and thus FSS-SiC_f/Si₃N₄ can maintain outstanding mechanical properties (flexural strength of 330 ± 20 MPa, tensile strength of 147 ± 13 MPa). The above experimental results confirm that this work successfully realizes the preparation of high-strength absorbing materials by constructing FSS type fiber cloth.