Abstract: To achieve superior microwave absorption performance, electromagnetic absorbing materials must possess both excellent impedance matching and strong attenuation capability. Outstanding absorption results can be attained by employing microwave-transparent material coatings to enhance interfacial polarization and by incorporating magnetic components for dielectric-magnetic coupling effects. In this study, binary SiO₂@SiC composites were synthesized via a sol-gel method using an ethanol-water mixed solvent. Subsequently, SiO₂@SiC/ZnFe₂O₄ ternary composites were prepared through a following sintering process. The influence of the ethanol-to-water volume ratio (V_A/W) on the structure and electromagnetic parameters of SiO₂@SiC was systematically investigated, and the microwave absorption properties of the ternary composites were further tuned by varying the ZnFe₂O₄ content. The results indicate that the binary SiO₂@SiC composites exhibited limited absorption performance due to its weak dielectric attenuation capacity, achieving a minimum reflection loss (RL_min) of only -13 dB at V_A/W = 3:1. Upon incorporation of ZnFe₂O₄, the dielectric loss of the composites was significantly enhanced, and the impedance matching was effectively improved. The optimized ternary composite achieved an RL_min of -48.2 dB at a matching thickness of 2.5 mm with V_A/W = 1:1. Meanwhile an effective absorption bandwidth (EAB) of 6.7 GHz was obtained at V_A/W = 5:2. These excellent absorption properties are primarily attributed to the strong interfacial polarization arising from the abundant heterogeneous interfaces constructed among ZnFe₂O₄ nanoparticles, SiO₂, and SiC, as well as the optimized impedance matching enabled by the dielectric-magnetic synergistic coupling.

Key words: SiC, interfacial polarization, electromagnetic absorption, ZnFe₂O₄ ferrite