Fabrication of SiCN(Fe)/Al2O3 wave-absorbing ceramics with enhanced electromagnetic performance

The SiCN(Fe)/Al2O3 composite ceramics containing C, α-Fe, and Al4C3 were designed by impregnating and pyrolysis polysilazane adding iron(III) acetylacetonate (FeAA) to porous alumina matrix. This composite material can absorb over 90% of electromagnetic wave in the range of 9–13 GHz with a thickness of 3.5 mm. The minimum reflectivity was −18 dB at 12 GHz with the addition of 3 wt% FeAA, demonstrating over 99% electromagnetic wave absorption at this frequency. Additionally, a circular metamaterial structure was designed and its wave absorption performance was simulated. The reflection coefficient of the sample in the range of 4.7–18 GHz is above 90%, and the electromagnetic absorption rate at 7.152 GHz is nearly 100%. This paper presents a novel porous alumina ceramic loaded with SiCN(Fe) composite material with excellent wave absorption performance. It also analyzes the loss and absorption mechanisms of electromagnetic wave at different frequencies, providing an experimental and theoretical basis for the practical application of porous ceramic matrix composite wave absorbing materials.