Enhanced mechanical and wave-absorption properties of SiC–Si3N4–FeSi porous ceramics by introducing Al

SiC-based porous ceramic wave-absorbing materials have attracted much attention due to their excellent properties such as low density, high-temperature resistance, and oxidation resistance. In this work, the impedance matching of SiC ceramics is improved by introducing Si 3 N 4 wave-transparent phase, and the dielectric loss capability of SiC ceramics is enhanced by introducing FeSi wave loss phase. To achieve a balance between impedance matching and absorption loss in porous ceramics, different molar contents of Al were introduced into FeSi to tailor electromagnetic parameters. The effects of introducing FeAl x Si 1− x on the phase composition, microstructure, dielectric loss, and microwave absorption mechanism of SiC–Si 3 N 4 porous ceramics were systematically investigated. When FeAl 0.25 Si 0.75 is added, the minimum reflection loss of the porous ceramics is as low as −58.02 dB, and the flexural strength is as high as 87.23 MPa. The presence of Al promotes the transformation of the Si 3 N 4 crystal and the generation of Al 2 O 3 . The introduction of FeAl 0.25 Si 0.75 into SiC–Si 3 N 4 has constructed “inductor–capacitor–resistance” microcircuit, which enhances polarization loss, conductivity loss, and magnetic loss, and realized the double enhancement of the mechanical and wave-absorbing properties of porous ceramics.