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

Abstract

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 Si3N4 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 FeAlxSi1−x on the phase composition, microstructure, dielectric loss, and microwave absorption mechanism of SiC–Si3N4 porous ceramics were systematically investigated. When FeAl0.25Si0.75 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 Si3N4 crystal and the generation of Al2O3. The introduction of FeAl0.25Si0.75 into SiC–Si3N4 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.