β-SiC/AlN microwave attenuating composite ceramics with excellent and tunable microwave absorption properties

In this study, β-SiC is utilized as a novel attenuating agent. A series (5–40 vol%) of β-SiC/AlN microwave attenuating composites with full density are prepared by hot-pressing sintering. The β-SiC incorporation is found to slow AlN grain growth and generate SiC-AlN solid solution during sintering. As the β-SiC content increases to 40 vol%, the conductivity of the composites monotonously increases and demonstrates typical percolation behavior at 17.5 vol%. The microstructure of homogeneously distributed β-SiC and SiC-AlN solid solution endows the composites with enhanced complex permittivity, dielectric loss and absorption capacity. After adjusting the content of β-SiC, the 25 vol% sample shows optimal microwave absorption performance with four absorption peaks at 3.5–5 mm thicknesses. The absorption performance in terms of optimal absorption frequency and thickness is significantly tunable for 25–40 vol%β-SiC samples. This work highlights the great potential of β-SiC/AlN composites as efficient microwave attenuating materials with effectively regulated absorption performance.