High mechanical properties and microwave absorption performances of SiCw/Si 3 N 4 ceramic composites

In this work, a structural–functional integrated SiCw/Si 3 N 4 composite with high mechanical and microwave (MW) absorption properties was prepared by hot pressing at 1800 °C. By adding the amount of 20 wt% SiC whiskers (SiCw), the SiCw/Si 3 N 4 composite achieved excellent relative density (98.6%) and mechanical properties, i.e., bending strength (938.6 ± 40.7 MPa), fracture toughness (9.40 ± 0.72 MPa m 1/2 ), hardness (20.5 ± 0.8 GPa) and Young’s modulus (216.3 ± 21.7 GPa). Additionally, the SiCw/Si 3 N 4 composite exhibits an effective absorption bandwidth of 2.74 GHz at 1.6 mm thickness. The improved mechanical properties were mainly attributed to crack deflection and pullout of SiCw and Si 3 N 4 grains. Meanwhile, the improved MW absorbing properties of the material were due to the dielectric loss of the SiC phase and good impedance matching. Overall, the SiCw/Si 3 N 4 composite presented in this study demonstrates the potential for the preparation of structural and functional integrated ceramics.