High mechanical properties and microwave absorption performances of SiCw/Si3N4 ceramic composites

In this work, a structural-functional integrated SiCw/Si3N4 composite with high mechanical and microwave (MW) absorption properties was prepared by hot pressing at 1800 degrees C. By adding the amount of 20 wt% SiC whiskers (SiCw), the SiCw/Si3N4 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/Si3N4 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 Si3N4 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/Si3N4 composite presented in this study demonstrates the potential for the preparation of structural and functional integrated ceramics.