Improved mechanical and microwave absorption properties of SiC fiber/mullite matrix composite using hybrid SiC/Ti₃SiC₂ fillers

SiC fiber reinforced mullite matrix (SiC_f/Mu) composites were prepared via an infiltration and sintering process using SiC and Ti₃SiC₂ as inert fillers. The effects of SiC and Ti₃SiC₂ fillers on microstructure, mechanical, dielectric and microwave absorption properties of the composites were studied. The composite with 15 wt% SiC filler obtained a flexural strength of 300 MPa. The complex permittivity of the composite was enhanced from 12.3−j22.1 to 14.2−j39.7 at 10 GHz when the Ti₃SiC₂ content increased from 10 wt% to 30 wt%. By adding 15 wt% SiC and 10 wt% Ti₃SiC₂ in the matrix, both mechanical and microwave absorption properties of the SiC_f/Mu composites were significantly improved. A flexural strength of 292 MPa and a failure displacement of 0.47 mm were obtained for the composite with hybrid SiC/Ti₃SiC₂ fillers. The composite with a thickness of 2.9 mm obtained an effective absorption bandwidth of 3.3 GHz (from 9 to 12.3 GHz), with a minimum reflection loss of −53 dB at 8.64 GHz. Results indicated that the SiC_f/Mu composite with hybrid SiC/Ti₃SiC₂ fillers was one of the excellent structural-functional candidates for military application.