Enhanced high-temperature dielectric and microwave absorption properties of SiC fiber-reinforced oxide matrix composites

Because of outstanding performances of the SiC fiber-reinforced ceramic matrix composites in aircraft/aerospace systems, two silicon carbide fiber-reinforced oxide matrices (SiC_f/oxides) composites have been prepared by a precursor infiltration and sintering method. Results indicate that the flexural strength of the SiC_f/Al₂O₃–SiO₂ composite reaches 159 MPa, whereas that of the SiC_f/Al₂O₃ composite is only 50 MPa. The high-temperature microwave absorption properties of the composite are significantly enhanced due to choosing Al₂O₃ and SiO₂ as the hybrid matrices. Particularly, the minimum reflection loss (RL) value of the SiC_f/Al₂O₃–SiO₂ composite reaches −37 dB in the temperature of 200 °C at 8.6 GHz, and the effective absorption bandwidth (RL ≤ −5 dB) is 4.2 GHz (8.2–12.4 GHz) below 400 °C. The superior microwave absorption properties at high temperatures indicate that the SiC_f/Al₂O₃–SiO₂ composite has promising applications in civil and military areas.