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 (SiCf/oxides) composites have been prepared by a precursor infiltration and sintering method. Results indicate that the flexural strength of the SiCf/Al2O3-SiO2 composite reaches 159MPa, whereas that of the SiCf/Al2O3 composite is only 50MPa. 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 SiCf/Al2O3-SiO2 composite reaches -37dB in the temperature of 200 degrees C at 8.6 GHz, and the effective absorption bandwidth (RL-5 dB) is 4.2 GHz (8.2-12.4 GHz) below 400 degrees C. The superior microwave absorption properties at high temperatures indicate that the SiCf/Al2O3-SiO2 composite has promising applications in civil and military areas. (c) 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47097.