Dielectric and Microwave Absorption Properties of TiC-Al₂O₃/Silica Coatings at High Temperature

The dielectric property and microwave attenuation performance of a TiC micropowder-filled Al₂O₃/silica coating were studied. The permittivity of the coating increases gradually with increasing TiC content, which can be attributed to the enhancement of polarization ability and the increase of coating conductivity. Meanwhile, the high-temperature microwave attenuation property of the 30 wt.% TiC-loaded coating was investigated in the temperature range of 25–250°C. Both the real and imaginary parts of complex permittivity exhibit obvious temperature-dependent behavior and increase with the rise of temperature. In the studied temperature range, this coating exhibits an excellent microwave absorption property. A strong absorption peak with minimum RL of −55.2 dB is obtained at 11.8 GHz when the temperature reaches 150°C. Furthermore, the absorption bandwidth (RL ≤ −10 dB) exhibits a widening tendency with the increase of temperature. As the temperature rises from 25°C to 250°C, the effective bandwidth (RL ≤ −10 dB) expands from 2.2 GHz to 3.2 GHz. These results suggest that the TiC-Al₂O₃/silica coating could be a desirable candidate for microwave absorbtion in the measured frequency and temperature ranges.