High-temperature dielectric and microwave absorption property of plasma sprayed Ti₃SiC₂/cordierite coatings

The high-temperature dielectric and microwave absorption property of plasma sprayed Ti₃SiC₂/cordierite coatings at temperature ranging from 25 to 700 °C in the frequency of 8.2–12.4 GHz were investigated. Both the real and imaginary part of permittivity increase with the elevating temperature, which can be ascribed to the shortened relaxation time and the enhanced electrical conductivity, respectively. Moreover, for as-sprayed Ti₃SiC₂/cordierite coatings, the results show that the relaxation loss dominates the ε″ at a lower temperature and the electrically conductive loss dominates the ε″ at a higher temperature. Further investigations of microwave absorption property were carried out based on the calculated reflection loss and indicated that the Ti₃SiC₂/cordierite coating was an excellent absorber at high temperature. At the temperature of 400, 500 and 600 °C, the coating with a thickness of 1.5 mm exhibits a proper microwave absorption property with an effective absorption bandwidth (≤−5 dB) across the whole measured frequency, which indicates the Ti₃SiC₂/cordierite coating is an excellent absorber at high temperature.