Temperature-dependent dielectric properties and high-temperature microwave absorption performance of Ti3SiC2/Al2O3-13%TiO2 coatings

Ti3SiC2 exhibits considerable potential for high-temperature microwave absorption due to its relatively high melting point and conductivity. In this study, we successfully prepared Ti3SiC2/Al2O3-13%TiO2 heterogeneous coatings through granulation and plasma spraying techniques. This investigation covered composition, microstructure, oxidation resistance, and a focused analysis of the temperature-dependent permittivity of the coatings. The augmentation in Ti3SiC2 content leads to an escalation in the polarized component, consequently elevating susceptibility to dielectric dispersion. With rising temperature, polarization within the coatings gradually establishes, prompting a transition from polarization relaxation loss to conduction loss as the dominant dielectric loss mechanism. At 5 wt% Ti3SiC2 content, the coating achieves an effective bandwidth of 2.2 GHz at 873 K, with a mere 1.4 mm thickness. Moreover, the coating maintains exceptional oxidation resistance below 700 °C. Ti3SiC2/Al2O3-13%TiO2 coatings manifest as strong contenders for high-temperature microwave absorption applications, and plasma spraying emerges as a promising technique for fabricating high-performance microwave absorption coatings.