Temperature-insensitive and enhanced microwave absorption of TiB2/Al2O3/MgAl2O4 composites: Design, fabrication, and characterization

Developing high-temperature microwave absorption (MA) materials remains a challenge in the field of radar stealth. Here, we propose a design concept of meta-structure for temperature-insensitive and broadband MA. The three-phase TiB 2 /Al 2 O 3 /MgAl 2 O 4 composites are prepared to realize the temperature-insensitive MA properties, which is ascribed to the interaction of different components in terms of the electrical conductivity , dipolar polarization and interfacial polarization as temperature increases. On this basis, we design and fabricate a three-layer meta-structure composed of the SiO 2 ceramics as environmental adaptation layer, the patch-type and flat composites as MA layers. Compared with flat composites, the meta-structure can optimize its effective permittivity, thereby realizing enhanced MA properties at elevated temperatures. This meta-structure can realize a reflection loss (RL) less than −5 dB at 8.2–18.0 GHz in the temperature range of 25 °C to 1100 °C. The experiment matches well with the simulation. The temperature-insensitive and enhanced MA properties are attributed to the consequence of the combination of traditional absorbing materials and metamaterial structures.