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

Abstract

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 TiB2/Al2O3/MgAl2O4 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 SiO2 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.