Enhancement on high-temperature microwave absorption properties of TiB2–MgO composites with multi-interfacial effects

TiB 2 –MgO microwave absorbing materials with TiB 2 as the absorber, MgO as the matrix are prepared by spark plasma sintering (SPS). The influences of commercial TiB 2 content and sintering temperature on dielectric and microwave absorption (MA) properties are studied. Besides, to optimize the MA performance, TiB 2 –MgO composite containing TiB 2 synthesized by the carbonthermal process is prepared. Meanwhile, its high-temperature dielectric and MA properties are investigated. Indeed, both the commercial TiB 2 content and sintering temperature play key roles in dielectric and MA properties, as they reaching 8 wt% and 1400 °C, the composite presents the optimal MA performance. For composite with synthetic TiB 2 as the absorber, the temperature has a positive effect on dielectric and MA properties. The enhanced high-temperature MA properties with minimum reflection loss ( RL min ) of −52.11 dB at 1.6 mm under 500 °C and effective absorption bandwidth (EAB, RL  < −5 dB) of 4.2 GHz at 1.4–1.6 mm under 800 °C are obtained, which is mainly attributed to the temperature-dependent interfacial polarization compared to the temperature-insensitive conductivity. The excellent mechanical properties (flexural strength = 212.48 MPa), thin absorbing layer (d < 2 mm), enhanced thermal stability and high-temperature MA properties indicate that the TiB 2 –MgO composites can be considered as new candidates for high-temperature structure microwave absorbing materials.