High-temperature dielectric and microwave absorption performances of TiB2/Al2O3 ceramics prepared by spark plasma sintering

TiB 2 /Al 2 O 3 ceramics reinforced with MgO are prepared by spark plasma sintering (SPS). The dielectric and microwave (MW) absorption properties are discussed. The results indicate that both the commercial TiB 2 (C-TiB 2 ) content and preparing temperature play important roles in the dielectric properties. Simultaneously, TiB 2 /Al 2 O 3 composite shows the best MW absorption property when the C-TiB 2 content and preparing temperature are 9 wt% and 1400°C. To further improve the MW absorption properties, the composite containing 9 wt% synthesized TiB 2 (S-TiB 2 ) has been sintered at 1400°C. Its high-temperature complex permittivity is greater than that of TiB 2 /Al 2 O 3 composite with 9 wt% C-TiB 2 sintered at 1400°C and is directly proportional to the temperature. Besides, TiB 2 /Al 2 O 3 composite with 9 wt% S-TiB 2 possesses a better MW absorption at 25–500°C, its effective absorption bandwidth ( RL <−5 dB) can reach 4.2 GHz at 25–500°C. And the minimum reflection loss ( RL min ) value reaches −43.41 dB at the temperature of 800°C with a thickness of 1.45 mm for TiB 2 /Al 2 O 3 composite with 9 wt% C-TiB 2 . Consequently, the satisfying absorbing layer ( d <1.75 mm), flexural strength, heat stability and considerable high-temperature MW absorption ability grant TiB 2 /Al 2 O 3 ceramics practical applications as high-temperature microwave absorption materials (MAMs).