Dielectric and microwave absorption properties of ZrB2/Al2O3 composite ceramics

ZrB2/Al2O3 composite ceramics are prepared by hot-pressing sintering process. Influences of ZrB2 content and particle size on dielectric and microwave absorption properties of the ceramics are investigated. There are no chemical reactions between the ZrB2 and Al2O3 powders during the sintering process at high temperature. The bulk densities of the ceramics decrease with the rising ZrB2 content and decreasing particle size. The ceramic with finer ZrB2 owns higher complex permittivity when the content of ZrB2 is fixed. As the ZrB2 content increases from 0 to 15 wt.%, the real part increases from 6.53 to 6.64 to 21.22–21.67 and the imaginary part rises from 0.61 to 0.7 to 4.83–4.49 in the frequency range of 8.2–12.4 GHz. The ceramic containing 15 wt.% ZrB2 presents the most favorable microwave absorption performance. For the ceramic with 1.4 mm thickness, the effective absorption bandwidth (≤ 10 dB) is achieved in the frequency range of 10.3–12 GHz, with a minimum RL value of − 15.6 dB at 10.8 GHz.