摘要
The design of the high-temperature microwave absorbing materials (MAMs) with temperature-insensitive and considerable microwave absorption (MA) capacity is a tremendous challenge.Ti B2-Al_(2)O_(3)/Mg Al_(2)O_(4) MAMs are prepared by the spark plasma sintering (SPS).Further,the influences of the Al_(2)O_(3) content on the flexural strength,thermal stability,high-temperature electrical conductivity,dielectric and MA properties are discussed.The results show that the Al_(2)O_(3) content is associated with flexural strength,high-temperature thermal stability,electrical conductivity,dielectric and MA properties.Meanwhile,the temperatureinsensitive and considerable MA properties with the minimum reflection loss (RLmin) ranging from -19.4 to -14.3 dB and the effective absorption bandwidth (EAB,RL<-5 dB) of 3.19–3.55 GHz are attained at 25°C–700°C in 8.2–12.4 GHz as the Al_(2)O_(3) content increases from 70.6 wt%to 80.6 wt%.This is ascribed to the compensating effect of the positive and negative temperature coefficient materials on the high-temperature electrical conductivity as well as the co-play of the dipolar and interfacial polarization at elevated temperatures.Consequently,Ti B2-Al_(2)O_(3)/Mg Al_(2)O_(4) ceramics exhibit the ideal prospect as the high-temperature MAMs.
基金
the National Natural Science Foundation of China(Grant Nos.61701185 and 61801186)
the Natural Science Foundation of Hubei Province(Grant Nos.2020CFB509 and2020CFB511)。
