AlN-C(石墨)复相材料微波衰减性能的研究

Study on Microwave Attenuation Characteristics of AlN-C Composites

采用热压烧结工艺,通过合理的烧结温度及保温时间的控制,制备了性能优异的AlN-C复相微波衰减材料。通过网络分析仪、SEM等测试手段,研究了衰减剂C含量对AlN-C复相材料微波衰减性能的影响,结果表明,当衰减剂C含量极小时(w≤1.0 %),AlN-C复相材料不具备衰减电磁波的特性;当衰减剂C含量为3.0 %～5.0 %时,AlN-C复相材料呈现良好的宽频衰减特性;当衰减剂C含量大于7.0 %时,AlN-C复相材料呈现明显的选频衰减特性,且随着C含量的增加,材料的衰减量增大,有效衰减带宽减小,中心谐振频率f0有向高频漂移的趋势。对AlN-C复相材料的频谱特性进行了初步的分析。探讨了AlN-C复相材料的微波衰减机理,电导损耗、界面极化损耗是其主要的微波衰减机理。

AlN-C composites with excellent microwave attenuation characteristics were prepared by hot-pressing under the reasonable controls of sintering temperature and soaking time with the AlN and C powder as starting powder. The effect of the content of attenuator C on the microwave attenuation characteristics of AlN-C composites was investigated by network analyzer and SEM. The results show that: when the content of the attenuator C is very low(w ≤ 1.0%), AlN-C composites has not attenuate electromagnetic wave performance. When the content of attenuator C is in the range of 3.0 to 5.0 %, AlN-C composites represents the wide frequency band attenuation performance favorably. When the content of attenuator C is more than 7.0 %, AlN-C composite represents the narrow frequency band attenuation performance obviously. At the same time with the content of C increasing, the attenuation increases, the effective attenuation bandwidth decreases gradually and the center resonant frequency f0 will shift to high frequency. The dielectric characteristics of AlN-C composites are also analyzed. The mechanisms of microwave attenuation mainly ascribe to the electric conductive loss and the interfacial polarization loss.