漂珠/钡铁氧体复合材料的制备和吸波性能

Preparation and Microwave Absorption Properties of Cenospheres-Barium Ferrite Composites

采用溶胶-凝胶自蔓延燃烧法制备出漂珠/钡铁氧体低密度磁性复合材料,用扫描电镜、热重-差热分析仪、X射线衍射仪、振动样品磁强计和矢量网络分析仪表征了样品的形貌、结构、电磁性能和吸波性能。结果表明:在漂珠表面形成的钡铁氧体包覆层厚度为5-15 nm,颗粒粒径均小于60 nm。复合材料由六角晶钡铁氧体、α-氧化铁及少量莫来石和石英组成,其磁性能随钡铁氧体与漂珠质量比的增大而增强。复合材料在2-18 GHz频段具有较好的介电损耗和磁损耗性能,当吸波材料厚度为1.5 mm、在14.2 GHz处反射损耗峰值为-29.2 d B,反射损耗小于-10 dB的带宽为4.5 GHz。

The magnetic composites with low density of cenospheres- barium ferrite were prepared by a sol-gel self-propagating combustion technology. The morphology, structure, electromagnetic properties and microwave absorption properties of the composite powders were characterized by the scanning electron microscope, thermogravimetry- differential scanning calorimetry, X- ray diffraction, vibrating sample magnetometer and vector network analyzer. The results show that cenospheres were covered with barium ferrite coating of ca 5 nm to 15 nm in thickness. The size of barium ferrite coated particles is less than 60 nm. In addition, it is found that the composites are composed of barium ferrite, hematite, minor mullite and quartz, and the magnetic properties of the composite material could be enhanced with the increasing mass ratio of barium ferrite to cenospheres. Furthermore, the samples exhibit better dielectric loss and magnetic loss properties within a frequency range from 2 GHz to 18 GHz. The maximum reflection loss of the composite material of 1.5 mm in thickness reaches- 29.2 d B at 14.2 GHz and the bandwidth for reflection loss of-10 d B is 4.5 GHz.