LiZn铁氧体空心微珠的自反应淬熄法制备及其低频吸波性能研究

Preparation of LiZn Ferrite Hollow Microspheres by Self-reactive Quenching Technology and Their Low-frequency Microwave Absorption Properties

以Fe＋Fe2O3＋Li2CO3＋Zn O为主反应体系、聚乙二醇为表面活性剂,Bi2O3为助熔剂,KCl O4为营养剂,运用将火焰喷射技术与自蔓延高温合成技术及快速冷却凝固技术相结合的自反应淬熄法,制备了Li Zn铁氧体空心复相微珠。通过粒度分析、SEM、EDS、XRD和矢量网络分析仪等手段,分别分析了该空心微珠的粒径、结构、形貌、相组成和吸波性能。研究表明,该Li Zn铁氧体空心微珠粒径分布均匀,集中在60μm左右,包含实心、单孔和多孔型多种结构,以及部分不规则颗粒。空心微珠外表面出现了晶化程度不高的多边形片状晶,内表面为微纳米晶粒,相组成为Fe3O4、Fe2O3、Li0.435Zn0.195Fe2.37O4和Li0.5Fe2.5O4;该空心微珠吸波材料最佳匹配厚度为4 mm,在此厚度下低频吸波性能良好：最低反射率为-14.5 d B,对应的吸收频率为5.8 GHz,低于-10 d B的吸收频带为4.8-6.8 GHz,带宽达2 GHz。

Li Zn ferrite hollow microspheres were prepared by self-reactive quenching technology using Fe＋Fe2O3＋Li2CO3＋Zn O as the reactive system, polyethylene glycol as the foaming agent, Bi2O3 as the solubilizing assistant, and KCl O4 as the oxygen source. This technology was based on flame spraying technology, self-propagating high-temperature synthesis（SHS） technology and quick chilling technology. Particle size, morphology, structure, phase component and microwave absorption properties of the Li Zn ferrite hollow microspheres were investigated by SEM, XRD, EDS, particle size analyzer and vector network analyzer. Results show that the Li Zn ferrite has a uniform particle size distribution, approximately concentrating at 60 μm. Solid, uniaperturate and porous structures are included in hollow microspheres, as well as some irregular particles. Polygonal lamellar crystals with a low crystallization appear on the outside surface of hollow microspheres, and the inside surface takes on micro-nano crystals. Fe3O4, Fe2O3, Li0.435Zn0.195Fe2.37O4 and Li0.5Fe2.5O4 can be seen in XRD patterns. The matching thickness of the hollow microspheres absorbent is 4 mm, and the microwave absorption properties in low frequency are fine. The minimum reflectivity can reach to –14.5 d B at 5.8 GHz, and the frequency band lower than –10 d B is 4.8-6.8 GHz, with the bandwidth reaching to 2 GHz.