掺镁六角晶系钡铁氧体/环氧树脂复合材料的吸波性能

Microwave absorbing property of magnesium-doped Y-type barium hexaferrite/epoxy resin composite

采用柠檬酸和硝酸盐以溶胶-凝胶燃烧法制备了掺镁Y型六角晶系钡铁氧体Ba_2Mg_2Fe_(12)O_(22)(Mg_2Y)无机前驱体,将其分别置于900、1 000、1 050和1 100°C下煅烧,所得铁氧体与E44环氧树脂及EP固化剂均匀混合,得到一种Mg_2Y型钡铁氧体/环氧树脂复合材料。用X射线衍射仪和扫描电镜表征了前驱体粉末煅烧前后的物相结构和显微形貌。通过用矢量网络分析仪测试复合材料在X和Ku波段的电磁参数,考察了煅烧温度及厚度对复合材料吸波性能的影响。前驱体在1 050°C下煅烧5 h能形成单一结构的Y型铁氧体,用其制备的厚度为2.0mm的复合材料具有最佳的吸波性能:介电损耗高,在X和Ku波段均有较好的吸收,反射损耗峰值为-16 dB,反射损耗小于-10 dB的有效带宽达到4.1 GHz。

An inorganic precursor particle of magnesium-doped Y-type barium hexaferrite i.e.Ba2Mg2Fe12O22(Mg2Y)was synthesized by a sol–gel combustion method using citric acid and nitrates,and then calcined at 900,1 000,1 050,and 1 100°C,respectively.The hexaferrite was uniformly blended with E44 epoxy resin and EP curing agent,forming a Mg2Y-type barium hexaferrite/epoxy resin composite.The phase structure and micro-morphology of the precursor particles before and after calcination were characterized by X-ray diffraction and scanning electron microscopy,respectively.The effects of calcination temperature and thickness of the composite on its microwave absorption property were evaluated based on the electromagnetic parameters measured using a vector network analyzer at X and Ku bands.A single-phase Y-type ferrite with an uniform structure is formed by calcining the precursor at 1 050°C for 5 h,and the 2 mm-thick composite prepared therewith has the optimal microwave absorption properties,as shown by a high dielectric loss,a good absorption at X and Ku bands,a maximum reflection loss of?16 dB,and a frequency bandwidth of 4.1 GHz when the reflection loss is below?10 dB.