二氧化硅/片状金属磁粉壳核粒子制备及电磁特性

Preparation and electromagnetic properties of SiO2/flaky metal magnetic powder composites with core-shell structure

以正硅酸乙酯为前驱体，采用溶胶-凝胶工艺对厚度1um、直径5im左右的片状金属磁性微粉进行表面改性，获得SiO2／金属壳-核结构复合粒子。用SEM、TEM、RA—IR等方法对磁粉表面Si02纳米粒子膜的形貌、结构进行表征，并对改性前后磁粉／石蜡复合材料的复磁导率和复介电常数等微波电磁参数进行测试。结果表明：SiO2纳米粒子吸附在磁粉表面，形成高电阻率的包覆膜；将该微粉按质量比（5：1）与石蜡复合，在2～18GHz频率范围内测量介电常数，与未改性样品比较，其介电常数实部平均下降约20，虚部平均下降约7，而对应的复磁导率变化较小。用金属磁粉制备1mm厚的吸波涂层，涂层在8dB的吸收带宽由改性前的3．2GHz（7．0～10．2GHz）增加到改性后的7GHz（7．6～14．6GHz），改善了吸收剂的吸波性能。

The surface of flaky metal magnetic powders with diameter size of 5 um and thickness of 1 um was modified by SiO2. The appearance, structure and phase constitution of the powders before and after treatment were characterized by SEM, TEM and RA-IR. And the powders were randomly dispersed in paraffin at a mass ratio of 5：1 for microwave electromagnetic parameters test and comparison in the frequency range of 2-18 GHz. The results show that a high resistivity film is formed on the powder surface, and the real and imaginary parts of complex permittivity of the sample decrease by 20 and 7 in average but the corresponding complex permeability decreases slightly. The coatings with thickness of 1 mm give a microwave absorption of 8 dB with a band width of 7 GHz 7.6-14.6 GHz） and the microwave absorption of the modified flaky metal magnetic powders is improved.