Abstract FeSi powders were surface modified and coated with TEOS, CoCl2∙6H2O and FeCl3∙6H2O, which were used as raw materials to fabricate FeSi@SiO2@CoFe2O4 composite powders by chemical co-precipitation method. The effects of calcination temperature on the coating layer structure, magnetic properties and electromagnetic wave absorption properties of composite powders were systematically investigated. The results show that with the increase of calcination temperature from 500 ℃ to 800 ℃, CoFe2O4@SiO2 particles evenly were covered on the surface of FeSi powders gradually gather and grow up, which lead to the destruction of the local structure of the coating. The composite powders calcined at 600 ℃ have a uniform and dense SiO2@CoFe2O4 coating layer structure, high saturation magnetization (173.2 (A∙m2)/kg, high coercivity (3 047.8 A/m) and excellent electromagnetic wave absorption properties. All of the composite powders exhibit maximum reflection loss (RLmax) of (-53.5)-(-56.5) dB and effective bandwidths (RL≤-10 dB) of 4.64-5.68 GHz. Specially, the composite powders calcined at 600 ℃ achieve effective and strong absorption properties in a wide frequency band under thin thickness. They have three strong absorption peaks with the RLmax values of -56.5 dB (8.76 GHz, 2.78 mm), -49.2 dB (14.00 GHz, 2.11 mm) and -40.5 dB (15.28 GHz, 1.60 mm), and wide effective bandwidths with the effective bandwidths (RL≤-10 dB) of 4.80 GHz, 6.24 GHz and 3.44 GHz, respectively. The electromagnetic wave loss mechanism of the powder is excellent impedance matching characteristics, high electromagnetic wave attenuation constant, multiple dielectric relaxation process, multiple interface polarization, high magnetic loss and dielectric loss ability.
LAN Haixin,CHEN Qiuli,ZHU Shengzhi, et al. Electromagnetic wave absorption properties of FeSi@SiO2@CoFe2O4 composite powders prepared by chemical co-precipitation method[J]. Materials Science and Engineering of Powder Metallurgy, 2021, 26(4): 329-337.
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2021, Vol. 26 
