目的 利用过氧化氢（H2O2）溶液对片状磁性吸波剂粒子进行活化,增强吸波剂表面活性,促进Al2O3在表面的流化湿法包覆效果,以降低介电常数,改善阻抗匹配,提高低频吸波性能。方法 通过改变反应时间,探究H2O2活化吸波剂的最佳条件,利用湿法包覆流化床将异丙醇铝（AIP）雾化沉积在合金粉表面,经水解和煅烧后得到FeSiAlCr@Al2O3复合吸波剂。结果 吸波剂经H2O2活化后出现氧化、亲水性增强,在表面包覆AIP后,其粉末电阻率较原粉提高了3个数量级,在2 GHz时介电常数实部降低了30%;煅烧后粉末电阻率提高了5个数量级,介电常数实部降低幅度达到42%,磁导率保持不变。经活化、改性和煅烧后,复合材料在厚度为2 mm时,低频吸波性能得到显著增强,反射率在1.4~3.4 GHz频段均低于-5 dB,反射率峰值由原粉的-6.79 dB升至-8.64 dB。结论 采用H2O2溶液对吸波剂进行活化,通过增加吸波剂表面活性位点和缺陷提高了合金粉的动态湿法包覆Al2O3效果,可有效降低介电常数,拓宽低频吸收带宽,增强低频吸波强度。
Abstract
The work aims to adopt a hydrogen peroxide (H2O2) activation strategy to enhance the fluidized wet-coating of Al2O3 on flaky FeSiAlCr magnetic absorbents, to reduce dielectric constant, improve impedance matching, and boost low-frequency absorption performance. The optimum conditions for activating absorbents with H2O2 were explored by changing the reaction time. The aluminum isopropoxide (AIP) was deposited on the surface of alloy powder via atomization in a wet-coating fluidized bed, followed by hydrolysis and calcination to prepare FeSiAlCr@Al2O3 composite absorbents. After being activated by H2O2, the absorbents were oxidized, with hydrophilicity enhanced. After the surface was coated with AIP, the powder resistivity increased by three orders of magnitude compared with the original powder, and the real part of the dielectric constant decreased by 30% at 2 GHz. After calcination, the powder achieved five-order-of-magnitude resistivity improvement with 42% dielectric constant reduction while maintaining permeability. After activation, modification and calcination, when the thickness of the composite was 2 mm, the low-frequency absorption performance was significantly enhanced, and the reflectivity was lower than -5 dB in the frequency band of 1.4-3.4 GHz, and the peak reflectivity increased from -6.79 dB to -8.64 dB. Through activation of absorbents with H2O2, the effect of dynamic wet-coating of Al2O3 with alloy powder is improved by increasing the active sites and defects on the surface of the absorbent, which can effectively reduce the dielectric constant, broaden the low-frequency absorption bandwidth and enhance the low-frequency absorption strength.
关键词
H2O2活化 /
湿法包覆流化床 /
异丙醇铝 /
氧化铝包覆 /
介电常数
Key words
H2O2 activation /
wet-coating fluidized bed /
aluminum isopropoxide /
Al2O3 coating /
dielectric constant
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