Preparation And Performance Research Of Flake Absorbing Materials On FeSi Magnetic Alloy

This topic researches process factors of FeSiAl and FeSiCr flake powder’spreparation，which effect flattened form of magnetic powder, including milling time，milling speed and ball diameter. Paraffin as matrix, when preparing absorbing materials,FeSiAl and FeSiCr flake powder is as absorbent in paraffin,which is the matrix. Studiedthe milling time, milling speed, ball diameter size, the type of dispersant, heat treatment,paraffin content, FeSiAl and FeSiCr flaky effect on the ratio of magnetic andelectromagnetic absorbing properties of the material. Magnetic particle morpholoinggywas observed by SEM, bsorbing material of complex permittivity and complexpermeability is tested aby RF impedance analyzer at different frequencies, reflectivity iscalculated and absorbing properties is studyed.The experimental results showed that:(1) milling time, ball speed and balldiameter is an important factor in the process of preparation of flaky powder. As themilling time increases, the shape of the powder, the more FeSiAl and FeSiCr tends toflatten when the milling time is50h, the magnetic optimal flattening effect, themaximum diameter to thickness ratio. But milling time is too long, flat powder ispulverized and diameter to thickness ratio decreases. With the milling speed increases,the flattening effect of the magnetic FeSiAl and FeSiCr changed for the better, whenthe speed reaches180r/min, powder have the best degree of flattening and themaximum diameter to thickness ratio. When milling ball diameter is too big or toosmall, sheet structure are difficult to form. When the ball diameter is Ф5time, FeSiCrabsorbing powder to flatten the best.(2) In the250MHz~2.5GHz frequency range, withmilling time increases, reflection peak of FeSiAl and FeSiCr absorbing material moves to the low frequency, when the milling time was50h, the band width is0.38GHz and0.5GHz on FeSiAl and FeSiCr absorbing material，the minimum reflectivity of FeSiAlabsorbing materials in the1.75GHz is-18dB; the minimum reflectivity on FeSiCrabsorbing materials in the2GHz is-18dB; within the frequency range of250MHz~2.5GHz, with milling speed increases, FeSiAl and FeSiCr absorbing materialreflection peaks move to the low frequency, and the bandwidth is increasing,bandwidth on reflectivity of less than-10dB is respectively0.5GHz and0.49GHz.When speed is180r/min, FeSiAl absorbing materials have minimum reflectance-18dBat2.1GHz frequency, FeSiCr absorbing materials have minimum reflectance-17.5dBat2.1GHz frequency; adding a silane coupling agent in the milling process，absorbingmaterial have a good electromagnetic wave absorption property in the low frequency,and the bandwidth is larger, the bandwidth of reflectance of less than-10dB is0.38GHz,at2GHz frequency, FeSiAl absorbing material has a minimum reflectance-17dB; whenwhen milling diameter Ф5, band width on FeSiCr absorbing material reflectance valuesof less than-10dB is0.5GHz, at2GHz frequency minimum reflectivity on FeSiCrabsorbing material is-17dB; milled powder after heat treatment FeSiAl and FeSiCrreflection peak toward the low frequency, and the band is widened, bandwidth of thereflectivity of less than-10dB is respectively0.75GHz and0.63GHz, minimumreflectivity on FeSiAl absorbing materials is-18dB at2GHz frequency. minimumreflectivity on FeSiCr absorbing materials in the1.8GHz frequency is-17dB; withparaffin content increasing，reflection peak of absorbing materials moves toward thehigh frequency, when the paraffin content is30wt%, band width on reflectivity of lessthan-10dB of FeSiAl absorbing material is0.63GHz, the minimum reflectance onFeSiAl absorbing material is-17dB at2GHz frequency; with absorbing materialthickness increases, reflection peak of FeSiAl and FeSiCr absorbing material towardthe low frequency, and the bandwidth is increasing, when the thickness is3mm, thebandwidth on the reflectance of less than-10dB is respectively1.25GHz and1.125GHz.When the thickness of1.5mm, the2GHz frequency, the minimum reflectivity ofFeSiAl absorbing material is-18dB, the minimum reflectivity of FeSiCr absorbingmaterial is-19dB. FeSiAl absorbing powder is composited with FeSiCr absorbingpowder in a certain ratio, the reflectance of the composite material increases, as the ratio of FeSiAl increases in composite magnetic powder, the reflection peak movestoward the high frequency, when the ratio is7:3, the bandwidth on the reflectance ofless than-10dB of the composite is0.38GHz, at1.8GHz frequency, the minimumreflection rate of the composite is-15dB.