Study On Constant Permeability Of Fe₇₈Si₉B₁₃ Amorphous Strip Core

Fe78Si9B13amorphous alloys due to the excellent soft magnetic properties arewidely used in electronic components, the miniaturization of electronic componentsleads to the magnetic components become more and more miniaturized. But most ofthe filter inductor works in larger current, core is easily saturated, so large volumes ofthe core to be prepared can meet the requirements. Therefore, how to improve the DCsuperimposed characteristic of the inductor core, and reduce the volume and theweight of the magnetic components has become an important development direction.In this dissertation, we mainly focus on the research of the Fe78Si9B13amorphous alloy strips. Firstly, the influence factors of the constant magneticproperties for the Fe78Si9B13amorphous cores are systematically investigated, anddesign an instance according to the research results. Secondly, the corrosionproperties of Fe78Si9B13amorphous cores under different circumstances were studied.Finally, the permanent magnet pre-magnetized technology is used to improve the DCsuperimposed characteristic of the Fe78Si9B13amorphous cores in larger current,make a creative achievement.The studies show that the air gap length, annealing temperature and theoperating temperature are the main influence factors of the DC superimposedcharacteristic of the Fe78Si9B13amorphous cores. When the annealing temperature isbetween350~400oC, the cores having an excellent DC superimposed characteristic,annealing temperature is too high or too low will worsen the DC superimposedcharacteristic of the cores. When the working temperature is higher than50oC, theeffective permeability of the cores is gradually decreased with the ambienttemperature.Fe78Si9B13amorphous cores placed in different environments, the corrosionresistance of the core in the water environment is worst, the surface color changesevident, and the soft magnetic properties decreased greatly, the saturation magneticflux density Bs decrease from1.47T to1.38T, the residual magnetic flux density Brdecrease from0.95T to0.85T, the initial permeability decrease from5.33k to3.96k, decreased by25.7%, so it is necessary to encapsulate the cores.Permanent magnets placed in the air gap of magnetic cores don’t deteriorate theeffective permeability of Fe78Si9B13amorphous cores. And within a certain range, thegreater the surface magnetic of the permanent magnet, the better the DCsuperimposed characteristic of magnet bias cores. When the surface magnetic ofpermanent magnet is constant, the greater the air gap of the cores, the permanentmagnet pre-magnetized effect is less obvious, the DC superimposed characteristiccurve of the core offset to the right less, and the DC superimposed characteristic ofmagnet bias core affected by frequency is greater than the traditional core, comparedwith the frequency f=1kHz, the effective permeability of traditional magnetic coredecreased by2.1%,6.4%respectively at25kHz,100kHz, the effective permeabilityof magnet bias core decreased by7.4%,26.3%respectively at25kHz,100kHz.The DC superimposed characteristic curve of the magnet bias cores has goodrepeatability, the permanent magnets without demagnetization after repeated use, thepermanent magnet pre-magnetized technology can be used in practical applications,so the scheme of using the permanent magnet pre-magnetized technology to improvethe DC superimposed characteristic of the Fe78Si9B13amorphous cores is feasible.