The early magnetic core was a "bonded" metal soft magnetic core formed by the suppression of ferrosilicon aluminum alloy magnetic powder. This ferrosilicon aluminum magnetic core is often referred to as the "iron core." Its typical preparation process is: the Fe-Si-Al alloy magnetic powder(commercially available component is Fe: Si: Al = 84 %: 10 %: 6 %) is flattened by the ball mill and coated with an insulating layer by chemical means, Then add about 15 Wt % of the binder, mix evenly and mold solidify, and finally heat treatment(stress removal) to make the product. This traditional "iron core" product mainly works at 20kHz to 200kHz. Because they have much higher saturation flux density, good DC superposition characteristics, magnetostrictive coefficient close to zero, no noise at work, good frequency stability, and high performance prices than ferrite operating in the same frequency band, It has been widely used in electronic components such as high-frequency electronic Transformers. Their disadvantages are that non-magnetic fillers not only produce magnetic dilution, but also make the flux path discontinuous, and the local demagnetic field leads to a decrease in permeability. Therefore, it is mainly used in workplaces where the requirements for Bm are high and the magnetic conductivity requirements are not very strict.
The recently developed high-performance iron powder core is different from the traditional ferrosilicon aluminum magnetic powder core. The raw material used is not alloy magnetic powder but pure iron powder coated with insulating layer. The amount of binder is very small, so the flux density is greatly improved.. They work in the medium-low frequency segment below 5 kHz, usually Jibaihezi, which is much less than the operating frequency of the ferrosilicon aluminum magnetic core. The target market is to replace Silicon steel sheets used in motors with its advantages of low loss, high efficiency, and easy three-dimensional design.