Magnetic Spectra of Soft Magnetic Composites Based on Fe-Si-Cr-B Amorphous and Carbonyl-Iron Powders
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Fe–Si–Cr–B amorphous and carbonyl-iron powders insulated with phosphoric acid solution were used to prepare soft magnetic composites. The mass ratios of phosphoric acid insulation solution and the carbonyl-iron powder dependences of the magnetic spectrum, the density, and the resistivity were studied. Both the real part and the imaginary part of the core’s complex permeability increased after an initial decrease with the acid mass ratio increasing. This is similar to the variation tendency of the core’s density and opposite to the variation tendency of the core’s resistivity. The amount of the air gap, reflected by the density, was proposed to be the most important factor that has a great influence on the composite’s magnetic properties. The increase of the air gap reduced the effective demagnetizing field and the resistivity. This improved the permeability and the hysteresis loss and deteriorated the eddy-current loss. Carbonyl-iron powder addition was found to improve the moldability and the permeability of the composite based on the Fe-Si-Cr-B amorphous powder, although its loss was higher than that of the amorphous powder. All these findings can be referenced when designing an amorphous-based soft magnetic composite (SMC) core with balanced permeability, loss, and cost for high-frequency inductor within a MHz band.
KeywordsSoft magnetic composite Fe-Si-Cr-B amorphous powder Carbonyl-iron powder Magnetic spectra Loss mechanism
This work was supported by the National Key R&D Program of China (Nos. 2017YFB0903904 and 2017YFB0903900), the Grant Project of Shenzhen Microgate Technology Co., Ltd. (2017-2020), the Open Research Fund of Jiangsu Provincial Key Laboratory for Nanotechnology, Nanjing University (2018-2019), the Huaian Key Research & Development Plan (No. HAG201629), and the Innovation Training Program for Students of Hefei University of Technology (2018CXCYS034).
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