Fe/Submicron FeNi Soft Magnetic Composites with High Working Frequency and Low Loss

doi:10.15541/jim20230599

Abstract

Abstract:

Application of high-power electronic equipment requires inductors with greater high-frequency performance and higher energy efficiency than ever, and thus it is urgent to develop new soft magnetic composites to meet these requirements. To reduce the eddy current loss of soft magnetic composites and obtain molded inductors with high working frequency, low loss and high power, high purity submicron FeNi particles were prepared by plasma torch, and effect of these particles on eddy current loss of soft magnetic composites was examined by simplified finite element model. Soft magnetic composites and molded inductors were prepared by mixing carbonyl iron powder and submicron FeNi particles with different mass fractions. The influence of submicron FeNi particles on the properties of soft magnetic composites and molded inductors is analyzed emphatically. With 30% of mass fraction of submicron FeNi particles, the imaginary part of permeability (μ") of the ring core decreases from 1.57 to 1.36 (reduced by 13.4%), compared with that of the soft magnetic composite made by only pure carbonyl iron powder. The quality factor Q of the molded inductors at 10 MHz increases from 13 to 20 (increased by 53.8%), while the self-resonance frequency increases by 12.7% and the saturation current increases from 2.148 A to 2.352 A. Submicron FeNi particles can effectively reduce eddy current loss and improve stability of the high frequency permeability of soft magnetic composites by increasing the internal resistance of materials and reducing the size of eddy current flow region. Therefore, this study demonstrates that compounding submicron FeNi particles is a promising method to obtain molded inductors with high frequency, low loss, and good comprehensive performance at low cost on a large scale.

Key words: soft magnetic composite, molded inductor, submicron FeNi particle, eddy current, quality factor

CLC Number:

TB333

HE Sizhe, WANG Junzhou, ZHANG Yong, FEI Jiawei, WU Aimin, CHEN Yifeng, LI Qiang, ZHOU Sheng, HUANG Hao. Fe/Submicron FeNi Soft Magnetic Composites with High Working Frequency and Low Loss[J]. Journal of Inorganic Materials, 2024, 39(8): 871-878.

Figures/Tables 11

Fig. 1 Schematic diagram of microstructure model of SMC (a) Geometric size of Fe and submicron FeNi particles; (b) SMC model of micron Fe powder; (c) SMC model of submicron FeNi particles; (d) SMC model after mixing Fe and submicron FeNi particles

Table 1 Material properties of SMC model

Material	Conductivity/ (S·m^-1)	Relative permeability	Relative permittivity
Iron	1.12×10⁷	4000	1
FeNi alloy	1.70×10⁶	8000	1
Matrix	0.1	1	9

Fig. 2 XRD patterns of carbonyl iron powder (CIP) and submicron FeNi particles

Fig. 3 SEM images of two powders (a) CIP; (b) Submicron FeNi particles

Table 2 Particle size distributions of CIP and submicron FeNi particles

Material	d₁₀/μm	d₅₀/μm	d₉₀/μm	d_ave/μm
Carbonyl iron powder	2.6	3.7	4.9	3.9
Submicron FeNi powder	0.390	0.668	0.980	0.645

Fig. 4 Hysteresis loops of CIP and submicron FeNi particles Inset: enlarged view of the part within the orange box

Fig. 5 Eddy current distribution and current density |J| in SMC microstructure at 1 and 100 MHz (a, b) SMC model of micron Fe powder; (c, d) SMC model of submicron FeNi particles; (e, f) SMC model after mixing Fe and submicron FeNi particles; Colorful figures are available on website

Fig. 6 Cross-section SEM images of SMCs with different contents of submicron FeNi particles (a) 0; (b) 100%; (c) 30% (in mass); (d) 70% (in mass)

Fig. 7 Compaction density of SMCs with different contents of FeNi submicron particles

Fig. 8 Complex permeability of SMCs with different contents of submicron FeNi particles (a) Real part of permeability, μ'; (b) Imaginary part of permeability, μ"

Fig. 9 Structure and performance of molded inductor (a, b) Cross-sectional views of molded inductor; (c) Direct current bias performance; (d) Saturation current; (e) Inductance-frequency curves and (f) quality factor-frequency curves of molded inductors with different contents of submicron FeNi particles

References 31

[1]	SHOKROLLAHI H, JANGHORBAN K. Soft magnetic composite materials (SMCs). Journal of Materials Processing Technology, 2007, 189(1/2/3): 1.
[2]	PÉRIGO E A, WEIDENFELLER B, KOLLÁR P, et al. Past, present, and future of soft magnetic composites. Applied Physics Reviews, 2018, 5(3): 031301.
[3]	SILVEYRA J M, FERRARA E, HUBER D L, et al. Soft magnetic materials for a sustainable and electrified world. Science, 2018, 362(6413): eaao0195.
[4]	LEARY A M, OHODNICKI P R, MCHENRY M E. Soft magnetic materials in high-frequency, high-power conversion applications. JOM, 2012, 64(7): 772.
[5]	吴深, 李杰超, 管英杰, 等. 软磁复合材料制备工艺的研究进展. 电子元件与材料, 2022, 41(3): 221.
[6]	ZHAO R L, HUANG J J, YANG Y, et al. The influence of FeNi nanoparticles on the microstructures and soft magnetic properties of FeSi soft magnetic composites. Advanced Powder Technology, 2022, 33(8): 103663.
[7]	LIU J Q, DONG Y N, WANG P, et al. Improved high-frequency magnetic properties of FeSiBCCr amorphous soft magnetic composites by adding carbonyl iron powders. Journal of Non-Crystalline Solids, 2023, 605: 122166.
[8]	池强, 谢磊, 常良, 等. 羰基铁粉/FeSiBCCr复合非晶磁粉芯的性能. 材料导报, 2021, 35(10): 10023.
[9]	ZHANG Y, CHI Q, CHANG L, et al. Novel Fe-based amorphous compound powder cores with enhanced DC bias performance by adding FeCo alloy powder. Journal of Magnetism and Magnetic Materials, 2020, 507: 166840.
[10]	汪洋. 大功率新型一体成型电感器设计及应用前景分析. 电子元器件与信息技术, 2020, 4(1): 1.
[11]	黄家毅, 唐建伟, 龚志良, 等. 大功率金属粉芯模压电感设计与验证. 电子元器件与信息技术, 2022, 6(11): 43.
[12]	SUGIMURA K, MIYAJIMA Y, SONEHARA M, et al. Formation of high electrical-resistivity thin surface layer on carbonyl-iron powder (CIP) and thermal stability of nanocrystalline structure and vortex magnetic structure of CIP. AIP Advances, 2016, 6(5): 055932.
[13]	JIN X W, LI T, JIA Z L, et al. Over 100 MHz cut-off frequency mechanism of Fe-Si soft magnetic composites. Journal of Magnetism and Magnetic Materials, 2022, 556: 169366.
[14]	YIN L F, WEI D H, LEI N, et al. Magnetocrystalline anisotropy in permalloy revisited. Physical Review Letters, 2006, 97(6): 067203.
[15]	ZHANG H, WANG K, HUANG Y D, et al. The excess loss analysis of an easy-plane FeSiAl@SiO₂ soft magnetic composite with high permeability. Journal of Magnetism and Magnetic Materials, 2023, 588: 171471.
[16]	KOLLÁR P, BIRČÁKOVÁ Z, FÜZER J, et al. Power loss separation in Fe-based composite materials. Journal of Magnetism and Magnetic Materials, 2013, 327: 146.
[17]	GANGOPADHYAY S, HADJIPANAYIS G C, DALE B, et al. Magnetic properties of ultrafine iron particles. Physical Review B, 1992, 45(17): 9778.
[18]	LIU D H, LIU X, WANG J, et al. The influence of Fe nanoparticles on microstructure and magnetic properties of Fe-6.5wt%Si soft magnetic composites. Journal of Alloys and Compounds, 2020, 835: 155215.
[19]	REN X T, CORCOLLE R, DANIEL L. A 2D finite element study on the role of material properties on eddy current losses in soft magnetic composites. The European Physical Journal Applied Physics, 2016, 73(2): 20902.
[20]	KIM E S, HAFTLANG F, AHN S Y, et al. Effects of processing parameters and heat treatment on the microstructure and magnetic properties of the in-situ synthesized Fe-Ni permalloy produced using direct energy deposition. Journal of Alloys and Compounds, 2022, 907: 164415.
[21]	WU L Z, DING J, JIANG H B, et al. High frequency complex permeability of iron particles in a nonmagnetic matrix. Journal of Applied Physics, 2006, 99(8): 83905.
[22]	ANHALT M. Systematic investigation of particle size dependence of magnetic properties in soft magnetic composites. Journal of Magnetism and Magnetic Materials, 2008, 320(14): e366.
[23]	BERTOTTI G. General properties of power losses in soft ferromagnetic materials. IEEE Transactions on Magnetics, 1988, 24(1): 621.
[24]	WANG J H, SONG S Q, SUN H B, et al. Insulation layer design for soft magnetic composites by synthetically comparing their magnetic properties and coating process parameters. Journal of Magnetism and Magnetic Materials, 2021, 519: 167496.
[25]	HUAN L, TANG X L, SU H, et al. Effects of SnO₂ on DC-bias superposition characteristic of the low-temperature-fired NiCuZn ferrites. IEEE Transactions on Magnetics, 2014, 50(11): 2006104.
[26]	龚志良, 黄家毅, 舒恺, 等. 各类高频电感电气参数及其电路应用的论述和探讨. 电子元器件与信息技术, 2022, 6(8): 69.
[27]	HE J, YUAN H, NIE M, et al. Soft magnetic materials for power inductors: state of art and future development. Materials Today Electronics, 2023, 6: 100066.
[28]	LI T, WANG Y, SHI H G, et al. Impact of skin effect on permeability of permalloy films. Journal of Magnetism and Magnetic Materials, 2022, 545: 168750.
[29]	BARTOLI M, REATTI A, KAZIMIERCZUK M K. Modelling Iron-powder Inductors at High Frequencies. Denver:Proceedings of 1994 IEEE Industry Applications Society Annual Meeting, 1994.
[30]	HUANG Y D, ZHANG H, SHANG R X, et al. Improved magnetic properties in amorphous FeSiBCr soft magnetic composites with easy-plane anisotropy for high-frequency applications. Journal of Physics D: Applied Physics, 2023, 56(6): 065004.
[31]	HSU Y, FONTANA R, WILLIAMS M, et al. High frequency high field permeability of patterned Ni₈₀Fe₂₀ and Ni₄₅Fe₅₅ thin films. Journal of Applied Physics, 2001, 89(11): 6808.