Properties Of Soft Magnetic Composites Research Articles

An improved dynamic magnetic hysteresis model in soft magnetic composites

In this paper, an improved static Jiles-Atherton (J-A) hysteresis model is proposed to simulate the hysteresis properties of soft magnetic composites (SMC) by introducing an excitation factor to control the rotational component of magnetic domains in the effective magnetic field based on the internal demagnetization effect and magnetization mechanism. On the other hand, Since SMC is usually applied in the mid-frequency band, an improved dynamic hysteresis model is necessary to be proposed. The analytical expression for calculating the intraparticle eddy current loss is proposed based on the microstructural parameters of the SMC. And the microstructural parameters are determined by discrete element method DEM. For the intraparticle eddy current loss, the squared term of the mean particle size in the expression is further clarified. Eventually, this improved dynamic J-A hysteresis model was derived through the theory of magnetic field separation. The results show that SMC hysteresis loops with magnetic flux densities up to 1.5 T and frequencies up to 1 kHz can be evaluated by the proposed model.

Investigating the Effect of Carbonyl Iron Powder Doping on the Microstructure and Magnetic Properties of Soft Magnetic Composites

This study proposes the thermal decomposition of salt compounds and doping of carbonyl iron powders (CIPs) to optimize the preparation of an insulating layer through the solid-phase interface reaction. First, (Fe–Si–Cr + CIPs)/ZnSO4 composite powders were synthesized using the hydrothermal method and (Fe–Si–Cr + CIPs)/ZnO·SiO2·Cr2O3 SMCs with a ZnO·SiO2·Cr2O3 composite insulation layer were prepared through heat treatment and cold pressing. The effect of the CIP doping content on the microstructure and magnetic properties of the (Fe–Si–Cr + CIPs)/ZnO·SiO2·Cr2O3 SMCs were then investigated. During the heat treatment, ZnSO4 decomposed into solid ZnO and gaseous SO2 and O2. The O2 drives the solid-phase reaction, prompting the migration of nonmagnetic Si and Cr atoms from the interior of the Fe–Si–Cr soft magnetic powder to the surface insulation layer, finally forming the ZnO·SiO2·Cr2O3 insulation layer. The doped CIPs also show good plasticity during the coating process, combining with the coating layer to fill the internal pores of SMCs. Moreover, as the particles are small with a high surface area, they increase the number of reaction sites for ZnSO4 decomposition and facilitate the growth of the composite insulation layer, promoting its uniform distribution on the surfaces of the soft magnetic powders and CIPs. The lattice mismatch between the insulation layer and soft magnetic powder is reduced while the magnetic-phase content is increased, allowing the effective doping of CIPs sin the insulation layer. The magnetic properties of SMCs can be precisely regulated by changing the doping amount of CIPs. Unlike other insulating layer–preparation strategies based on the interfacial solid-phase reaction, the proposed method exploits the high plasticity and specific surface area of CIPs and removes the lattice mismatch between the insulation layer and soft magnetic powder.

Preparation and magnetic properties of high DC-bias performance Fe-Si-Nb-B-Cu/carbonyl iron chip inductors

In this study, a gradient temperature rise technique was employed to prepare ultra-fine nanocrystalline alloy magnetic powder with excellent high-frequency and low-loss characteristics. It was found that increasing the holding time effectively refines the grain structure in the perpendicular direction of the Fe-Si-Nb-B-Cu alloy's (220) crystal plane. This refinement contributes to a reduction in eddy current losses within the soft magnetic composite material. The addition of carbonyl iron to the nanocrystalline magnetic powder resulted in further enhancements in the density, strength, and magnetic properties of soft magnetic composites under high-frequency magnetic fields. Consequently, soft magnetic composites exhibiting superior DC bias performance were successfully obtained, with a power loss of 2629.50 kW/m3 at a magnetic induction of 20 mT and a frequency of 3 MHz, and more than 70 % percent permeability in a DC biased magnetic field of 7.96 kA/m. The relationship between relative permeability and quasi-static hysteresis loops was established. Additionally, the dynamic hysteresis loops of the soft magnetic composites revealed a relaxation phenomenon, which elucidated the mechanism behind the variations in power loss with changes in magnetic induction strength and frequency. Finally, through simulations, it was determined that the number of turns and the winding method significantly influenced the internal magnetic field and inductance of the chip inductor. Utilizing this information, a chip inductor with ultra-small inductance, compact size, and excellent DC bias characteristics for 10 A circuits was successfully fabricated.

Magnetic Properties of Soft Magnetic Composites Based on Iron Powder with a Multilayer Insulating Coating

Magnetic Properties of Soft Magnetic Composites Based on Iron Powder with a Multilayer Insulating Coating

Magnetic properties of soft magnetic composites fabricated from amorphous Fe73Si11B11C3Cr2 powder by hot pressing under a low pressure

Amorphous Fe73Si11B11C3Cr2 powders were coated with a layer of Fe3O4 through hydrothermal reactions. The coated powder was used to fabricate soft magnetic composites (SMCs) in which the eddy current was confined in individual amorphous particles by the insulating Fe3O4 layer, and the magnetic diluting effect, caused by non-magnetic insulating layer and widely reported in previous research, can be avoided, thanks to the ferromagnetic properties of Fe3O4. The results indicated that when the coated powder was hot-pressed at temperatures near the glass transformation temperature of the metallic glass powder, SMCs with high density and good magnetic properties could be obtained under a low pressure of 600 MPa. The SMCs fabricated at 430 °C exhibited the best magnetic properties, having an effective permeability of 41(at 100 kHz) and a core loss of 707 kW/m3 (at 100 kHz, 50 mT). The properties could be further improved after the sample was annealed at 430 °C to release the internal stresses generated in hot pressing. As a result, the effective permeability was increased to 43(at 100 kHz) and the core loss was reduced to 498 kW/m3 (at 100 kHz, 50 mT) for the annealed sample.

Comparative investigation of insulation techniques based on APTES for different structures and magnetic properties of soft magnetic composites

FeNi powders were insulated with APTES by solution method and solidification method, respectively. Different coating mechanisms have been systematically studied according to analysis on microstructure, surface charge state, thermal stability of magnetic powders and magnetic properties of corresponding soft magnetic composites (SMCs). It was found that a slight amount of polysiloxane and amorphous silica would be deposited on FeNi powders in solution method, resulting in an ultra-thin insulation layer. In contrast, continuously increasing concentration of polysiloxane in reaction zone gives rise to a thick and smooth SiO2 layer in solidification method. Owing to unique growth mechanisms of solidification method, it is easy to control the thickness of SiO2 layer by adjusting the concentration of APTES, which is in favor of improving insulation quality. Accordingly, FeNi SMCs prepared in solidification method own much higher resistivity, lower μ″ and lower tanδ (particularly at high frequency), compared with samples obtained by solution method with the same volume of APTES. Besides, increasing volume of APTES in solidification method leads to the decrease of both μ′ and μ″. This work may not only provide novel insights into APTES-based insulation process, but also offer powerful technique for fabricating high-frequency SMCs.

Magnetic properties of soft magnetic composites used in electromechanical engineering

The article discusses the methods of using composite magnetic alloys for elements of electrical engineering. The main methods of obtaining soft magnetic composite materials have been studied in order to obtain high-performance MMC particles, as it should be subjected to electrically insulated powder to obtain high-density parts. High densities generally improve magnetic properties, both to keep hysteresis losses low and to obtain high flux density. These give an effect when used for the cores of electric motors based on magnetically soft composite materials.

Microstructure and Magnetic Properties of Grain Boundary Insulated Fe/Mn0.5Zn0.5Fe2O4 Soft Magnetic Composites.

Mn0.5Zn0.5Fe2O4 nano-powder was coated on Fe microparticles by mechanical ball milling combined with high-temperature annealing. The effects of milling time on the particle size, phase structure and magnetic properties of core–shell powder were studied. Scanning electron microscopy (SEM), energy-dispersive spectroscopy and X-ray diffraction showed that the surface of the milled composite powder was composed of thin layers of uniform Mn0.5Zn0.5Fe2O4 insulating powder. SEM also revealed a cell structure of Fe particles, indicating that the Fe particles were well separated and isolated by the thin Mn0.5Zn0.5Fe2O4 layers. Then, Fe/Mn0.5Zn0.5Fe2O4 soft magnetic composites were prepared by spark plasma sintering. The amplitude permeability of Fe/Mn0.5Zn0.5Fe2O4 SMCs in the Fe/Mn0.5Zn0.5Fe2O4 soft magnetic composites was stable. The resistivity decreased with the increase in sintering temperature. The loss of the composite core was obviously less than that of the iron powder core. Hence, the preparation method of Mn0.5Zn0.5Fe2O4 insulating iron powder is promising for reducing core loss and improving the magnetic properties of soft magnetic composites.

Comparative Investigation of Insulation Coating Mechanisms Based on Aptes for Controllable Structure and Magnetic Properties of Soft Magnetic Composites

Comparative Investigation of Insulation Coating Mechanisms Based on Aptes for Controllable Structure and Magnetic Properties of Soft Magnetic Composites

Effects of nitriding and Ni doping for the frequency of domain wall resonance peak and high-frequency magnetic performance of easy-plane Y2Fe17

Rare earth soft magnetic alloys have potential in high frequency applications due to strong easy-plane anisotropy. As the research progressed, a new resonance peak in the MHz frequency band, the domain wall resonance peak was observed, which seriously affects applications of magnetic materials in power device. A way to decrease it is by increasing domain wall resonance frequency (fdw). In this paper, the composites of easy-plane Y2Fe17 and polyurethane were presented and the easy-plane Y2Fe17 were treated by nitriding and doping. It is found that both nitriding and doping are effective in increasing the permeability. And the frequency of domain wall resonance peaks is varied due to the variation in exchange interaction by nitriding and doping. These results provide insight into soft magnetic properties of soft magnetic composites (SMCs) in the MHz frequency band, particularly for SMCs in power devices applications.

Magnetic properties of soft magnetic composites fabricated by injection molding of bimodal amorphous Fe73Si11B11C3Cr2 and crystalline Fe50Co50 powders

Hybrid soft magnetic composites are fabricated using bimodal amorphous Fe73Si11B11C3Cr2 and crystalline Fe50Co50 powders via MIM. When Fe73Si11B11C3Cr2 powder is partially substituted by Fe50Co50 powder which forms a bimodal distribution, permeability decreases with, but the saturation induction increases with increasing fraction of Fe50Co50. Composites with high fraction of Fe50Co50 have good magnetic saturation and improved bias performances. Core loss is more influenced by particle size distribution. Finer Fe50Co50 powders are distributed in interstices and lead to a more loosely packed structure. On one hand, loosely packed structure increasing the interspacing of magnetic powders gives rise to low eddy current loss. On the other hand, loosely packed structure increases flowability of powders and results in low-viscosity feedstock, which can be molded with low injection pressure resulting in small internal stresses, giving rise to low core loss. As a result, hybrid SMCs with 50% fraction of Fe50Co50 powder exhibits the best comprehensive magnetic properties.

Improved properties of soft magnetic composites with hollow microstructures

Soft magnetic composites (SMCs) possess promising electromagnetic characteristics and attract intense research and application interest in the engineering community. Fabrication of composites with customized architecture is feasible due to the recent advances in additive manufacturing (AM) techniques. The systematic progress of computational optimization has opened up the possibility of devising such structures. This article presents newly structured SMCs which can recently be possible by AM. The effective permeability and eddy current losses are studied in comparison to those properties of traditionally fabricated SMCs. With this hollow inclusion arrangement, for the same iron volume fraction, the effective permeability can be greatly enhanced (more than tenfold) while the eddy current losses decrease considerably. For the same magnetic property, we save iron material, make the composite lighter, and benefit from a lower level of eddy current losses with the hollow configuration.

Influence of particles size fraction on magnetic properties of soft magnetic composites prepared from a soft magnetic nanocrystalline powder with no synthetic oxide layer

Soft magnetic composites (SMCs) are usually prepared from microcrystalline Fe, Fe-Si or Fe-Si-Al powders. Other powders, including nanocrystalline ones, are relatively rarely used. The objective of this work was to prepare SMCs from milled Fe-Si-B-Nb-Cu nanocrystalline ribbon and study their magnetic properties. These SMC cores exhibited very low coercivity and, despite no synthetic oxide layer, relatively high resistivity. A combination of these properties resulted in exceptionally low core loss at low frequency and in some initial tests at higher frequencies. Moreover, the influence of powder size fraction on the magnetic properties was also investigated, leading to a conclusion that the use of coarser particles resulted in higher permeability. Further increase in permeability was achieved by mixing the coarsest powder size fraction with the finest one. The presented results show a promising future for this kind of materials.

Properties of soft magnetic composites based on Fe fibres coated with SiO2 by hydrothermal method

The paper reports on the preparation and characterisation of a new type of soft magnetic composites in which the ferromagnetic particles are replaced by Fe fibres. The fibres were coated via hydrothermal method with a SiO2 layer having a thickness of 150–200 nm. Also, a hybrid coating was developed by adding a supplementary layer of polymer on top of the SiO2 layer. The coated fibres were compacted via cold pressing at the pressure of 700 MPa. Our results indicate that using only SiO2 as the insulating layer leads to compacts characterised by lower hysteresis losses. However, it seems that during compaction, the SiO2 layer is damaged leading to the development of large eddy currents at high frequencies. Conversely, the additional polymer layer manages to prevent the development of excessive eddy currents in the compact, but with a significant increase of the hysteresis losses of the compacts being observed. A significant improvement of the magnetic characteristics of the fibre-based soft magnetic composites can be achieved by an annealing treatment with the condition of maintaining the integrity of the insulating layer, or minimising the diffusion between the fibres and the SiO2 coating during the annealing.

Analysis of nonlinear magnetic properties of soft magnetic composite using 2D and 3D discrete element methods

This paper presents the three-dimensional modeling of soft magnetic composite (SMC) based on the discrete element method. The proposed method makes it possible to take the possible contact among the magnetic particles in SMC as well as the distributed particle size into consideration. Based on this modeling, the macroscopic B-H characteristics is computed with the finite element method considering magnetic saturation. It is shown that the three-dimensional model of SMC can have larger initial permeability in comparison with the two-dimensional model even if they have the same filling factor.

Effects of annealing on the magnetic properties of Fe-based amorphous powder cores with inorganic-organic hybrid insulating layer

In order to improve the magnetic properties of soft magnetic composites (SMCs), the Fe-based amorphous powder cores (AMPCs) based on spherical FeSiBCCr amorphous magnetic powders coated with inorganic-organic (TiO2-epoxy resin) hybrid insulating layer were prepared. The influence of annealing temperature on the soft magnetic properties of the AMPCs has been systematically researched in this work. It was found that the reasonable annealing temperature could increase the permeability and decrease the core loss of the AMPCs. The AMPCs annealed at 480 °C showed a constant permeability of 81.5 up to 10 MHz, and low total core loss of 275 mW/cm3. This study demonstrated that the present Fe-based AMPCs with inorganic-organic hybrid insulating layer have a great promising future in the field of medium and high frequency for the various electronic components.

Influences of machining and acid etching on magnetic properties of soft magnetic composites

Soft magnetic composites (SMCs) are magnetic materials obtained by compression molding of iron powders with an insulating coating and are suitable for a core of a motor having a complicated structure. It is known that its magnetic property is deterio

Effect of Compaction Parameters on the Magnetic and Corrosive Properties of Soft Magnetic Composites with Parylene Insulation

Iron-based soft magnetic composites insulated with parylene C film were prepared via chemical vapor deposition polymerization, and their morphologies, magnetic properties, and corrosive resistance were investigated. Scanning electron microscopy and Fourier transform infrared spectrum confirmed that the surface of the iron particle was completely uniform insulated with parylene C, resulting in reducing the core loss of the synthetic compacts. The results show that compressed pressure has an important influence on the magnetic properties of the soft magnetic composites, enhance the magnetic induction value from 0.64 to 1.01 T and is obtained with increased the compressed pressure from 300 to 650 MPa. The loss separation results show that the hysteresis loss coefficient of 4 wt% parylene C insulated samples decreased from 1.743 to 1.657 and eddy current loss coefficient decreased from 0.019 to 0.012 as compared with uncoated compacts under the same compress pressure. The acid and salt corrosion resistance of the iron particles is apparently enhanced when the chemically stable parylene C layer was exited in the surface.

Synthesis and Magnetic Properties of Soft Magnetic Composites Based on Silicone Resin-Coated Iron Powders

Iron-based soft magnetic composites with silicone resin coating have been designed to reduce the core loss and improve the magnetic properties of cores. The silicone resin serving as electrical insulating layer was modified by 3-glycidoxypropyltrimethoxy silane, and the effect of silicone resin content, coupling agent, annealing treatment, and thermal cycling on the magnetic properties of composites was investigated in the frequency range from DC to 150 kHz. The coated silicone resin insulating layer was characterized by scanning electron microscopy and energy dispersive spectroscopy. The results showed that the optimum coating content of silicone resin to attain the acceptable permeability and the minimum magnetic loss for the prepared composites is 4 wt%. The sample with silicone resin coat exhibited better DC-bias superposition characteristics compared to the uncoated sample, 6 wt% silicone resin coating sample have excellent percentage effective permeability (84.8%) under 50 Oe applied field. AC magnetic properties evaluated at 1 and 100 kHz do not vary with a 95% confidence interval with the number of thermal cycles; therefore, the properties of the silicone resin-insulating composites are stable under thermal cycling.

Mechanical Properties of Soft Magnetic Composites at the Temperature of Liquid Nitrogen

Mechanical Properties of Soft Magnetic Composites at the Temperature of Liquid Nitrogen