Properties Of Soft Magnetic Materials Research Articles

Magnetic Characterization of Soft Magnetic Cores at Cryogenic Temperatures

It is important to investigate and understand the magnetic properties of soft magnetic materials at cryogenic temperatures for the optimal design of superconducting machines and superconducting transformers. The magnetic properties of soft magnetic materials at room temperatures have been studied extensively. However, there is almost no information available for the magnetic properties of these materials at cryogenic temperatures. This paper for the first time presents the experimental results for the magnetic characterization of four soft magnetic materials from room temperature down to 21 K. The experimental results demonstrate that the core losses at 21 K is higher than room temperature for all the materials. They also show that the permeability of all the materials reduce at 21 K compared to room temperature. The optimal temperature in terms of the best magnetic properties is identified for each material. The data presented in this paper will provide valuable guidance for practical design and optimization of superconducting machines and superconducting transformers with soft magnetic cores.

Fast Electromagnetic Analysis of a 3-D Magnetic Circuit in a Balanced Armature Receiver

This paper proposes a lumped parameter method to analyze the nonlinear magnetic characteristics of a magnetic circuit in a balanced armature (BA) receiver with a U-shaped armature. A parallel flux loop is proposed in the equivalent magnetic circuit, which can reveal the internal flux flow of the magnet housing of the receiver. Nonlinear magnetic equations can be obtained and established by Kirchhoff’s current and voltage laws and solved using the under-relaxed Newton–Raphson iteration method while considering the nonlinear magnetic properties of soft magnetic materials. The nonlinear magnetic characteristics can be verified by 3-D finite-element method, including the total force, cogging force, force factor, flux linkage, speedance, and inductance. However, there are still gaps that need to be improved while considering the flux leakage and refraction flux. The proposed method is a simple and fast way to analyze the 3-D magnetic circuit of a BA receiver and can be used in the analysis of a new structure design.

Analysis of magnetic losses in Fe-polymer composites

Abstract The most important properties of soft magnetic materials are peak induction and magnetic losses, determining the size and efficiency of electric devices. Conventional soft magnetic materials are not suitable for the construction of miniaturized magnetic cores. Soft magnetic composites meet miniaturization requirements of electric and electronic devices. In this paper, magnetic losses in self-developed Fe-polymer composites are analyzed. The frequency dependencies of magnetic losses are measured at different level of maximum induction. The influence of Fe-grain size on magnetic losses is also discussed.

Accuracy Analysis of Sensing Coils in 2-D Magnetic Properties Measurement

There has been an increasing awareness of research on magnetic properties of soft magnetic materials. In reality, the soft magnetic materials are likely to be magnetized by 2-D rotating magnetic field. Moreover, the magnetic properties could be influenced by mechanical stress. In order to investigate the magnetic properties thoroughly, numerous measurement apparatuses have been developed, which could take rotating magnetic flux or mechanical stress into account. However, there is limited research on the investigation of 2-D magnetic properties affected by laminated direction mechanical stress, as few mature devices could be employed, since the traditional $B$ – $H$ sensing coils are easily damaged by laminated direction stress. Therefore, the sensing structure with cubic specimen is proposed for 2-D magnetic properties measurement considering laminated direction stress. The printed circuit board (PCB)-based $B$ – $H$ sensing coils, which are attached to the surrounding surface of the cubic specimen, could be free of the impact of the $z$ -direction mechanical stress. The accuracy of $B$ – $H$ sensing part is analyzed in detail by means of the finite-element method as well as experiments. And, more remarkable, the deficiency of the artificial $H$ -coils wound by enameled wire is presented. Hence, a modified $H$ -coil made of four layer PCBs is proposed in this paper, the measurement accuracy is proven through experiments.

Electrodeposition of Fe, Co, Mn and Their Alloys from Choline Chloride/Urea Based Deep Eutectic Solvents

Despite their industrial use for many decades, there is still desire and opportunity to improve the properties of soft magnetic materials. Applications such as hard drive write heads must attain higher saturation magnetization and low coercivity in order to maintain the ability to write to increasingly dense storage media[1]. Electrodeposition is often the favored fabrication method for such soft magnetic films due to its several advantages such as fast deposition rate, ease of growth on arbitrary shaped or recessed surfaces, and simplicity of orienting film anisotropy[2]. However, it is fairly limited in the number of different elements that can be deposited in high quality. In the past several years, room temperature ionic liquids, the current generation also being known as deep eutectic solvents (DES), have become an attractive alternative to traditional aqueous deposition baths. These solvents avoid the hydrogen generation that often reduces deposit quality and efficiency in aqueous baths, and enable the incorporation into the deposit of metals with more negative deposition potentials than are viable in aqueous baths. Despite significant progress in literature on the electrodeposition of various material from DESs, their suitability for improving characteristics of magnetic films is relatively little-studied[3]. This work studies the deposition behavior of Fe, Co, and FeCo ferromagnetic alloys from the DES formed of a 1:2 mole ratio of choline chloride and urea (ChCl-urea). Deposited films are then characterized to determine their morphology, crystal structure, and magnetic properties. Mn, which has been predicted to increase the magnetization of FeCo materials[4], has been incorporated to form a tertiary FeCoMn ferromagnetic alloy, and its effects of the film properties are determined. Initial voltammetric studies (Fig. 1) and depositions show that deposition of Fe-Co from ChCl-urea proceeds by induced codeposition, wherein Fe deposition is promoted by Co, allowing the alloy film to be obtained at potentials less negative than required for pure Fe. Increasing the deposition overpotential leads to higher Fe content in the film, and a mass transfer limit is quickly reached for both depositing species at which the film composition no longer depends on overpotential. Composition of the deposit is easily controlled by changing the metal ion concentration in the bath. Mn is also found to deposit by an induced codeposition mechanism with Fe-Co, wherein it can be incorporated into FeCo films in small amounts at an underpotential to pure Mn electrodeposition. The incorporation of Mn in alloy films is constant at around 3 wt. % when depositing in underpotential conditions. The effects of several deposition conditions including temperature, metal ion concentrations, and bath agitation, were studied and will be discussed in the presentation.

Effect of mechanical stress on different iron loss components up to high frequencies and magnetic flux densities

PurposeThe purpose of this paper is to study the variation of the specific iron loss components of electrical steel sheets when applying a tensile mechanical load below the yield strength of the material. The results provide an insight into the iron loss behaviour of the laminated core of electrical machines which are exposed to mechanical stresses of diverse origins.Design/methodology/approachThe specific iron losses of electrical steel sheets are measured using a standardised single-sheet tester equipped with a hydraulic pressure cylinder which enables application of a force to the specimen under test. Based on the measured data and a semi-physical description of specific iron losses, the stress-dependency of the iron loss components can be studied.FindingsThe results show a dependency of iron loss components on the applied mechanical stress. Especially for the non-linear loss component and high frequencies, a large variation is observed, while the excess loss component is not as sensitive to high mechanical stresses. Besides, it is shown that the stress-dependent iron loss prediction approximates the measured specific iron losses in an adequate way.Originality/valueNew applications such as high-speed traction drives in electric vehicles require a suitable design of the electrical machine. These applications require particular attention to the interaction between mechanical influences and magnetic behaviour of the machine. In this regard, knowledge about the relation between mechanical stress and magnetic properties of soft magnetic material is essential for an exact estimation of the machine’s behaviour.

FRACTAL STRUCTURE AND PROPERTIES OF SOFT MAGNETIC POWDER MATERIAL OF THE ALLOYING SYSTEM Fe-P

The necessity of using theory of fractals — self-similar sets of fractional dimension — for analysis of the processes occurring in soft magnetic powder materials (SMPM) of the Fe-P alloying system which determine a body of their magnetic properties is shown. Flow diagrams for SMPM production, differing in the degree of deformation and thermal impact on the consolidating powder material of the Fe-P alloying system, methodology and results of magnetic measurements are considered. The technique of studying SMPM surface topography with a scanning probe microscope, providing a link between the length of the scan line L in a desired section, distance between the scanning point R in the same section, scaling parameters and fractal dimension D are presented, as well as the results of three-dimensional surface reconstruction and scanning data processing. The revealed features of formation of the magnetic properties of SMPM attributed to the history of their production, the use of proven methods of measuring the magnetic properties of soft magnetic materials obtained by the proved technology used in powder metallurgy, demonstrated the possibility of using theory of fractals in production of the materials with desired properties to form a link between the technological features of the manufacture, fractal structure and magnetic properties of SMPM through determination of the topographic properties and geometric characteristics of the surface.

Single Sheet Tester With Variable Dimensions

This paper presents a new concept of the single sheet tester (SST) with variable dimensions. First, the author points out standards specifying requirements for systems, that allow to determine the properties of soft magnetic materials. Then, the concept of the SST system and its calibration are described in detail. Calibration of the system was carried out both by performing additional measurements as well as by Finite Element Method (FEM) modeling and execution of numerical simulation. Using the described measuring system, the measurements of two grain-oriented magnetic materials cut at an angle of 0° and 90° with respect to the rolling directions, were executed. The results of the measurements were compared with results obtained from the Epstein frame (carried out in accordance with the International Electrotechnical Commission international standard). Moreover, the author refers to other SST systems having nonstandard dimensions.

A novel conversion of the groundwater treatment sludge to magnetic particles for the adsorption of methylene blue

Iron sludge, produced from filtration and backwash of groundwater treatment plant, has long been considered as a waste for landfill. In this study, iron sludge was reused to synthesize Fe3O4 magnetic particles (MPs) by using a novel solvothermal process. Iron sludge contained abundant amounts of silicon, iron, and aluminum and did not exhibit magnetic properties. After treatment for 4h, the amorphous Fe in iron sludge was transformed into magnetite Fe3O4, which could be easily separated from aqueous solution with a magnet. The prepared particles demonstrated the intrinsic properties of soft magnetic materials and could aggregate into a size of 1μm. MPs treated for 10h exhibited excellent magnetic properties and a saturation magnetization value of 9emu/g. The obtained particles presented the optimal adsorption of methylene blue under mild conditions, and the maximum adsorption capacity was 99.4mg/g, which was higher than that of granular active carbon. The simple solvothermal method can be used to prepare Fe3O4 MPs from iron sludge, and the products could be applied to treatment of dyeing wastewater.

Sensor applications of soft magnetic materials based on magneto-impedance, magneto-elastic resonance and magneto-electricity.

The outstanding properties of selected soft magnetic materials make them successful candidates for building high performance sensors. In this paper we present our recent work regarding different sensing technologies based on the coupling of the magnetic properties of soft magnetic materials with their electric or elastic properties. In first place we report the influence on the magneto-impedance response of the thickness of Permalloy films in multilayer-sandwiched structures. An impedance change of 270% was found in the best conditions upon the application of magnetic field, with a low field sensitivity of 140%/Oe. Second, the magneto-elastic resonance of amorphous ribbons is used to demonstrate the possibility of sensitively measuring the viscosity of fluids, aimed to develop an on-line and real-time sensor capable of assessing the state of degradation of lubricant oils in machinery. A novel analysis method is shown to sensitively reveal the changes of the damping parameter of the magnetoelastic oscillations at the resonance as a function of the oil viscosity. Finally, the properties and performance of magneto-electric laminated composites of amorphous magnetic ribbons and piezoelectric polymer films are investigated, demonstrating magnetic field detection capabilities below 2.7 nT.

Influence of laser processing and magnetically active inorganic coatings on the dynamic magnetic properties of soft-magnetic materials

We have studied the influence of magnetically active inorganic coatings and local laser processing on grain-oriented steels (Fe-3% Si) and amorphous alloys (Fe78Ni1Si9B12 (2NSR), Fe81Si7B12, and Fe81Si4B13C2). The potentialities of different types of laser processing have been assessed. Local laser processing and coating parameters have been shown to have a significant effect on the domain structure and electromagnetic properties of the materials. A reduction in coercive force and magnetic loss by 20–28% has been demonstrated.

Sub-Optimization of a Claw-Pole Structure According to Material Properties of Soft Magnetic Materials

The focus of this paper is on the development of a single phase PM machine with wave-windings where the design variables are the winding layout and design of a soft magnetic powder core for a stator. A number of BH curves are synthesized in order to characterize some of the existing powder cores and to study the influence of magnetic permeability on starting torque and mean driving torque. The goal of the wave-winding design is to increase the material utilization factor and minimize the resistive power losses in the winding of a radial-to-transversal flux machine with an iron powder core. The outcomes of this paper is a 3D FE magnetic analysis of a number of suggested stator layouts supported with a rapid prototype with a dummy coil.

A measurement setup for acquiring the local magnetic properties of plastically deformed soft magnetic materials

This paper introduces a new measurement setup for extraction of the local magnetic properties. With the help of finite element method simulations, modifications are made on the previous double-C-yoke method. Small dimension measuring coils are applied in the stray field produced by the magnetic circuit to evaluate the local magnetic properties of the specified part of the specimen. Through the measurements with the plastically deformed materials at different temperatures, it indicates that the magnetic properties of soft magnetic materials are quite sensitive to plastic straining. After high-temperature thermal treatment on the plastically deformed specimen, the local magnetic properties exhibit an obvious recovery.

Quantitative Structure Analysis of Nano-sized Materials by Transmission Electron Microscopy

AbstractNanostructured materials from almost all classes of materials are of great interest because the reduced dimensionality may drastically change the physical properties. In general, these properties are a function of size, shape, arrangement and chemical composition of the nano-sized materials. Transmission electron microscopy (TEM) is a powerful tool to get a detailed insight into the material characteristics. To correlate microstructure as well as microchemistry and materials properties the various TEM techniques for imaging, diffraction and spectroscopy have to be combined. The potential applicability of quantitative TEM will be demonstrated for different nano-sized objects, particularly for semiconductor islands, nanowires, quantum dots and for soft magnetic materials. The classical diffraction contrast method of conventional TEM is applied to analyse the size, shape and arrangement of nano-sized structures, where a quantitative analysis often requires image simulations of diffraction contrast for theoretical structure models. An alternative and powerful method is the three-dimensional reconstruction of the shape from two-dimensional phase mapping by means of electron holography. This reqires the exact calculation of the mean inner potential of the specimen. Quantitative high-resolution transmission electron microscopy (qHRTEM) has to be applied to analyse structure and chemical composition on an atomic scale of magnitude. Particularly the application of aberration-corrected HRTEM offers new possibilities for quantitative structure analysis due to a contrast transfer by means of negative spherical aberration imaging (NCSI) and the resulting strong suppression of image delocalisation effects. An example for quantitative composition analysis will be demonstrated for ternary semiconductor quantum structures by means of a combined analysis of dark-field imaging and qHRTEM. The results will be compared with analytical TEM data (energy-dispersive X-ray spectroscopy (EDXS), electron energy-loss spectroscopy (EELS), and energy-filtered TEM (EFTEM)). The retrieval of chemical information with atomic resolution will be illustrated for III-V semiconductor nanostructures using STEM (scanning TEM) Z-contrast imaging. The correlation of structure and magnetic properties of soft magnetic materials will be demonstrated by combined application of Lorentz microscopy and electron holography. The potential applicability of the different quantitative TEM methods will be shown for following systems:(i) (Si,Ge) islands(ii) ZnTe and (Zn,Mn)Te nanowires(iii) Ga(As,Sb) quantum dots (QDs) on GaAs substrate(iv) nc softmagnetic FeCo alloysThe possibilities and limitations of the various methods applied will be critically evaluated.

Hysteresis of Soft Materials Inside Formulations: Delayed Diffusion Equations, Fields Coupling, and Nonlinear Properties

The aim of this paper is to propose and argue specific electromagnetic formulations including dynamic electric and magnetic properties of soft materials, working with transient signals and time harmonics within the quasi-static approximation. Special attention will be paid to origin, nature, and relevance of these so-called dynamic properties, which will act on both the diffusion process and coupling between regions. Nonlinear transient experimental identifications of a homogenized dynamic magnetic property are also carried out and discussed. It can provide useful experimental data of soft magnetic materials for simulation and conception purposes.

Connection between microstructure and magnetic properties of soft magnetic materials

The magnetic behavior of soft magnetic materials is discussed with some emphasis on the connection between macroscopic properties and underlying micromagnetic energy aspects. It is shown that important conceptual gaps still exist in the interpretation of macroscopic magnetic properties in terms of the micromagnetic formulation. Different aspects of hysteresis modeling, power loss prediction and magnetic non-destructive evaluation are discussed in this perspective.

Micromechanical characterization of electroplated permalloy films for MEMS

In order to improve the reliability of MEMS designs, evaluating the mechanical properties of soft magnetic materials is needed. In this paper, we present a tensile testing method to characterize the mechanical properties of microscale electroplated permalloy (80 wt% Ni, 20 wt% Fe) films. The gauge section of the specimen is 50 μm wide, 100 μm long and 5 μm thick. The measured Young’s modulus of permalloy films is 96.4 GPa, and the tensile strength is 1.61 GPa. The fracture strain measured by the images of specimens is about 2%.

Employment of the artificial neural networks for prediction of magnetic properties of the metallic amorphous alloys

The aim of this work is to employ the artificial neural networks for modelling the magnetic properties of the amorphous alloys with the iron and cobalt matrix. The artificial neural networks implemented in StatSoft Statistica Neural Network PL 4.0F were used to determine the relationship between the chemical compositions of amorphous alloys, heat treatment parameters and magnetic properties. The attempt to use the artificial neural networks for predicting the effect of the chemical composition and heat treatment parameters on the magnetic flux density BS succeeded, as the level of the obtained results was acceptable, as the level of the obtained results was acceptable. For different magnetic properties of soft magnetic materials, further calculations are planned. The results of calculation makes it possible to design new advantageous combinations of concentrations of the particular elements to develop grades of the soft magnetic alloys. This paper employs the artificial neural networks for modelling chemical composition and heat treatment parameters of amorphous soft magnetic alloys to obtain the best magnetic properties. [Received 15 August 2007; Accepted 20 October 2007]

Use of novel adaptive digital feedback for magnetic measurements under controlled magnetizing conditions

There are increasing calls to employ conventional magnetic testers, such as the Epstein frame and single sheet tester, for the accurate measurements of magnetic properties of soft magnetic materials under fully controlled nonsinusoidal flux density waveforms. This paper presents a computerized automated adaptive digital feedback system built for that purpose. We present several examples of the ability of the system to control an arbitrary shape of the flux density waveforms over the frequency range of the data acquisition system (0.5 Hz to 2 kHz) and for peak flux density up to 90% of saturation. The control algorithm is capable of magnetizing magnetic material under controlled sinusoidal, triangular, trapezoidal, and pulsewidth-modulated magnetizing conditions as well as other arbitrary waveforms that do not contain dc components. We provide a full description of the adaptive digital feedback technique together with measurements showing the B-H loops for several magnetic materials under various controlled excitation conditions.

Characterization of soft ferromagnetic materials by inductance spectroscopy and magnetoimpedance

Inductance spectroscopy and magnetoimpedance are extremely sensitive to a wide variety of intrinsic and extrinsic magnetic properties of soft magnetic materials; as a result, they can be used as a characterization tool. In this paper, the basic principles underpinning these magnetic phenomena are briefly discussed. The use of equivalent circuits is presented, as well as the correlations between the elements of such circuits and the relevant physical parameters of materials. Some specific cases are discussed.