Characterization Of Soft Magnetic Materials Research Articles

Electromagnetic characterization of ring-shaped specimens with a model-based parameter estimator

This work focuses on the characterization of soft magnetic materials with ring-shaped specimens. The authors present a novel concept based on analytical models for determining their electromagnetic material parameters, e.g., the non-linear magnetization curve, the electric conductivity, and iron losses.

Hysteresis and Loss Characteristics of Soft Magnetic Materials Based on Nonlinear Preisach Model

Hysteresis and Loss Characteristics of Soft Magnetic Materials Based on Nonlinear Preisach Model

Harmonic and DC Bias Hysteresis Characteristics Simulation Based on an Improved Preisach Model.

Transformers, reactors and other electrical equipment often work under harmonics and DC-bias working conditions. It is necessary to quickly and accurately simulate the hysteresis characteristics of soft magnetic materials under various excitation conditions in order to achieve accurate calculations of core loss and the optimal design of electrical equipment. Based on Preisach hysteresis model, a parameter identification method for asymmetric hysteresis loop simulation is designed and applied to the simulation of hysteresis characteristics under bias conditions of oriented silicon steel sheets. In this paper, the limiting hysteresis loops of oriented silicon steel sheets are obtained through experiments under different working conditions. The first-order reversal curves(FORCs) with asymmetric characteristics is generated numerically, and then the Everett function is established under different DC bias conditions. The hysteresis characteristics of the oriented silicon steel sheets under harmonics and DC bias are simulated by improving FORCs identification method of the Preisach model. By comparing the results of simulation and experiment, the effectiveness of the proposed method is verified, so as to provide an important reference for material production and application.

TiO2-Doped Ni0.4Cu0.3Zn0.3Fe2O4 Nanoparticles for Enhanced Structural and Magnetic Properties.

TiO2 (0–10 wt %)-doped nanocrystalline Ni0.4Cu0.3Zn0.3Fe2O4 (Ni–Cu–Zn) ferrites were synthesized using the sol–gel route of synthesis. The cubic spinel structure of the ferrites having the Fd3m space group was revealed from the analysis of Rietveld refined X-ray diffraction (XRD) data. The secondary phase of TiO2 with a space group of I41/amd was observed within the ferrites with doping, x > 3 wt %. The values of lattice parameter were enhanced with the addition of TiO2 up to 5 wt % and reduced further for the highest experimental doping of 10 wt %. Field emission scanning electron microscopy (FESEM) images exhibit the spherical shape of the synthesized particles with some agglomeration, while the compositional purity of prepared ferrite samples was confirmed by energy-dispersive X-ray spectroscopy (EDX) and elemental mapping. The cubic spinel structure of the prepared ferrite sample was confirmed by the Raman and Fourier transform infrared (FTIR) spectra. UV–visible diffuse reflectance spectroscopy was utilized to study the optical properties of the ferrites. The value of band gap energy for the pristine sample was less than those of the doped samples, and there was a decrement in band gap energy values with an increase in TiO2 doping, which specifies the semiconducting nature of prepared ferrite samples. A magnetic study performed by means of a vibrating sample magnetometer (VSM) demonstrates that the values of saturation magnetization of the ferrites decrease with the addition of TiO2 content, and all investigated ferrites show the characteristics of soft magnetic materials at room temperature. The Mössbauer study confirms the decrease in the magnetic behavior of the doped ferrites due to the nonmagnetic secondary phase of TiO2.

Measuring And Computing System for Studying the Magnetic Characteristics of Soft Magnetic Materials

Non-destructive eddy current diagnostics of the structure, composition, physical and mechanical properties of ferromagnetic materials, as well as eddy current monitoring of the operational parameters of products manufactured from them, requires knowledge of the magnetic characteristics of these materials. In eddy current measurements, the results obtained are influenced by a significant number of factors — magnetic and electrical properties of materials, geometric characteristics of products, measurement conditions, design features of an eddy current sensor, etc. Also, the magnetic properties themselves have high structural sensitivity. Thus, identification of the diagnosed parameters puts great importance on the tasks to separate the influencing factors and isolate the contribution of the magnetic properties.
 This paper describes the measuring and computing system that allows automatic determination of the magnetic permeability of soft magnetic ferromagnetic materials at various values of the strength of the external magnetizing field. The system has been tested using soft magnetic ferrites samples. An experimental dependence of the magnetic permeability on the magnitude of the magnetic field for the initial section of the main magnetization curve is presented. The obtained initial magnetic permeability is compared with the data of independent indirect measurements.
 The proposed system provides an increase in the reliability and accuracy of the results of the experimental determination of magnetic characteristics and can be used for non-destructive diagnostics of products made of soft magnetic ferromagnetic materials.

CaFe2O4 ferrite nanofibers via solution blow spinning (SBS)

Abstract CaFe2O4 nanofibers were successfully synthesized via solution blow spinning (SBS), and the influences of heat-treatment on morphological, microstructural, magnetic, and optical properties of the nanofibers were evaluated. In the synthesis process, stoichiometric amounts of iron and calcium nitrates were dissolved in an aqueous solution containing polyvinylpyrrolidone (PVP) and, after that, hybrid nanofibers (PVP/precursors) were produced by SBS. The hybrid nanofibers were calcined and then subjected to microstructural, morphological, and magnetic characterizations. The results evidenced that the fibers presented the crystalline nature of the single-phase CaFe2O4, with a crystallite size of 32.7 and 34.4 nm for the samples calcined at 800 and 1000 °C, respectively. The CaFe2O4 fibers calcined at 600 and 800 °C presented a homogeneous morphology, without beads, and mean diameters of 521 and 427 nm, respectively. The results also revealed nanofibers with low band gaps of approximately 1.98 eV and characteristics of soft magnetic materials.

Deep drawing with radial segmental blank holder based on magnetic control

<p indent=0mm>We propose a radial segmental blank holder technique based on the electro-permanent magnet (EPM) technology, in which we can obtain a more reasonable blank holding force (BHF). The magnetic pole unit was constructed according to the characteristics of soft magnetic materials and adjusted the magnetic state of the magnetic pole unit by an instantaneous low-intensity current. The tensile test revealed that the magnetic pole unit can provide a sufficiently large magnetic attraction force to satisfy the blank holding requirements. The measurement results of the temperature rise experiment verified that the magnetic pole unit would not cause overheating. According to the characteristics of the drawing process, the blank holder device and the drawing die based on EPM technology were designed. The BHF applied during the drawing process does not need to be continuously energized, so it has the advantages of energy-saving and safety. Theoretical derivation was used to determine the feasibility of the radial segmental blank holder technique and analyzed the initial distribution of the BHF on sheet metal using FEA. The results show that, compared with the conventional blank holder, we could implement the BHF applied by the new method in a larger radial area. We further verified the efficiency of the radial segmental blank holder technique by performing simulation. Since the BHF is more rationally distributed in the radial direction, we could control the sheet thickness variation better. Finally, the drawing experiment of the galvanized sheet revealed that the EPM technology is feasible for the blank holder, and the radial segmental blank holder technique can efficiently suppress wrinkling and enhance the performance.

SNR enhancement for the second harmonics in fluxgate sensor

The fluxgate sensor uses the nonlinear characteristics of soft magnetic materials to measure the geostationary magnetic field, which has the characteristics of high sensitivity, wide magnetic measurement range and easy portability, and is widely used in geological exploration, navigation, space technology and other fields. In this paper, the research is based on the second harmonic method of the development of fluxgate sensor, since the second harmonic contains static magnetic field direction and amplitude information, so the second harmonic signal to noise ratio enhancement can effectively improve the resolution of the fluxgate sensor. In this paper, the induction signal is first resonated to the second harmonic frequency using a resonant circuit, and then filtered after an amplification circuit, the second harmonic signal-to-noise ratio is significantly enhanced by 13 times.

Microwave Response of Gd-Doped YIG Based Y-Junction Stripline Circulator for Use at Very High Frequencies

This study aimed to evaluate Fe2O3 based magnetic ferrite performance and its composition using Rare Earth Oxide (REO) of Yttrium as dopant and Gadolinium as co-dopant elements. Lot of specimens were prepared through dry pressing technique, and sintered into the high temperature tube furnace up to 1450°C. Sintering duration of 5 hours results the best magnetic properties. The existence of Gadolinium element tends to improve magnetic properties of magnetic ferrite Gd-doped YIG structure. Remacomp brand Magnet-Physik was used to determine the characteristics of soft magnetic materials in the measurement frequency range of 10 Hz to 70 kHz. Microwave response was measured using the Vector Network Analysis to provide insertion loss and isolation data. The obtained insertion loss of Gd0.75Y2.25Fe5O12 is 0.4270 dB (at 3.7 GHz) and 0.2455 dB (at 4.2 GHz), while the isolation value is 11.3840 dB (at 3.7 GHz) and 17.8250 dB (at 4.2 GHz). The further experiment will be carried out to improve the microwave response and better magnetic properties of Gd-doped YIG structure.

Accuracy of frame-shaped samples based measurements of magnetoelastic characteristics of soft magnetic materials

Abstract Frame-shaped samples method is commonly used for testing the magnetoelastic characteristics of bulk soft magnetic materials, such as ferrites or steels. However, unusual shape of such samples limits the accuracy of estimation of magnetic path length as well as efficient magnetic cross-section of the samples carried out accordingly to the IEC 60205:2016 standard. Paper presents, how to overcome this drawback with finite elements method. The quality of estimation of magnetic path length and efficient magnetic cross-section of the frame-shaped samples were verified from the point of view of non-linear magnetization characteristics of soft magnetic materials. The results indicate that proper correction of core’s parameters calculated accordingly to the IEC 60205:2016 standard enable significant increase of measurements accuracy of soft magnetic materials’ characteristics.

Measurement and modeling of hysteresis characteristics in ferromagnetic materials under DC magnetizations

The static hysteresis characteristics of soft magnetic materials were measured by the static performance testing system (SPTS). With a toroidal-shape specimen and Epstein frame, the DC magnetizations of different forms of magnetic steel sheet and grain-oriented (GO) silicon steel sheet can be realized by setting a DC excitation. Besides, the corresponding first-order reversal curves (FORCs), higher-order reversal curves (HORCs) and concentric hysteresis loop are measured. Based on the measured FORCs, the parameter identification was carried out, and the Everett function was established. Thus the inverse Preisach model was obtained. The consistency between the simulated results and the measured ones verifies the validity of the measurement method and the accuracy of the numerical simulation method of magnetic hysteresis characteristics.

Structural and impedance spectroscopy characterization of Soft Magnetic Materials

Abstract This work studies the relationship between the structural characteristics and the final magnetic properties of two different iron-based materials: one basic Soft Magnetic Material (SMM) and a Soft Magnetic Composite (SMC). The micrometric size of the starting powder, the pure iron composition of the core and the presence of a phosphate isolating shell in the composite sample were revealed by powder X-ray diffraction, Laser Diffraction and Fourier Transformed Infrared Spectroscopy respectively. Moreover, Scanning Electron Microscopy confirms the range of sizes of the powder samples and their non-perfect spherical shape. Magnetic and Impedance Spectroscopy measurements evidence the effects that the isolating shell has on the effective magnetic permeability and the relaxation frequency at which magnetic losses appear. Results obtained are of great interest from a technological point of view because the frequency range at which each material can effectively operate is measured. Furthermore, different structural aspects (such as particle size or the presence of an isolating shell) are related with the final functional properties. Besides, these results can help in the design of new soft magnets with lower magnetic losses over a wide range of frequencies.

Characterisation of soft magnetic materials by measurement: Evaluation of uncertainties up to 1.8 T and 9 kHz

Magnetic measurements are indispensable for the characterization of soft magnetic material used e.g. in electrical machines. Characteristic values are used as quality control during production and for the parametrization of material models. Uncertainties and errors in the measurements are reflected directly in the parameters of the material models. This can result in over-dimensioning and inaccuracies in simulations for the design of electrical machines. Therefore, existing influencing factors in the characterization of soft magnetic materials are named and their resulting uncertainties contributions studied. The analysis of the resulting uncertainty contributions can serve the operator as additional selection criteria for different measuring sensors. The investigation is performed for measurements within and outside the currently prescribed standard, using a Single sheet tester and its impact on the identification of iron loss parameter is studied.

Study and characterization of soft magnetic materials for beam intensity monitors at CERN

At CERN, the circulating beam current measurement is provided by two types of transformers, the DC Current Transformer (DCCT) and the Fast Beam Current Transformer (FBCT). Each transformer is built based on toroidal cores made from a magnetic material. Depending on the type of measurement to be performed these cores require different magnetic characteristics for parameters such as permeability, coercivity and the shape of the magnetization curve. In order to study the effect of changes in these parameters on the current transformers, several interesting raw materials based on their as-cast properties were selected. The materials have been characterised to determine a suitable annealing processes to tailor their properties. As-cast properties such as the permeability, coercivity and Barkhausen noise have also been measured to enable the study of the effect of thermal treatment in the microstructure of the alloys, and the correlation of this with the change in the magnetic properties. The comparison of the measured properties have narrowed down the best materials for further study.

Characterization of Soft Magnetic Materials in AC Magnetic Fields by Digital Methods

Characterization of Soft Magnetic Materials in AC Magnetic Fields by Digital Methods

Investigation on Electromagnetic Models of High-Speed Solenoid Valve for Common Rail Injector

A novel formula easily applied with high precision is proposed in this paper to fit the B-H curve of soft magnetic materials, and it is validated by comparison with predicted and experimental results. It can accurately describe the nonlinear magnetization process and magnetic saturation characteristics of soft magnetic materials. Based on the electromagnetic transient coupling principle, an electromagnetic mathematical model of a high-speed solenoid valve (HSV) is developed in Fortran language that takes the saturation phenomena of the electromagnetic force into consideration. The accuracy of the model is validated by the comparison of the simulated and experimental static electromagnetic forces. Through experiment, it is concluded that the increase of the drive current is conducive to improving the electromagnetic energy conversion efficiency of the HSV at a low drive current, but it has little effect at a high drive current. Through simulation, it is discovered that the electromagnetic energy conversion characteristics of the HSV are affected by the drive current and the total reluctance, consisting of the gap reluctance and the reluctance of the iron core and armature soft magnetic materials. These two influence factors, within the scope of the different drive currents, have different contribution rates to the electromagnetic energy conversion efficiency.

Transport and Magnetic Properties of Nano Compounds of Nickel-Zinc Ferrite for Frequency Reliant Applications

Nano particles of NixZn(1-x)Fe2O4(x = 0.1:0.2:0.9) synthesized by bio-mediated combustion using Memosa pudica plant extract as fuel followed by immediate ultrasonication. The prepared samples were characterized by powder X-ray diffraction; scanning electron microscopy and Fourier transform infrared spectroscopy. The samples were subjected to electrical impulse and magnetic fields to study their electrical and magnetic properties. The variation of magnetic parameters like saturation magnetization, remanence and coercive fields were studied for three compositions of zinc nickel ferrite using vibrating sample magnetometer with a maximum applied field of 20 kG. The hysteresis loops display the characteristics of soft-magnetic materials. The saturation magnetization, coercivity and remanent magnetization were decreased with increase in Ni content. The variation of dielectric constant with frequency shows the values of real part has very less than its imaginary part makes the system as more anisotropic. The prepared samples may be useful for various frequency reliant applications.

Design of a measurement system for investigating the magnetic characteristics of soft magnetic materials for non-sinusoidal periodic excitations

Abstract This article is about the design of a measurement system for measuring the iron losses in soft magnetic materials exerted by periodic flux density characteristics. The losses are due to hysteresis and eddy currents effects. The aim is to predict the iron losses which occur in electric machines. Common loss modeling techniques are derived by considering sinusoidal flux density characteristics. As nowadays highly-utilized machine designs with special winding topologies are employed, the periodic flux density characteristics in a big part of the ferromagnetic components are far off from being sinusoidal. Hence, the here presented measurement system and the associated control are especially developed for analyzing any periodic flux density characteristics. A further part of this article is dedicated to the comparison of state-of-the-art iron loss modeling techniques and measurement results. Several scenarios with different flux density harmonic magnitudes and frequencies are considered. It turns out that currently available loss modeling techniques show significant modeling errors for non-sinusoidal periodic flux density excitations. Thus, future work has to be on deriving more accurate models by considering their applicability for computer-aided engineering software.

Tunable Optical Mode Ferromagnetic Resonance in FeCoB/Ru/FeCoB Synthetic Antiferromagnetic Trilayers under Uniaxial Magnetic Anisotropy

Ferromagnetic resonance (FMR) is one of the most important characteristics of soft magnetic materials, which practically sets the maximum operation speed of these materials. There are two FMR modes in exchange coupled ferromagnet/nonmagnet/ferromagnet sandwich films. The acoustic mode has relatively lower frequency and is widely used in radio‐frequency/microwave devices, while the optical mode is largely neglected due to its tiny permeability even though it supports much higher frequency. Here, a realistic method is reported to enhance the permeability in the optical mode to an applicable level. FeCoB/Ru/FeCoB trilayers are carefully engineered with both uniaxial magnetic anisotropy and antiferromagnetic interlayer exchange coupling. This special magnetic structure exhibits a high optical mode frequency up to 11.28 GHz and a maximum permeability of 200 at resonance. An abnormally low inverse switch field (&lt;200 Oe, less than 1/5 of the single layer) is observed which can effectively switch the system from optical mode with higher frequency into acoustic mode with lower frequency. The optical mode frequency and inverse switch field can be controlled by tailoring the interlayer coupling strengths and the uniaxial anisotropy fields, respectively. The tunable optical mode resonance thus can increase operation frequency while reduce operation field overhead in FMR based devices.

A Practical Method for the Characterization of Soft-Magnetic Materials

This paper presents a practical method for obtaining the constants that define the saturation and losses of soft-magnetic materials, making the separation of the magnetic field in four parts: 1) anhysteretic field; 2) static hysteresis field; 3) Foucault losses field; and 4) excess losses field. The proposed practical method for the characterization of soft-magnetic materials consists of the following steps: 1) an acquisition of the experimental data of voltage and current in a simple magnetic circuit (considering uniform field); 2) an assembly of tables with a period of the curve with the magnetic induction versus magnetic field; 3) a linear least square simulation to obtain the characteristic parameters of the material; and 4) error analysis. The ease of obtaining data, the objectivity of the algorithm, and root mean square error among the simulated and experimental hysteresis curves situated in the range of 6% are showing the efficacy of this methodology.