Characterization Of Soft Magnetic Materials Research Articles

Model Specific Characterization of Soft Magnetic Materials for Core Loss Prediction in Electrical Machines

This paper describes a methodology to characterize soft magnetic materials for a core loss model, which is capable of predicting both instantaneous and average loss. The characterization method dispenses with the need for close loop control, which significantly extends the range of non-linearity and frequency that can be covered with a given experimental apparatus. It derives the various model coefficients from a combination of quasi-static (B)-(H) loop measurements, known material properties and dimensions and dynamic loss measurements on arbitrary (i.e., non-sinusoidal) flux density. The methodology is applied to a sample of Vacodur S+Cobalt Iron.

Vector hysteresis measurements of not oriented grain SiFe steels by a biaxial hall sensors array

This work discusses the vector measurement of the effective magnetic field inside a not oriented grain SiFe steel sample, taking into account the effect of the demagnetizing field. We propose an array of biaxial Hall sensors, placed up to the sample surface. The calibration of the system and a suitable extrapolation data strongly reduce the uncertainties of the direct measurement and provide an accurate evaluation of the magnetic field inside the material sample. Although the approach proposed can be also used for industrial frequencies, 50–60Hz or more, the analysis is limited here to the static case, because we are mainly interested in static magnetic measurements. These measurements are especially useful for the vector characterization of soft magnetic materials and, in particular, for the identification and the experimental validation of vector hysteresis models. The experimental analysis presented in the paper deals with commercial not oriented grain SiFe steels. Experimental data about hysteresis loops and static power losses are given.

Preparation and characterization of electroless Ni-Fe-P alloy films on fly ash cenospheres

The process of depositing Ni-Fe-P alloy films on fly ash cenospheres (FACs) through modified electroless plating is documented. A coupling procedure was used with γ-aminopropyltriethoxy silane (APS) as coupling agent and silver nitrate as activator. The resultant Ni-Fe-P/FACs composites were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), X-ray diffractometry (XRD) and vibrating sample magnetometry (VSM). The results show that continuous and uniform films of Ni-Fe-P alloy were obtained on the surfaces of the FACs. DSC traces indicated that two distinct exothermic peaks appeared during the heat treatment, which moved to higher temperature with decrease in mole ratios of Ni2+/Fe2+ in the coating. XRD spectra confirmed that electroless Ni-Fe-P alloy deposits were amorphous in the as-plated condition, which transformed from the amorphous to crystalline phase with increase in calcining temperature. In addition, VSM data revealed that the resulting sample exhibited characteristics of soft magnetic materials at room temperature. The magnetic performances of the composites would be ameliorated with an increase in iron content in the coating and calcining temperature.

Fe<SUB>3</SUB>O<SUB>4</SUB>/PANI/P(MAA-co-NVP) Multilayer Composite Microspheres with Electric and Magnetic Features: Assembly and Characterization

A core-shell multilayered composite microsphere with electric and magnetic features was designed and prepared on the basis of mutilayered fabrication. This kind of microspheres was obtained by introducing a rod-like conductive polyanilline (PANI) or its derivatives onto the surface of magnetic Fe3O4 nanoparticles with 4,4'-diphenylmethane diisocyanate as a anchor molecule. Subsequently, the Fe3O4/PANI or Fe3O4/aniline oligomers microspheres, as a secondary core, were covered with a cross-linked shell layer which was constructed by a dispersion polymerization process of methacrylic acid and vinyl pyrrolidone. The structure and morphologies were characterized by using a FTIR, XRD, UV-vis, SEM, TEM and TGA. The average diameter of Fe3O4 nanoparticles prepared is about 10.7 nm, and the PANI nanobars hold the size in the range of about 20.4-25.6 nm. The PANI nanobars are covalently assembled on the surface of Fe3O4 nanoparticles mainly in a mode of extended or horizontal arrangements through XRD and TEM results. The electromagnetic properties were examined based on different polymerization degrees and component ratios of PANI or its derivatives, showing characteristics of soft magnetic materials and controllable conductivity. The multilayer microspheres can be readily used to perform separation and magnetism guide, even electric and pH-modulated drug release in the light of swelling determination and a laser diffraction particle size analyzer, and are potentially of interest for drug targeting purpose.

Microwave characteristics of soft magnetic materials: FeZrN thin films and their dependence on nitrogen concentration

Ferromagnetic resonance (FMR) studies of FeZrN films prepared by RF sputtering with N2 partial pressure=0.05, 0.075, 0.10 and 0.15 are used to determine their microwave characteristics. These room temperature studies at 9.29 GHz and for in-plane orientation of the applied field H show that both the resonance field Hr and the line-width ΔH have 180° symmetry representing uniaxial anisotropy Hk. However with increase in x, Hk decreases but ΔH and Hr increase. The calculated cut-off FMR frequency for H=0 systematically decreases from 1.62 GHz for x=0.05 to 1.34 GHz for x=0.15. This suggests that the film with x=0.05 has the best overall microwave properties for high-frequency applications.

A setup for measuring the magnetic characteristics of soft magnetic materials and articles

An automated setup for measuring the normal magnetization curve, the major and minor magnetic-hysteresis loops, and the main (initial permeability, maximum permeability, residual magnetic induction, induction coercive force, and saturation induction) and additional (the permeability at a field equal to the coercive force, the field strength at which the saturation induction is reached, and the induction at fields equal to the coercive force and the double coercive force) magnetic parameters of soft magnetic materials and articles produced from them is described. Measurements are performed in an open or closed magnetic circuit at a magnetization-reversal frequency of 0.05–0.5 Hz. The block diagram of the setup and its main parameters and characteristics are presented. The operation of the setup and the possibilities of its application are considered.

Three-dimensional hysteresis of soft magnetic composite

Hysteresis phenomenon is one of the important characteristics of soft magnetic materials. A three-dimensional (3D) magnetic property measurement system has been developed. This system can effectively control the locus of the time-varying magnetic flux density vector B and measure the corresponding magnetic field strength vector H in a cubic sample of soft magnetic material. The sample involved in this study is a soft magnetic composite sample made of highly pure iron powder. This paper investigates the B and H loci in 3D space and the power loss when the B loci are controlled to become circles and ellipses lying in three orthogonal planes. It is found that the B and H loci lie in the same magnetization plane, but the H loci and losses depend strongly on the orientation, position, and process of magnetization. On the other hand, the H vectors evolve into a unique locus pattern, and the power losses approach a unique value when the B vectors evolve into the same loci through either a series of small circles or ellipses.

Vector characterization of soft magnetic materials

A three-dimensional (3D) magnetic property testing system has been completed and successfully used to measure 3D hysteresis loci of soft magnetic material. This paper presents the techniques to characterize soft magnetic materials under 3D magnetic excitations in detail. Using three couples of excitation coils controlled by a computer to generate the magnetic fields in three orthogonal axes, various types of flux density loci, such as circular or elliptical rotating vectors of flux density with any given orientations in 3D space, can be obtained. Based on 3D finite element analysis and a comparative study, a sandwich arrangement comprising a sample, guard pieces, and search coils with double-layer structure was proposed. Compared with the conventional surface search coils, this arrangement can significantly improve the accuracy of measurement. The comprehensive calibration process and the experimental results of the 3D hysteresis loci of soft magnetic composite materials are also presented.

Global Characterization of Soft Magnetic Materials Under Rotating Flux Density Conditions

Although several authors have proposed different devices to measure the iron loss in magnetic sheets used in the building of electrical machines, few of them take into account the real electromagnetic working context. This paper deals with the possibility of determining the iron loss and the apparent magnetic permeability from the measurement of the flux density in the air gap with the use of the Maxwell's tensor and an analog computer. We propose new methods to obtain the power loss and the magnetic permeability of magnetic samples.

Magnetic characterization of soft magnetic materials—experiments and analysis

Various kinds of magnetic measurement methods suited for soft magnetic materials are critically surveyed. Emphasis was laid on AC-susceptibility methods, the hysteresis loop and the magnetostriction. The analysis of the temperature dependence of the magnetization and the magnetostriction is demonstrated on the amorphous system Fe–Co–B.

The effect of Zn ion substitution on electromagnetic properties of low-temperature fired Z-type hexaferrite

The influence of Zn substitution on the densification, microstructure, lattice parameters and electromagnetic properties of planar Z-type hexaferrites, which have stoichiometric composition of Ba 3Co 2(10.8− x) Zn 2 x Cu 0.4Fe 24O 41, were investigated. The results show that the Zn 2+ substitution has no obvious effect on the densification, but Z-type hexagonal phase can form and demonstrate typical planar anisotropic characteristics of soft magnetic materials ( σ r⩽6.20 emu/g) in the range of x⩽0.25. The of lattice parameters of planar a (0.588 nm) and axial c (5.25 nm) remain stable. At the certain temperatures, the sintered hexaferrites with an optimal density of about 4.62 g/cm 3 show better electromagnetic properties for x=0.15 than the samples without Zn 2+ incorporation: initial permeability of about 9.0, cut-off frequency of above 800 MHz, resisitivity of above 3.20 Ω cm and dielectric constant of less than 35.

Simplified spectrum characterization of soft magnetic materials under PWM excitation

This paper explains how to simplify the harmonic description of the behaviour of a soft magnetic material tested by Epstein method under non-sine conditions. PWM waves are used to illustrate the method. Comparison of the harmonic parameters corresponding to a complete characterization and a simplified one validates this method.

Synthesis of nanocrystalline permalloy

The advantages of nano-processing for the overall performance characteristics of soft magnetic materials used in recording head applications are discussed. Preliminary results pertaining to the synthesis of nano-processed permalloy for this application are presented.

Characterization of soft magnetic materials using a modified Stoner-Wohlfarth model

In this paper a modification of the Stoner-Wohlfarth (SW) model is used to simulate the magnetic properties of soft materials. This modification has been used before in modelling the incoherent reversal processes in magnetic fine particles of the kind generally used in magnetic recording. In the case of particulate media the model gave good results, particularly in the prediction of the angular variation of the switching fields. In our model we consider that the magnetic properties of the soft magnetic materials can be obtained as a superposition of quasi-SW particles. These particles have different axial and transverse switching fields. The axial switching field corresponds to the low energy process of wall displacement with the domain walls crossing over the material imperfections, but the transverse one is a high field corresponding to the crystalline anisotropy field and to the reversible rotation of the particle moment. The example presented considers the case of aligned materials, with the magnetic field applied along the alignment direction. In the case of rotational hysteresis, torque curves were calculated for different values of the applied field strength.

A system for AC low fields magnetic characterization of soft magnetic materials

A system for magnetic characterization of soft magnetic materials in low field is described. Fields of 0.02 A/m can be applied and a good sensibility is achieved by means of a Lock-In amplifier. Signals of 1 nV can be measured, and magnetic characterization with external stresses can be made. The measurements can be done from room temperature up to 973 K. The system allows to perform permeability, pinning field, Curie temperature and disaccommodation measurements automatically. >

Accuracy of digital measurement of dynamic magnetic characteristics of soft-magnetic materials

The errors of measurements of dynamic magnetic characteristics of soft-magnetic materials due to sampling in time and signal-level quantization during analog-digital conversion are analyzed considering the effect of the computing algorithm for sinusoidal signals.

New power supply method for soft magnetic material characterization at high flux density values

A novel power supply is proposed to improve the characterization of soft magnetic materials at high flux density. The power supply consists of a high-frequency switching power supply (PWM inverter) with a voltage regulator to control the distortion of the electromotive force induced in the device under test (Epstein yoke, wound, core, etc.). Experimental results confirm the good features of the proposed solution for flux density values up to 1.9-2.1 T.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The authors' replies to the discussion on “Some special characteristics of soft magnetic materials used in instrument manufacture”, “The properties of insulating materials used in instruments” and “Components for instruments”

The authors' replies to the discussion on “Some special characteristics of soft magnetic materials used in instrument manufacture”, “The properties of insulating materials used in instruments” and “Components for instruments”

Discussion on “Some special characteristics of soft magnetic materials used in instrument manufacture”, “The properties of insulating materials used in instruments” and “Components for instruments” before the Measurements Section, 30th May, 1651

Discussion on “Some special characteristics of soft magnetic materials used in instrument manufacture”, “The properties of insulating materials used in instruments” and “Components for instruments” before the Measurements Section, 30th May, 1651

Some special characteristics of soft magnetic materials used in instrument manufacture

Some special characteristics of soft magnetic materials used in instrument manufacture