Magnetic characterization of soft magnetic materials—experiments and analysis (original) (raw)
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CHARACTERISATION OF HARD MAGNETIC MATERIALS
Different methods determining the hysteresis loop of permanent magnets are summarised. In industry the use of a hysteresograph (based on fluxmeters) within an electromagnet as a field source is most common. This is a magnetic closed system where no demagnetizing effects have to be considered. A Vibrating Sample Magnetometer (VSM) is a magnetically open system, but it offers a significantly higher sensitivity. If as a field source a superconducting coil is used fields up to 10T are easy to get. The system with the highest sensitivity, which allows the measurement of single grains or thin films, is a SQUID-magnetometer. SQUID magnetometers are available with external fields up to 7 T, however such instruments are more common in scientific laboratories. A Pulsed Field Magnetometer (PFM) offers sufficient high external fields (10 T and more) together with a fast measuring system. Disadvantageous is that in such system time dependent effects such as eddy currents and magnetic viscosity may limit the achievable accuracy. However for a quality control a PFM is a very suitable instrument. K e y w o r d s : hard magnetic materials, magnetometers, pulsed fields
Vector characterization of soft magnetic materials
Journal of Applied Physics, 2005
A three-dimensional ͑3D͒ 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.
Characterization of Soft Magnetic Materials in AC Magnetic Fields by Digital Methods
PRZEGLĄD ELEKTROTECHNICZNY
For the characterization of soft magnetic materials in AC magnetic fields, digital methods are commonly used nowadays. Magnet-Physik offers a family of computer controlled BH-loop tracers. These allow the automated measurement of AC hysteresis loops under various conditions. For instance, an automated separation of the total loss per cycle of the hysteresis loops in dependence of the frequency into hysteretic loss, eddy current loss and anomalous loss (excess loss) is implemented within the software. Furthermore, an automated determination of the total power loss in dependence of H max or B max can be achieved. Streszczenie. Firma Magnet Physik oferuje rodzinę komputerowo sterowanych testerów pętli histerezy. Umożliwiają one automatyczne badanie pętli histeezy w różnych warunkach. Na przykład możliwa jest automatyczny rozdział strat w unkcji częstotliwości. Ponadto możliwe jest określanie strat w zależności od wartości indukcji inatężenia pola magnetycznego. Badania miękkich materiałów magnetycznych przy prądzie przemiennym metodami cyfrowymi
Journal of Applied Physics, 2011
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. V
Thermal annealing of soft magnetic materials and measurements of its magnetoelastic properties
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Paper presents both methods of the most advanced thermal annealing as well as available methods of testing the magnetoelastic properties of soft magnetic materials for technical applications. Selected features and conditions important for annealing of ring-shaped cores made of the magnetoelastic amorphous ribbons are described and an example of thermo- magnetic processing is shown. Unified methodologies for testing of magnetoelastic properties of the frame-shaped and the ring- shaped cores, for both compressive and tensile stresses are presented.
An investigation of soft magnetic and non magnetic materials under low frequency
2011
The recent development of magnetic sensors in biomedical sector has called for urgent investigation on the characterization and relative magnetism of magnetic and nonmagnetic materials. This paper proposes a novel technique to categorize the magnetic and non-magnetic materials by obtaining their impedance peaks. The magnetization effect of a magneto-inductive sensor was detected in low frequency range for different magnetic and nonmagnetic core materials. The distinctive impedance peak values have been obtained for each materials used as core which result in showing different magneto-inductive effect. The results have shown a dominant behaviour of magnetic materials over non-magnetic materials due to the variation of permeability and magnetic strength (number of turns). Moreover, variations in permeability originated by the applied alternative current field results in changing the depth (insertion depth) and also in the impedance. The influence of the permeability on materials with different frequencies is detailed. Also, concentration is paid to the recent studies in the application base. It should be mentioned that high impedance peaks mean high output voltage in the secondary side. The novelty of this technique lies in the simplicity of ordinary circuits which are used in the experimental setup for characterization purpose. As a whole, this paper aims to investigate and characterize magnetic and non-magnetic materials; thus opening up a new branch of research for the application of soft magnetic materials in biomedical field.
Surface Magnetoimpedance Measurements in Soft-Ferromagnetic Materials
We present an investigation of the surface magnetoimpedance (Z S ) in ribbons of the amorphous alloy Co 70.4 Fe 4.6 Si 15 B 10 for a broad range of frequencies (2 Â 10 3 Hz f 2 Â 10 8 Hz) and magnitudes of the ac electrical current (2 mA I ac 75 mA). The experimental data are interpreted in terms of a theoretical model valid for any value of the skin depth d, which is based on a modification of the currently used semi-infinite sample geometry model, in order to account for a broad range of d. The shape of the Z S versus applied field (H) curve is mainly determined by the variation of d with H, which can attain several orders of magnitude in the field range of the experiments (± ±3.2 Â 10 3 A/m H 3.2 Â 10 3 A/m). The results of the model fit very well the Z S versus f data using three adjustable parameters: the domain-wall relaxation time t (= 250 ns for all values of I ac used in the experiments), the transversal magnetic permeability c T (I ac ) and a resonance linewidth DH which depend on the value of H.
An Investigation on Soft Magnetic and Non Magnetic Materials Under Low Frequency
The recent development of magnetic sensors in biomedical sector has called for urgent investigation on the characterization and relative magnetism of magnetic and nonmagnetic materials. This paper proposes a novel technique to categorize the magnetic and non-magnetic materials by obtaining their impedance peaks. The magnetization effect of a magneto-inductive sensor was detected in low frequency range for different magnetic and nonmagnetic core materials. The distinctive impedance peak values have been obtained for each materials used as core which result in showing different magneto-inductive effect. The results have shown a dominant behaviour of magnetic materials over non-magnetic materials due to the variation of permeability and magnetic strength (number of turns). Moreover, variations in permeability originated by the applied alternative current field results in changing the depth (insertion depth) and also in the impedance. The influence of the permeability on materials with ...