Coercive force of double layer ferromagnetic materials

Peculiarities of the coercive force (CF) measuring of inhomogeneous ferromagnetic materials, in particular layered ones, are considered. The concept of effective CF of layered ferromagnetic materials is introduced. The analysis of the magnetic fluxes distribution in a double layer ferro-magnetic material during its reversal magnetization by an attachable transducer with a U-shaped core made of soft magnetic material is carried out. An analytical expression of the effective CF for such class of materials for the case of the same layers’ thickness and linear approximation of their demagnetization curves is obtained. It was found that the effective CF of a double layer ferromagnetic material is determined not only by the CF of its individual layers, but also by the values of their residual induction. Experimental verification of the obtained results was performed on experimental samples, which were collected from steel 08kp (sample # 1) and steel St3 (sample # 2) plates. Each of the samples was a stack of 6 plates each measuring 87×50×1 mm. With tight compression of the plates and complete elimination of the gaps between them, these samples can be considered as single layer ferromagnetic structures with a thickness of 6 mm. To model a double layer ferromagnetic material with the same layer thickness, sample № 3 was used. Its the upper part consisted of the three steel 08kp plates and the lower part – of the three steel St3 plates. To measure the magnetic parameters of these samples the KRM-Ts-MA type magnetic analyzer was used. The device permit to measure the CF, residual induction and other parameters of the hysteresis loops of ferromagnetic materials in the closed magnetic circuit by attachable type transducers with U-shaped core. The transducer used with the magnetic analyzer during the experiments had poles with an area of 16×32 mm and the distance between the edges of the poles: inner – 32 mm, outer – 64 mm. It is shown that the discrepancy between the calculated value of the effective CF of the double layer ferromagnetic material (sample # 3) from steel 08kp and St3 according to the obtained expression and the measurement results is about 3%. This confirms the adequacy of the proposed model of reversal magnetization of double layer ferromagnetic material and the correctness of analytical calculations.

Development of Application Specific Intelligent Framework for the Optimized Selection of Industrial Grade Magnetic Material

This article attempts to introduce a simple and robust way for the classification of soft magnetic material by using multivariate statistics. The six magnetic properties including coercive magnetic field, relative magnetic permeability, electrical resistivity magnetic inductions, i.e., remanence and saturation along with Curie temperature are used for the classification of 16 soft magnetic materials. Descriptive statistics have been used for defining the prioritization order of the mentioned magnetic characteristics with coercive magnetic field and Curie temperature as the most and least important characteristics for classification of soft magnetic material. Moreover, it has also justified the usage of cluster analysis and principal component analysis for classifying the enlisted materials. After descriptive statistics, cluster analysis is used for classification of materials into four groups, i.e., excellent, good, fair and poor while defining the prioritization order of materials on a relative scale. Principal component analysis reveals that the relative permeability is responsible for defining 99.69% of total variance and is also negatively correlated with the coercive magnetic field. Therefore, these two characteristics are considered the responsible factors for categorically placing the enlisted materials into four clusters. Furthermore, principal component analysis also helps in figuring out the fact that a combined influential consequence of relative permeability, coercive magnetic field, electrical resistivity and critical temperature are responsible for defining prioritization ordering of materials within the clusters. The material’s suitability index is identified while making use of adjacency and decision matrices obtained from material assessment graph and relative importance of magnetic properties, respectively. Afterward this material suitability index is used to rank the enlisted materials based on selected attributes. According to the suitability index, the best choice among enlisted soft magnetic materials is Supermalloy, Magnifer 7904 which is present in group 1 labeled as excellent by multivariate analysis. Therefore, the results of graph theory are in accordance with cluster analysis and principal component analysis, thus confirming the potential of this intelligent approach for the selection application specific magnetic materials.

Wireless Torque and Power Transfer Using Multiple Coils with LCC-S Topology for Implantable Medical Drug Pump

In this paper, we propose a method of wirelessly torque transfer (WTT) and power (WPT) to a drug pump, one of implantable medical devices. By using the magnetic field generated by the WPT system to transfer torque and power to the receiving coil at the same time, applications that previously used power from the battery can be operated without a battery. The proposed method uses a receiving coil with magnetic material as a motor, and can generate torque in a desired direction using the magnetic field from the transmitting coil. The WPT system was analyzed using a topology that generates a constant current for stable torque generation. In addition, a method for detecting the position of the receiving coil without using additional power was proposed. Through simulations and experiments, it was confirmed that WTT and WPT were possible at the same time, and in particular, it was confirmed that WTT was stably possible.

Evaluation of magnetic properties of thin magneto-dielectric films deposited from beam plasma in medium vacuum

By electron-beam evaporation of a solid state dielectrics (alumina ceramics) and a magnetic material (steel-3) in fore-vacuum, thin films of several μm, possessing both dielectric and magnetic properties, were deposited on a substrate. The work shows that the microstrip resonator method can be used to assess the presence of magnetic properties in films.

Analysis of selected properties of powdered compacts

Magnetic materials are large and specific group of materials with interesting properties and useful applications. Some of them have been known for many years, but many important materials have only been discovered in recent decades. It can be expected that many newly discovered materials with specific properties will soon be used in applications in which magnetic materials have been used for a long time, but their properties will be better. The development of new magnetic materials will certainly bring the possibility of their use in such applications in which they have not been used before. This paper contains the review of the results of research focused on the study of soft magnetic ferromagnetic materials. Specifically, they are materials of chemical composition Fe19Ni81 (called Permalloy) and Fe16Ni79Mo5 (called Supermalloy). These materials were prepared in the form of powders by the technique of the mechanical milling. Subsequently, these powders were compacted with aim to prepare a compacted material of the desired shape and size with excellent magnetic properties. This research was focused on the study of the structure and magnetic properties of massive magnetic materials prepared by the compaction of the powders in order to prepare soft magnetic material with excellent properties competing with the material used so far.

Information storage in permalloy modulated magnetic nanowires

A long piece of magnetic material shaped as a central cylindrical wire (diameter $$d=50$$ d = 50 nm) with two wider coaxial cylindrical portions (diameter $$D=90$$ D = 90 nm and thickness $$t=100$$ t = 100 nm) defines a bimodulated nanowire. Micromagnetism is invoked to study the equilibrium energy of the system under the variations of the positions of the modulations along the wire. The system can be thought of as composed of five independent elements (3 segments and 2 modulations) leading to $$2^5=32$$ 2 5 = 32 possible different magnetic configurations, which will be later simplified to 4. We investigate the stability of the configurations depending on the positions of the modulations. The relative chirality of the modulations has negligible contributions to the energy and they have no effect on the stability of the stored configuration. However, the modulations are extremely important in pinning the domain walls that lead to consider each segment as independent from the rest. A phase diagram reporting the stability of the inscribed magnetic configurations is produced. The stability of the system was then tested under the action of external magnetic fields and it was found that more than 50 mT are necessary to alter the inscribed information. The main purpose of this paper is to find whether a prototype like this can be complemented to be used as a magnetic key or to store information in the form of firmware. Present results indicate that both possibilities are feasible.