Ferromagnetic Microwires Research Articles

Electromagnetic modeling and analysis based on multilayer domain structure for GMI behavior in high frequency

Existing theoretical models on the frequency dependence of the magnetoimpedance (MI) in ferromagnetic microwires primarily describe the MI phenomenon at the limiting cases of lower MHz (<several hundred MHz) or higher GHz (>several GHz) ranges. However, in the intermediate region between these two ranges, known as the transition region, MI curves undergo complex transformations. These transformations have been documented in the literature, but their underlying causes remain poorly understood. Unambiguous knowledge of the domain structure and its correlation with MI properties is essential for elucidating this behavior. In this study, we have, for the first time, observed the inner core magnetic structure of Co-based microwires and revealed its relationship with the high-frequency MI effect. A distinct magnetic structure comprising longitudinal domains in the inner core (IC), circular domains in the outer shell (OS), and a transition region (TR) has been identified. This structure originates from compositional gradients and residual stresses during microwire fabrication. The IC/TR/OS structure manifests in the complex transformations of the MI behavior, exhibiting a turning point at GHz frequencies before the characteristic double MI peak. We developed a multilayer planar model that considers this more realistic magnetic structure, including the TR layer. This model successfully reproduces the key features of the MI curves and provides deeper insights into the high-frequency MI phenomenon. Our findings pave the way for optimizing the sensing capabilities of Co-based ferromagnetic microwires and demonstrate the potential of using high-frequency MI measurements to map their magnetic microstructures.

Tuning of magnetic bistability and domain wall dynamics in magnetic microwires

A unique combination of unusual magnetic properties, such as magnetic bistability associated with ultrafast domain wall propagation or ultrasoft magnetic properties, together with excellent mechanical and corrosion properties can be obtained in amorphous microwires. Such ferromagnetic microwires coated with insulating and flexible glass-coating with diameters ranging from 0.1 to 100 can be prepared using the Taylor-Ulitovsky method. Magnetic properties of glass-coated microwires are affected by chemical compositions of the metallic nucleus and can be substantially modified by post-processing. We provide an overview of the routes allowing tuning of hysteresis loops and domain wall dynamics in amorphous microwires and new experimental results on the dependence of hysteresis loops on external stimuli, such as applied stress and temperature.

Research on Magnetic Field-Based Damage Detection Technology for Ferromagnetic Microwires

Composite materials are frequently exposed to external factors during their operational service, resulting in internal structural damage which subsequently impacts their structural performance. This paper employs ferromagnetic materials for their sensitivity to magnetic field strength. By detecting variations in the magnetic field within the embedded ferromagnetic microwires of composite materials, the aim is to indirectly assess the health status of the composite materials. Firstly, a theoretical numerical model for magnetic field intensity at the crack site was established. Subsequently, a finite element model was employed to analyze the variations in the magnetic characteristics of ferromagnetic microwires at the crack site. Under different parameter conditions, the patterns of magnetic signals at the crack site were determined. The results indicate that with an increase in the angle between the external magnetic field and the crack, the fitted curve of the magnetic signal shows a linear increase. The distance between the peak and valley of the radial magnetic signal in the axial direction decreases, and the axial magnetic signal transitions from double-peak to single-peak. With the increase in crack depth, the fitted curve of the magnetic signal shows a linear increase, and the magnetic signal at the crack tip also exhibits a linear increase. An increase in crack width leads to a non-linear decrease in the fitted curve of the magnetic signal, and after reaching a certain width, the magnetic signal stabilizes. For two identical cracks at different distances, the magnetic signal exhibits a transition from a complete pattern to two complete patterns. With the increase in the external magnetic field, the magnetic signal shows a completely regular linear increase. By analyzing and calculating the variations in magnetic signals, the patterns of magnetic characteristics under the damaged state of ferromagnetic microwires were obtained. This serves as a basis for assessing whether they can continue in service and for evaluating the overall health status of composite materials.

Free Space Microwave Sensing of Carbon Fiber Composites With Ferromagnetic Microwire Inclusions

Free Space Microwave Sensing of Carbon Fiber Composites With Ferromagnetic Microwire Inclusions

Influence of Tensile Stress on Microwave Scattering Parameters of Continuous Ferromagnetic Microwire Embedded into Glass Reinforced Composites

Influence of Tensile Stress on Microwave Scattering Parameters of Continuous Ferromagnetic Microwire Embedded into Glass Reinforced Composites

Gigahertz permeability of Fe-Cu-Nb-Si-B ferromagnetic microwires and micromagnetics simulations

Fe-Cu-Nb-Si-B ferromagnetic microwires had been successfully prepared. Mössbauer spectroscopy had been employed to identify the phases and to find the volume fraction of nanograins. The GHz permeability spectra (0.5–12 GHz) had been measured and fitted with the Lorentzian dispersion law which assumes two ferromagnetic phases simultaneously making contributions to the GHz permeability. Voronoi diagrams were generated to model the nanostructures revealed by HR-TEM and Mössbauer measurements, then the micromagnetics simulations were carried out to simulate the GHz permeability spectra. The results validate that these microwires can exhibit obvious GHz permeability due to their strong shape anisotropic fields and unique two-phases nanostructures.

Magnetic Properties and Applications of Glass-coated Ferromagnetic Microwires

A remarkable magnetic softness and giant magnetoimpedance (GMI) effect at GHz frequency range havebeen observed in glass-coated microwires subjected to appropriate postprocessing. Co-based microwires present higher GMI effect. Insulating and flexible glass-coating allows use of magnetically soft amorphous glass-coated microwires for stresses or temperature monitoring insmartcomposites using free space facility. Such composites with magnetic microwire inclusions can present tunable magnetic permittivity. We report on in-situ the evolution of the transmission and reflection parameters of the polymer containing magnetic microwire inclusions during the polymerization process. A remarkable change of the reflection and transmission in the range of 4-7 GHz upon the matrix polymerization is observed. Observed dependencies are discussed in terms of the effect of the temperature and stresses variation on magnetic properties of glass-coated microwires during the thermoset matrix polymerization. Obtained results are considered as a base for novel sensing technique allowing non-destructive and non-contact monitoring of the composites utilizing ferromagnetic glass-coated microwire inclusions with magnetic properties sensitive to tensile stress and temperature.

COMBINED FILAMENTS WITH A FERROMAGNETIC ROD, THEIR STRUCTURE AND PROSPECTS FOR USE

The paper analyzes the existing methods for obtaining threads and yarns. It has been established that the largest combined (reinforced) threads make it possible to produce textile products with specified special properties. Tensile tests were carried out on a combined three-component yarn, one of the components of which was a ferromagnetic microwire. It has been established that when such a thread is stretched, the breakage of the components does not occur simultaneously. First of all, the component with the highest rigidity, the ferromagnetic microwire, is torn. The breaking elongation of the microwire is practically equal to the deformation of the warp thread during weaving on shuttleless looms. Therefore, for a stable weaving process, it is necessary to select the appropriate technological modes, or to develop threads of a special structure with increased breaking elongation.

Tuning the giant magnetoimpedance response of a glass-coated microwire reinforced polymer by in-situ laser annealing

The ability to modify the giant magnetoimpedance (GMI) effect in amorphous glass-coated ferromagnetic Co-based microwire reinforced polymer via laser irradiation is presented. Through in-situ laser annealing of microwires embedded into a polymer matrix, a 25 % improvement in the GMI response is demonstrated after only 4.9 min of annealing. This improvement is compared to a conventional oven anneal technique, requiring an hour of oven annealing, subsequent sample cooling and polymer casting. This unique in-situ technique offers a novel and expedient path toward tailorable multi-functional composites in the areas of tunable electromagnetic shielding, structurally integrated antennas and magnetic sensors.

Measurements of Stray Magnetic Fields of Fe-Rich Amorphous Microwires Using a Scanning GMI Magnetometer

A scanning magnetometer based on a magnetoimpedance sensor with a 1 mm spatial resolution and 10 nT sensitivity was used to study stray magnetic fields of Fe74B13Si11C2 amorphous ferromagnetic microwires. Spatial magnetic images and vertical component profiles of stray magnetic fields of the studied microwires were obtained in a longitudinal homogeneous magnetic field of Helmholtz coils with a strength in the range of ±600 A/m. A magnetic calculation method is suggested that allows for using the measured magnetic fields to determine the magnitude and pattern of magnetization for the microwire. Characteristic values of the microwires’ average magnetization and width of closure domains for various values of bias fields were found.

ANALYSIS OF TEXTILE MATERIALS USED FOR PROTECTION AGAINST ELECTROMAGNETIC RADIATION

The article is devoted to the actual problem of developing a woven material that would protect against electromagnetic radiation and meets modern requirements for functional performance properties, as well as the technology of its manufacture. The analysis of the works revealed that this topic has not been sufficiently studied. To solve the problem posed in the work, it is necessary: to analyse the complex yarn obtained by connecting a ferromagnetic microwire with cotton yarn in order to determine the possibility of making fabric from it; methods for designing special fabrics with desired properties; to perform the design of a fabric for workwear, with military fabrics used as a prototype.

High-Sensitivity Wireless Sensing Using Amorphous Magnetic Microwires

Glass-coated amorphous ferromagnetic microwires subjected to variations in mass loading and parallel wire arrays with 0.5–6-cm interwire spacing were found to deliver exceptional magnetomechanical and wireless giant magnetoimpedance (GMI) responses, in the kilohertz and microwave range, respectively. The microwires allow wireless quantification of microgram mass differences: the magnetomechanical resonance frequency measured in zero applied field demonstrates an approximately linear decrease of 3 Hz/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{g}$ </tex-math></inline-formula> , and a sensitivity response that is ten times greater than that reported for commercial METGLAS-type amorphous magnetic ribbons of comparable length. Microwave giant magnetoimpedance data collected from planar arrays of parallel microwires show either constructive or destructive interference when compared to data obtained from a single microwire. The exceptional responsiveness of the glass-coated amorphous ferromagnetic microwires to mass loading and to geometric arrangement, along with their small diameter and ease of fabrication, highlights their promise for a wide variety of sensor applications, including biosensing, civil infrastructure monitoring, and high-throughput remote detection schemes.

Application of Ferromagnetic Microwires as Temperature Sensors in Measurements of Thermal Conductivity

A method for the determination of the thermal conductivity of polymer composite materials by using Co-based ferromagnetic microwires is proposed. Microwire segments were integrated into the samples of studied materials during their manufacture and used as current microheaters and resistance thermometers. As a representative material, we used a material based on nitrile butadiene rubber filled with hexagonal boron nitride after its low-temperature carbonization and a significant increase in thermal conductivity. The thermal conductivity values of composite samples determined during experiments varied from 1.0 W/(m·K) to 1.8 W/(m·K) depending on the percentage of boron nitride. The thermal conductivity values obtained are in good agreement with the estimates obtained by the standard laser flash method.

Prospects for using amorphous ferromagnetic alloy microwire for reinforcement of cement mortar

Traditionally, fibers for fiber-reinforced concrete are made of metal, polypropylene, basalt or glass. На сегодняшний день для строительства актуально использование волокон с уникальными электрофизическими свойствами. The possibilities of using a microwire made of an amorphous ferromagnetic alloy based on cobalt with a shell of borosilicate glass in concrete technologies are studied in this paper. The influence of the content of fibers of different sizes (length 7 and 15 mm) on the rheological and physico-mechanical properties of the solution was established. The deterioration of the workability of mixtures and the average density of the composite with the introduction of the studied fiber is shown. It has been established that the spread diameter of the mortar mixture with a fiber content of 0.5...3.0 % by weight of Portland cement is reduced by 9.8...26.1% compared to the control composition. It is shown that the short fiber (7 mm) at the maximum content (3 %) leads to a more significant decrease in the average density (up to 9.6 %) compared to the long fiber (15 mm) of the same concentration (reduction is no more than 4 %). A positive effect on the flexural strength and crack resistance of the solution was established. The increment of flexural and compressive strength ranges from 1.11 to 1.54 and from 0.99 to 0.78 respectively with increasing fiber concentration. The presence of fiber in the composition of the solution allows you to increase the crack resistance from 0.098 to 0.164. The increase in the crack resistance coefficient for compositions with a fiber 7 mm long is 51...68 % and compositions with a fiber 15 mm long is 22...37 %. The possibility of using such microwire based on a ferromagnetic alloy for dispersed reinforcement of cement solutions opens up prospects for the creation of “smart” materials.

РЕМОНТНЫЕ СТРОИТЕЛЬНЫЕ РАСТВОРЫ, ПОЛУЧЕННЫЕ ПЛАЗМЕННОЙ МОДИФИКАЦИЕЙ И ВИХРЕВОЙ АКТИВАЦИЕЙ

Introduction: The service life of reinforced-concrete structures can be increased with the use of effective repair compositions obtained by activating the original components. Purpose of the study: We aimed to develop effective repair compounds obtained by activating the original components. Methods: To process the original components, low-temperature non-equilibrium plasma (LTNP) and electromagnetic activation in a vortex layer device were used. In the course of the study, we used polypropylene, steel, glass, and basalt fiber and fiber made of structured ferromagnetic microwire. Electron microscopy and X-ray diffraction analysis were applied. Results: It was established that the combined use of the above methods for the modification of raw components makes it possible to improve the strength of these materials by more than 50%, which is due to the characteristics of structure formation in the developed compositions. For instance, LTNP increases the amount of portlandite and reduces the main phases of cement stone— C3S and β-C2S, and vortex activation contributes to an increase in the total number of crystalline phases. Quartz powder particles processed in an electromagnetic mill are characterized by layered structure, high surface roughness, large developed cracking, as well as inclusions as a result of impact action. All that improves the physical and mechanical properties of the resulting repair compositions by an average of 20%. Repair compositions additionally treated with plasma modification feature new hydrated formations on quartz grains.

Tailoring electromagnetic response of three-dimensional waffle-like metacomposite based on arrangement angle of ferromagnetic microwires

Three-dimensional waffle-like metacomposite (3DWM) composed of ferromagnetic microwires is proposed with the aim of integrating structure and microwave absorption performance. The metamaterial units were formed by weaving the ferromagnetic microwires into certain pattern along with the quartz fiber substrate, making it a layer-by-layer integral structure without delamination. Based on the significance of angle arrangement of ferromagnetic microwires on the electromagnetic response during the rotation of metacomposite in practical application, this study conducted experiment and simulation considering different angle arrangements ranging from 90° to 165° to reveal their electromagnetic response characteristics and microwave absorption mechanism within X and Ku bands. It has been found that the arrangement angle of ferromagnetic microwire can adjust the complex permittivity. The dielectric loss of 3DWM was mainly originated from multiple Debye relaxation process and the primary magnetic loss came from eddy current loss and exchange resonance. The threshold angle was found to be 135°, within which the improvement of impedance matching led to the enhancement of microwave absorption. In addition, the angle arrangement of ferromagnetic microwire affected the direction of electric and magnetic fields, which determines the dielectric loss and magnetic loss mechanisms. The 3DWM proposed in this study is promising in adjusting electromagnetic response of microwaves as a radar absorbing material in engineering applications.

Theoretical and numerical analysis of the effective medium properties of a ferromagnetic microwire lattice

Effective medium properties of a 3D-lattice consisting of an infinite number of ferromagnetic microwires are theoretically and numerically analyzed in the presented work. All microwires are considered to be embedded in free space, parallel to one another and a constant magnetic field is applied to the whole composite sample along the axis of microwires. The local and average fields are computed within a unit cell, by solving the scattering problem through satisfying the tangential boundary conditions. Hence, effective permittivity and permeability are analyzed within a unit cell. Field dependent permittivity and permeability characteristics are observed due to a high sensitivity of the ac surface impedance of a ferromagnetic wire to a magnetic field. Effects of the operating frequency, radius of microwires, microwire spacing and applied external magnetic field , on the effective medium properties are discussed in detail. Numerical results are simulated only for polarization for normal incidence. Validation is done through the comparison of proposed numerical results with the results available in the literature for .

Influence of impact on electromagnetic response of three-dimensional angle-interlock metacomposites

A radar absorbing structure named three dimensional angle-interlock metacomposites (3DAM) was proposed based on the metamaterial units formed by three dimensional angle-interlock structure and ferromagnetic microwire as the functional element. To investigate the electromagnetic damage tolerance of 3DAM and its electromagnetic response towards impact, a 10J impact was applied on the 3DAM, and three representative regions, including impact center, impact edge and no impact have been selected. From the perspectives of permittivity, S parameters and impedance matching, the electromagnetic response of 3DAM at different regions have been investigated. It has been found that 3DAM presented negative permittivity before and after impact under X band, and the resonance frequency can be adjusted by impact position as a result of the structural change of metamaterial units formed by ferromagnetic microwires. The permittivity shifted to positive with less influence by impact under Ku band. It has been verified by micro-CT that the movement and fracture of ferromagnetic microwires induced by impact led to a dimensional change of metamaterial units; therefore, reconfiguration of metamaterial units dominated the electromagnetic response of 3DAM after impact, which is advantageous to maintain the absorption ability. The absorption mechanism for the 3DAM before and after impact has been explored by both simulations and equivalent RLC circuit analyses. It has been found that the reconfiguration of microwires caused by impact led to a circuit rearrangement, hence, the electromagnetic response and absorption keeps high efficiency after impact, exhibiting a high electromagnetic damage tolerance.

Determination of small magnitudes of magnetostriction in amorphous microwires with an arbitrary type of magnetic anisotropy

The magnetic anisotropy and magnetic structure of amorphous ferromagnets are largely determined by magnetoelastic interactions due to the absence of magnetocrystalline anisotropy, e.g., in amorphous microwires with a glass sheath, the source of anisotropy is the mechanical stresses that arise in the ferromagnetic core upon manufacturing. Hence, to control the magnetic structure and magnetization reversal processes occurred in amorphous magnetics, it is necessary to know the magnetostriction coefficient of the material. We propose an improved approach to measuring extremely small values of the magnetostriction coefficient of ferromagnetic microwires with an arbitrary type of magnetic anisotropy and magnetic microstructure. The samples of amorphous wires in a glass sheath made of Co67Fe5B12Si14Cr3 alloys were studied. The type of magnetic anisotropy of the samples (from axial to circular) was changed using current annealing. The developed method is based on small-angle precession of magnetization around the wire axis, resulted from the effect of the axial magnetic field induced by an alternating current passed through the wire. A voltage signal generated in a detection coil wound around the sample at a frequency doubled with respect to the frequency of the alternating current was recorded using a lock-in amplifier. When exposed to external mechanical loads, the voltage signal changes, and an additional axial magnetic field (bias field) is required to maintain a constant level of this signal. The value of magnetostriction is determined from the dependence of the displacement field on mechanical loads. The maximum sensitivity of measurements in the range of 10–8 – 10–7 is achieved at a uniform magnetization, increased frequency of the alternating current, and high value of the ratio between the length and diameter of tested wire samples. The sign and magnitude of the magnetostriction constant change upon current annealing which correlates with modification of the magnetization curves. The results obtained can be used to determine and adjust the parameters of the actuators developed on the basis of the considered microwires (in particular, microsensors of mechanical stresses and microactuators).

Metacomposite based on three-dimensional ferromagnetic microwire architecture for electromagnetic response

Metacomposite based on three-dimensional ferromagnetic microwire architecture for electromagnetic response