Magnetic Induction Research Articles

Rapid Synthesis of Ruthenium-Copper Nanocomposites as High-Performance Bifunctional Electrocatalysts for Electrochemical Water Splitting.

Development of high-performance, low-cost catalysts for electrochemical water splitting is key to sustainable hydrogen production. Herein, ultrafast synthesis of carbon-supported ruthenium-copper (RuCu/C) nanocomposites is reported by magnetic induction heating, where the rapid Joule's heating of RuCl3 and CuCl2 at 200A for 10s produces Ru-Cl residues-decorated Ru nanocrystals dispersed on a CuClx scaffold, featuring effective Ru to Cu charge transfer. Among the series, the RuCu/C-3 sample exhibits the best activity in 1m KOH toward both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), with an overpotential of only -23 and +270mV to reach 10mAcm-2, respectively. When RuCu/C-3 is used as bifunctional catalysts for electrochemical water splitting, a low cell voltage of 1.53V is needed to produce 10mAcm-2, markedly better than that with a mixture of commercial Pt/C+RuO2 (1.59V). In situ X-ray absorption spectroscopy measurements show that the bifunctional activity is due to reduction of the Ru-Cl residues at low electrode potentials that enriches metallic Ru and oxidation at high electrode potentials that facilitates the formation of amorphous RuOx. These findings highlight the unique potential of MIH in the ultrafast synthesis of high-performance catalysts for electrochemical water splitting.

Thermally-assisted magnetization of magnetic composites for enhanced micro actuator performance: a low-cost approach using permanent magnets

A micro actuator based on magnetic composite materials can control its deformation and movement through varying magnetic fields, showcasing significant applications in fields such as soft robotics and biomedicine. However, existing magnetic composite materials still require complex magnetization processes involving sophisticated equipment and demanding external magnetic fields. This paper proposed a low-cost, thermally-assisted magnetization process based on permanent magnets. It was observed that the maximum magnetic induction intensity on the surface of magnetic composites is linearly correlated with the heating temperature. Additionally, magnetically treated materials at elevated temperatures can achieve traditional high-field magnetization effects at lower field strengths. Specifically, we synthesized a magnetic composite with 50%wt NdFeB@PDMS and investigated the conditions of the thermally-assisted magnetization process based on permanent magnets, along with mechanical and magnetic performance characterization methods. Experimental results indicate that below 200 °C, the tensile strength and elastic modulus of the base material increase with rising temperatures, demonstrating a trend of high-temperature hardening. However, when the temperature exceeds 200 °C, the elevated temperature leads to the decomposition of the base material, resulting in a rapid decrease in the tensile strength and elastic modulus of the magnetic composite. Furthermore, high temperatures can disrupt the magnetic domains of the magnetic material, reducing its coercive force and making it more susceptible to external magnetic fields and heat, thereby compromising the stability of the magnetic material. These findings provide new insights into the development of more stable and controllable magnetic composite materials.

Squeezing hydromagnetic nanofluid flow between two parallel plates with joule heating effects and induced magnetic field

Over the years, cooling high energy devices has become a major challenge to most industries. Thus, squeezing hydromagnetic nanofluid flow between two parallel plates has garnered alot of attention. In the present study, an unsteady, incompressible, hydromagnetic gold and water nanofluid flow squeezed between two parallel plates with Joule heating and a magnetic field that is induced is considered. The model considers the impacts of Joule heating,Viscous dissipation and induced magnetic field. In contrast with other studies which may have focussed on only one or two of these aspects this comprehensive approach provides a more accurate depiction of the flow pattern. Employing the finite difference method, the flow's non-linear differential equations are numerically solved and then implemented in MATLAB. The effect of changing various parameters on flow variables such as velocity, magnetic induction and thermal profiles are determined and the results obtained are presented graphically. Increasing magnetic parameter and Prandtl magnetic number caused a decline in temperature,velocity and magnetic induction profiles. Further, increasing the Eckert number and Joule heating parameter lead to an increase in temperature profiles. This findings have a direct impact on high-energy cooling devices which frequently experience heat dissipation. Additionally, engineers can ensure optimal performance and the longevity of plate heat exchangers in industries.

Advances in magnetic induction hyperthermia.

Magnetic induction hyperthermia (MIH), is a technique that has developed rapidly in recent years in the field of tumor thermotherapy. It implants a magnetic heating medium (millimeter-sized heat seeds, micron-sized magnetic particles and nanometer-sized magnetic fluids, etc.) inside the tumor. The material heats up under the induction of an external alternating magnetic field (100-500kHz), which causes a high temperature zone to rapidly form in the local biological tissues and induces apoptosis in tumor cells. Magnetic induction hyperthermia has the advantages of high safety, strong targeting, repeatable treatment, and the size of the incision during treatment is negligible compared to surgical resection, and is currently used in clinical treatment. However, the millimeter-scale heat seed heating that is typically used in treatments can result in uneven temperatures within the tissue. Common MIH heating devices are bulky and complex in design, and are not easy for medical staff to get their hands on, which are issues that limit the diffusion of MIH. In this view, this paper will discuss the basic theoretical research on MIH and the progress of MIH-related technologies, with a focus on the latest research and development results and research hotspots of nanoscale ferromagnetic media and magnetic heat therapy devices, as well as the validation results and therapeutic efficacy of the new MIH technology on animal experiments and clinical trials. In this paper, it is found that induction heating using magnetic nanoparticles improves the uniformity of the temperature field, and the magneto-thermal properties of nanoscale ferromagnetic materials are significantly improved. The heating device was miniaturized to simplify the operation steps, while the focusing of the magnetic field was locally enhanced. However, there are fewer studies on the biotoxicity aspects of nanomedicines, and the localized alternating magnetic field uniformity used for heating and the safety of the alternating magnetic field after irradiation of the human body have not been sufficiently discussed. Ultimately, the purpose of this paper is to advance research related to magnetic induction thermotherapy that can be applied in clinical treatment.

Mechanical and high-temperature characterization of additively manufactured Ni-superalloys at SALSA neutron strain diffractometer

Neutron diffraction is a well-established method for the measurement and characterization of internal stresses in metallic and ceramic materials at room temperature. Some cases have been reported in the literature in which the method has been extended to higher temperatures. In this paper we report both novel setups for in-situ heat treatments and for in-situ mechanical testing at high temperature at SALSA in the Institut Laue-Langevin (ILL). Characterization of internal stresses in Ni-superalloys demonstrated the feasibility, stability and exploitation of results achieved by a tailored induction heating system. Different coils are adapted to accommodate several sample geometries for accurate focusing of the magnetic heating induction field on the sample, to achieve high heating rates up to 50 °C/s and therefore limiting the microstructural evolution impact during ramping-up to the target temperature. In return, this enhances the choice of reference d0, by either measurements at room temperature and extrapolated values to high temperature, or by direct measurements also at high temperature. A detailed strategy of d0 stress-free reference approaches for such in-situ experiments at high temperature is discussed.

Ignition of Self-Sustained <i>Е</i>×<i>В</i> Discharge; Ion Contribution to Understanding the Process

We determined critical values for the ignition voltage and magnetic induction for a self-sustained plasma discharge in crossed electric and magnetic fields, both at inert gases and in their mixtures. As parameters that enabled to visualize igniting an E×B discharge, we used the ion current and the induction current derivative, and provided the temporal characteristics for the process. We found a double structure of the ion current (discharge current) during the ignition. The working media initial state for the discharge current first jump is a neutral gas, whereas the working media initial state for the second jump is plasma. A peak of ions originated within the near-cathode area is detected on the energy distributions of the ions obtained during the ignition. Also detected is a wide ion energy spectrum related to the discharge gap. We show a various discharge ignition character for Penning pairs, when the gas changes its role (main or admixture) in the mixture. The character is determined by features of forming the electric potential distribution in the near-cathode layer.

Structural Optimization of a Giant Magnetostrictive Actuator Based on BP-NSGA-II Algorithm

This study introduces an integrated structural optimization design method based on a BP neural network and NSGA-II multi-objective genetic algorithm. Initially, a two-dimensional axisymmetric finite element model of the Giant Magnetostrictive Actuator (GMA) was established, and the coupling simulation of the electromagnetic field, structural field, and temperature field was conducted to obtain the GMA’s performance parameters. Subsequently, the structural parameters of the GMA magnetic circuit, including the magnetic conducting ring, magnetic conducting sidewall, magnetic conducting body, and coil, were used as inputs, and the axial magnetic induction intensity, uniformity of axial magnetic induction intensity, and coil loss on the Giant Magnetostrictive Material (GMM) rod were used as outputs to establish a back propagation (BP) neural network model. This model delineated the nonlinear relationship between structural parameters and performance parameters. Then, the BP-NSGA-II algorithm was applied to perform multi-objective optimization on the actuator’s structural parameters, resulting in a set of Pareto optimal non-dominated solutions, from which a set of optimal solutions was obtained using the entropy weight method. Finally, simulation analysis of this optimal solution was conducted, indicating that under a 5 A power supply excitation, the maximum axial magnetic induction intensity on the optimized GMM rod increased from 0.87 T to 1.12 T; the uniformity of axial magnetic induction intensity improved from 93.1% to 96.5%; and the coil loss decreased from 7.79 × 104 W/m3 to 4.97 × 104 W/m3. Based on the optimization results, a prototype actuator was produced, and the test results of the prototype’s output characteristics proved the feasibility of this optimization design method.

Self-Assembly of Three-Dimensional Hyperbranched Magnetic Composites and Application in High-Turbidity Water Treatment.

In order to improve dispersibility, polymerization characteristics, chemical stability, and magnetic flocculation performance, magnetic Fe3O4 is often assembled with multifarious polymers to realize a functionalization process. Herein, a typical three-dimensional configuration of hyperbranched amino acid polymer (HAAP) was employed to assemble it with Fe3O4, in which we obtained three-dimensional hyperbranched magnetic amino acid composites (Fe3O4@HAAP). The characterization of the Fe3O4@HAAP composites was analyzed, for instance, their size, morphology, structure, configuration, chemical composition, charged characteristics, and magnetic properties. The magnetic flocculation of kaolin suspensions was conducted under different Fe3O4@HAAP dosages, pHs, and kaolin concentrations. The embedded assembly of HAAP with Fe3O4 was constructed by the N-O bond according to an X-ray photoelectron energy spectrum (XPS) analysis. The characteristic peaks of -OH (3420 cm-1), C=O (1728 cm-1), Fe-O (563 cm-1), and N-H (1622 cm-1) were observed in the Fourier transform infrared spectrometer (FTIR) spectra of Fe3O4@HAAP successfully. In a field emission scanning electron microscope (FE-SEM) observation, Fe3O4@HAAP exhibited a lotus-leaf-like morphological structure. A vibrating sample magnetometer (VSM) showed that Fe3O4@HAAP had a relatively low magnetization (Ms) and magnetic induction (Mr); nevertheless, the ferromagnetic Fe3O4@HAAP could also quickly respond to an external magnetic field. The isoelectric point of Fe3O4@HAAP was at 8.5. Fe3O4@HAAP could not only achieve a 98.5% removal efficiency of kaolin suspensions, but could also overcome the obstacles induced by high-concentration suspensions (4500 NTU), high pHs, and low fields. The results showed that the magnetic flocculation of kaolin with Fe3O4@HAAP was a rapid process with a 91.96% removal efficiency at 0.25 h. In an interaction energy analysis, both the UDLVO and UEDLVO showed electrostatic repulsion between the kaolin particles in the condition of a flocculation distance of <30 nm, and this changed to electrostatic attraction when the separation distance was >30 nm. As Fe3O4@ HAAP was employed, kaolin particles could cross the energy barrier more easily; thus, the fine flocs and particles were destabilized and aggregated further. Rapid magnetic separation was realized under the action of an external magnetic field.

Characteristics of Controlled Bridge Circuit and Its Application in Magnetic Field Induction Measurement

Characteristics of Controlled Bridge Circuit and Its Application in Magnetic Field Induction Measurement

ABOUT THE POSSIBILITY OF USING CORROSION-RESISTANT STEEL 08X22H6T IN THE DESIGNS OF MAGNETIC COUPLINGS AND MAGNETIC SYSTEMS

The influence of the brand of the material from which the magnetic conductors are made on the power characteristics of the magnetic system and magnetic coupling with highly coercive permanent magnets Nd–Fe–B with a residual magnetic induction of 1.1 T is considered. The material of the magnetic conductors is steel 15 or corrosion-resistant steel 08Х22H6T. On average, in the range of air gaps between sections of the magnetic system from 4 to 10 mm, the decrease in the specific shear force with magnetic conductors made of corrosion-resistant steel 08Х22Н6T, relative to magnetic conductors made of steel 15 is 18.15 %.

Full-Duplex Magnetic Induction Communication: Opportunities and Challenges

Full-Duplex Magnetic Induction Communication: Opportunities and Challenges

In-depth investigation of phase transition phenomena in network models derived from lattice models

Lattice models exhibit significant potential in investigating phase transitions, yet they encounter numerous computational challenges. To address these issues, this study introduces a Monte Carlo-based approach that transforms lattice models into a network model with intricate inter-node correlations. This framework enables a profound analysis of Ising, JQ, and XY models. By decomposing the network into a maximum entropy component and a conservative component, under the constraint of detailed balance, this work derives an estimation formula for the temperature-dependent magnetic induction in Ising models. Notably, the critical exponent β in the Ising model aligns well with the established results, and the predicted phase transition point in the three-dimensional Ising model exhibits a mere 0.7% deviation from numerical simulations.

Influence of annealing treatment on grain growth, texture and magnetic properties of a selective laser melted Fe-6.5 wt% Si alloy

The high-density Fe-6.5 wt% Si soft magnetic alloy samples were prepared using selective laser melting (SLM) technology. Annealing treatments with different temperatures were employed to promote grain growth. The microstructure, texture and magnetic hysteresis loops were characterized, aiming to investigate the relationship between microstructure and magnetic properties. The as-printed Fe-6.5 wt% Si alloy had weak texture and low density of ordered phases, and was featured by coarse grains in the top-view section and columnar grains in the side-view section. After annealing at 800 °C–1000 °C, the textures were slightly weakened, while the grain growth was not significant. Increasing the annealing temperature to 1100 °C led to abnormal grain growth behaviors. The grains of the as-printed Fe-6.5 wt% Si alloy showed randomly abnormal growth behaviors rather than oriented growth, which may be related to the low stored energy and initial size advantage before annealing. After annealed at 1100 °C for 1 h, the abnormal grain growth and the formation of large Goss ({110}<001>) and Cube ({100}<001>) grains resulted in microstructure coarsening and texture optimization. Thus, the corresponding ring-shaped sample exhibited excellent magnetic performance. The magnetic induction B8 is 1.21 T, the maximum relative permeability is 14.71 × 103 and the core loss P10/50 is 11.69 W/kg.

Enhanced ofloxacin degradation in water by a novel integrated photocatalysis and rotating magnetic field system

In this work, a novel integrated Fe3O4/g-C3N4 (FC) composite and rotating magnetic field (RMF) system was developed to enhance the photodegradation of ofloxacin (OFX) in water. The RMF was excited by three-phase alternating current, providing great flexibility on the magnetic field and avoiding mechanical transmission. By integrating RMF, the OFX degradation by FC photocatalysis was greatly enhanced. With the optimal FC composition of 20 % (wt) Fe3O4 (FC20), >87 % OFX degradation could be achieved with 1 g/L FC20, an RMF-excited current of 2 A, and a reaction time of 300 min, compared to OFX decomposition of ∼65 % by FC20 photocatalysis alone. The magnetic induction intensity, solution pH, and water matrices all affected OFX degradation by the integrated FC-RMF system. The FC20 was reliable for OFX degradation in water with minimal efficacy reduction after four consecutive reuses. In the integrated FC-RMF system, reactive species' contribution to OFX degradation was in the order of holes > superoxide anions > hydroxyl radicals. The electron transfer mechanisms during OFX degradation and five potential degradation pathways were proposed. In summary, the integrated FC-RMF system demonstrated a potential route for enhancing the removal of OFX and possibly other antibiotic contaminants from water.

Influence of calcination temperature and particle size distribution on the physical properties of SrFe12O19 and BaFe12O19 hexaferrite powders

The paper deals with the economic optimisation of ferrite powder preparation during producing hard ferrite magnets. The magnetic properties of ferrites are investigated by replacing feedstock and reducing calcination temperature and particles in the order of tens of microns. The granulates about 8–10 mm in size were calcined for 2 h in the temperature range from 1100 °C to 1300 °C and additionally crushed and milled to an average particle size of about 80–90 µm. The scanning electron microscopy images confirmed the agglomerates of particles with different shapes and sizes in tens of µm. The X-ray diffraction measurements revealed that, besides the SrFe12O19 and BaFe12O19 phases, there was also the presence of 2–39% hematite. The highest values of maximum energy product (BH)max = 930 J/m3 and remanent magnetic induction Br = 72.8 mT were obtained at a calcination temperature of 1300 °C. The Henkel plots confirmed the presence of exchange-coupling and dipolar magnetic interactions at lower and higher magnetic fields, respectively. The strength of interactions was also dependent on the calcination temperature. Replacing strontium with barium led to a deterioration of the magnetic parameters, which were optimal at a lower calcination temperature (1100 °C). This phenomenon was partly overcome by reducing the mean particle size of Ba-based hexaferrites to 45–50 µm.

Design of the distribution of iron oxide (Fe3O4) nano-particle drug in realistic cholangiocarcinoma model and the simulation of temperature increase during magnetic induction hyperthermia

The prognosis for Cholangiocarcinoma (CCA) is unfavorable, necessitating the development of new therapeutic approach such as magnetic hyperthermia therapy (MHT) which is induced by magnetic nano-particle (MNPs) drug to bridge the treatment gap. Given the deep location of CCA within the abdominal cavity and proximity to vital organs, accurately predict the individualized treatment effects and safety brought by the distribution of MNPs in tumor will be crucial for the advancement of MHT in CCA. The Mimics software was used in this study to conduct three-dimensional reconstruction of abdominal computed tomography (CT) and magnetic reso-nance imaging images from clinical patients, resulting in the generation of a realistic digital geometric model representing the human biliary tract and its adjacent structures. Subsequently, The COMSOL Multiphysics software was utilized for modeling CCA and calculating the heat transfer law resulting from the multi-regional distribution of MNPs in CCA. The temperature within the central region of irregular CCA measured approximately 46°C, and most areas within the tumor displayed temperatures surpassing 41°C. The temperature of the inner edge of CCA is only 39 ∼ 41℃, however, it can be ameliorated by adjusting the local drug concentration through simulation system. For CCA with diverse morphologies and anatomical locations, the multi-regional distribution patterns of intratumoral MNPs and a slight overlap of drug distribution areas synergistically enhance intratumoral temperature while ensuring treatment safety. The present study highlights the practicality and imperative of incorporating personalized intratumoral MNPs distribution strategy into clinical practice for MHT, which can be achieved through the development of an integrated simulation system which incorporates medical image data and numerical calculations.

Experimental investigation on magnetorheological shear thickening polishing characteristics for SiC substrate

Silicon carbide (SiC) substrates are widely used in semiconductor and photoelectric applications due to excellent electrical and chemical properties. However, due to its inherent hard-brittle properties and chemical inertness, traditional polishing processes are facing great challenges to obtain excellent surface and subsurface quality for the SiC substrates. In this work, a novel polishing process i.e. magnetorheological shear thickening polishing (MRSTP) was proposed to explore the feasibility for the polishing of the SiC substrates. The MRSTP experiments were conducted using multiple magnetic-pole-coupled tools. The magnetic field characteristics of the polishing area were investigated via finite element simulation and actual measurements. The magnetic-pole-coupled tool was capable of generating high magnetic induction strength in the polishing area. The MRSTP medium was designed and prepared. The media were formed magnetic brushes by the excited magnetic field. The MRSTP experiments were conducted to investigate the effects of processing parameters on the polished surface roughness. The optimum process parameters were determined as the spindle rotational speed of 700 rpm, the feed rate of 600 mm/min, the work gap of 0.5 mm and MRSTP media CIPs particle size of 100 μm. The surface roughness of the workpieces was improved from initial 1.414 μm to 27.6 nm. It is verified that the MRSTP is the feasible ultraprecision polishing process for the SiC substrates.

Minitype Arrays of Acoustically Actuated Magnetoelectric Antennas for Magnetic Induction Communication

The magnetoelectric (ME) antennas rely on the mechanical movement of magnetic dipoles, making it possible to break the constraints on physical dimensions decided by the wavelength of the electromagnetic wavelength. The ME antennas achieve super-low frequency (SLF) communications with a smaller size to provide a novel solution for long-range, underwater, and underground communications; navigation over the horizon; and geological exploring. As a result, further theoretical research and optimization of ME antennas have been an open challenge for decades. Here, we report on minitype arrays of acoustically actuated ME antenna and their more rigorous equivalent circuits. These arrays of ME antenna adjust amplitude-frequency response through the mechanical regulation method. The mechanical parameters of ME antennas in the arrays result in regulating amplitude-frequency response, such as working frequency, fractional bandwidth, and intensity of magnetic induction. Our work provides a more accurate theoretical model and diverse array form over state-of-the-art ME antenna arrays. The frequency, fractional bandwidth, and magnetic induction strength of the ME antenna arrays were achieved to be adjustable in the ranges of 84 to 181 Hz, 3.9% to 8.3%, and two to four times, respectively. In addition, we have calculated the attenuation characteristics of ME antennas and their minitype arrays in seawater. The results show that the ME antenna array described in this manuscript is able to enhance the radiation intensity and information-loading capability, which has a positive potential for application in SLF communication systems.

Modeling of EMHD ternary hybrid Williamson nanofluid flow over a stretching sheet with temperature jump and magnetic induction

This study explores the heat transfer and fluid flow characteristics of an incompressible Williamson ternary hybrid nanofluid (WTHNF) over an unsteady stretching surface, influenced by external electric and magnetic fields, thermal radiation, and a porous boundary. The WTHNF consists of ZrO2, MoS2, and GO nanoparticles suspended in water. By applying suitable transformations, the fundamental equations are simplified and solved numerically using the Explicit Runge Kutta Method (ERKM). The research investigates how various physical parameters, such as electric and magnetic field strengths, thermal radiation, porous plate permeability, velocity slip, and temperature jump, impact the velocity, temperature, skin friction coefficient, and local Nusselt number. The findings offer valuable insights into the interactions between WTHNF and external factors, which can inform the design and optimization of advanced heat transfer and fluid flow systems in engineering. Additionally, this study demonstrates the potential of WTHNF to enhance heat transfer rates, making it a promising candidate for cooling systems, heat exchangers, and energy storage devices. The research contributes to developing more efficient and sustainable technologies in aerospace, biomedical engineering, and renewable energy. Moreover, the results provide a foundation for future research on the behavior of complex fluids under various external influences. This could lead to the creation of more advanced fluid flow systems, improving efficiency and performance across numerous applications.

Effect of current intensity on molten pool and solidification in vacuum arc remelting process of Ti60 alloy

Current intensity is a critical parameter in the vacuum arc remelting (VAR) process, significantly impacting the molten pool, solidification structure, and ultimately, the quality of the ingot. This study establishes a transient electromagnetic-fluid-thermal-solidified coupled model to examine the effects of current intensity on the shape of molten pool and the solidification process of Ti60 alloy ingots produced by VAR process. Findings indicate that with the increase in current intensity, there is a corresponding rise in the magnetic induction intensity, current density, and Lorentz force. This enhancement leads to more vigorous flow in the liquid phase, creating a vortex flow opposing to the ingot's center at the boundary, influenced by the strong current. As a consequence, the molten pool's shape tends to shift from a “V” shape to a “U” shape, and the depth of molten pool increases while the mushy zone thickness diminishes. For instance, at 17000 A, the depth of molten pool surges by 57.43%, and the mushy zone thickness contracts by 62.01% compared to 5000 A. Over time, the depth of molten pool gradually decreases, with its reduction range ( Δh) within 400 to 6000 s inversely related to current intensity. At 17000 A, Δh is 23.71% less than at 5000 A. Furthermore, elevating the current intensity results in a higher temperature gradient within the ingot and a marked reduction in local solidification time, particularly in the ingot's central area.