Kind Of Soft Magnetic Materials Research Articles

Formation, thermal stability and soft magnetic properties of Fe-Co-B-Si amorphous alloys with ultrahigh saturation magnetic induction of 2.0 T

This paper studies the influence of metallic element composition on the formation ability, thermal stability and magnetic properties of melt-spun (Fe1-xCox)B15–19Si1 (x =0.2–0.4) amorphous alloy ribbons. The maximum metal concentration at which an amorphous phase is formed during melt spinning has been determined in conjunction with the metal content dependence of crystallization processes and crystallized phases. The amorphous (Fe0.8Co0.2)84B15Si1 alloy with the highest metal content in an optimally annealed state exhibits an extremely high saturation induction (MS) of 2.0 T, low coercive force of 7.6 A m−1, high effective permeability of 13500 at 1 kHz and low core losses of 5.5 W kg−1 at 100 mT and 19.7 W kg−1 at 200 mT at 10 kHz which have not been simultaneously obtained for all kinds of soft magnetic materials up to date. The replacement of Fe with Co significantly increases the Curie temperature of the amorphous phase, resulting in very high thermal stability of the high MS alloys. The combination of excellent soft magnetic properties with ultrahigh MS value makes them candidates for use in highly loaded high-speed electric motors capable of operating at temperatures up to 473 K.

Efficient removal of Pb(II) using modified chitosan Schiff base@Fe/NiFe

A novel modified chitosan Schiff base@Fe2O3-NiFe2O4 (CsSB@Fe/NiFe) was prepared and characterized using FT-IR, XRD, SEM, EDX, TGA, DSC and VSM. FT-IR and XRD results confirm that the nanoparticles of Fe/NiFe distributed throughout the surface of CS-OH and successfully prepared CsSB@Fe/NiFe. SEM image shows that the Fe/NiFe nanoparticles were assembled in the surface and inside of CS-OH. Coercivity (Hc) of CsSB@Fe/NiFe is ≈ 110 Oe, indicated that it was kind of soft-magnetic materials with saturation magnetization (Ms) of 6.45 emu/g. In addition, CsSB@Fe/NiFe was further explored as an new sorbent for the removal of Pb(II) ion from aqueous solution and the influence of various important parameters such as solution pH, contact time, dosage of adsorbent and initial Pb(II) concentration were studied and optimized. Optimum conditions for Pb(II) removal were found to be pH 5, adsorbent dosage 0.05 g, initial Pb(II) concentration of 75 ppm and contact time of 120 min. The maximum Pb(II) removal percentage was found to be 97%. Also, CsSB@Fe/NiFe shows about 88% Pb(II) removal after five adsorption-desorption cycles. The results suggested that the sorption of Pb(II) onto CsSB@Fe/NiFe was feasible and spontaneous.

Influence of Calcination Temperature on Microstructure and Properties of (NiCuZn)Fe2O4 Ferrite Prepared via Ultrasonic-Assisted Co-Precipitation

(NiCuZn)Fe2O4 ferrite is a kind of soft magnetic material widely used in multilayer chip inductors because of its high resistivity and excellent magnetic properties at high frequencies. In this study, (Ni0.4Cu0.2Zn0.4)Fe2O4 ferrite powder was prepared by ultrasonic-assisted chemical co-precipitation method, the effect of calcination temperature on the structure and properties of ferrite powders was investigated by modern analytical methods that include differential thermal analysis, X-ray diffraction, transmission electron microscopy, infrared spectroscopy, and vibrating sample magnetometer, respectively. The results show that the grain size increased from 23.5 nm to 38.6 nm and the lattice size increased from 8.384 A to 8.390 A with the increase of calcination temperature from 600°C to 900°C. The TEM shows that the powder particle was uniform and dispersible, and the particle size was about 30nm at 800°C calcination. The saturation magnetization of ferrite powder increases from 45.85emu/g to 50.65emu/g and the coercivity decreases from 65.50Oe to 46.23Oe with the increase of calcination temperature from 700°C to 900°C. The uniform and fine nano-crystalline ferrite particles would reduce the sintering temperature and improve the stability of the properties for spinel ferrite. The preparation of nano-spinel ferrite by ultrasonic-assisted co-precipitation is a worthy wet process for application.

Study on the influence of armature on the efficiency of reluctance accelerator

The armature is an important part affecting the energy conversion efficiency of a reluctance accelerator. In this paper, six kinds of soft magnetic materials are chosen and four structures are designed for the armature. At first, the circuit and magnetic force are theoretically analyzed. Then the armatures with different materials and structures are used in the simulation, and the performances are compared and analyzed. At last, the experiment verifies the theory analysis and simulation design. It is concluded that the saturation flux density and conductivity of the material are the key factors affecting the armature force, and the optimization of armature structure can effectively restrain the eddy current, reduce negative force and improve efficiency. Compared with cutting slits in solid armatures, laminating the sheets radially can reduce the eddy current more efficiently. Although slitting can prevent the eddy current to a certain extent, meanwhile, it will decrease the magnetic force because of the losing of magnetized volume and the surface area. Hence, choosing the high saturation flux density material and making out the armature with radially_laminated sheets will improve the efficiency of the reluctance accelerator. In this paper, the silicon steel radially_laminated armature is a better choice for the armature design of the reluctance accelerator.

Adsorption and regeneration characteristics of phosphorus from sludge dewatering filtrate by magnetic anion exchange resin

Removal and recovery of phosphorus (P) from sewage are essential for sustainable development of P resource. Based on the water quality determination of sludge dewatering filtrate from a wastewater treatment plant in Beijing, this study investigated the adsorption and regeneration characteristics of P by magnetic anion exchange resin (MAEX). The experiments showed that the P adsorption capacity of MAEX could reach a maximum of 2.74mg/mL when initial P concentration was 25mg/L and dosage of MAEX was 8mL/L. The P adsorption on MAEX resin was suitable for large temperature range (283-323K). However, the adsorption capacity was reduced in various degrees due to the interference of different anions (Br-, SO42-, Cl-, NO3-, HCO3-, CO32-) and organic compounds (bovine serum albumin, humic acid). Kinetics studies indicated that the P adsorption process followed the pseudo-second-order model. The MAEX resin had a rapid P adsorption rate and the P adsorption capacity at 30min could reach 97.7-99.3% of qe. Increase of temperature was favorable to P adsorption on MAEX, and the adsorption isotherm data fitted to Langmuir model more than Freundlich model. Meanwhile, the thermodynamics parameters were calculated; it was shown that the adsorption process was an endothermic reaction. Desorption and regeneration experiments showed that NaHCO3 was a suitable regenerant, and the P adsorption capacity could reach 90.51% of the original capacity after 10 times of adsorption-desorption cycles; this indicated that MAEX resin has an excellent regeneration performance and thus has a very good application prospect of P removal and recovery. Fourier transform infrared spectroscopy (FTIR) analysis confirmed that ion exchange, charge attraction, and hydrogen bonding affected the removal of P by the MAEX resin. The vibrating sample magnetometer (VSM) analysis revealed that MAEX resin was a kind of soft magnetic materials with good magnetism.

Performance investigation on DCSFCL considering different magnetic materials

In order to protect high voltage direct current (HVDC) system from destructive consequences caused by fault current, a novel concept of HVDC system fault current limiter (DCSFCL) was proposed previously. Since DCSFCL is based on saturable core reactor theory, iron core becomes the key to the final performance of it. Therefore, three typical kinds of soft magnetic materials were chosen to find out their impact on performances of DCSFCL. Different characteristics of materials were compared and their theoretical deductions were carried out, too. In the meanwhile, 3D models applying those three materials were built separately and finite element analysis simulations were performed to compare these results and further verify the assumptions. It turns out that materials with large saturation flux density value Bs like silicon steel and short demagnetization time like ferrite might be the best choice for DCSFCL, which can be a future research direction of magnetic materials.

Ni-Zn Ferrite Core Characterization for Magnetic-based Energy Harvesting Application

In this work, the magnetic properties of Ni-Zn ferrite cores are characterized in order to apply this kind of soft magnetic material in energy harvesting system. Morphology studies and magnetic characterizations have been performed by scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). A commercial ferrite core was analyzed in order to be applied in a magnetic- induction based energy harvester setting up on power lines. The samples behaved as a soft magnetic materials with magnetization 60 emu•g-1 and presented homogeneous morphology consisting of agglomerates of hexagonal particles. Using this kind of magnetic core, it was assembled an electrical coil on it and the obtained coil/core set was set up on a power line from an experimental test platform. According to the obtained experimental results, the energy harvested from the set is capable of supplying up to 1.69 mW by harvesting the alternate magnetic field produced by a 5A current passed into the power line. This obtained harvested energy would be applied to supply low-power electronic devices mainly in wireless sensor network.

Preparation and magnetic properties of novel hybrid magnetic powder cores

Magnetic powder cores are an important kind of soft magnetic materials that are widely used in various electrical and magnetic devices. In this work, high performance hybrid magnetic powder cores have been prepared by compacting silicon resin coated soft magnetic composite (SMC) powders. The SMC powders are obtained from mixing suitable proportions of FeSi and FeNi powders uniformly with pure iron powders. A high density of over 7·27 g cm−3 can be obtained in hybrid magnetic powder cores. The core loss of the magnetic cores prepared from mixing 90 wt-%Fe and 10 wt-%FeSi powders measured at a frequency of 50 Hz and an induction level of 1 T is 7·5 W kg−1, which is much lower than that of pure iron powder cores (8·4 W kg−1), and their magnetic induction measured at an induction level of 10 kA m−1 is 1·38 T, which is higher than that of pure iron powder cores (1·34 T).

Enhancement of magnetization damping coefficient of permalloy thin films with dilute Nd dopants

For spintronics application, which requires fast field switching, it is important to have a kind of soft magnetic material with large damping coefficient. Here, we present the studies of the Nd dopant-level-dependent damping coefficient of Nd${}_{x}$-Py${}_{(1\ensuremath{-}x)}$ thin films (30 nm) in a dilute region utilizing ferromagnetic resonance (FMR). With the Nd content increasing, the film structure was found to be changing from polycrystalline to amorphous when the Nd content is around 3.4%. Meanwhile, the magnetization decreases linearly. Interestingly, we find that along the easy axis, both low coercivity and high hysteresis squareness are simultaneously maintained in the system; i.e., the magnetic softness has been well kept. By theoretical fitting of the angular dependence of the FMR field, the first- and second-order magnetic anisotropy constants, ${K}_{1}$ and ${K}_{2}$, and the Lande $g$ factor are obtained and discussed quantitatively. The measurements of angular and frequency dependence of the ferromagnetic resonance linewidth, as well as the theoretical fitting by considering the contributions of Gilbert damping, two-magnon scattering, and inhomogeneous broadening, show that the damping coefficient $\ensuremath{\alpha}$ increases rapidly (about 25-fold) as the Nd content increases to 11.6%, which is mainly due to the enhanced spin-orbit coupling by the Nd additives, supported by x-ray magnetic circular dichroism measurements.

Effect of Ti content on structure and properties of Al2CrFeNiCoCuTix high-entropy alloy coatings

Abstract The Al 2 CrFeNiCoCuTi x high-entropy alloy coatings were prepared by laser cladding. The structure, hardness, corrosion resistance, wear resistance and magnetic property were studied by metallurgical microscope, scanning electron microscopy with spectroscopy (SEM/EDS), X-ray diffraction, micro/Vickers hardness tester, electrochemical workstation tribometer and multi-physical tester. The result shows that, Al 2 CrFeNiCoCuTi x high-entropy alloy samples consist of the cladding zone, bounding zone, heat affected zone and substrate zone. The bonding between the cladding layer and the substrate of a good combination; the cladding zone is composed mainly of equiaxed grains and columnar crystal; the phase structure of Al 2 CrFeNiCoCuTi x high-entropy alloy coatings simple for FCC, BCC and Laves phase due to high-entropy affect. Ti element promotes the formation of a BCC structure in a certain extent. Compared with Q235 steel, the free-corrosion current density of Al 2 CrFeNiCoCuTi x high-entropy alloy coatings is reduced by 1–2 orders of magnitude, the free-corrosion potential is more “positive”. With the increasing of Ti content, the corrosion resistance of Al 2 CrFeCoCuNiTi x high-entropy alloy coatings enhanced in 0.5 mol/L HNO 3 solution. Compared with Q235 steel, the relative wear resistance of Al 2 CrFeCoCuNiTi x high-entropy alloy coatings has improved greatly; both the hardness and plasticity are affecting wear resistance. Magnetization loop shows that, Ti 0.0 high-entropy alloy is a kind of soft magnetic materials.

Development of Soft Magnetic Materials Prepared by Metal Injection Molding

Several kinds of soft magnetic materials prepared by metal injection molding (MIM), including pure iron, soft magnetic stainless steel, Fe-Si alloy, Fe-Co alloy, Fe-Ni alloy are introduced. The advantages of soft magnetic materials prepared by MIM are exhibited, the research status and development of soft magnetic materials prepared by MIM are reviewed.

Preparation and magnetic properties of nano size nickel ferrite particles using hydrothermal method

BackgroundNickel ferrite, a kind of soft magnetic materials is one of the most attracting class of materials due to its interesting and important properties and has many technical applications, such as in catalysis, sensors and so on. In this paper the synthesis of NiFe2O4 nanoparticles by the hydrothermal method is reported and the inhibition of surfactant (Glycerol or Sodium dodecyl sulfate) on the particles growth is investigated.MethodsFor investigation of the inhibition effect of surfactant on NiFe2O4 particles growth, the samples were prepared in presence of Glycerol and Sodium dodecyl sulfate. The X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM) and inductively coupled plasma atomic emission spectrometer (ICP-AES) techniques were used to characterize the samples.ResultsThe results of XRD and ICP-AES show that the products were pure NiFe2O4 and also nanoparticles grow with increasing the temperature, while surfactant prevents the particle growth under the same condition. The average particle size was determined from the Scherrer's equation and TEM micrographs and found to be in the range of 50-60 nm that decreased up to 10-15 nm in presence of surfactant. The FT-IR results show two absorption bands near to 603 and 490 cm-1 for the tetrahedral and octahedral sites respectively. Furthermore, the saturated magnetization and coercivity of NiFe2O4 nanoparticles were in the range of 39.60 emu/g and 15.67 Qe that decreased for samples prepared in presence of surfactant. As well as, the nanoparticles exhibited a superparamagnetic behavior at room temperature.ConclusionsNanosized nickel ferrite particles were synthesized with and without surfactant assisted hydrothermal methods. The results show that with increasing of temperature, the crystallinity of nanoparticles is increased. In the presence of surfactants, the crystallinity of NiFe2O4 nanoparticles decreased in comparison with surfactant- free prepared samples. All of the nickel ferrite nanoparticles were superparamagnetic at room temperature.Graphical abstract

A Solid-State Reaction Route to Synthesize Crystallinic FeB Nanoflowers and their Magnetic Properties

In this paper, crystallinic FeB nanoflowers were successfully prepared at 500°C for 8h with FeCl3 and NaBH4 as the reactants. Field-emission scanning electronic microscope (FESEM) and transmission electronic microscope (TEM) images showed that the flowers composed of thin flakes are in the thickness of about 30 nm. More significantly, this is the first time to synthesize crystallinic FeB nanoflowers self-assembled by thin flake. Magnetic measurement showed that the flowers were a kind of soft magnetic materials (Hc = 600 Oe, Mr = 34.6 emu/g).

In situ Lorentz microscopy in an alternating magnetic field

An alternating magnetizing system has been developed for in situ Lorentz microscopy for soft magnetic materials in an alternating magnetic field. The electron trajectory in the system is discussed using a simulation based on a simple model. It is clarified that the frequency and amplitude of the alternating magnetic field and the defocus of the objective mini lens can be selected as desired values. The system is successfully applied to the observation of domain wall motion in a soft magnetic material, Fe(84.9)Al(5.5)Si(9.6) (wt%) (Sendust). The system is very promising for investigating interactions between domain walls and lattice defects in various kinds of soft magnetic materials.

The study of electroless Ni-W-P alloy plating on glass fibers

Ni-W-P coatings were deposited on the surface of glass fibers by the electroless plating process. The bath was very stable through the palladium salt test. There was no phenomenon of peeling and blistering on the surface of the Ni-W-P alloy glass fibers in the thermal shock test. It showed that the deposit had high impact strength and good adhesion. The morphology of the coatings was observed by scanning electron microscope (SEM). The elements and their contents were tested and analyzed by energy dispersion spectrometer (EDS). The tungsten content reached up to 12.1 wt.%. The effects of the concentrations of NiSO 4, Na 2WO 4, and NaH 2PO 2·H 2O on the conductivity of the coatings were studied. The resistivity of the Ni-W-P alloy glass fibers reached 7.39 × 10 −3 Ω·cm. The alloy coatings on glass fibers were analyzed by XRD. The results indicated that the deposit had an amorphous structure and good heat stability. The suitable work temperature range was lower than 190°C. Finally, the electromagnetic parameters of the Ni-W-P alloy glass fibers were tested and analyzed primarily. The magnetic loss reached 0.04023 and the dielectric loss reached -5.80239. The plated alloy is a kind of soft magnetic material.

Unified evaluation of soft magnetic materials of sheets and ribbons for ELF magnetic shielding effectiveness

Magnetic shielding effectiveness of various kinds of soft magnetic materials from electrical steel sheets to amorphous and nano-crystalline ribbons was examined in the shields of same size and same thickness in the electromagnetic field of extremely low frequency range. The evaluation o f material's factors for shielding effectiveness is studied and the practical selection of shielding materials was tried technologically.

High-frequency permeability of (Fe, Co, Ni)62Nb8B30 amorphous alloys with a wide supercooled liquid region

The increase in B content to 30 at. % for Fe–Co–Ni–Nb–B amorphous alloys caused an extension of a supercooled liquid region before crystallization, and a wide supercooled liquid region greater than 80 K was obtained in a wide composition range of 5–42 at. % Co and 0–10 at. % Ni for Fe62−x−yCoxNiyNb8B30 amorphous alloys. High B-containing amorphous alloys with low Ni content below 10 at. % have high electrical resistivity above 230 μΩ cm and exhibit good soft magnetic properties, i.e., a low coercive force of 2 A/m, low saturated magnetostriction of 2–7×10−6, and high permeability of 21 000–29 300 at 1 kHz and 5000–7500 at 1 MHz. The high-frequency permeability characteristics at 1 MHz are much better than those for any kind of soft magnetic materials, and have been presumed to result from the decrease in eddy current loss caused by the increase in electrical resistivity. The synthesis of the Fe–Co–Nb–B amorphous alloys exhibiting a wide supercooled liquid region greater than 80 K and high-frequency permeability of 7500 at 1 MHz is promising for future development as a type of soft magnetic material.

New bulk amorphous Fe–(Co,Ni)–M–B (M=Zr,Hf,Nb,Ta,Mo,W) alloys with good soft magnetic properties

We have found that an amorphous phase with a wide supercooled liquid region reaching 85 K before crystallization is formed in Fe–(Co, Ni)–(Zr, Nb, Ta)–B, Fe–Co–(Zr, Nb)–(Mo, W)–B and Co–Fe–Zr–B systems. The high stability of the supercooled liquid enabled the production of bulk amorphous alloys with diameters up to 5 mm by copper mold casting. These amorphous Fe–(Co, Ni)–M–B alloys exhibit good soft magnetic properties, i.e., saturation magnetization of 0.95 to 1.1 T, low coercivity of 1 to 8 A/m, Curie temperature of 560 to 590 K and low magnetostriction of 8–14×10−6. The effective permeability of the Co–based alloys exceeds 25 000 at 1 kHz and keeps high values above 5000 at the high frequency of 1 MHz. The permeability at 1 MHz is much higher than those for any kinds of soft magnetic materials. The frequency at which the imaginary part of permeability shows a maximum is also about 1 MHz. The success of synthesis of new Fe- and Co-based amorphous alloys with good soft magnetic properties and high glass-forming ability is promising for future development of a new type of soft magnetic material.