Soft Magnetic Characteristics Research Articles

Soft Magnetic Characteristics and Magnetoimpedance Phenomenon in Copper Wire Coated with Permalloy Film Electroplated from a Sodium Gluconate-Based Bath

Soft Magnetic Characteristics and Magnetoimpedance Phenomenon in Copper Wire Coated with Permalloy Film Electroplated from a Sodium Gluconate-Based Bath

Effect of Ga substitution on grain orientation and magnetostrictive properties of polycrystalline CoFe2O4 ceramics prepared by the solid-state method

As a kind of magnetostrictive ceramics, cobalt ferrites are widely concerned because of its large magnetostriction and high resistivity, which are ideal for high-frequency applications. But, the high driving magnetic field due to the high magnetocrystalline anisotropy limits the practical applications of cobalt ferrites, thus, it is a still a challenge to find a balance between high magnetostriction properties and low driving magnetic fields. In this work, we investigated the effects of partially substitution of Ga3+ for Fe3+ on grain orientation and magnetic properties, attempting to maintain high magnetostriction while reducing the driving magnetic field. The CoFe2-xGaxO4 (x=0, 0.05, 0.1, 0.15) with single-phase spinel structure were prepared by the conventional solid-state method. The saturation magnetization MS increased with the increase of Ga concentration, meanwhile the coercivity Hc and magnetocrystalline anisotropy constant K1 significantly decreased, which indicates the better soft magnetic characteristics of the Ga-doped cobalt ferrites. The oriented CoFe2-xGaxO4 samples were obtained using magnetic field orientation technique during the powder forming process. The <001> preferred orientation was achieved in CoFe2O4 samples. However, the <001> orientation degree decreased with the substitution of Ga, and the preferred orientation has changed into <111> at x=0.15. The Ga substitution affected the magnetocrystalline anisotropy and grain orientation, thereby affecting the magnetostrictive properties. As for the non-oriented samples, although the maximum magnetostrictive strain slightly decreased with Ga substitution, while there was a significant drop in the magnetostrictive saturation field. However, the magnetostriction of the oriented samples decreased significantly with the substitution of Ga due to the change of grain orientation from <001> to <111>.

Annealing temperature effects on microstructure and magnetic properties of Fe-6.5wt. %Si alloy strips prepared by TSTRC process

The Fe-6.5wt.%Si alloy exhibits remarkable soft magnetic characteristics, such as high magnetic permeability, low coercivity, high resistivity, and nearly zero magnetostriction. These attributes establish it as an ideal material for low-power, low-noise electric motors and transformers. This investigation aimed to assess the impact of annealing temperature (ranging from 800 to 1200 °C for 1 h) on the microstructure, texture, and magnetic properties of a 0.15 mm thick Fe-6.5wt.%Si alloy sheet, which was obtained by subjecting the strips produced through the top side-pouring twin-roll casting (TSTRC) process to multi-pass warm rolling in the temperature range of 600 ∼ 800 °C, avoiding hot rolling. Additionally, the recrystallization mechanism of the annealed sheet at 1100 °C for 1 h was explored. The findings indicate that enhancing the annealing temperature corresponded to a reduction in magnetic induction (B8 and B50) as well as iron losses (P10/50, P10/400, and P2/1000). The annealed sheet at 1200 °C for 1 h demonstrated the most favorable magnetic properties, displaying iron losses of 0.486 W/kg, 6.895 W/kg, and 1.232 W/kg for P10/50, P10/400, and P2/1000, respectively. These results illustrate excellent overall magnetic characteristics. The coercivity (Hc) of both B8 and B50 decreased as the annealing temperature increased in the hysteresis loop measurements. Specifically, for B8, it decreased from 62.84 A/m to 24.50 A/m, and for B50, it decreased from 78.10 A/m to 35.50 A/m. The average grain size of the samples gradually increased as the annealing temperature ranged from 800 to 1200 °C. The dominant texture observed was {111}, and the volume fraction of {111} texture increased while the volume fractions of {100} and {110} textures decreased. Upon annealing at 1100 °C for 8 s, the elongated and flattened deformed structures were mainly replaced by equiaxed grains, indicating the completion of the recrystallization process. However, there was a noticeable distinction in the coarsening degree of equiaxed grains based on their orientations. The presence of λ-oriented grains was less prominent, while α-oriented and γ-oriented grains were relatively more abundant. As the annealing time increased from 8 s to 1 h, there was a decrease in the presence of λ-oriented and α-oriented grains, while the presence of γ-oriented grains significantly increased.

Effect of Nb doping on the magnetic properties and its fluxgate behavior of CoFeNbSiB amorphous ribbons

Co-based amorphous alloys are often utilized as magnetic core for fluxgate sensor due to their excellent comprehensive performance with eminent permeability and insignificant coercivity. Herein, we investigated the effects of Nb doping on the phase composition, amorphous formation, magnetic domain structure and soft-magnetic characteristics of (Co0.7Fe0.5Si0.15B0.1)100-xNbx (x = 0, 1, 3, 5, 7) alloy ribbons and its fluxgate performance. Additionally, related magnetic parameters as magnetic permeability μi and coercivity Hc of the ribbon under zero magnetic-field annealing (ZFA) as well as longitudinal magnetic-field annealing (LFA) and fluxgate sensitivity and noise value were also tested. It is verified that the Nb doping is well able to optimize their amorphization, thermostability and soft magnetic properties. When x = 3, the ribbon presents the most well-distributed magnetic domain structure and the inferior soft magnetic properties, with an initial permeability μi of 8900 and a coercivity Hc of 1.51 A/m. Compared with ZFA, LFA is more effective on improving the soft magnetic and fluxgate behavior. The highest μi of 24,520 and the lowest Hc of 0.18 A/m are obtained at x = 3 for the LFA sample, where the fluxgate sensitivity is up to 44.15 mV/μT, accompanied by the peak-to-peak noise (denoted by Noisep-p) value is as low as 1.38 nT.

Modeling of Dual-Phase Composite Magnetic Material and Its Application in Transformers

Dual-phase composite magnetic materials have magnetic and permanent magnetic properties. They can realize the dual-phase conversion of soft magnetic and permanent magnetic composites with a small amount of excitation energy. They have the advantages of good control and conversion characteristics and save energy, and they have a wide range of application scenarios in regard to power equipment. In this paper, the magnetization modeling of dual-phase composite magnetic materials is carried out based on micromagnetic theory, and a specific mathematical expression is given. Secondly, the preparation process of the dual-phase composite magnetic material is studied, the dual-phase composite magnetic material is prepared, and the demagnetization curve of the dual-phase composite magnetic material is measured. Finally, the application of dual-phase composite magnetic materials in power equipment is carried out. Using the soft magnetic and permanent magnetic characteristics of dual-phase composite magnetic materials, their impact on DC bias suppression in transformers is assessed. Magnetic circuit reluctance theory is used to develop the structure and electromagnetic design of a transformer. A transformer prototype with DC bias suppression ability based on dual-phase composite magnetic materials is manufactured, and simulation and experimental research are carried out. The simulation and experimental results verify the correctness of the proposed scheme. Although this scheme requires a more complex core structure, the energy-saving effect is remarkable without changing the transformer’s neutral grounding. The indicators meet the actual requirements of the project.

Modulating the magnetic anisotropy in SmCo/Co nanocomposites through alteration in spin–orbit coupling

In the present work, one-dimensional (1-D) as-synthesized SmCo/Co magnetic nanocomposites were prepared through magnetically-assisted chemical reduction method. The samples were prepared with the varying reaction times between 1 and 10 h labelled as SC1, SC2, SC5, SC7 and SC10. The Rietveld refinement of XRD patterns revealed the presence of Sm(OH)3 (P63/m), hcp-Co (P63/mmc), cubic-Co (Fm-3 m) and Sm2Co17 (P63/mmc) phases with varying phase fractions. The nanocomposites were found to possess the highest aspect ratio (∼7) with lowest crystallite size (∼50 nm) along with the highest developed lattice strain in SC5. The decisive influence of the reaction time was observed on the magnetic response of the samples indicating highest saturation magnetization of ∼ 150 emu/g and effective magnetic anisotropy of ∼ 1.5 x 106 erg/cm3 in SC5. The generalized form of Bloch law was employed to study the origin of magnetic anisotropy determined as spin–orbit coupling which was found to be highest in SC5. It was suggested that the enhanced magnetic properties of the nanocomposites are attributable to the high fraction of magnetic phases with the soft magnetic character and coupling between multiple phases.

Effects of Stress on Loss and Magnetic Properties of Fe80Co3Si3B10P1C3 Amorphous Iron Cores

The research on how to reduce energy consumption and improve the efficiency of amorphous motors has extensive coverage. This study systematically investigates the influence of internal stress induced by impregnation curing and interference fit on the soft magnetic properties and loss characteristics of Fe80Co3Si3B10P1C3 (CAF4) amorphous alloy iron cores. The amorphous iron core samples undergo analysis through differential scanning calorimetry (DSC), transmission electron microscopy (TEM), X-ray diffraction (XRD), magnetic performance testing equipment, flexible pressure sensors, and magnetostriction testers. The CAF4 amorphous iron core after impregnation curing (AIC) exhibits the lowest loss of P1.2T,1.5 kHz = 22.8 W/kg when annealed at 260 °C, representing a 21% increase compared to the pre-impregnation curing (BIC) state. Within the commonly utilized interference fit range, the loss growth rate of CAF4 amorphous iron cores is lower than that of Fe80Si9B11 (1K101). Likewise, at a frequency of 50 Hz and an excitation of 1000 A/m, the magnetostriction coefficient of CAF4 is smaller than that of 1K101. Within the typical interference fit range, the magnetization performance of CAF4 amorphous iron cores surpasses that of 1K101, favoring lightweight and compact motor designs and reducing copper losses. Consequently, CAF4 amorphous iron cores exhibit significant advantages when employed in motors.

Magnetic response to microstructure and phase evolution in laser thermal treated FeSiB amorphous alloy

In the current work, laser thermal treatment of the FeSiB amorphous foil with a single linear laser track was carried out. The resultant microstructure and phase evolution were examined with the aid of x-ray diffraction, differential scanning calorimetry, and site-specific transmission electron microscopy. The laser power was kept constant at 100 W, whereas, laser beam scanning speeds were varied in the range of 500–235 mm/s, generating corresponding laser fluences of 0.42–0.91 J/mm2 on the sample surface. Laser fluences of up to 0.48 J/mm2 structurally relaxed the FeSiB foil, retaining the amorphous structure. Laser fluences of higher than 0.48 J/mm2 led to partial crystallization of FeSiB amorphous foils. The crystallite sizes were in the range of 11–31 nm (laser fluence of 0.49–0.91 J/mm2). α-FeSi formed as a major phase of partial crystallization while its quantity steadily increased from 3.6 to 46 vol. % with laser fluence (laser fluence 0.49–0.91 J/mm2). Fe2B formed in recognizable quantities (≥2%) for laser fluences ≥0.53 J/mm2. Laser fluences leading to structural relaxation and evolution of predominantly α-FeSi phase exerted minimal effects on ratios of intrinsic coercivities to saturation compared to the as-cast FeSiB amorphous foil. On the contrary, formation of Fe2B in significant quantities (≥2%) led to the steady increase in intrinsic coercivities and remanence to saturation ratios as a function of laser fluence indicating a loss in soft magnetic characteristics. Nonetheless, continuous increase in fractions of α-FeSi with laser fluence led to a steady improvement in saturation magnetostriction of the FeSiB foil.

Growth rate and substrate temperature dependent magnetic and magneto-microstructural properties of sputtered Fe-Co-Al thin films

This work reports the effect of growth rate and substrate temperature on the structural, magnetic and magneto-microstructural properties of Fe-Co-Al alloy thin films. 75 nm thick Fe-Co-Al films were deposited on Si 〈100〉 substrates at room temperature by high power impulse magnetron sputtering at different growth rates viz., 0.67–1.6 Å/s. All the films exhibited a uniform composition of about Fe60Co25Al15 irrespective of growth rates. In addition to this, all the films crystallized in single phase with bcc type structure. Growth rate was found to have a considerable impact on the magnetic properties of Fe-Co-Al thin films. Film grown at 1.3 Å/s exhibited an in-plane magnetic anisotropy with large saturation magnetization combined with low coercivity when compared with other films. To improve the magnetic properties further, Fe-Co-Al films were also processed at different substrate temperatures (Ts) viz., 300, 400 and 500 °C. Substrate temperature of about 300 °C was found to have beneficial effect on the soft magnetic characteristics of Fe-Co-Al films. While the crystal structure did not show any perceptible change with processing conditions, magnetic microstructures traced from magneto optic Kerr microscopy displayed substantial change. Upon increase in substrate temperature, during magnetization reversal process, magnetic domain images traced along the easy magnetization direction magnetization showed transformation from branched band domains (as-deposited) → wide band domains (Ts = 300 °C) → less periodic branched band domains (Ts = 400 °C) → ripple domains (Ts = 500 °C). Attempts were made to correlate the achieved magnetic properties in Fe-Co-Al with magnetic microstructures.

Investigation of Sm Addition on Microstructural and Optical Properties of CoFe Thin Films.

CoFe-based alloys and rare earth (RE) elements are among the most studied materials in applying magnetic devices to improve soft magnetic characteristics. A series of Co40Fe40Sm20 films are deposited on a glass substrate via the sputtering technique, followed by an annealing process to investigate their effect on microstructural and optical properties of Co40Fe40Sm20 films. In this study, the increase in the thickness of Co40Fe40Sm20 films and annealing temperatures resulted in a smoother surface morphology. The 40 nm Co40Fe40Sm20 films annealed 300 °C are expected to have good wear resistance and adhesive properties due to their high values of H/E ratio and surface energy. Optical transparency also increased due to the smoother surface of the Co40Fe40Sm20 films.

Enhanced magnetodielectric properties of Co2Z ferrite ceramics for ultrahigh frequency applications achieved via Cr3+ ion doping

Phase formation, microstructure, magnetic properties, and dielectric properties of Ba1.5Sr1.5Co2Fe(23−x)CrxO41 (0.0 ≤ x ≤ 1.0) ceramics, in which Fe3+ ions were substituted by Cr3+ ions, were systematically investigated. X-ray diffraction results reveal that Z-type hexagonal ferrite was formed by sintering at 1250 °C, and Cr3+ ions successfully enter lattice without destroying crystal structure. Analysis of the microstructure reveals that Cr3+ ion doping has significant effect on crystal micromorphology. Samples with x = 0.4 have the most homogeneous micromorphology and the highest sintering density of 5.12 g/cm3. In addition, under the influence of external magnetic field, all samples exhibit typical soft magnetic character and hysteresis characteristics, with saturation magnetization up to 63.86 emu/g (x = 0.6). Particularly, compared with undoped sample, Cr-doped samples have outstanding magnetic–dielectric properties. Firstly, with increasing Cr3+ amount, real part of the permeability (μ′) reaches the maximum value of 10.70 at x = 0.4, while cutoff frequency exceeds 2 GHz, and Snoek constant reaches ∼19.50 GHz. Furthermore, due to more homogeneous microstructure, samples with x = 0.4 have low magnetic loss and can maintain high quality factor (Q) over a broad frequency range. Moreover, real part of the permittivity (ε′) reaches the maximum value of 16.90 at x = 0.6, and dielectric loss remains lower than 0.013 for frequencies below 0.7 GHz. Consequently, magnetic–dielectric materials prepared in this work are expected to have extensive application prospects for ultrahigh-frequency devices.

Magnetic Adsorbent Based on Faujasite Zeolite Decorated with Magnesium Ferrite Nanoparticles for Metal Ion Removal

Magnetic nanoparticles are a promising alternative as a support in adsorption processes, aiming at the easy recovery of the aqueous medium. A faujasite zeolite (FAU) surface was decorated with magnesium ferrite (MgFe2O4) nanoparticles. FAU is a porous adsorbent with high specific surface area (SSA) and chemical stability. The FAU:MgFe2O4 nanocomposite 3:1 ratio (w w−1) promotes the combination of the surface and magnetic properties. The results showed the effectiveness of the MgFe2O4 immobilization on the FAU surface, exhibiting a high SSA of 400 m2 g−1. The saturation magnetization (Ms) was verified as 5.9 emu g−1 for MgFe2O4 and 0.47 emu g−1 for FAU:MgFe2O4, an environmentally friendly system with soft magnetic characteristics. The magnetic nanocomposite achieved high adsorption values of around 94% removal for Co2+ and Mn2+ ions. Regarding its reuse, the nanocomposite preserved adsorption activity of above 65% until the third cycle. Thus, the FAU:MgFe2O4 nanocomposite presented favorable adsorptive, magnetic, and recovery properties for reuse cycles in polluted water.

Eddy current suppression and soft magnetism enhancement in FeGaB-based magnetic composites with alumina lamination

FeGaB thin films have excellent magnetostrictive and soft magnetic properties. Unfortunately, severe eddy current loss (ECL) due to its low resistivity makes its employment in energy-efficient structures challenging. Inserting insulating layers into magnetostrictive films is an effective technique to suppress ECL and enhance soft magnetic characteristics. Unresolved is how to exhaustively account for multiple contributing factors and obtain the optimal composite materials design. This study constructed an ECL simulation model of a soft magnetic composite (SMC) using finite element analysis in the COMSOL multiphysics software. To unify the two competing conditions of ECL suppression and magnetostriction reduction, the impacts of inserted alumina (thickness and the number of layers), FeGaB size (thickness and area), and applied frequency (0.01–1 GHz) were studied. SMC inserted with four layers of 5 nm Al2O3 can achieve remarkable overall performance, including good ECL suppression (85 %) but slightly reduced magnetostriction (1.8 %). Moreover, it was revealed that the ECL suppression has a size effect at high frequencies (1 GHz) when the SMC thickness surpasses 0.6–1 μm. To achieve the unification of simulation and experiment, a 120 nm/(Al2O3 5 nm/FeGaB 120 nm)4 SMC was produced and compared to a single-layer thin film of FeGaB. The SMC showed a superior soft magnetic characteristic and permeability after inserting Al2O3 sheets. Its ultra-low coercivity (0.017 Oe) resulted from the excellent material interface and the domain wall elimination; the permeability was enhanced by the frequency width half maximum lowered to 0.48 GHz, and the higher value of the imaginary component of magnetic permeability was 1303. Consequently, the experiment confirmed that the improvement in the dynamic response characteristics of the SMC is mainly attributable to the suppression of ECL and the enhancement of soft magnetic properties. The composite magnetic film in this study provides a potential solution for energy-efficient high-frequency structures.

Effect of electrolyte additives on structural and magnetic properties of cobalt ferrous tungsten phosphorous based thin films

This work used urea as a cross - linking agent and phosphorous as precursors to electrodeposit crystalline Co-Fe-W-P thin films at a pH of around 8. To get the ideal soft magnetic characteristics needed for the next generation magnetic head core, electrodeposition conditions have to be altered. The formed films were characterised using SEM, EDAX, XRD, and VSM. The deposited films' SEM micrographs showed more homogeneous surface morphology and no micro-voids. X-ray diffraction patterns revealed that the films had an FCC phase structure. All of the coatings were nanocrystalline, as determined by calculating the average crystal size of the films using the debye Scherrer equation. The VSM findings showed that as grain size decreased, the coercivity of something like the nanocrystalline films drastically decreased. However, the chemical makeup of the films had a considerable impact on the magnetic moment, although grain size had little impact.

Reprogrammable liquid-metal/NdFeB/silicone composite magnetic elastomer

Programming the patterned magnetization profile on the magnetic elastomer can enable the magnetic soft robot to produce controlled deformation. But the magnetization profiles are usually unchangeable, which leads to the single function of magnetic soft robot. This paper presents a reprogrammable mangetic elastomer based on liquid-metal/NdFeB/Silicone composites. Liquid-metal/NdFeB functional groups wrapped in silicone matrix can realize repeated magnetization through thermal-assisted magnetic programming. By using several liquid metals (melting points &amp;lt;60 °C), we have manufactured composite magnetic elastomer with regulate-temperature at 15.7, 29.7, 41.5 and 47 °C, respectively. SEM and EDS results exhibits the elastomer’s micromorphology and element content. The elstomer’s magnetic properties are tested by the comprehensive physical property measurement system (PPMS). The moment–temperature (M–T) curve shows the material’s moment jumps at the melt point of the liquid metal. And the moment–magnetic field (M–H) curves indicate that the elastomer exhibit hard and soft magnetic characteristics. At last, a hexagon-shape robot is manufactured and then programmed to two modals of grasping and standing. The experimental results verify the reprogrammability of the proposed composite elastomer. The elastomer is expected to be utilized to manufacture multi-modal magnetic soft robot.

Manipulating topological Hall-like signatures by interface engineering in epitaxial ruthenate/manganite heterostructures.

Topologically protected non-trivial spin textures (e.g. skyrmions) give rise to a novel phenomenon called the topological Hall effect (THE) and have promising implications in future energy-efficient nanoelectronic and spintronic devices. Here, we have studied the Hall effect in SrRuO3/La0.42Ca0.58MnO3 (SRO/LCMO) bilayers. Our investigation suggests that pure SRO has hard and soft magnetic characteristics but the anomalous Hall effect (AHE) in SRO is governed by the high coercivity phase. We have shown that the proximity effect of a soft magnetic LCMO on SRO plays a critical role in interfacial magnetic coupling and transport properties in SRO. Upon reducing the SRO thickness in the bilayer, the proximity effect becomes the dominant feature, enhancing the magnitude and temperature range of THE-like signatures. The THE-like features in bilayers can be explained by a diffusive Berry phase transition model in the presence of an emergent magnetic state due to interface coupling. This work provides an alternative understanding of THE-like signatures and their manipulation in SRO-based heterostructures, bilayers and superlattices.

Magnetic characteristics of sengon wood-impregnated magnetite nanoparticles synthesized by the co-precipitation method

&lt;abstract&gt; &lt;p&gt;This study was conducted to synthesize magnetic wood through the ex situ impregnation method of magnetite nanoparticles and analyze its physical properties and characterization. The process was initiated with the synthesis of magnetite nanoparticles by the co-precipitation method and the nano-magnetite was successfully synthesized with a particle distribution of 17–233 nm at an average size of 75 nm. Furthermore, the impregnation solution consisted of three different levels of magnetite nanoparticles dispersed in furfuryl alcohol, untreated and furfurylated wood for comparison. Sengon wood (&lt;italic&gt;Falcataria moluccana&lt;/italic&gt; Miq.) was also used due to its low physical properties. The impregnation process was conducted by immersing the samples in the solution at a vacuum of −0.5 bar for 30 min, followed by a pressure of 1 bar for 2 h. There was also an improvement in the physical properties, such as weight percent gain, bulking effect, anti-swelling efficiency and density, while the water uptake continued to decrease. Additionally, magnetite nanoparticles appeared in wood microstructure image, supported by the result of ferrum content in chemical element analysis. The results showed that chemical change analysis proved the presence of Fe–O functional group cross-linked with wood polymer. The diffractogram also reported the appearance of magnetite nanoparticles peak and a decrease in crystallinity due to an increase in the concentration. Based on the analysis, sengon wood was classified as a superparamagnetic material with soft magnetic characteristics and the optimum treatment was furfurylated-magnetite 12.5% wood.&lt;/p&gt; &lt;/abstract&gt;

Corrosion-resistant polymer-based nanocomposite materials with a high level of microwave absorption and soft magnetic materials based on iron oxide nanopowder obtained by electroerosion dispersion

Nanopowder of iron oxide (mainly Fe3O4) has been obtained by electroerosion dispersion method and was used for manufacturing of gradient polymer-based microwave absorbing materials which absorb (1) on 36.6 GHz with a level of absorption of 99% (with a maximum penetration −40 dB and reflection −23 dB) and (2) on 10 GHz and 36.6 GHz with an absorption of 90% and 98.4%, correspondently (with a maximum reflection −18 dB and −10 dB and penetration −40 dB and −60 dB, respectively). It was demonstrated, that change of magnetic properties of the absorbing material under mechanical load can be used for non-destructive control. Sintered under high pressure-high temperature conditions (2 GPa, at 900, 1000, 1100, 1200 and 1300 °C for 4 min) iron oxide nanopowder in presence of hexagonal boron nitride (hBN) demonstrated soft magnetic behavior. Electron Backscatter Diffraction (EBSD) study has showed that during sintering the grains have grown beyond the superparamagnetic size limit inspire short annealing time. The structure of sintered materials was investigated using X-ray diffraction with a full-profile fitting procedure. The materials sintered at 2 GPa at 900 and 1000 °C contained 75–80 wt% of FeO and 25–20 wt% Fe. Materials sintered at 1100 oC, along with 32 wt% FeO and 2 wt% Fe, contained a significant amount of Fe3N: 66 wt%. However, materials sintered at 1200–1300 °C contain almost pure Fe3N phase. Thus, under conditions of high pressures and temperatures with increasing sintering temperature, reduction of iron oxide was observed, followed by its nitriding with nitrogen released from the boron nitride, which led to a reduction of coercive force and thus improving soft magnetic characteristics of the sintered materials. The scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) study of the sample, sintered at 1300 oC showed approximate composition of Fe3N0.8C0.3-0.6O0.06-0.3.

Achieving polycrystalline diamond magnetic abrasive tools via double-stage gas atomization

Although magnetic abrasive finishing (MAF) is an efficient surface finishing technique, its promotion and use in the precise polishing of high-hardness objects are constrained by the poor finishing performance and short service life of magnetic abrasive powders (MAPs). In this study, a double-stage atomization technique is employed to successfully manufacture MAPs with a polycrystalline diamond (PCD) as an abrasive phase. Analysis was performed on the graphitization of PCD abrasive and the circularity of the created MAPs as a result of cooling temperature. Therefore, the pressure ranges of the first-stage atomizer are suggested based on the theoretically designed kinetic model of PCD abrasives' penetration behavior into liquid metal. As revealed in the preparation experiment findings, PCD abrasives with their original crystal structure were deeply embedded on the surface of a spherical iron matrix. The generated PCD MAPs with smaller particle sizes exhibited better soft magnetic characteristics due to the atomization process’ quick cooling. The MAF results implied that PCD MAPs curtailed the roughness of cemented carbide from 302 nm to 85.2 nm, and their service life exceeds 60 min. The findings of this research can provide technical assistance for the creation of high-performance PCD MAPs.

The Effect of Varying Current on the Impedance Phase Characteristics of CoFeSiB Amorphous Ribbon

The impedance magnitude characteristics of the giant magnetoimpedance (GMI) sensors have been extensively researched since the magnetoimpedance (MI) effect was discovered 20 years ago. However, unlike earlier impedance amplitude studies, the current study shows that the characteristic shift of the GMI impedance phase is more sensitive to the change in the magnetic field. CoFeSiB exhibits excellent GMI effect and soft magnetic characteristics. The impedance phase characteristics of an amorphous ribbon of CoFeSiB are examined in this work in relation to fluctuations in the excitation current. The impedance phase characteristics are significantly influenced by the magnitude and frequency of the ac excitation current as well as the degree to which the dc current overlapped the ac current. When the dc bias current is zero, the sensitivity in the weak field is roughly 0.79%/Oe. The sensitivity can reach up to 3.97%/Oe in the same field when the dc bias current is set to 20 mA. The GMI phase sensitivity change rate has seen a further increase of almost 402.5%. It indicates that the appropriate excitation current amplitude and frequency can excite the maximum impedance phase change.