Mechanical surface smoothing of micron-sized iron powder for improved silica coating performance as soft magnetic composites

Slovenský, Peter; Kollář, P.; Mei, Nanxuan; Jakubčin, Miloš; Zeleňáková, A.; Halama, Maroš; Wallinder, Inger Odnevall; Hedberg, Yolanda

doi:10.1016/j.apsusc.2020.147340

Cited by 24 publications

(20 citation statements)

References 48 publications

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“…The development of modern magnetic materials has once again become the focus of development thanks to the growing market of energy-efficient electrical equipment. Due to their low coercivity and the low eddy current losses induced in them, soft magnetic composites can result in a more efficient, faster, more compact, high-permeability, high frequency device [1,2]. In the majority of cases, an iron-based powder was coated with an organic, or an inorganic insulator, or a mixture of the two.…”

Section: Introductionmentioning

confidence: 99%

“…The magnetic properties of the soft magnetic composites (SMCs) are strongly degraded by accumulated dislocations and lattice distortions, however their effects can be reduced by heat treatment processes. Organic insulators can be heat-treated at low temperatures (less than 400 °C), where lattice defects are not annihilated, so in these cases only inorganic insulators can be used [1]. The selection of the ferromagnetic element or alloy focuses on the electrical resistance of the powder particles and thus on the locally induced eddy current losses.…”

Section: Introductionmentioning

confidence: 99%

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Preparation and characterization of Fe-SiO₂ soft magnetic composites prepared by classic and modified Stöber Method

Kocsis

Varga²,

Zsoldos

2022

IOP Conf. Ser.: Mater. Sci. Eng.

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In this study, gas atomized iron powder with the particle size of 10 - 100 μm was coated in two different ways. The coating was created by a chemical procedure, the powder was treated for different periods of time with the classical and modified Stöber process. Toroidal samples were then prepared using different pressures. These samples were heat treated in an argon shielding gas. The complex permeability spectra of the green and heat-treated samples were measured and the effect of pressure, chemical coating time and heat treatment was investigated. The formation of the coatings in each case was confirmed by scanning electron microscopic examinations. Samples with long-term chemical treatment and without heat treatment were appropriate in high-frequency applications (μstat = 50, fFMR = 5 − 15 MHz). After the heat treatment, the relative initial permeability has increased significantly (160-180) and the resonance frequency has decreased (400-4000Hz). Furthermore, it can be stated that a more coherent, thicker coating can be obtained with the modified Stöber method.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Preparation and characterization of Fe-SiO₂ soft magnetic composites prepared by classic and modified Stöber Method

Kocsis

Varga²,

Zsoldos

2022

IOP Conf. Ser.: Mater. Sci. Eng.

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“…While simple tetraethyl orthosilicate (TEOS) hydrolysis in ammonia solution deposits uniformly coating to nano- and micro-particles of iron, modification of large, 200-μm-particles requires additional surface activation. Surface active agents were shown to successfully increase the uniformity of the SiO 2 coating (see references within [ 12 ]). Mechanical milling also improves the adhesion of the silica coating to coarse iron powders [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

“…Surface active agents were shown to successfully increase the uniformity of the SiO 2 coating (see references within [ 12 ]). Mechanical milling also improves the adhesion of the silica coating to coarse iron powders [ 12 ]. Another technique to increase the uniformity of the SiO 2 is the use of L-lysine instead of ammonia solution [ 4 ].…”

Section: Introductionmentioning

confidence: 99%

Deposition of a SiO2 Shell of Variable Thickness and Chemical Composition to Carbonyl Iron: Synthesis and Microwave Measurements

Dolmatov

Zezyulina²,

Osipov³

et al. 2021

Sensors

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Protective SiO2 coating deposited to iron microparticles is highly demanded both for the chemical and magnetic performance of the latter. Hydrolysis of tetraethoxysilane is the crucial method for SiO2 deposition from a solution. The capabilities of this technique have not been thoroughly studied yet. Here, two factors were tested to affect the chemical composition and the thickness of the SiO2 shell. It was found that an increase in the hydrolysis reaction time thickened the SiO2 shell from 100 to 200 nm. Moreover, a decrease in the acidity of the reaction mixture not only thickened the shell but also varied the chemical composition from SiO3.0 to SiO8.6. The thickness and composition of the dielectric layer were studied by scanning electron microscopy and energy-dispersive X-ray analysis. Microwave permeability and permittivity of the SiO2-coated iron particles mixed with a paraffin wax matrix were measured by the coaxial line technique. An increase in thickness of the silica layer decreased the real quasi-static permittivity. The changes observed were shown to agree with the Maxwell Garnett effective medium theory. The new method developed to fine-tune the chemical properties of the protective SiO2 shell may be helpful for new magnetic biosensor designs as it allows for biocompatibility adjustment.

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“…The present work describes the explanation of the influence of the interaction of powder Fe-Ni-Mo particles (with non-smoothed particle surfaces and smoothed particle surfaces) that are part of the compacted material based on two complementary approaches to the analysis of dc hysteresis loss and ac core losses. The smoothing process [8,14] significantly influences surface layers of individual particles used for preparation of the compacts. We expect positive influence of the smoothing, when, the surface irregularities hindering the domain wall displacement can be partially removed.…”

Section: Introductionmentioning

confidence: 99%

Energy loss separation in NiFeMo compacts with smoothed powders according to Landgraf’s and Bertotti’s theories

et al. 2021

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This submitted paper presents the detailed description of the energy loss separation for dc and ac low-frequency magnetic fields of NiFeMo (supermalloy) compacted powder prepared by innovative method of smoothing the surfaces of individual particles. The positive impact of mechanical treatment method on domain wall displacement is explained on the basis of Landgraf approach for dc loss analysis, and the effective dimension for eddy current in ac magnetic field is explained according to Bertotti approach for core loss analysis.

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Mechanical surface smoothing of micron-sized iron powder for improved silica coating performance as soft magnetic composites

Cited by 24 publications

References 48 publications

Preparation and characterization of Fe-SiO₂ soft magnetic composites prepared by classic and modified Stöber Method

Preparation and characterization of Fe-SiO₂ soft magnetic composites prepared by classic and modified Stöber Method

Deposition of a SiO2 Shell of Variable Thickness and Chemical Composition to Carbonyl Iron: Synthesis and Microwave Measurements

Energy loss separation in NiFeMo compacts with smoothed powders according to Landgraf’s and Bertotti’s theories

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Mechanical surface smoothing of micron-sized iron powder for improved silica coating performance as soft magnetic composites

Cited by 24 publications

References 48 publications

Preparation and characterization of Fe-SiO2 soft magnetic composites prepared by classic and modified Stöber Method

Preparation and characterization of Fe-SiO2 soft magnetic composites prepared by classic and modified Stöber Method

Deposition of a SiO2 Shell of Variable Thickness and Chemical Composition to Carbonyl Iron: Synthesis and Microwave Measurements

Energy loss separation in NiFeMo compacts with smoothed powders according to Landgraf’s and Bertotti’s theories

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Preparation and characterization of Fe-SiO₂ soft magnetic composites prepared by classic and modified Stöber Method

Preparation and characterization of Fe-SiO₂ soft magnetic composites prepared by classic and modified Stöber Method