Effects of axial pressure on the evolution of core–shell heterogeneous structures and magnetic properties of Fe–Si soft magnetic powder cores during hot-press sintering

Qiu, Yudong; Wang, Rui; He, Yihai; Kong, Hui; Li, Shaogang; Wu, Zhaoyang

doi:10.1039/d2ra02497g

Cited by 8 publications

(4 citation statements)

References 30 publications

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“…P hyst values increased almost linearly with the frequency for all the Fe-Si-Cr-based SMCs. The excessive thickness of the insulating layers restricted the motion of the domain walls, resulting in a gradual increase in the hysteresis loss with an increase in the SS mass fraction [24]. Moreover, the core-shell heterogeneous structure of Fe-Si-Cr-based SMCs primarily reduced the dynamic loss by improving resistivity and restricting the effective operating diameter of the eddy currents [25].…”

Section: Microstructures and Magnetic Properties Of The Alloy Powders...mentioning

confidence: 99%

Fabrication and Soft Magnetic Properties of Fe–Si–Cr Composites with Double-Insulating Layers Suitable for High-Frequency Power Applications

Huang,

et al. 2023

Magnetochemistry

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Soft magnetic composites (SMCs) are composed of alloy materials with the core and insulating layers as the shell. These composites exhibit high saturation magnetic sensitivity and low hysteresis loss, making them a promising material for various applications. The investigation of double layers is considered valuable as it can effectively address the issues of low resistivity and high dynamic loss that arise from non-uniform insulating layers in SMCs. In this study, Fe-Si-Cr/SiO2 particles with a core–shell heterostructure were produced via chemical vapor deposition (CVD). The Fe-Si-Cr/SiO2 materials were coated with different weight percentages (1–6%) of sodium silicate (SS). Subsequently, Fe-Si-Cr-based SMCs were synthesized through high-pressure molding and heat treatment. The effect of the SS weight percentage on microscopic changes and magnetic characteristics was investigated. These findings indicated that a concentration of 4 wt% of SS was the most effective at enhancing magnetic characteristics. The resultant SMCs exhibited high resistivity (21.07 mΩ·cm), the lowest total loss (P10 mt/300 kHz of 44.23 W/kg), a relatively high saturation magnetization (181.8 emu/g), and permeability (35.9). Furthermore, it was observed that the permeability exhibited stabilization at lower frequencies. According to these findings, the combination of CVD and double layers could lead to the further development of SMCs in a variety of applications.

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Section: Microstructures and Magnetic Properties Of The Alloy Powders...mentioning

confidence: 99%

Fabrication and Soft Magnetic Properties of Fe–Si–Cr Composites with Double-Insulating Layers Suitable for High-Frequency Power Applications

Huang,

et al. 2023

Magnetochemistry

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“…As a consequence, the resistivity is increased because the Fe-Si particles are prevented from interacting. Another explanation for this is SiO 2 and Fe-Si particles were exchange-coupled, resulting in an efficient surface spin orientation [25]. Nevertheless, after heat treatment at higher temperatures, the permeability of the Fe-Si/SiO 2 SMCs stabilizes at higher frequencies because a complete insulating layer favors an increase in the depth of the skin effect as the working frequency rises [26].…”

Section: Evolution Of the Core-shell Heterostructure Within The Fe-si...mentioning

confidence: 99%

Microstructure and Magnetic Property Evolution Induced by Heat Treatment in Fe-Si/SiO2 Soft Magnetic Composites

Li,

Ju,

Wang

et al. 2023

Magnetochemistry

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SiO2 has been extensively studied as a superior insulating layer for innovative Fe-based soft magnetic composites (SMCs). During the preparation process of SMCs, appropriate heat treatment can effectively alleviate internal stress, reduce dislocation density, decrease coercivity, and enhance permeability. Maintaining the uniformity and integrity of SiO2 insulating layers during heat treatment is a challenging task. Hence, it is crucial to explore the heat-treatment process and its effects on the magnetic properties of SMCs and their insulating layers. Herein, Fe–Si/SiO2 particles were prepared using chemical vapor deposition (CVD), and Fe–Si/SiO2 SMCs having a core–shell heterostructure were synthesized through hot-press sintering, and investigations were conducted into how heat-treatment temperature affected the microstructure of SMCs. This study thoroughly investigated the relationship between the evolution of SiO2 insulating layers and the magnetic properties. Additionally, the impact of the heat-treatment time on the magnetic properties of Fe-Si/SiO2 SMCs was evaluated. The results showed that in the temperature range of 823–923 K, the core–shell heterostructures grew more homogeneous and uniform. Concurrently, the stress and defects inside the Fe-Si/SiO2 SMCs were eliminated. When the temperature was raised over 973 K, the core–shell heterostructure was disrupted, and SiO2 began to disperse. After following a heat-treatment process (923 K) lasting up to 60 min, the resulting SMCs had high resistivity (1.04 mΩ·cm), the lowest hysteresis loss (P10 mt/100 kHz of 344.3 kW/m3), high saturation magnetization (191.2 emu/g). This study presents a new technique for producing SMCs using ceramic oxide as insulating layers. This study also includes a comprehensive analysis of the relationship between microstructure, magnetic properties, and heat treatment process parameters. These findings are crucial in expanding the potential applications of ceramic oxide.

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“…Choi et al [17] prepared Al 2 O 3 insulating layers of varying thicknesses on the surface of Fe-Si-Cr alloy powders using the sol-gel method, thereby fabricating a composite with an effective permeability of 33.9 and a loss of 252 mW/cm 3 at 50 mT and 100 kHz. Although previous studies [18][19][20][21] have demonstrated that metal oxides are promising candidates for use as insulating layers in the production of Fe-based SMCs, recent studies have predominantly focused on developing new metal oxide insulating layers and improving the properties of Fe-based SMCs [22,23].…”

Section: Introductionmentioning

confidence: 99%

Effect of Various Metal Oxide Insulating Layers on the Magnetic Properties of Fe-Si-Cr Systems

Huang

et al. 2023

Coatings

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Iron-based soft magnetic composites (SMCs) are the key components of high-frequency electromagnetic systems. Selecting a suitable insulating oxide layer and ensuring the integrity and homogeneity of the heterogeneous core–shell structure of SMCs are essential for optimizing their magnetic properties. In this study, four types of SMCs—Fe-Si-Cr/ZrO2, Fe-Si-Cr/TiO2, Fe-Si-Cr/MgO, and Fe-Si-Cr/CaO—were prepared via ball milling, followed by hot-press sintering. The differences between the microscopic morphologies and magnetic fproperties of the Fe-Si-Cr/AOx SMCs prepared using four different metal oxides were investigated. ZrO2, TiO2, MgO, and CaO were successfully coated on the surface of the Fe-Si-Cr alloy powders through ball milling, forming a heterogeneous Fe-Si-Cr/AOx core–shell structure with the Fe-Si-Cr alloy powder as the core and the metal oxide as the shell. ZrO2 is relatively hard and less prone to breakage and refinement during ball milling, resulting in a lower degree of agglomeration on the surface of the composites and prevention of peeling and collapse during hot-press sintering. When ZrO2 was used as the insulation layer, the magnetic dilution effect was minimized, resulting in the highest resistivity (4.2 mΩ·cm), lowest total loss (580.8 kW/m3 for P10mt/100kHz), and lowest eddy current loss (470.0 kW/m3 for Pec 10mt/100kHz), while the permeability stabilized earlier at lower frequencies.

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Effects of axial pressure on the evolution of core–shell heterogeneous structures and magnetic properties of Fe–Si soft magnetic powder cores during hot-press sintering

Abstract: Silicon dioxide (SiO2) has attracted much attention as an ideal coating material for iron (Fe)-based soft magnetic powder cores (SMPCs).

Cited by 8 publications

References 30 publications

Fabrication and Soft Magnetic Properties of Fe–Si–Cr Composites with Double-Insulating Layers Suitable for High-Frequency Power Applications

Fabrication and Soft Magnetic Properties of Fe–Si–Cr Composites with Double-Insulating Layers Suitable for High-Frequency Power Applications

Microstructure and Magnetic Property Evolution Induced by Heat Treatment in Fe-Si/SiO2 Soft Magnetic Composites

Effect of Various Metal Oxide Insulating Layers on the Magnetic Properties of Fe-Si-Cr Systems

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