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通过优化偶联剂含量改善磁粉芯综合性能

  • 余红雅1,2,3

    机 构：

    1. 东莞铭普光磁股份有限公司 东莞 523330

    2. 华南理工大学材料科学与工程学院 广州 510640

    3. 华南协同创新研究院 东莞 523808

    ×
  • ， 袁涵2,3

    机 构：

    2. 华南理工大学材料科学与工程学院 广州 510640

    3. 华南协同创新研究院 东莞 523808

    ×
  • ， 李竞舟1

    机 构：

    1. 东莞铭普光磁股份有限公司 东莞 523330

    ×
  • ， 刘仲武2,3

    机 构：

    2. 华南理工大学材料科学与工程学院 广州 510640

    3. 华南协同创新研究院 东莞 523808

    ×
  • ， 郭宝春1,2,3

    机 构：

    1. 东莞铭普光磁股份有限公司 东莞 523330

    2. 华南理工大学材料科学与工程学院 广州 510640

    3. 华南协同创新研究院 东莞 523808

    ×
  • ， 杨建民1

    机 构：

    1. 东莞铭普光磁股份有限公司 东莞 523330

    ×
  • ， 陈榕寅1

    机 构：

    1. 东莞铭普光磁股份有限公司 东莞 523330

    ×

1. 东莞铭普光磁股份有限公司 东莞 523330；
2. 华南理工大学材料科学与工程学院 广州 510640；
3. 华南协同创新研究院 东莞 523808；

Improvement of the Overall Performance of Magnetic Powder Cores by Optimising the Coupling Agent Content

  • YU Hongya1,2,3

    Affiliation：

    1. Dongguan Mentech Optical & Magnetic Co., Ltd., Dongguan 523330 , China

    2. School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 , China

    3. South China Institute of Collaborative Innovation, Dongguan 523808 , China

    ×
  • ， YUAN Han2,3

    Affiliation：

    2. School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 , China

    3. South China Institute of Collaborative Innovation, Dongguan 523808 , China

    ×
  • ， LI Jingzhou1

    Affiliation：

    1. Dongguan Mentech Optical & Magnetic Co., Ltd., Dongguan 523330 , China

    ×
  • ， LIU Zhongwu2,3

    Affiliation：

    2. School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 , China

    3. South China Institute of Collaborative Innovation, Dongguan 523808 , China

    ×
  • ， GUO Baochun1,2,3

    Affiliation：

    1. Dongguan Mentech Optical & Magnetic Co., Ltd., Dongguan 523330 , China

    2. School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 , China

    3. South China Institute of Collaborative Innovation, Dongguan 523808 , China

    ×
  • ， YANG Jianmin1

    Affiliation：

    1. Dongguan Mentech Optical & Magnetic Co., Ltd., Dongguan 523330 , China

    ×
  • ， CHEN Rongyin1

    Affiliation：

    1. Dongguan Mentech Optical & Magnetic Co., Ltd., Dongguan 523330 , China

    ×

1. Dongguan Mentech Optical & Magnetic Co., Ltd., Dongguan 523330 , China；
2. School of Materials Science and Engineering, South China University of Technology, Guangzhou 510640 , China；
3. South China Institute of Collaborative Innovation, Dongguan 523808 , China；

作者简介:

余红雅，女，1973年出生，博士，副教授，硕士研究生导师。主要研究方向为磁性材料及器件。E-mail:yuhongya@scut.edu.cn;

袁涵，男，博士研究生。主要研究方向为软磁材料及器件。E-mail:304479622@qq.com

中图分类号:TF123；TM272

DOI:10.11933/j.issn.1007-9289.20230420001

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目录contents

    摘要

    磁粉芯在工程应用中会遇到体积变化引起的开裂、磁性能低等问题，目前未见关于这方面的研究。通过在羰基铁粉磁粉芯（包含磁环、磁片和一体成型电感）中加入不同含量 KH550 硅烷偶联剂，研究其成型性、磁性能和力学性能，并利用 SEM、TMA 和 LCR 等测试分析偶联剂对磁粉芯性能影响的作用机理。研究表明偶联剂能将树脂“约束”在磁粉表面，并在固化过程中带动磁粉颗粒重排，从而增加磁粉芯的膨胀系数。添加 0 wt.%和 0.1 wt.%偶联剂的磁粉芯具有负的膨胀系数，容易收缩开裂。当偶联剂含量达到 0.3 wt.%、0.5 wt.%和 0.7 wt.%时，树脂固化过程中磁粉芯的膨胀系数升高，从而增加磁粉芯的体积，有效抑制磁粉芯的开裂倾向。但是，体积的增加会降低磁粉芯的密度、磁导率、Q 值和力学性能，增加损耗。综合考虑磁粉芯的成型性和其他性能，偶联剂添加的最佳比例是 0.3 wt.%。揭示了偶联剂对磁粉芯膨胀系数等综合性能的影响规律，可为高性能磁粉芯的工程化应用提供重要理论依据。

    Abstract

    Magnetic powder cores, also known as soft magnetic composite materials (SMCs), consist of metal magnetic powders coated with an insulating layer formed through a specific pressing process. In engineering applications, magnetic powder cores may be subjected to issues such as cracking, reduced magnetic permeability, and diminished mechanical strength. The insulation coating of the magnetic powder core includes inorganic and organic coatings. Coupling agents, a type of polymer composite additive, have both inorganic and organophilic molecular groups, allowing them to modify the surface of the magnetic powder and serve as a “bridge” between the inorganic and organic coating layers. The gap between academic and industrial research on the cracking and expansion coefficients of magnetic powder cores leads to a poor understanding of the underlying mechanisms. The moldability, magnetic properties, and mechanical properties of carbonyl iron powder (CIP) magnetic powder cores (including magnetic rings, magnetic discs, and molding inductors) with different contents of the KH550 silane coupling agent were investigated in this study. Scanning electron microscopy (SEM), thermomechanical analysis (TMA), and LCR techniques were used for analysis. The SEM images of the magnetic powder core sections indicate that increasing the amount of coupling agent reduces powder agglomeration, which increases the area percentage of the nonmagnetic phase and porosity. With an increase in the coupling agent content, the area percentage of the nonmagnetic phase increased from 18.4% to 31.4%. Notably, the magnetic disc experimental outcomes, influenced by the coupling agent content, thickness, molding pressure, and curing rate, revealed that a higher curing rate, increased thickness, and higher molding pressure made the magnetic discs more susceptible to cracking. However, coupling agents can reduce the cracking tendency of the molding inductors and magnetic rings, thereby enhancing their moldability. The density of the magnetic discs is influenced by both the molding pressure and coupling agent content. When the coupling agent content remains constant, an increase in the molding pressure results in increased density. However, for discs subjected to identical molding pressures, a higher coupling agent content corresponded to a reduced density. Density of the magnetic discs with 0.1 wt.% coupling agent content are abnormal. The TMA showed that the coupling agent can stabilize the resin on the magnetic powder surface and facilitate powder particle rearrangement during curing, thereby increasing the core expansion coefficient. Magnetic powder cores with 0 wt.% and 0.1 wt.% coupling agents have negative expansion coefficients, leading to potential shrinkage and cracking. In contrast, the cores with 0.3 wt. %, 0.5 wt.%, and 0.7 wt.% coupling agents yielded an increased expansion coefficient during resin curing, thereby effectively reducing the core's cracking tendency. However, increasing the coupling agent content can affect the magnetic properties of the core. As the non-magnetic phase and porosity change, the density and magnetic permeability of the magnetic powder core initially increase and subsequently decrease. Similarly, the core loss and quality factors exhibit opposite trends. As the porosity increases, it induces additional coercivity proportional to the square root of the specific pore surface area, consequently leading to increased core loss. The core loss first decreases and then increases, and the quality factor increases before eventually decreasing. This paper also demonstrates that the meshing capability of magnetic powders directly affects their mechanical properties. As the coupling agent content increases, the mechanical strength of the magnetic powder core improves and then declines. Given the moldability of the core and other characteristics, the ideal coupling agent content is 0.3 wt.%. This study explored the effect of the coupling agent on the expansion coefficient of magnetic powder core during curing and unveiled its influence on other properties, laying a robust theoretical foundation for the application of high-performance magnetic powder cores.

  • 0 前言

  • 在 5G 网络的推动下，高效、快速、广泛的网络时代到来，给通信及 3C 市场带来技术改革及技术升级的机会，同时也对电子元器件有了更高的要求。电感和变压器等电子元器件正向着小尺寸、大电流、高频低损耗和高可靠性等方向发展。软磁材料在其中起着至关重要的作用。软磁材料主要有硅钢、铁氧体、坡莫合金、非晶 / 纳米晶带材和软磁复合材料等。硅钢主要用于电力变压器[1]；锰锌铁氧体和镍锌铁氧体可烧结成 EP、PQ 和 EE 等多种形状，成本低、应用频率高，但饱和磁感应强度（Bs ≈ 0.5 T）低，不利于小型化[2]；非晶 / 纳米晶带材磁导率高、损耗低，但环形结构限制了其使用场景[3]； 坡莫合金含有镍元素，价格较为昂贵，民用市场较小；软磁复合材料作为近些年备受市场关注和青睐的软磁材料[4-6]，具有形状可调、价格便宜、性能优异等特点，已广泛应用于环形电感和一体成型电感等器件。

  • 软磁复合材料又称磁粉芯，是以金属磁粉作为原材料，在其表面进行绝缘包覆，并通过特定的工艺方法压制成型而成。常用的绝缘包覆有无机包覆和有机包覆两种方式。无机包覆包括磷酸盐包覆（磷酸铁、磷酸锌和磷酸锰等）[7-9]、氧化物包覆（如 Fe3O4、SiO2、Al2O3 和 MgO 等）[10-12]和铁氧体包覆等[13]。有机包覆分为热塑性树脂包覆和热固性树脂包覆[14]。由于非磁性相绝缘包覆层的加入会降低磁粉的磁导率，因此在符合电感性能的要求下，要尽量减少绝缘包覆层的厚度，以满足必要的磁性能。

  • 偶联剂作为一类特殊的高分子复合材料助剂，其分子结构中含有两种化学性质不同的基团，即亲无机物基团和亲有机物基团，因此可以对磁粉表面进行改性，在无机包覆层与有机包覆层之间起到“桥接”的作用[15-16]。目前常用的偶联剂包括硅烷偶联剂和钛酸酯偶联剂。TAGHVAEI 等[17]利用硅烷偶联剂提高铁粉和酚醛树脂之间的润湿性和均匀性，增强了磁粉芯的绝缘效果；WANG 等[18]利用 KH550 偶联剂改性 FeSiCr 粉末，提高了 FeSiCr / PA6 复合材料的冲击强度；HSIANG 等[19]证明钛酸盐偶联剂的表面改性可以显著提高材料的相对密度和磁性能 （如初始磁导率、磁芯损耗和矫顽力）。然而，目前尚未见文献报道偶联剂对磁粉芯膨胀系数的影响。

  • 本文通过在羰基铁粉中添加不同含量的硅烷偶联剂，探究偶联剂在磁粉芯固化过程中膨胀系数的变化，进而影响磁粉芯的磁性能和成型性，为磁粉芯和一体成型电感的学术研究和工业应用提供指导。

  • 1 试验准备

  • 1.1 样品制备

  • 采用江苏天一超细金属粉末有限公司生产的羰基铁粉，D50 = 6.5 μm；采用广州丰禹化工有限公司生产的 KH550 硅烷偶联剂（AR 级）；采用可适用于磁环和一体成型电感的混合树脂，其由改性的环氧树脂和有机硅树脂按 1∶1 组份比例混合而成。

  • 首先采用0.5 wt.%磷酸-丙酮溶液对羰基铁粉进行磷化处理，120℃干燥 1 h 后得到磷化羰基铁粉。配制 5 wt.%混合树脂-丙酮溶液，分别加入不同含量的偶联剂（0、0.1、0.3、0.5 和 0.7 wt.%），再与磷化羰基铁粉混合搅拌均匀，然后经 70℃干燥 1 h 后过筛 40～200 目，最后再加入 0.2 wt.%的硬脂酸钡脱模剂得到成品粉。

  • （1）将 6 g 成品粉置于磁环模具中，经 600 MPa压强压制成尺寸为外径 20 mm、内径 12 mm、高度约 5 mm 的磁环。将磁环放入鼓风干燥箱，2℃ / min 升温至 180℃保温 30 min 后固化。

  • （2）将适量成品粉置于一体成型电感模具中，线圈规格为线径 0.4 mm、中柱直径 2.8 mm、线圈匝数 7.5 TS，经 600 MPa 压强压制成尺寸为 6.8 mm× 6.5 mm×2.8 mm 的一体成型电感。将一体成型电感放入鼓风干燥箱，2℃ / min 升温至 180℃保温 30 min 后固化。

  • （3）分别将 4、7 和 10 g 成品粉置于磁片模具中，再分别经 400、800、1 200 和 1 600 MPa 压强压制成尺寸为外径 20 mm 但高度不同的磁片。将磁片放入鼓风干燥箱，1℃ / min 和 2℃ / min 升温至 180℃保温 30 min 后固化。

  • 1.2 结构表征及力学性能测试

  • 采用 SU8220 扫描电子显微镜对磁粉芯的切片截面形貌进行分析；采用 TMA Q400 对磁片固化过程中的高度进行测试，测试温度从室温 25℃～200℃；采用阿基米德排水法测试磁粉芯的密度； 采用 IM3536 LCR 测试仪测试磁粉芯的磁导率；采用 Agilent 4294A 精准阻抗分析仪测试磁粉芯的品质因数（Q 值）；采用 MATS-3010SA 软磁材料动态测量装置测试磁粉芯的损耗；采用 FL-8621 磁芯破裂试验机测试磁粉芯的机械强度（径向压溃强度）

  • 2 结果与讨论

  • 图1 为不同偶联剂含量的磁粉芯固化后切片 SEM 图像。随着偶联剂含量的增加，磁粉与磁粉之间的团聚减少，间距增大，磁粉均匀地分散在有机树脂中，说明偶联剂能有效地提升磁粉和有机树脂的混合均匀性[17]。表1 是根据图1 计算出的不同偶联剂含量的磁粉芯中非磁性相的面积占比。可以看出，偶联剂含量越多，非磁性相的面积占比越大，磁性相的面积占比就越小，磁粉芯的孔隙率就越大。此前也有文献报道较高的硅烷偶联剂浓度会增加孔隙率[20]。但是，0.1 wt.%偶联剂的样品比较特殊，非磁性相面积占比反而比 0 wt.%偶联剂的样品小，由于后续多项试验数据出现类似的规律，因此将统一讨论。

  • 图1 不同偶联剂含量的磁粉芯固化后切片 SEM 图像

  • Fig.1 SEM images of magnetic powder core sections with different coupling agent content

  • 表1 不同偶联剂含量的磁粉芯中非磁性相的面积占比

  • Table1 Area percentage of non-magnetic phase of magnetic powder cores with different coupling agent content

  • 图2 为肉眼观察到不同偶联剂含量的一体成型电感和磁环宏观形貌。0 wt.%和 0.1 wt.%偶联剂含量的一体成型电感有明显开裂，0 wt.%偶联剂含量的磁环侧面出现明显开裂，正面则有开裂倾向，其余样品外观良好，未出现开裂。这说明偶联剂能显著降低一体成型电感和磁环开裂倾向性，有效改善其成型性。

  • 为进一步研究偶联剂含量对磁粉芯外观的影响，设计了不同偶联剂含量、不同厚度、不同模压压强和不同升温固化速率磁片的试验，试验结果如表2、3 所示。“×”表示磁片外观开裂，“√”表示磁片外观无裂纹。

  • 由表2、3 可知，0 和 0.1 wt.%偶联剂含量的部分磁片出现开裂，0.3、0.5 和 0.7 wt.%偶联剂含量的磁片都未出现开裂。升温固化速率越大、厚度越厚、模压压强越大，磁片越容易出现开裂。由于磁粉芯为复合材料，包含磁粉、无机包覆层和有机包覆层等，且后续的制备工艺也至关重要，因此影响磁粉芯开裂的机制有很多。由以上结果推断，偶联剂含量是影响磁粉芯开裂的一个重要原因之一。

  • 图2 不同偶联剂含量的一体成型电感宏观形貌、磁环侧面宏观形貌和磁环正面宏观形貌

  • Fig.2 Images of molding inductor, the front of the magnetic ring and the side of the magnetic ring with different coupling agent content

  • 表2 不同偶联剂含量的 1℃ / min 升温固化速率磁片外观

  • Table2 Appearance of the magnetic discs with different coupling agent content at 1 °C / min curing rate

  • 表3 不同偶联剂含量的 2℃ / min 升温固化速率磁片外观

  • Table3 Appearance of the magnetic discs with different coupling agent content at 2 °C / min curing rate

  • 图3 显示磁片固化前后的密度变化。对于相同偶联剂含量的固化前的磁片，模压压强越大，密度越大，但当模压压强增加到 1 200 MPa 以后，密度增加不明显；对于相同模压压强的磁片，偶联剂含量越大，密度越小，0.1 wt.%偶联剂含量的磁片密度反而比 0 wt.%和 0.3 wt.%偶联剂含量的磁片密度高；不同偶联剂含量下，磁片在固化前后的密度变化也一样，0 和 0.1 wt.%偶联剂含量的磁片固化后的密度比固化前高，但 0.3、0.5 和 0.7 wt.%偶联剂含量的磁片固化后的密度都比固化前低。固化前后密度的变化体现了磁粉芯膨胀系数的变化。

  • 图3 磁片固化前后的密度变化

  • Fig.3 Density of magnetic discs before and after curing

  • 图4 为不同偶联剂含量磁粉芯固化过程 TMA 图像。表4 是根据图4 统计出来的数据。Hs 表示起点高度，即磁粉芯固化前的高度；He表示终点高度，即经历 200℃固化后的高度；ΔH = He − Hs，即固化后与固化前的高度差；ΔHHs×100% 表示固化后的高度差变化率，可以表征膨胀系数。结合图4 和表4，磁片固化过程中的膨胀并不是线性增加的，说明温度不仅影响了金属铁粉的体积变化，更重要的是影响了绝缘层（特别是有机包覆层）体积的变化。随着温度升高，在 60～110℃范围内，树脂尚未开始固化，但磁粉芯体积开始急剧变化，说明这个过程中树脂软化，开始带动磁粉出现颗粒重排，而偶联剂对这个过程中起着至关重要的作用。偶联剂能将树脂紧紧地拘束在磁粉表面，增加有机树脂与磁粉的粘结性[20-21]。偶联剂含量越多，约束在磁粉表面的树脂就越多，磁粉之间的间距就越大，磁粉芯膨胀就越大（如图5 所示）。姚金光等[22]发现偶联剂吸附在羰基铁粉表面产生空间位阻效应，使得羰基铁粉间不能接触，从而防止团聚体的产生。而 0.1 wt.%偶联剂既起到了润湿性的作用，又起到了约束的作用，是两种作用竞争的结果，因此出现了反常。当温度升高到 150℃以后，树脂固化，磁粉芯的体积基本不变。所以随着偶联剂含量的增加，磁粉芯固化前后体积变化也越大，膨胀系数也逐渐从 0.1 wt.%偶联剂含量的−0.60% 增加到 0.7 wt.%偶联剂含量的 2.40%。体积的急剧变化也造成了磁粉芯外观的变化。当偶联剂含量太少（≤0.1 wt.%）时，磁粉芯的体积在固化后呈现收缩，但收缩太大因而出现开裂，这也就是为什么升温固化速率越大、厚度越厚、模压压强越大，磁粉芯越容易开裂的原因。对于一体成型电感，则是因为升温过程中内部线圈受热膨胀，外部磁粉固化收缩，从而出现开裂。

  • 图4 不同偶联剂含量磁粉芯固化过程 TMA 图像

  • Fig.4 TMA image of the curing process of magnetic powder cores with different coupling agent content

  • 表4 不同偶联剂含量磁粉芯固化过程 TMA 数据

  • Table4 TMA data for the curing process of magnetic powder cores with different coupling agent content

  • 图5 偶联剂作用示意图

  • Fig.5 Diagram of the action of coupling agent

  • 磁粉芯体积的变化也会影响磁性能和力学性能。图6 显示不同偶联剂含量下磁粉芯的磁导率。偶联剂含量增加，磁粉芯密度减少，磁导率下降。 0.1 wt.%偶联剂含量的磁粉芯密度最大，达到 25.5，前述已解释原因，这里不再赘述。

  • 图6 不同偶联剂含量下磁粉芯的磁导率

  • Fig.6 Permeability of magnetic powder cores with different coupling agent content

  • 图7a 和图7b 分别为不同偶联剂含量下磁粉芯的损耗和 Q 值。根据以前的研究[23-24]，磁芯损耗 （Pcv）可以表示为磁滞损耗（Phv）和涡流损耗（Pev） 之和，残余损耗只在非常低的感应水平和非常高的频率下才考虑，这里忽略不计[25]：

  • Pcv≈Phv+Pev=f∮HdB+CB2f2d2ρ
    (1)

  • 式中，C 是常数，B 代表磁通密度，f 代表频率，d 是磁粉大小和间距，ρ 是电阻率。损耗出现先下降、再上升、然后再下降的规律。偶联剂含量从 0 wt.% 增加到 0.1 wt.%，磁粉芯密度增加，孔隙率减少，非磁性相体积分数减少。当偶联剂含量继续增加时，磁粉芯密度减小，孔隙率增加，非磁性相体积分数增加。增加孔隙率会产生额外的矫顽力，矫顽力与比孔隙表面积的平方根成正比，因此导致损耗增加[26]。但当偶联剂含量为 0.7 wt.%时，磁粉间的间距增加到一定程度，涡流损耗反而减少，从而整体损耗减少。Q 值定义为储能和耗能之比，与损耗呈现相反的规律，因此 Q 值先增加后减少。

  • 图8 显示不同偶联剂含量下磁粉芯的机械强度。随着偶联剂含量增加，磁粉芯的机械强度先从 36 kg 增加到 42 kg，然后再逐渐减小，这与磁粉芯密度变化的规律相一致。磁粉芯的力学性能与成分、密度、树脂粘结性、加工工艺等因素有关[27]，本试验中磁粉芯的力学性能主要由磁粉芯的密度决定。密度越大，磁粉间的啮合能力越强，力学性能也越好。

  • 图7 不同偶联剂含量下磁粉芯的损耗和 Q 值

  • Fig.7 Core loss and quality factor of magnetic powder cores with different coupling agent content

  • 图8 不同偶联剂含量下磁粉芯的机械强度

  • Fig.8 Mechanical strength of magnetic powder cores with different coupling agent contents

  • 3 结论

  • 通过在羰基铁粉磁粉芯中加入不同含量的偶联剂，研究其成型性、磁性能和力学性能，得到以下结论：

  • （1）偶联剂的加入可以改善磁粉芯的成型性，减少开裂，但过多的偶联剂也会降低磁性能和力学性能。

  • （2）偶联剂通过影响磁粉芯的膨胀系数，从而影响磁粉芯的成型性、磁性能和力学性能。

  • （3）磁粉芯的工业应用需综合考虑成型性、磁性能和力学性能。

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  • 基本信息

    中图分类号: TF123；TM272
    DOI: 10.11933/j.issn.1007-9289.20230420001

    基金信息

    东莞市引进创新科研团队项目（2020607231010）；
    广东省自然科学基金（2021A1515012464）；
    Dongguan Innovative Research Team Program (2020607231010)；
    Provincial Natural Science Fund of Guangdong (2021A1515012464)；

    引用信息

    余红雅，袁涵，李竞舟，等. 通过优化偶联剂含量改善磁粉芯综合性能[J]. 中国表面工程，2024，27(2)：260-268.

    YU Hongya, YUAN Han, LI Jingzhou, et al. Improvement of the overall performance of magnetic powder cores by optimising the coupling agent content[J]. China Surface Engineering, 2024, 27(2): 260-268.

    稿件历史

    收稿日期: 2023-04-20
    录用日期: 2023-12-26

  • 参考文献

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    • [2] 刘亚丕，何时金，包大新，等.软磁材料的发展趋势[J].磁性材料及器件，2003(3)：26-29，32.LIU Yapi,HE Shijin,BAO Daxin,et al.Development trend of soft magnetic materials[J].Journal of Magnetic Materials and Devices,2003(3):26-29,32.(in Chinese)

    • [3] HERZER G.Modern soft magnets:Amorphous and nanocrystalline materials[J].Acta Materialia,2013,61(3):718-734.

    • [4] SUNDAY K J,TAHERI M L.Soft magnetic composites:recent advancements in the technology[J].Metal Powder Report,2017,72(6):425-429.

    • [5] SHOKROLLAHI H,JANGHORBAN K.Soft magnetic composite materials(SMCs)[J].Journal of Materials Processing Technology,2007,189(1-3):1-12.

    • [6] KRINGS A,BOGLIETTI A,CAVAGNINO A,et al.Soft magnetic material status and trends in electric machines[J].IEEE Transactions on Industrial Electronics,2016,64(3):2405-2414.

    • [7] XIA C,PENG Y,YI Y,et al.The magnetic properties and microstructure of phosphated amorphous FeSiCr/silane soft magnetic composite[J].Journal of Magnetism and Magnetic Materials,2019,474:424-433.

    • [8] HSIANG H I,FAN L F,HUNG J J.Phosphoric acid addition effect on the microstructure and magnetic properties of iron-based soft magnetic composites[J].Journal of Magnetism and Magnetic Materials,2018,447:1-8.

    • [9] XIE D Z,LIN K H,LIN S T.Effects of processed parameters on the magnetic performance of a powder magnetic core[J].Journal of magnetism and magnetic materials,2014,353:34-40.

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