Abstract: Insulation cladding through interfacial reaction engineering is an important way to optimize the properties of soft magnetic composites (SMCs), but the traditional method faces the problem of lattice mismatch between the insulating layer and soft magnetic powder leading to interfacial cracks. In this study, a carbonyl iron powders (CIPs) doping strategy is innovatively proposed to construct CaSiO3?Ca2Al2O5?CaO composite insulating layer by utilizing their high plasticity and high specific surface area properties in synergy with the thermal decomposition of alkaline compounds. The results show that Ca(OH)2 decomposes into solid-phase CaO and gas-phase H2O during thermal treatment, where CaO tends to nucleate on the surface of FeSiAl soft magnetic powder matrix and grows along the doped CIPs, ultimately forming a composite insulating layer composed of CaSiO3?Ca2Al2O5?CaO. The combination of high plasticity CIPs and the cladding layer effectively fills the internal pores of the SMCs. The high specific surface area of the small particle size CIPs provides more reaction sites for the decomposition of Ca(OH)2 and the growth of the composite insulating layer, which promotes the uniform distribution of the insulating layer on the surfaces of the soft magnetic powders and the CIPs, and realizes the effective doping of the CIPs inside the insulating layer, which weakens the negative impacts of the lattice mismatches between the insulating layer and the soft magnetic powders. The negative effect of the lattice mismatch between the insulating layer and the soft magnetic powder is weakened. By changing the doping amount of CIPs, the magnetic properties of SMCs can be precisely regulated, and when the doping amount of CIPs is 20wt%, the SMCs show the best comprehensive magnetic properties. At 10 mT, 200 kHz, the saturation magnetization intensity reaches 145.1 A?m2/kg, the permeability is 40.5, and the loss is as low as 50.6 kW/m3, which is ideal for high-performance electromagnetic components. Compared with other insulating layer preparation strategies based on interfacial reaction engineering, the method proposed in this study takes advantage of the high plasticity and high specific surface area of CIPs, and the combination with interfacial reaction engineering is expected to be a new idea for solving the lattice mismatch between insulating layers and soft magnetic powders, which provides an ideal solution for performance optimization of SMCs.

Key words: soft magnetic composites, interfacial reaction engineering, carbonyl iron powder, magnetic properties, intergranular insulation

摘要： 通过界面反应工程实现绝缘包覆是优化软磁复合材料(SMCs)性能的重要途径，但传统方法面临绝缘层与软磁粉末晶格失配导致界面裂纹的问题。本研究创新性地提出引入羰基铁粉(CIPs)掺杂策略，利用其高塑性和高比表面积特性，协同碱性化合物热分解构建CaSiO3?Ca2Al2O5?CaO复合绝缘层。结果表明，Ca(OH)2在热处理过程中会分解为固相CaO和气相H2O，其中CaO倾向于在FeSiAl软磁粉末基体表面形核，并沿着掺杂的CIPs生长，最终形成由CaSiO3?Ca2Al2O5?CaO组成的复合绝缘层。高塑性CIPs与包覆层结合后，有效填补SMCs内部孔隙；小粒径CIPs的高比表面积为Ca(OH)2分解及复合绝缘层生长提供更多的反应位点，促进绝缘层在软磁粉末和CIPs表面均匀分布，实现CIPs在绝缘层内部的有效掺杂，削弱绝缘层与软磁粉末间晶格失配带来的负面影响。通过改变CIPs掺杂量，能够实现SMCs磁性能的精确调控，当CIPs掺杂量为20wt%，SMCs展现出最佳的综合磁性能。在10 mT, 200 kHz条件下，饱和磁化强度达145.1 A?m2/kg，磁导率为40.5，磁损耗低至50.6 kW/m3，是高性能电磁元件的理想选择。与其他基于界面反应工程的绝缘层制备策略相比，本研究提出的方法利用CIPs的高塑性和高比表面积的优势，通过与界面反应工程结合，有望成为解决绝缘层与软磁粉末间晶格失配的新思路，为SMCs的性能优化提供了理想解决方案。

关键词: 软磁复合材料, 界面反应工程, 羰基铁粉, 磁性能, 粒间绝缘