Particles size-dependent magnetic properties of a FeSiAl soft magnetic composite with hybrid insulating coating for MHz applications

• Published in: Materials science & engineering. B, Solid-state materials for advanced technology Solid-state materials for advanced technology, 2023-05, Vol.291, p.116387, Article 116387
• Main Authors: Li, Wanjia, Li, Wangchang, Wu, Junke, Han, Xiaofeng, Ying, Yao, Yu, Jing, Zheng, Jingwu, Qiao, Liang, Li, Juan, Che, Shenglei
• Format: Article
• Language: English
• Subjects: Complex permeability; FeSiAl soft magnetic composites; Hybrid insulating layer; Magnetic loss; MHz applications; Particle size
• ISSN: 0921-5107; 1873-4944
• DOI: 10.1016/j.mseb.2023.116387

In this paper, the ultrafine spherical FeSiAl soft magnetic composites were prepared by the particles coated with organosilane modified water-soluble silicone resin. The magnetic response of the sample fabricated with 15.36 μm particle is up to 358 MHz, and the real part of permeability exceeds 57. The Pcv of this composite is just 604.85 kW/m3 and 606.44 kW/m3 at 200 kHz,100 mT and 1 MHz, 30 mT, respectively. In addition, the DC bias performance improved reaches to 61.3%, comparing to the sample fabricated by the large particles. The domain wall movement dominates the permeability when large particles are employed. However, the spin rotation plays a more important role in the case of small particles. Two stages with different loss mechanisms were investigated for different particle sizes. When the frequency exceeds 70 kHz, the declination of the insulating coating resistivity results in a loss jump, due to the space charge polarization. The FeSiAl crystalline termination at the grain boundary exhibits a symmetry break, thus resulting in a sharp local rise in the anisotropy field which provides a barrier to the domain wall motion and enhance the DC bias properties. This ultrafine FeSiAl composite shows great potential in the MHz magnetic power application. [Display omitted] •Spherical-FeSiAl soft magnetic composites were prepared. The magnetic response of the sample fabricated with 15.36 μm particle is up to 358 MHz. The Pcv of this composite is just 604.85 kW/m3 and 606.44 kW/m3 at 200 kHz, 100 mT and 1 MHz, 30 mT, respectively.•It is found that the domain wall movement dominates the permeability when large particles are employed. However, the spin rotation plays a more important role in the case of small particles.•It also clarified a novelphenomenon that a sudden jump in loss curve at the frequency of near 70 kHz is observed for the short circuit of the insulating coating, due to the space charge polarization.•The electrochemical analysis demonstrates that this organosilane modified water-soluble silicone resin hybrid insulating layer can effective reduce the eddy current loss in high frequency. In this work, organosilane modified water-soluble silicone resin coated spherical-FeSiAl soft magnetic composites with different particle sizes were prepared, and the effects of the particle size on the permeability, magnetic loss, and DC bias were investigated. For large particles composite, multi-domain lead to the introduction of domain wall resonance, which