Performance Of Soft Magnetic Composites Research Articles

Correlation the microstructure and magnetic properties of Fe-Ni-Mo soft magnetic composites fabricated via polymer-derived ceramics

The coatings play a crucial role in enhancing the performance of soft magnetic composites (SMCs). This study aims to create coatings for Fe-Ni-Mo SMCs using polysilazane (PSZ) as the precursor. The transformation mechanism of the PSZ/resin mixture is studied by analyzing functional groups and chemical bonds at various temperatures. During the self-polymerization process of PSZ at 350 °C, N–H, C = C–H, Si-H bonds, –CH3, and Si-CH3 groups undergo crosslinking reactions to form C–C and Si-N bonds. When the temperature reaches 600 °C, PSZ polymer cleavage, O-Si-C and Si-N-Si bond dominate in the coating. Additionally, PSZ can effectively enhance the heat resistance of silicone resin through its reaction with Si-OH groups, which has a significant effect on increasing the resistivity of SMCs and reducing high frequency core loss. Optimizing the PSZ content to 0.5 wt% enhances the magnetic properties of Fe-Ni-Mo SMCs, resulting in a μe of 74.0 at 100 kHz and a corresponding core loss (Pcv) of 547.7 mW/cm3 at 100 kHz/100 mT. The findings provide valuable insights for optimizing PSZ content to improve magnetic performance in SMCs.

Influence of nanocrystalline Fe-based powder particles size on the magnetic performance of soft magnetic composites for high frequency applications

The soft magnetic composite (SMC) toroidal cores were prepared by the compaction method from ball-milled Fe-Si-B-Nb-Cu nanocrystalline ribbon with 20 vol% (3.7 wt%) resin addition as a binder. The objective of this work was to study their internal structure and magnetic performance at high excitation frequency. The computed tomography results showed that 70–80 vol% of ferromagnetic phase content was present in all samples, depending on the porosity. These composites exhibited much higher permeability and lower core loss at high frequency than the reference sample made of Somaloy® which contained almost 100 vol% of ferromagnetic phase. They exhibited constant level of permeability in the entire measurement range. The influence of the powder size fraction on the magnetic properties was determined as well. It appeared that coarser particles result in higher permeability and it can be increased even further by mixing the coarsest powder size fraction with the finest one. The presented results show that these materials are very attractive for high frequency applications.

Analysis of the magnetic properties of a silicate-coated spherical FeSiAl-based soft magnetic composite for high-frequency power-applications

In this paper, the relationship of the frequency-dependent magnetic permeability, magnetic loss, and DC-bias of a soft magnetic composite was analyzed. The permeability is divided into a domain wall movement component at low frequencies and a spin-rotation part at high frequencies. The resonance-frequency increases when the pressure decreases and, simultaneously, the permeability also decreases following the Snoek limit. Magnetic loss is separated into hysteresis loss, eddy-current loss, and excess loss, which is found to closely relate to the density of the powder core. The DC-bias properties of the composite tend to deteriorate slightly with the density increase. This is due to a decrease in the gap between the particles, which is associated with the pinning of the domain wall movement and coercivity. It is found that DC-bias is positively correlated with hysteresis loss and excess loss with respect to coercivity and pinning of the movable domain-wall. These results provide insights into the soft magnetic performance of soft magnetic composites, particularly with respect to compact, high-DC applications with high frequency and high magnetic saturation for high-power supply.

Fe-Si/MnZn(Fe2O4)2 Core-shell Composites with Excellent Magnetic Properties by Mechanical Milling and Spark Plasma Sintering (SPS)

The Fe-Si/MnZn(Fe2O4)2 composite powders are synthetized by means of the mechanical milling, and Fe-Si/MnZn(Fe2O4)2 soft magnetic composites are prepared by spark plasma sintering (SPS). The impact of milling time on particle size, phase structure and magnetic properties of the investigative core-shell structure powders along with that of sintering temperature on microstructure and magnetic properties of FeSi-MnZn(Fe2O4)2 soft magnetic composite are studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), and vibrating sample magnetometer (VSM). The experimental results demonstrate a layer of MnZn(Fe2O4)2 forming a coating on the surface of Fe-Si powder after mechanical milling, and the soft magnetic composites exhibiting excellent magnetic performance at 900 °C: 212.49 emu/g for saturation magnetization, with 6.89 Oe for coercivity, 3 × 10−4 Ω.m for electrical resistivity and stable amplitude permeability and low core loss over a wide frequency range. Therefore, SPS offers a convenient and swift way to enhance performance of soft magnetic composites using magnetic materials as insulting layer.