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• Ferrite coating layer can enhance SMCs' permeability, but lead to a relatively low DC-bias property. • C-SMCs exhibit lower P e of 20.2% of P cv as compared to that of 61.9% for R-SMCs coated alone with resin. • FeSi@SiO 2 &ferrite SMCs with fine magnetic properties faced shortcomings of long preparation time and high synthesis temperature. • SMC coated with inorganic material can be widely used in industry due to its friendly preparation conditions. The soft magnetic performances of the Fe-6.5 wt.%Si (FeSi) soft magnetic composites (SMCs) insulated with different materials, including organic, inorganic, and soft magnetic materials with high resistivity, and composite coating of inorganic-magnetic layer, under the same fabrication condition have been compared and analyzed by synchronously considering their coating preparation parameters. The core–shell structure of the coated powder was characterized by using a combination of SEM-EDS, FTIR, and XRD. Loss separation fitting model was established to evaluate the source of each part loss for the corresponding FeSi SMCs above. Due to the fact that the SMCs insulated with inorganic or/and magnetic ferrite materials exhibit high bulk resistivity more than 1.4 Ω·m, their eddy current losses account for lower contribution of only 20.2 ~ 22.1% of total core loss compared with that of 61.9% for the SMCs coated alone with organic resin. As compared to the other insulation materials, the SMCs coated using inorganic material (SiO 2 or TiO 2) exhibit a better DC-bias over 75.5%, higher retain real-part permeability exceed 44.6 at an applied field of 7960 A/m, a relatively low total core loss of 1040.6 kW/m3 at 100 kHz, 0.1 T, and can be fabricated at room temperature with a total preparation time of 70 min, which is favorable for being widely used in industry. The results of this work offered a referable ideal to design insulating layer for other SMCs. [ABSTRACT FROM AUTHOR]

• The FeSiBCCr amorphous powder cores annealed at 763 K for 0.5 h exhibit favorable magnetic properties. • The FeSiBCCr/FeSi compound powder cores doped with 12 wt% of FeSi powders show the best magnetic properties. • The inter-particle eddy current loss has almost no effect on the total energy loss of powder cores. • The sum of hysteresis loss and residual loss is likely to hit 90% of total energy loss. • The residual loss is proportional to frequency to the power of 1.509 ~ 1.760. The influences of annealing temperature and mass fraction of gas-atomized FeSi powders within a range of 0 ~ 16 wt% on the soft magnetic properties of Fe-based powder cores, prepared by cold compacting the mixture of the water-atomized FeSiBCCr amorphous powders with diameter of 23 ~ 75 μm and the FeSi powders with size below 13 μm, has been systematically investigated. Loss contribution analysis for the corresponding Fe-based compound powder cores was also conducted. The core–shell structure of magnetic powders was characterized using scanning electron microscopy, energy dispersive X-ray spectroscopy analysis, and fourier transform infrared spectroscopy. The inter- and intra-particle eddy current losses have a much less impact on the total energy loss as compared to the hysteresis loss and residual loss in the entire testing frequency range. The residual loss is frequency to the power of 1.509 ~ 1.760. As compared to the FeSiBCCr amorphous powder cores, the effective permeability was enhanced by 17.8% with no-degraded DC-bias property over 63.2% of percent permeability at an applied field of 7960 A/m, while the core loss was reduced by 11.1% for the Fe-based powder cores doped with 12 wt% of the micron-size FeSi powders annealed at 763 K for 0.5 h. The compound Fe-based powder cores with excellent magnetic properties could contribute to minimization of the electrical and electronics components with high efficiency in the high power application field. [ABSTRACT FROM AUTHOR]

• One-pot highly efficient synthesis method for SiO 2 -coating with only 1.9 h was developed. • An industry-oriented automated coating device was designed. • Eddy current loss contributes only 13.5 ~ 18.1% of total loss when TEOS concentration over 0.09 ml/g. • Fe-based amorphous SMCs insulated using TEOS concentration of 0.09 ~ 0.14 ml/g exhibit excellent magnetic properties. A new one-pot highly efficient synthesis method implemented using an industry-oriented roboticized coating device was designed and developed for obtaining high quality SiO 2 -coating on the surface of commrercial Fe 78 Si 13 B 9 (FeSiB) amorphous flaky powder at the room temperature. Hereinto, the conventional instilling method was modified as directly pouring the ultra-diluted precursor by anhydrous ethanol into the reaction mixture, favorable for both simple operation and shortening the total manufacture time to 1.9 h (including the drying time of about 0.7 h). Comparison and analysis on the soft magnetic properties of the FeSiB amorphous powder cores insulated using different precursor concentration within the range of 0 ~ 0.25 ml/g were investigated in detail. SEM, EDS, and FTIR were employed to characterize the core-shell structure of magnetic powders. The increment of pinning sites induced by the raising precursor concentration can cause a reduction in effective permeability, while result in the increases of hysteresis loss and excess loss. The eddy current loss contributes only about 13.5% ~ 18.1% of total core loss for the coated powder cores under the TEOS concentration over 0.09 ml/g, indicating that the corresponding magnetic composites have a good electro-insulating layer. This work offered a referable idea for efficiently coating other inorganic insulations on the magnetic powders within different shapes. [ABSTRACT FROM AUTHOR]