Sodium silicate coatings for improving soft magnetic properties of FeSiAl powder cores with industrial compatibility

Gas-atomized FeSiAl powder was coated with the same concentration of epoxy resin, sodium silicate (NS), silicone resin and aluminum dihydrogen phosphate and the corresponding magnetic powder cores (MPCs) were prepared, and the performance superiority of the NS coating was proved by the related performance characterization and theoretical calculations. Among the four insulating coatings, the average insulation layer thickness of NS was the thinnest (only 0.57 μm), and the density of the FeSiAl@NS was also the largest (6.56 g cm −3 ), indicating that the FeSiAl@NS contained the least amount of nonferromagnetic phase and was easy to reach magnetic saturation. Although the DC bias performance deteriorated, the FeSiAl@NS also exhibited the highest permeability (70.5 at 100 kHz). The loss test results showed that the core loss of the FeSiAl@NS under 100 kHz and 0.05 T was 137.2 mW cm −3 , only 20% of that of other MPCs. In order to analyze the loss profile, loss separation was conducted, and it was found that the FeSiAl@NS had remarkably low hysteresis loss. Compared to other insulators, the NS coatings not only effectively improve the comprehensive performance of MPCs, but also has a wide annealing process window. The FeSiAl@NS prepared in this study has high permeability and low core loss, and exhibits industrial application potential in the field of medium and high-frequency electronics and electricity due to the simple process.