Fe-Rich Fe–Si–B–P–Cu Powder Cores for High-Frequency Power Electronic Applications

The Fe-rich Fe_83.3Si₄B₈P₄Cu_0.7 magnetic powder with the particle size below 150 $\mu $ m was obtained by spinning water atomization process. The as-prepared powder shows almost amorphous structure. The toroidal cores with outer diameter 13 mm and inner diameter 8 mm with height $\sim 4$ –6 mm were compacted and sintered at different temperature by spark plasma sintering technique under the maximum load of $\sim 800$ MPa. High relative density (with respect to nanocrystalline ribbons of the same composition) up to $\sim 89$ % was obtained. The powder particles in the sintered core consist of nanocrystalline $\alpha $ Fe grains in the amorphous matrix. A constant initial permeability ( $\mu _{i}$ ) more than 50 was obtained up to the frequency range of 50 MHz. As expected, the permeability was found to increase with the increase in density of the core (maximum initial permeability of 364). Low magnetic coercivity ( $H_{c}$ ) can be obtained in these cores, closed to $\sim 80$ A/m. Lowcore loss ( $W$ ) is due to reduced eddy-current loss (at high frequencies), resulting from the electrical insulation of the powder particles by resin. Our soft magnetic powder cores (PCs) exhibit lower core loss than the Somaloy PCs measured under a relatively high magnetic induction, e.g., 0.5 and 1 T, which may fill the gaps in high-frequency high induction application of ferrite materials.