The correlation between particle size distribution of FeSiBCuNb powders and properties of soft magnetic composites

The FeSiBCuNb soft magnetic composities (SMCs) with five different particle size distribution (PSD) were prepared. The PSD of powders was quantified by using the logarithmic distribution width (Δ) and particle size (D₅₀), respectively. Moreover, the thickness of the coating layers (δ) for powders and the density (ρ) of SMCs, as key factors affecting permeability (μ_e) and eddy current loss (P_e) of SMCs, were also estimated in detail. The results showed that the PSD has an effective effect on the ρ and μ_e of SMCs. The ρ and μ_e of SMCs increased with the increase of the Δ. The δ of powder surface was positively correlated with D₅₀. The results of loss separation showed that the total losses (P_cv) were influenced by both D₅₀ and Δ. The hysteresis losses and residual losses dominated the P_cv and were closely related to Δ, while P_e was mainly affected by D₅₀. The present works had a guiding significance for the selection of PSD for the preparation of SMCs.