粒子形状が圧粉磁心の直流重畳特性に及ぼす影響とそのモデル化

抄録

  DC-biased magnetic properties of powder cores made of pure iron powder have been investigated using a nonmagnetic grain boundary (NMGB) model taking into account the distribution of gap width between particles. Three kinds of powder were prepared by water atomization (a), sphericalization (b), and gas atomization (c). Various amounts of additives were added to (a) to investigate the gap width effect between the particles on the powder core (aa). B-H loops were measured, and differential permeability (μ_dif) was calculated at each magnetic field. They were compared with the value calculated from the NMGB model taking into account the gap width distribution. The more spherical particles were, the lower the μ_dif was at low magnetic field, and the smaller the fall rate of μ_dif was at high magnetic field. That indicated the DC-biased magnetic properties improved. From the calculation using the NMGB model, the geometric average value (δ_gave) of the gap width increased, and the geometric standard deviation(σg) decreased. The effect of μ_dif on DC-biased magnetic properties was also investigated. The greater the amount of aluminum oxide added to (a), the larger δ_gave became, the smaller σ_g became, and the smaller decreasing ratio of μ_dif at 6 k A/m against 0 k A/m became. However, the decreasing ratio of μ_dif(C) was smaller than that of (b). Relative inaccuracies for all samples between measured and calculated μ_dif were under ±6.20% at a magnetic field 0.6-17 k A/m .