Analysis of Frequency Dependence of Permeability in Fe-Si-Al Gas-atomized Powder Cores

摘要

Powder cores have relatively small permeability, and the enhancement of the permeability may be attained with improvement of particle properties. In this study, permeability and effective demagnetizing factor of a particle were estimated from a measured permeability of the powder core using the equation of Takajyo et al.It was found that effective demagnetizing factor, N of a particle were 0.06, which were independent of particle size or heat treatment temperature of the powder core. It was also found that permeability of a particle, mu_1 increased exponentially with increasing heat treatment temperature: about 100, 300 and 600 for the temperature of 673, 773 and 873 K, respectively.This study exhibited that the utilization of particle with higher aspect ratio rather than high temperature heat treatment was effective for the permeability enhancement.