The invention belongs to the field of preparation of metallic soft magnetic materials, and particularly relates to a preparation method for a mu75
magnetic powder core of soft magnetic
ferrosilicon aluminum, which includes steps of
smelting, rough smashing, heat treatment, fine smashing, annealing treatment,
powder grading,
powder insulating,
compression molding, secondary heat treatment and
coating treatment and requires components, by weight, 9.10% of
silicon, 5.95% of aluminum and the rest iron. The preparation is performed with the
smelting temperature of 1600 DGE C, the
compression molding pressure
ranging from 1700MPa to 2000Mpa,
magnetic powder core pressing temperature
ranging from 600 DEG C to 800 DEG C, and one hour for warm keeping in a
nitrogen-
oxygen mixed
atmosphere. The
magnetic powder core mu=75+-6 at 100kHz, the magnetic
conductivity mu is smaller than 1% in variation under 1000kHz, the magnetic
powder core loss is accordant to Pcv (powder loss) 50kHZ / 50mT<=100Mw / cm3, and the direct-current bias
magnetic field is not lower than 70Oe when the magnetic
conductivity is reduced to 50%. The preparation method for the mu75 magnetic powder core of soft magnetic
ferrosilicon aluminum has the advantages that added binder is
solid organic binder, the heat treatment after molding includes keeping warm for one hour in the
nitrogen-
oxygen mixed
atmosphere, and the prepared magnetic powder core is free of pulverization, high in strength and stable in performance and has fine
direct current bias characteristics, frequency stability and low loss.