Pressure Extrusion Formation And Soft Magnetic Properties Study Of Composite Magnetic Powder Cores

Fe73.5Cu1Nb3Si13.5B9 nanocrystalline magnetic powder core possessses a small particle size and strong rigidity, therfore, it is difficult to be formationed by pressure molding. Pressure Extrusion Formation method bears high production efficiency and low processing equipment costs. The research studied the production of Fe73.5Cu1Nb3Si13.5B9 nanocrystalline magnetic powder core by Pressure Extrusion Formation method, and found the method could greatly improve production efficiency, with a broad marketing prospects.This paper systematically studied the Pressure Extrusion Formation method, designed a multi-cavity mold, devised an adhesive formula, contrived solvent degreasing techniques, and produced the magnetic powder cores by using the twin screw compounding extruder; Later, to improve the density of the powder core, the experiment mixed with different powder sizes to produce the magnetic powder core, tried to improve adhensive formula, and studied the effects of composite powder FeSiAl had on the magnetic powder core's density; Finally, the research compared the soft magnetic properties of magnetic powder cores prepared by different pressure extrusion method, optimized the magnetic powder core with desired soft magnetic properties and production procedures.Studies showed that using twin screw compounding extruder could make Fe73.5Cu1Nb3Si13.5B9 nanocrystalline magnetic powder core with multi-cavities, while the "stearic acid-Polypropylene-paraffin" adhesive formula demonstrated good bonding effect and easy formationing.300 mesh Fe73.5Cu1Nb3Si13.5B9 nanocrystalline powder core could be adopted to produce the magnetic powder core of a density less than 2.5g/cm3. Better density can be achieved if other sized powders are added. Mixture of 300 mesh,200 mesh and 100 mesh powders with weight ratio of 6:3:2, in comparison to 300 mesh Fe73.5Cu1Nb3Sil3.5B9 nanocrystalline powder, the core density increases by 5%, with a value up to 3.76 g/cm3. Bonding additionals, or adhensives also can improve the magnetic core density. FeSiAl powder, mixed with Fe73.5Cu1Nb3Si13.5B9 powder, with a weight binder ratio of 10:1, as opposed to powder by the Fe73.5Cu1Nb3Si13.5B9 nanocrystalline only, magnetic core density improves 31%, to 4.69g/cm3.60.1% of theoretical density. After degreasing and heat treatment, the nanocrystalline intergranular's gap reduces, magnetic conductivityμe rises; At the same time, vortexing turbulence loss of the magnetic powder core increases, its center frequency decreases. Magnetic powder core, of 30%(wt%) 200 mesh FeSiAl powder, plus 30%(wt%) 300 mesh Fe73.5Cu1Nb3Si13.5B9 nanocrystalline powder, with powder/binder (weight ratio 10:1), has the best magnetic properties after heat treatment at temperature of 180℃for one hour. It achievesμe=16.45, the center frequency of 600kHz, Q value of 57.5.