Enhancements of preparation efficiency and magnetic properties for Fe-based amorphous magnetic flake powder cores upon the adoption of a novel double-paralleled slits nozzle

The thick and brittle amorphous ribbons with the maximum thickness up to 58 mu m were successfully fabricated using melt-spinning method upon the adoption of a novel double-paralleled slits nozzle (DPSN). The magnetic properties of the two magnetic flake powder cores (MFPCs) prepared from the conventional thin ribbon pulverization and the thick ribbon pulverization were analyzed and compared. Hereinto, a coupling model of fluid flow with free surface and surface tension, and heat transfer with phase transform was developed to design the slit spacing for the DPSN, and sol-gel method was employed to create SiO2 insulation layer on the surfaces of the magnetic flake powders to improve electrical resistivity. Results show that a quasi-steady-state can be reached for the puddle with the upstream and downstream menisci in crescent and slope shapes, respectively, by adopting the DPSN with slit spaces of 2.0 mm and 2.5 mm. The embrittlement process for the conventional thin ribbon can be omitted to enhance the efficiency of the powder preparation when using the thick ribbon before the ribbon pulverization. The MFPCs fabricated using the thick amorphous ribbon pulverization exhibit a higher permeability of 65.27, lower total core loss with the frequency being less than 234 kHz for B-m = 0.08 T, and a better DC-bias property of 70.97% as compared to the MFPCs made from the conventional thin amorphous ribbon pulverization. This work provides a promising approach to further development of Fe-based amorphous MFPCs with high preparation efficiency and excellent magnetic properties at the frequency below 234 kHz.