Influence of Fabrication Process on Magnetic Properties of Co-Finemet Nanocrystalline Powder Core

Abstract

Abstract. Rapidly quenched ribbons of Fe63.5Co10Si13.5B9Cu1Nb3alloy were annealed at 550°C in a vacuum for 1h and milled to powders. Cold-pressed nanocrystalline powder cores were fabricated using 1-5wt.% of epoxy E-44 as the binder and 1wt.% of Zn-stearate for lubrication under the pressure 155-200KN. The microstructure and morphology of powders were characterized with XRD and SEM. The effective permeability (μe) and quality factor (Q) were tested by using LCR HiTESTER 3532-50 in the range of 1–5000 kHz. The results show that the μe of the powder cores increased with the particle size. Powder cores with 2wt.% binder exhibited higher μe, but lower Q compared with samples with 3wt.% binder. Increase of the forming pressure helps improve μe, but the excessive stress caused by the forming pressure had a negative effect for μe.