Industrial-scale fabrication of amorphous magnetic powder cores with excellent high-frequency magnetic properties: Optimization for kinds and content of insulating agents

Abstract

Based on the powder metallurgy method, FeBSiC amorphous powders were produced by a novel gas-water combined atomization process and were co-coated by five kinds of insulating agents (polyamide, aluminum dihydrogen phosphate, calcium phosphate, zinc phosphate and hydrochloric acid) and epoxy resins. The content of each insulating agents was optimized to improve the magnetic properties of the amorphous magnetic powder cores (AMPCs). The results showed that the FeBSiC powders showed extremely high saturation magnetization (171.1 emu·g–1) and low coercivity (6.11 Oe), which could provide excellent raw materials for AMPCs. Among the five insulating agents, the polyamide-coated AMPCs had the worst electrical insulating effect and magnetic properties. Although the AMPCs coated with aluminum dihydrogen, zinc phosphate, calcium phosphate and hydrochloric acid all exhibited low eddy current losses, only the AMPCs coated with calcium phosphate exhibited extremely low hysteresis losses. As the calcium phosphate content increased, the density and resistance of the AMPCs both increased and then decreased, and the core losses decreased and then increased. When the calcium phosphate content was 0.5 wt.%, the FeBSiC@ calcium phosphate + epoxy resins core-shell structured AMPCs had high permeability of 28.1 ± 0.3, high DC bias% of 96.1 ± 0.2 at a DC magnetic field of 5671.5 A·m–1, and low core loss of 18.0 ± 0.8 kW·m–3 at 100 kHz and 0.02 T, which showed excellent magnetic properties at high frequency and confirmed to the current development trend of miniaturization, high-frequency and high-efficiency in electrical and electronic fields.