Annealing effects on magnetic properties of silicone-coated iron-based soft magnetic composites

This paper focuses on novel iron-based soft magnetic composites synthesis utilizing high thermal stability silicone resin to coat iron powder. The effect of an annealing treatment on the magnetic properties of synthesized magnets was investigated. The coated silicone insulating layer was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. Silicone uniformly coated the powder surface, resulting in a reduction of the imaginary part of the permeability, thereby increasing the electrical resistivity and the operating frequency of the synthesized magnets. The annealing treatment increased the initial permeability, the maximum permeability, and the magnetic induction, and decreased the coercivity. Annealing at 580 °C increased the maximum permeability by 72.5%. The result of annealing at 580 °C shows that the ferromagnetic resonance frequency increased from 2 kHz for conventional epoxy resin coated samples to 80 kHz for the silicone resin insulated composites.

▸ Silicone uniformly coated the powder, increased the operating frequency of SMCs. ▸ The annealing treatment increased the DC properties of SMCs. ▸ Annealing at 580 °C increased the maximum permeability by 72.5%. ▸ Compared with epoxy coated, the SMCs had higher resistivity annealing at 580 °C.