Magnetic properties and microstructure of iron-based soft magnetic composites with Al2O3 insulating coating by one-pot synthesis method

In this work, the effects of the Al2O3 insulating coating and surfactant on magnetic properties of the iron powders coated with Al2O3 by one-pot synthesis method were investigated. The morphology, phase composition and magnetoelectric properties of iron powders coated with Al2O3 were tested respectively. Compared with uncoated iron powder, the composite powder of Al2O3 insulating layer not only has better permeability stability in the frequency range of 5-300 kHz, but also has lower core loss, especially eddy current loss in the frequency range of 5-100 kHz. The surface of iron powder modified by surfactant will change crystallization process of aluminum hydroxide. After the addition of dodecyl trimethyl ammonium bromide (DTAB) as the surfactant, the Al2O3 insulating coating becomes denser and smoother, and the core loss of coated powders is further reduced.