Fe-Si-Al Soft Magnetic Composites with Significantly Reduced Core Loss via Constructing Uniform TiO2 Insulation Layer.

Core–shell structured Fe-Si-Al@TiO₂ with uniform coating layers have been used for preparing soft magnetic composites (SMCs) with good magnetic properties. The quality of the TiO₂ insulation layer has been optimized by tuning the content of tetrabutyl titanate (TBOT), the reaction time, and the volume of acetic acid. It is proved that the conditions of 5 ml TBOT, 1-h reaction time, and 100 µl acetic acid would lead to uniform and dense TiO₂ layer. As a result, the high-frequency eddy-current loss can be effectively decreased, which is related with increased resistivity. Moreover, optimal Fe-Si-Al@TiO₂ powders would ensure high density of SMCs, resulting in high effective permeability and low hysteresis loss. When the effective permeability of optimal SMCs reaches 85 (measured at 100 kHz/1 V), the core loss is only 691.33 mW/cm³ (measured at 500 kHz/50 mT), which is much lower than those of Fe-Si-Al SMCs insulated with Al₂O₃ and phosphate. Owing to high-quality TiO₂ insulating layer, as-prepared SMCs show unique superiority in achieving high effective permeability and low core loss simultaneously, in contrast with other reported SMCs. This work may provide novel insights into the synthesis of SMCs with excellent magnetic properties via building uniform oxide coating layer. [ABSTRACT FROM AUTHOR]