Properties Optimization of Soft Magnetic Composites Based on the Amorphous Powders with Double Layer Inorganic Coating by Phosphating and Sodium Silicate Treatment

Core-shell structured amorphous FeSiBCr@phosphate/silica powders were prepared by phosphating and sodium silicate treatment. The soft magnetic composites (SMCs) fabricated based on these powders. effects of phosphoric acid (H3PO4) concentration annealing temperature their properties investigated. During the process, powder coated with a low H3PO4-ethanol solution leads to uneven phosphate coating, while peeling coating occurs for high H3PO4 concentration. Using 0.5 wt.% solution, uniform dense insulation layer can be formed surface powder, resulting in increased resistivity reduced eddy current loss (ASMCs). This increase roughness surface, which is beneficial subsequent silicate. By optimizing treatment, complete SiO2 phosphated well, leading double core-shell structure excellent properties. SMCs further improved post due effectively released residual stress. enhanced permeability greatly core achieved at 773 K, but deterioration as over 798 mainly α-Fe(Si) Fe3B phases, hinder domain wall displacement moment rotation. μe = 35 Ps 368 kW/m3 50 mT/200 kHz have been obtained when 2 annealed K.