Core-shell structured FeSiAl/SiO2 particles and Fe3Si/Al2O3 soft magnetic composite cores with tunable insulating layer thicknesses

FeSiAl/SiO2 core-shell particles and FeSiAl/SiO2 composite cores with tunable insulating layer thicknesses have been synthesized via a modified Stober method combined with following high temperature sintering process. Most of the conductive FeSiAl particles could be coated by insulating SiO2 using the modified Stober method. During the sintering process, the reaction 4Al +3SiO(2) (sic) 2 alpha-Al2O3 +3Si took place and the new FeSiAl/SiO2 composite was formed. The FeSiAl/SiO2 composite cores displayed more excellent soft magnetic properties, better frequency stability at high frequencies, much higher resistivity and lower core loss than the raw FeSiAl core. Based on this, several types of FeSiAl/SiO2 particles and FeSiAl/SiO2 composite cores with tunable insulating layer thicknesses were selectively prepared by simply varying TEOS contents. The thickness of Al2O3 insulating layer and resistivity of FeSiAl/SiO2 composite cores increased with increasing the TEOS contents, while the permeability and core loss changed in the opposite direction. (C) 2015 Elsevier E.V. All rights reserved.