Metal-based magnetic fluids with core–shell structure FeB@SiO₂ amorphous particles

Abstract

FeB@SiO₂ amorphous particles were firstly introduced into Ga_85.8In_14.2 alloys to prepare metal-based magnetic fluids. The morphology of the FeB amorphous particles is spherical with an average particle size of about 190 nm. The shape of the particles is regular and the particle size is homogeneous. Stable core-shell structure SiO₂ modified FeB amorphous particles are obtained and the thickness of the SiO₂ coatings is observed to be about 40 nm. The results of VSM confirm that the saturation magnetization of the FeB amorphous particles is 131.5 emu g^-1, which is almost two times higher than that of the Fe₃O₄ particles. The saturation magnetization of the FeB@SiO₂ amorphous particles is 106.9 emu g^-1, an approximate decrease of 18.7% due to the non-magnetic SiO₂ coatings. The results from the torsional oscillation viscometer show that the metal-based magnetic fluids with FeB amorphous particles exhibit a desirable high temperature performance and are ideal candidates for high temperature use.