Preparation and Surface Modification of Fe<sub>3</sub>O<sub>4 </sub>Nano-Magnetic Powders

Because of aggregation and low chemical stability of nanomagnetic particles, we use Sol-Gel method as surface modification in this paper to improve the disperse ability and the chemical stability of Fe 3 O 4 particles. At first, Fe 3 O 4 were prepared by chemical-precipitation method. Then, the Sol-Gel method was used to modify the surface of the particles. Core-shell structural Fe 3 O 4 @ S iO 2 composite magnetic particles were prepared by hydrolysis and condensation of tetraethyl orthosilicate using Fe 3 O 4 nanomagnetic particles as seeds. XRD,VSM were applied to characterize the composite magnetic particles. The effects of rotational speed and the quantity of TEOS on the performance of Fe 3 O 4 @ S iO 2 composite magnetic particles were investigated.