Magneto-stimuli Rheological Response of Hierarchical Fe3O4 Submicron Spheres for High Performance Magnetorheological Fluid

Uniform Fe3O4 submicron spheres assembled by tiny nanocrystals were fabricated via a facile one-step sol-vothermal strategy. The morphology, crystal structure, mesoporous characteristics, elemental composition and magnetic properties of the resultant magnetic particles were investigated extensively through various charac-terization techniques. The resulting Fe3O4 submicron spheres were nearly monodisperse with an average diameter of 508 nm and demonstrated typical mesoporous structures and superparamagnetic behavior. The rheological responses of magnetorheological (MR) suspension composed of Fe3O4 submicron spheres to different intensity of magnetic fields were investigated and the sedimentation stability tests were conducted and compared with that of carbonyl iron particles. The formed MR fluid behaved as Newtonian fluid without an external magnetic field and turned into Bingham behavior under the action of magnetic field. In addition, no significant settlement was observed in the recording period, showing an excellent sedimentation stability for the developed MR fluid.