Development of manganese ferrite/graphene oxide nanocomposites for magnetorheological fluid with enhanced sedimentation stability

Abstract Novel nanocomposites consisting of manganese ferrite nanoparticles and graphene oxide nanosheets (MnFe 2 O 4 /GO) have been synthesized as a promising candidate for magnetorheological (MR) fluid. The morphology, microstructure, composition and magnetic properties of the obtained MnFe 2 O 4 /GO were studied in detail. It was found that the MnFe 2 O 4 nanoparticles with diameter of 8–12 nm were densely decorated on the surface of GO nanosheets. The magnetization investigation revealed that as-prepared MnFe 2 O 4 /GO had superparamagnetic behavior with saturation magnetization of 36.2 emu/g. The MR fluid was prepared by the obtained MnFe 2 O 4 /GO and the corresponding MR properties were investigated using a Physica MCR301 rheometer fitted with a magneto-rheological module. The MnFe 2 O 4 /GO-based MR fluid exhibited typical MR effect with increasing shear stress, yield stress and dynamic shear modulus depending on magnetic fields. More importantly, the sedimentation stability of the prepared MR fluid was found to be improved due to the unique sheet-like structure and the reduced density mismatch between the dispersed particles and the carrier medium. The MnFe 2 O 4 /GO-based fluid with typical MR effect and excellent sedimentation stability would provide a feasible candidate for practical applications.