High-Performance Magnetorheological Suspensions of Fe3O4-deposited Carbon Nanotubes with Enhanced Stability

The magnetorheological (MR) performance of suspensions based on the Fe3O4-deposited carbon nanotubes (CNTs) was investigated by using a vibrating sample magnetometer (VSM) and a rotational rheometer. The Fe3O4-deposited CNTs were synthesized by the reduction process in which nano-Fe3O4 nanoparticles were generated and adsorbed on the surface of CNTs. All tested suspensions displayed excellent MR behaviors with high yield strengths. The morphology was observed by scanning electron microscope (SEM) and transmission electron microscope (TEM). It was revealed that Fe3O4 particles adsorbed on the surface of CNT particles led to make the surface topology bumpy and rough which decreased the particle sedimentation velocity. Finally, Turbiscan apparatus was used to test the sedimentation properties of Fe3O4-deposited CNTs suspensions. The suspensions showed excellent stability against sedimentation, much better than bare Fe3O4 particle suspension due to the inherent low density of CNT and its inside pore which can reduce the density mismatch between the nanoparticles and the carrier medium as well as the surface topology change due to the adsorption of Fe3O4.