Synthesis of rGO/CoFe 2 O 4 Composite and Its Magnetorheological Characteristics

In this study, composite particles of rGO/CoFe O were synthesized using a solvothermal method to fabricate a low-density magnetorheological (MR) material with enhanced sedimentation stability. The morphology and crystallographic features of rGO/CoFe O were characterized via SEM, TEM, and XRD, and its magnetic properties were tested using VSM. The MR fluid was formulated by blending rGO/CoFe O particles into silicone oil. Under different magnet strengths ( ), a rotational rheometer was used to test its MR properties. Typical MR properties were observed, including shear stress, viscosity, storage/loss modulus, and dynamic yield stress (τdy) following the Herschel-Bulkley model reaching 200 Pa when is 342 kA/m. Furthermore, the yield stress of the MR fluid follows a power law relation as increases and the index changes from 2.0 (in the low region) to 1.5 (in the high region). Finally, its MR efficiency was calculated to be about 10 % at of 342 kA/m.