Effect of Cobalt Ferrite Particles on Thermorheological Properties of Magnetic Grease

Magnetorheological (MR) grease is one smart material that consists of dispersion of magnetic particles within lubricating grease matrix that exhibit controllable rheological properties under the influence of magnetic field. However, the thermal stability regarding the rheological properties of MR grease has become a great challenge, especially in most engineering applications. Therefore, in this study, soft magnetic particles which are cobalt ferrite (CoFe2O4) particles have been utilized as additives in MR grease due to their high magnetic properties and high thermal stability. Before utilizing the additives in the MR grease, the CoFe2O4 particles is synthesized via the co-precipitation method. The fabricated MR grease was then investigated in terms of morphological properties and elemental composition via field emission electron scanning microscopy (FESEM), optical microscope and X-ray diffraction (XRD). The thermal resistivity of MR grease also has been analyzed by using KD2Pro. Next, the thermorheological properties of the fabricated MRG with 1wt% of CoFe2­O4 particles have been investigated corresponding to the wide range of temperature from 25℃ to 65℃ under 0T and 0.547T of magnetic field strength.­ The results indicate that the CoFe­2O4 particles significantly enhances the thermal stability in terms of thermal resistivity and viscosity, ­which offers superior performance due to the enhancement of magnetic particle interaction within the grease matrix. Thus, this study provides a comprehensive understanding of the role of ferrimagnetic particles in improving the thermorheological properties of MR grease, paving the way for advanced applications where thermal resilience is critical.