# Study of Magnetorheological Grease's Thermomagnetic Coupling Rheology
## 5 Conclusions  
This study utilized nanoscale MnFe\({}_{2}\)O\({}_{4}\) particles as magnetic fillers to prepare a 15% mass fraction of magnetorheological grease, utilizing NLGI00 lithium-based grease as the base fluid. The prepared magnetorheological grease underwent a comprehensive investigation of its thermomagnetic coupled rheological properties. The variation patterns of shear yield stress with increased magnetic field intensity at different temperatures were explored by fitting the rheological data using the Herschel-Bulkley (H-B) rheological model. The main conclusions obtained were as follows.  
1. At a constant shear rate without the presence of an applied magnetic field, an increase in temperature resulted in a decrease in both the shear stress and apparent viscosity of the magnetorheological grease. Under constant shear rate and temperature conditions, the shear stress and apparent viscosity of the magnetorheological grease increased with the intensification of the magnetic field intensity. However, once the magnetic field intensity reached 400 mT, further enhancement of the magnetic field had a negligible effect on the shear stress and apparent viscosity. Furthermore, under the same temperature and magnetic field conditions, an increase in shear rate resulted in a gradual reduction in the apparent viscosity of the magnetorheological grease.  
Figure 7: Parameters of magnetic particle magnetorheological grease H-B model. Black represents yield stress, red represents consistency coefficient, and blue represents shear thinning index.  
Under a constant applied magnetic field intensity, raising the temperature resulted in a decrease in the extent of the entanglement of soap fibers within the magnetorheological grease, leading to a reduction in damping force and shear stress. In the same temperature range, with the intensification of the applied magnetic field intensity, the load-bearing capacity of magnetic chains increased, resulting in an elevation of shear stress.
* Under the same magnetic field intensity, with the increase in temperature, the shear yield stress and consistency coefficient of the magnetorheological grease gradually decreased, while the shear thickening index progressively increased. Similarly, with the augmentation of the externally applied magnetic field intensity at a constant temperature, the shear yield stress and consistency coefficient of the magnetorheological grease gradually increased, whereas the shear thickening index gradually decreased.  
Conceptualization, J.P. and A.W.; data curation, R.L. and A.W.; funding acquisition, J.P.; investigation, J.P. and R.L.; methodology, R.L. and A.W.; project administration, J.P.; resources, J.P.; software, R.L.; supervision, J.P.; validation, R.L.; visualization, J.P.; writing--original draft, J.P. and A.W.; writing--review and editing, J.P. and R.L. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the Natural Science Foundation of the Anhui Higher Education for Outstanding Youth Science Foundation (2022 AH030099).  
Not applicable.  
The authors declare no conflict of interest.