The influence of temperature on the rheological properties of composite lithium-based magnetorheological grease

Abstract

This paper studies the effect of temperature on the rheological properties of composite lithium-based magnetorheological grease (MRG). Firstly, composite lithium-based MRG was prepared by a mechanical stirrer with a mass fraction of 70%, and the base oil kinematic viscosity was 10, 100, 350, and 500 mm2/s, they are called MRG10, MRG100, MRG350, and MRG500. Then the sedimentation stability of these MRGs was observed, it was concluded that the sedimentation stability of MRG500 was better than that of the other three MRGs. In addition, a magnetic field sweep experiment was performed on MRG500, it was found that with the increase of magnetic induction intensity, the change of shear stress, and viscosity of MRG500 passed through the growth area and the stable area. Finally, the viscosity curve and flow curve of MRG500 at different temperatures and magnetic induction intensity were tested and discussed. It was found that the viscosity curve of MRG500 exhibited shear thinning. When a magnetic field is applied, temperature will affect the apparent viscosity and shear stress of MRG500 and it will decrease as the temperature increases. In the mode of oscillating shear, the results show that the increase in temperature leads to a decrease in the storage modulus and loss factor. The rheological mechanism of MRG is studied through changes at different temperatures.