Synthesis and thixotropic characterization of micron-nanometer magnetic grease with high suspension stability

Abstract

The grid structure formed by the ionic bonding between bentonite and carrier liquid could support and uniformly disperse the micro-nanometer magnetic particles. In order to overcome the sedimentation of magnetorheological fluid the bi-dispersed magnetic grease with excellent magnetism suspension stability and thixotropy was prepared for the first time. The suspension stability was accurately measured by the L-C vibration detection. By observing the time dependence of the viscosity under coupling effect shear rate and magnetic field the thixotropy phenomenon was found and analyzed. The results showed that the addition of bentonite increased the suspension stability by 17.873%. A surprising thixotropy with changes regularly was found even the viscosity increased by an order of magnitude. Moreover the rate of viscosity changes was accelerated with the decrease of shear rate and the increase of magnetic field. Under the action of shear rate the formation and destruction of the magnetic response of the particle cloud structure were promoted by the grid structure with a large internal surface area. This work has improved the suspension stability of rheological fluid and found the thixotropic phenomenon with regular changes which is of great significance for the precise control and stable operation of damping braking and transportation systems.