Magnetorheological Effect And Sedimentation Stability Of Ionic Liquid-modified Silicone Oil-based Magnetorheological Fluid

There are many types of existing magnetorheological fluids with excellent magnetorheological properties,which have been used in automotive dampers,intelligent vibration reduction of building structures,etc.However,the shear yield strength of existing magnetorheological fluids cannot be Meet the needs of military heavy vehicles,large building vibration reduction and other fields.Magnetorheological fluid is mainly composed of magnetic particles and base fluid.Existing studies mainly improve the shear yield strength of magnetorheological fluids by modifying magnetic particles.This method usually leads to the increase of the zero-field viscosity of the magnetorheological fluid and the reduction of the relative adjustment range of the shear yield strength.Modifying the base fluid is another way to improve the shear yield strength of magnetorheological fluids.In this paper,an ionic liquid(1-octyl-3-methylimidazolium tetrafluoroborate)whose viscosity,density,and volatility are close to dimethyl silicone oil is used as the base fluid to prepare magnetorheological fluids,and ionic liquids with different proportions are further prepared.The modified silicone oil-based magnetorheological fluid was compared with that of the silicone oil-based magnetorheological fluid.The mechanism of action and the law of influence in magnetorheological fluids.The rheological properties,magneto-induced shear yield strength,magnetic shear yield strength,magnetic properties of ionic liquid-based magnetorheological fluids prepared with ionic liquid(1-octyl-3-methylimidazolium tetrafluoroborate)as base fluid were measured by rotational rheometer.The response time,magnetodynamic viscoelasticity,etc.were tested,and the sedimentation stability of the ionic liquid-based magnetorheological fluid and the silicone oil-based magnetorheological fluid was compared by the cuvette static method,and the effect of the ionic liquid on the magnetorheological fluid was explored.The results show that the maximum shear yield strength under the magnetic field strength of 436 k A/m is 29%higher than that of the silicone oil-based magnetorheological fluid,that is,the ionic liquid-based magnetorheological fluid shows a more excellent magnetorheological effect,but The sedimentation stability of ionic liquid-based magnetorheological fluids is weaker than that of silicone oil-based magnetorheological fluids,which is attributed to the fact that the spreadability and adsorption between ionic liquids and carbonyl iron particles are stronger than those between silicone oil and carbonyl iron particles under zero field;The interaction force between the ionic liquid and the carbonyl iron particles is enhanced under the action of the magnetic field,which optimizes the stability and firmness of the carbonyl iron particles to form a chain-like structure,so that the ionic liquid-based magnetorheological fluid exhibits more excellent magnetorheological properties.effect.The rheological properties and sedimentation stability of ionic liquid/silicone oil mixed-based magnetorheological fluids with different modification ratios were compared and tested,and the influence rule and mechanism of ionic liquid modified silicone oil proportions on the performance of magnetorheological fluids were explored and analyzed.The results show that the MR fluid with a modification ratio of 57% has the most excellent rheological properties and sedimentation stability,which is attributed to the fact that the silicone oil in the MR fluid with a modification ratio of 57% can be more completely absorbed by the ionic liquid.The polarization of the magneto-rheological fluid will generate a large inductive force and dispersion force,which will form a more effective molecular network structure on the surface of the carbonyl iron particles,and play a role in improving the performance of the magnetorheological fluid.When the proportion of ionic liquid in the mixed base fluid is small,the ionic liquid cannot effectively polarize the silicone oil,and the van der Waals force formed between the two is weak,resulting in weak rheology and sedimentation stability of the final magnetorheological fluid;When the proportion of ionic liquid in the mixed base fluid is too large,an effective molecular network structure cannot be formed,thereby weakening the rheological properties and anti-settling properties.