Magnetorheological fluid and application

Abstract

The magnetorheological fluid comprises an ionic liquid, a basic liquid, magnetic particles and an additive, and is characterized in that the magnetorheological fluid contains imidazole cations, the general formula of the imidazole cations is [R1R2N +] C3H4, R1 is selected from substituted or unsubstituted alkyl with the carbon atom number of 1-10, and R2 is selected from substituted or unsubstituted alkyl with the carbon atom number of 1-10. The magnetorheological fluid disclosed by the invention has excellent sedimentation stability, relatively low zero-field viscosity and relatively high shear yield stress.

Description

TECHNICAL FIELD

[0001] The application relates to an intelligent controllable fluid, in particular to a magneto-rheological fluid and application. BACKGROUND

[0002] The magneto-rheological fluid is a new type of intelligent composite material with engineering application value. Under the action of a magnetic field, the magneto-rheological fluid can rapidly change from a liquid flow state to a solid-like viscoelastic state, and when the magnetic field action is removed, the magneto-rheological fluid can rapidly restore to the initial liquid flow state. In this process, the rheological parameters (viscosity, shear stress, modulus, etc.), magnetic properties and other physical properties of the magneto-rheological fluid change in real time, rapidly and reversibly. The magneto-rheological fluid has the advantages of intelligence, stability and reliability, and has great engineering application development prospects in the field of automobile damping and the like.

[0003] In the field of intelligent suspension technology, the magneto-rheological fluid has been commercially applied as a core functional medium. Through real-time regulation and control of the damping characteristics of a damping device by an external magnetic field, the dynamic response performance and driving experience of a vehicle are significantly optimized. Although the current mainstream technical solution can realize dynamic performance adjustment under the action of a magnetic field, it is limited by inherent defects of the material system. The separation phenomenon caused by the density difference of the magnetic particles leads to insufficient sedimentation stability. Although the conventional method of increasing the viscosity of the base fluid to inhibit sedimentation can delay the deposition rate of the particles, it will aggravate the viscous effect of the fluid in the state without a magnetic field, and thus weaken the sensitivity and adjustment efficiency of the magnetic control response.

[0004] This contradictory technical problem poses a double challenge to the material performance: it is necessary to maintain low zero-field viscosity to ensure rapid magnetic response capability, and it is necessary to ensure high dynamic yield strength under a specific magnetic field strength, and it is also necessary to ensure uniform dispersibility of the particle system in long-term use. Solving this multi-objective collaborative optimization problem has become a key breakthrough for breaking through the technical bottleneck of the current magneto-rheological material and promoting the development of the next generation of intelligent suspension systems. SUMMARY

[0005] The application aims to provide a magneto-rheological fluid with excellent sedimentation stability, low zero-field viscosity and high shear yield stress, and application.

[0006] In order to achieve the above-mentioned purpose, the application discloses a first aspect, which provides a magneto-rheological fluid, comprising an ionic liquid, a base fluid, magnetic particles and an additive, characterized in that the magneto-rheological fluid contains imidazole cations, and the general formula of the imidazole cations is [R1R2N+]C3H4, wherein R1 is selected from substituted or unsubstituted alkyl with 1-10 carbon atoms, and R2 is selected from substituted or unsubstituted alkyl with 1-10 carbon atoms.

[0007] Preferably, in the imidazolium cation, the substituents of R1 and R2 are each independently selected from methoxy, ethoxy, halogen group, carbonyl, carboxyl, amino, nitrile group, amide group, linear alkyl group with 1-10 carbon atoms.

[0008] Preferably, the magnetorheological fluid further comprises anions, and the anions comprise fluoride ion, tetrafluoroborate ion, hexafluorophosphate ion, chloride ion, ammonium ion, methanesulfonimide ion, phosphate ion, hydrogen phosphate ion, dihydrogen phosphate ion, nitrate ion, nitrite ion, carbonate ion, sulfate ion, sulfite ion.

[0009] Preferably, the content of the magnetic particles is 60-85 wt% based on the total weight of the magnetorheological fluid.

[0010] Preferably, the magnetic particles comprise one or more of carbonyl iron powder, iron-nickel alloy, Fe3O4, Fe3O4 / PMMA, iron-cobalt alloy.

[0011] Preferably, the content of the base fluid is 10-25 wt% and the content of the additive is 1-10 wt% based on the total weight of the magnetorheological fluid.

[0012] Preferably, the base fluid comprises one or more of silicone oil, mineral oil, synthetic hydrocarbon oil, bio-based oil, fluorinated oil.

[0013] Preferably, the additive comprises thixotropic agent, anti-wear agent, antioxidant, surfactant, the content of the thixotropic agent is 1-5 wt%, the content of the anti-wear agent is 0.5-3 wt%, the content of the antioxidant is 0.1-2 wt%, and the content of the surfactant is 1-4 wt% based on the total weight of the magnetorheological fluid.

[0014] Preferably, the thixotropic agent comprises one or more of silicon dioxide, montmorillonite, bentonite, polyethylene glycol, xanthan gum, hydrogenated castor oil, polyolefin wax, polyamide wax; and / or, the anti-wear agent comprises one or more of polytetrafluoroethylene, molybdenum disulfide, graphite, boron nitride, organic molybdenum compound, chlorophosphorus / sulfur compound, phenolic compound; and / or, the antioxidant comprises one or more of phosphate ester, zinc alkyl thiocarbamate, copper compound, sodium nitrite, borax, organic phosphorus compound; and / or, the surfactant comprises one or more of polyethylene glycol, Tween 80, silane coupling agent, oleic acid, sodium dodecyl benzene sulfonate, alkyl phosphate ester.

[0015] The second aspect of the present application discloses the application of the magnetorheological fluid of the first aspect of the present application in a vehicle damping system.

[0016] The beneficial effects of the present application are that the above technical solution provides a magneto-rheological fluid and application, the above magneto-rheological fluid still has lower zero-field viscosity and higher shear yield stress under the condition of excellent sedimentation stability, is particularly suitable for use in a vehicle damping system, has the ability of rapid response and damping adjustment, and belongs to the performance and service life of the damping system. DETAILED DESCRIPTION

[0017] In the description of the present application, the meaning of one or more is one or more, the meaning of multiple is two or more, greater than, less than, more than, etc. are understood as not including the number, above, below, within, etc. are understood as including the number. If it is described that the first, the second is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of indicated technical features or implicitly indicating the sequence of indicated technical features.

[0018] In the description of the present application, unless otherwise explicitly limited, the words such as setting, installing, connecting, etc. should be broadly understood, and the person skilled in the art can reasonably determine the specific meaning of the above words in the present application in combination with the specific content of the technical solution.

[0019] The present application discloses a first aspect, which provides a magneto-rheological fluid, comprising an ionic liquid, a base liquid, magnetic particles and an additive, characterized in that the magneto-rheological fluid contains imidazole cations, and the general formula of the imidazole cations is [R1R2N+]C3H4, wherein R1 is selected from substituted or unsubstituted alkyl with 1-10 carbon atoms, and R2 is selected from substituted or unsubstituted alkyl with 1-10 carbon atoms. Wherein, the optimization of sedimentation is reflected in that the ions are adsorbed on the surface of the magnetic particles (such as carbonyl iron powder) to form a charged layer, enhance the electrostatic repulsion between particles, and reduce agglomeration. The optimization of the saturation yield stress is reflected in that the ions in the ionic liquid are polarized under the magnetic field to form an "ionic layer" wrapping the particles, enhancing the mechanical strength of the chain structure, and the polar groups in the ionic liquid form strong adsorption with the surface of the particles, reducing the chain structure fracture. The optimization of the zero-field viscosity is reflected in that the low molecular weight and high flowability of the short-chain ionic liquid can dilute the carrier liquid.

[0020] According to the present disclosure, in the imidazole cations, the substituents of R1 and R2 are each independently selected from methoxy, ethoxy, halogen groups, carbonyl groups, carboxyl groups, amino groups, nitrile groups, amide groups, and linear alkyl groups with 1-10 carbon atoms.

[0021] According to the present disclosure, the magneto-rheological fluid further contains anions, including fluoride ions, tetrafluoroborate ions, hexafluorophosphate ions, chloride ions, ammonium ions, methanesulfonimide ions, phosphate ions, hydrogen phosphate ions, dihydrogen phosphate ions, nitrate ions, nitrite ions, carbonate ions, sulfate ions, sulfite ions. Ionic liquids reduce the probability of particle aggregation and sedimentation through interfacial adsorption and the formation of a molecular network structure after mixing with the base fluid. At the same time, due to the polarization ability of ionic liquids, the chain structure of magnetic particles can be enhanced under the condition of a magnetic field, and the yield stress of the magneto-rheological fluid is improved.

[0022] According to the present disclosure, the content of the magnetic particles is 60-85% by weight based on the total weight of the magneto-rheological fluid.

[0023] According to the present disclosure, the magnetic particles include one or more of carbonyl iron powder, iron-nickel alloy, Fe3O4, Fe3O4 / PMMA, and iron-cobalt alloy.

[0024] According to the present disclosure, the content of the base fluid is 10-25% by weight based on the total weight of the magneto-rheological fluid, and the content of the additive is 1-10% by weight.

[0025] According to the present disclosure, the base fluid includes one or more of silicone oil, mineral oil, synthetic hydrocarbon oil, bio-based oil, and fluorinated oil.

[0026] According to the present disclosure, the additive includes a thixotropic agent, an anti-wear agent, an antioxidant, and a surfactant. The content of the thixotropic agent is 1-5% by weight based on the total weight of the magneto-rheological fluid, the content of the anti-wear agent is 0.5-3% by weight, the content of the antioxidant is 0.1-2% by weight, and the content of the surfactant is 1-4% by weight. Optimizing the sedimentation performance also reflects that the ions are adsorbed on the surface of the magnetic particles (such as carbonyl iron powder) to form a charged layer, enhance the electrostatic repulsion between particles, and reduce agglomeration. At the same time, the surfactant (such as oleic acid) cooperates to form worm-like micelles, which increase the structural viscosity of the fluid and provide a dynamic support network.

[0027] According to the present disclosure, the thixotropic agent includes one or more of silicon dioxide, montmorillonite, bentonite, polyethylene glycol, xanthan gum, hydrogenated castor oil, polyolefin wax, polyamide wax; and / or, the anti-wear agent includes one or more of polytetrafluoroethylene, molybdenum disulfide, graphite, boron nitride, organic molybdenum compound, chlorophosphorus / sulfur compound, phenolic compound; and / or, the antioxidant includes one or more of phosphate ester, zinc alkyl thiocarbamate, copper compound, sodium nitrite, borax, organic phosphorus compound; and / or, the surfactant includes one or more of polyethylene glycol, Tween 80, silane coupling agent, oleic acid, sodium dodecyl benzene sulfonate, alkyl phosphate ester. The thixotropic agent enhances the anti-settling ability of the magnetorheological fluid by forming a reversible network structure, while adjusting the rheological properties. The anti-wear agent prolongs the service life of the equipment by reducing the friction coefficient, and needs to balance the lubricity and the magnetorheological effect. The surfactant improves the particle dispersibility by reducing the interfacial energy.

[0028] The present disclosure discloses a second aspect, and provides the application of the magnetorheological fluid in the vehicle damping system. The magnetorheological fluid has excellent sedimentation stability, low zero-field viscosity and high shear yield stress, and is particularly suitable for use in the vehicle damping system, has the ability to quickly respond and adjust the damping, and belongs to the performance and service life of the damping system.

[0029] The present disclosure will be further described in detail below in combination with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present disclosure, and are not used to limit the present disclosure.

[0030] Embodiment 1

[0031] The content of the magnetorheological fluid components includes, by mass percentage, ionic liquid 1-octyl-3-methylimidazolium tetrafluoroborate ([OMIm][BF4]) 10%, base oil 15%, thixotropic agent 1.5%, anti-wear agent 1%, antioxidant 0.5%, and surfactant 2%.

[0032] Embodiment 2

[0033] The difference from embodiment 1 is that the ionic liquid component is 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4]). The weight percentage of each component of the magnetorheological fluid of the present embodiment is the same as that of embodiment 1.

[0034] Embodiment 3

[0035] The difference from embodiment 1 is that the ionic liquid component is 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIm][BF4]). The weight percentage of each component of the magnetorheological fluid of the present embodiment is the same as that of embodiment 1.

[0036] Embodiment 4

[0037] The difference from Example 1 is that the ionic liquid component is 1-hexyl-3-methylimidazolium tetrafluoroborate ([HMIm][BF4]). The weight percentages of the components of the magnetorheological fluid of this example are the same as those of Example 1.

[0038] Example 5

[0039] The difference from Example 1 is that the ionic liquid component is 1-octyl-3-methylimidazolium hexafluorophosphate ([OMIm][PF6]). The weight percentages of the components of the magnetorheological fluid of this example are the same as those of Example 1.

[0040] Example 6

[0041] The difference from Example 1 is that the ionic liquid component is 1-octyl-3-methylimidazolium methanesulfonate ([OMIm][NTf2]). The weight percentages of the components of the magnetorheological fluid of this example are the same as those of Example 1.

[0042] The magnetorheological fluids of the examples were subjected to sedimentation rate testing and magnetorheological performance testing according to the standard method JB / T 12512-2015. The test results are shown in Table 1.

[0043] The sedimentation rate testing method is as follows: the magnetorheological fluid is placed in a 25 mL measuring cylinder, sealed and left to stand at 25°C. The height of the supernatant is observed at the same time every day. The sedimentation rate is the ratio of the height of the supernatant to the total height (25 mL). The test time is 30 days.

[0044] The magnetorheological performance testing method is as follows: the zero-field viscosity and the shear yield stress value under a magnetic field of 0.8 T of the magnetorheological fluid are tested on a rheometer according to a set program.

[0045] Table 1

[0046]

[0047] The 30-day sedimentation rate of the magnetorheological fluid is 15% or less, the zero-field viscosity is 300 mPa·s or less, and the shear yield stress under a magnetic field of 0.8 T is 50 kPa or more. As can be seen from Table 1, the magnetorheological fluid prepared in the examples has excellent sedimentation stability, and still has a low zero-field viscosity and a high shear yield stress.

[0048] The above only discloses preferred embodiments of the present application, and of course cannot limit the scope of the patent rights of the present application. Therefore, equivalent changes made in accordance with the patent application scope of the present application still fall within the scope of the present application.

Claims

1. A magnetorheological fluid, characterized in that: The invention comprises an ionic liquid, a base liquid, magnetic particles, and additives, characterized in that the magnetorheological liquid contains an imidazole cation, wherein the imidazole cation has the general formula [R1R2N+]C3H4, wherein R1 is selected from substituted or unsubstituted alkyl groups having 1 to 10 carbon atoms, and R2 is selected from substituted or unsubstituted alkyl groups having 1 to 10 carbon atoms.

2. The magnetorheological fluid as described in claim 1, characterized in that, In the imidazole cation, the substituents of R1 and R2 are each independently selected from methoxy, ethoxy, halogen, carbonyl, carboxyl, amino, nitrile, amide, and straight-chain alkyl with 1 to 10 carbon atoms.

3. The magnetorheological fluid as described in claim 1, characterized in that, The magnetorheological fluid also contains anions, including fluoride ions, tetrafluoroborate ions, hexafluorophosphate ions, chloride ions, ammonium ions, methanesulfonylimide ions, phosphate ions, hydrogen phosphate ions, dihydrogen phosphate ions, nitrate ions, nitrite ions, carbonate ions, sulfate ions, and sulfite ions.

4. The magnetorheological fluid as described in claim 1, characterized in that, Based on the total weight of the magnetorheological fluid, the content of the magnetic particles is 60-85% by weight.

5. The magnetorheological fluid as described in claim 4, characterized in that, The magnetic particles include one or more of carbonyl iron powder, iron-nickel alloy, Fe3O4, Fe3O4 / PMMA, and iron-cobalt alloy.

6. The magnetorheological fluid as described in claim 1, characterized in that, Based on the total weight of the magnetorheological fluid, the content of the base fluid is 10-25% by weight, and the content of the additives is 1-10% by weight.

7. The magnetorheological fluid as described in claim 6, characterized in that, The base fluid includes one or more of the following: silicone oil, mineral oil, synthetic hydrocarbon oil, bio-based oil, and fluorinated oil.

8. The magnetorheological fluid as described in claim 1, characterized in that, The additives include thixotropic agents, anti-wear agents, antioxidants, and surfactants. Based on the total weight of the magnetorheological fluid, the content of the thixotropic agent is 1-5% by weight, the content of the anti-wear agent is 0.5-3% by weight, the content of the antioxidant is 0.1-2% by weight, and the content of the surfactant is 1-4% by weight.

9. The magnetorheological fluid as described in claim 1, characterized in that, The thixotropic agent comprises one or more of the following: silica, montmorillonite, bentonite, polyethylene glycol, xanthan gum, hydrogenated castor oil, polyolefin wax, and polyamide wax; and / or, The anti-wear agent includes one or more of polytetrafluoroethylene, molybdenum disulfide, graphite, boron nitride, organomolybdenum compounds, chlorine / phosphorus compounds, and phenolic compounds; and / or, The antioxidants include one or more of the following: phosphate esters, zinc alkyl thiocarbamate, copper compounds, sodium nitrite, borax, and organophosphorus compounds; and / or, The surfactant includes one or more of polyethylene glycol, Tween 80, silane coupling agent, oleic acid, sodium dodecylbenzenesulfonate, and alkyl phosphate.

10. The application of the magnetorheological fluid according to any one of claims 1-9 in a vehicle vibration damping system.

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