A magnetorheological fluid based on a eutectic mixture and a method for producing the same

Abstract

The application discloses a kind of magnetorheological fluid based on eutectic mixture and preparation method thereof, including non-ionic hydrophobic eutectic solvent base fluid and soft magnetic particles;Wherein, non-ionic hydrophobic eutectic solvent has abundant non-covalent intermolecular force, can significantly improve the sedimentation rate of soft magnetic particles in base fluid, and improve the shear yield stress of magnetorheological fluid.The preparation method is calculated with mass percentage, including: non-ionic hydrophobic eutectic solvent 10~40wt%;Soft magnetic particles 60~90wt%.The magnetorheological fluid prepared by the application has low zero magnetic field viscosity, high shear yield stress under saturated magnetic field, and has the advantages of simple preparation method, good environmental adaptability, etc., suitable for aerospace, off-road vehicles and other harsh environments in the field of vibration reduction.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of magnetorheological fluid damping, and particularly relates to a magnetorheological fluid based on a eutectic mixture and a preparation method thereof. BACKGROUND

[0002] Magnetorheological fluid (MRF) is a new type of smart material. In the absence of a magnetic field, magnetic particles are freely suspended in the base fluid, and the liquid exhibits normal flowability and low viscosity. When the magnetorheological fluid is exposed to an external magnetic field, the magnetic particles are magnetized and arranged into chain structures along the magnetic force lines. The presence of these chain structures causes the liquid viscosity to increase sharply, thereby increasing the internal friction of the liquid. Because the chain structures formed by the magnetic particles increase the viscosity of the liquid, the liquid encounters greater resistance when passing through a pipe or through a damper, thereby increasing the damping force.

[0003] In the prior art, due to the large difference in density between the magnetic particles and the base fluid, the magnetic particles may settle during long-term standing or storage, resulting in stratification of the liquid. Moreover, the magnetic particles may agglomerate in the absence of an external magnetic field, affecting their arrangement in the magnetic field and the formation of chain structures, which directly affects the performance of the magnetorheological fluid. Improving the sedimentation stability of the magnetorheological fluid through special morphology design and surface modification is an effective method, but it also causes the magnetic properties of the magnetic particles to decrease, thereby reducing the magnetorheological effect of the magnetorheological fluid. SUMMARY

[0004] In view of the problems existing in the prior art, the present application aims to provide a magnetorheological fluid based on a eutectic mixture and a preparation method thereof. The magnetorheological fluid prepared by the preparation method has low zero-field viscosity, high shear yield stress under a saturated magnetic field, and the advantages of simple preparation method and good environmental adaptability.

[0005] To achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0006] The present application provides a magnetorheological fluid based on a eutectic mixture, which comprises, in terms of mass percentage: 10-40 wt% of a non-ionic hydrophobic eutectic solvent; and 60-90 wt% of soft magnetic particles.

[0007] Further, the non-ionic hydrophobic eutectic solvent comprises a hydrogen bond donor and a hydrogen bond acceptor.

[0008] Further, the hydrogen bond donor is thymol, lauric acid, etc., and the hydrogen bond acceptor is menthol.

[0009] Further, the molar percentage of the hydrogen bond donor and the hydrogen bond acceptor is 1:0.5-1:2.

[0010] For example, the molar ratio of the hydrogen bond donor and the hydrogen bond acceptor is 1:0.5, 1:0.9 or 1:1.8.

[0011] Further, the soft magnetic particles are carbonyl iron powder, ferroferric oxide, cobalt-nickel, etc.

[0012] Further, the particle size of the carbonyl iron powder particles is 1-10 microns.

[0013] The application also provides a preparation method of the magnetorheological fluid based on the eutectic mixture.

[0014] Step one, preparing the non-ionic hydrophobic eutectic solvent, specifically, stirring and dissolving the hydrogen bond donor and the hydrogen bond acceptor under heating to obtain the non-ionic hydrophobic eutectic solvent.

[0015] Step two, weighing the required amount of raw materials, specifically, weighing 10%-40wt% of the non-ionic hydrophobic eutectic solvent and 60%-90wt% of the soft magnetic particles according to the mass percentage; uniformly mixing the non-ionic hydrophobic eutectic solvent and the soft magnetic particles according to a certain mass ratio to obtain the magnetorheological fluid.

[0016] Further, after mixing the hydrogen bond donor and the hydrogen bond acceptor, stirring at 500-1000 rpm at a temperature of 60-80℃ for 0.5-1 hour until a transparent and uniform liquid is formed.

[0017] Further, after mixing the non-ionic hydrophobic eutectic solvent and the soft magnetic particles, ultrasonic dispersion is used; the frequency of the ultrasonic dispersion is 200-240 W, and the dispersion time is 10-20 minutes.

[0018] The magnetorheological fluid based on the eutectic mixture is prepared by using the above preparation method.

[0019] The technical scheme of the application has the following beneficial effects:

[0020] The magnetorheological fluid based on the eutectic mixture and the preparation method thereof provided by the application include a non-ionic hydrophobic eutectic solvent base fluid and soft magnetic particles; the non-ionic hydrophobic eutectic solvent is obtained by stirring and dissolving the hydrogen bond donor and the hydrogen bond acceptor under heating, and the carbonyl iron powder particles are uniformly mixed according to a mass ratio of 1:9-2:3, and the magnetorheological fluid is prepared in two steps. The prepared magnetorheological fluid has low zero magnetic field viscosity and high shear yield stress under a saturated magnetic field, and has the advantages of simple preparation method, good environmental adaptability, etc.; at the same time, the magnetorheological fluid prepared by the method has good hydrophobic performance, and does not need to be dried during use and storage, which simplifies the steps and saves the cost.

[0021] Compared with the traditional base fluid silicone oil, the non-ionic hydrophobic eutectic solvent contains a large number of dynamic hydrogen bonds, and the hydrogen bond effect can effectively improve the dispersity and stability of the carbonyl iron powder particles, reduce the agglomeration and sedimentation between the particles, and can significantly improve the sedimentation rate of the soft magnetic particles in the base fluid, and effectively improve the shear yield stress of the magnetorheological fluid. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the specific embodiments of the present application or the technical solutions in the prior art, the drawings needed in the specific embodiments or the prior art description will be briefly introduced below, and it should be understood that the drawings in the following description are only some embodiments of the present application. For those skilled in the art, other related drawings can also be obtained without creative labor. In the drawings:

[0023] Figure 1 Shear stress vs. shear rate graph of the magnetorheological fluid of Examples 1-3 and Comparative Example 1;

[0024] Figure 2 Yield stress vs. magnetic field strength graph of the magnetorheological fluid of Examples 1-3 and Comparative Example 1;

[0025] Figure 3 Comparison graph of Examples 1-3 and Comparative Example 1 after 5 hours of sedimentation;

[0026] Figure 4 Yield stress vs. magnetic field strength graph of the magnetorheological fluid of Examples 1-3 and Comparative Example 1; DETAILED DESCRIPTION

[0027] In order to make the purpose, technical scheme and advantages of the present application more clear and definite, the present application will be further described in detail below in combination with specific embodiments. It should be understood that these embodiments are part of the embodiments of the present application, but not all the embodiments.

[0028] The instruments, reagents and consumables used in the examples are not specified by the manufacturer, and can be purchased from commercial companies.

[0029] The carbonyl iron powder particles used in the examples and comparative examples are from BASF SE in Germany, 3-4 μm; the silicone oil is from Shin-Etsu Chemical Co., Ltd., 20 cst.

[0030] The magnetic particles in the magnetorheological fluid prepared in Examples 1-3 are all carbonyl iron powder particles, and the base fluid composition is shown in Table 1.

[0031] Table 1. Combination of hydrogen bond donors and hydrogen bond acceptors in non-ionic hydrophobic eutectic solvent of Examples 1-3.

[0032]

[0033] A method for preparing a low eutectic mixture-based magnetorheological fluid comprises the following steps: step one, preparing a non-ionic hydrophobic eutectic solvent, specifically, a hydrogen bond donor and a hydrogen bond acceptor are mixed at 80°C under stirring to form a transparent and uniform liquid, thereby obtaining the non-ionic hydrophobic eutectic solvent; step two, mixing the carbonyl iron powder particles with the non-ionic hydrophobic eutectic solvent of examples 1-3 and stirring uniformly to obtain the magnetorheological fluid, wherein the mass fraction of the carbonyl iron powder particles in the magnetorheological fluid is 60 wt%.

[0034] Comparative example 1

[0035] The preparation method provided by the present comparative example is the same as that of examples 1-3, except that the base fluid in the present comparative example is silicone oil.

[0036] Test example 1

[0037] A parallel-plate rheometer (MCR 302, Anton Paar) is used to test the change rule of the shear stress τ of the magnetorheological fluid under different magnetic induction intensities with respect to the shear rate . The test temperature is constant at 25°C, the change range of the shear rate is set to 0.1-100 s -1 , steady shear is performed, the current is increased by 0.2 A every time, the magnetic field intensity is 0-490 mT, and the test results are shown in Figure 1 . Examples 1-3 and comparative example 1 have relatively close shear stresses at zero magnetic field, and the shear stresses of the magnetorheological fluids of examples 1-3 are higher than that of comparative example 1 at the saturated magnetic field intensity, indicating that the variable damping performance of examples 1-3 is better than that of comparative example 1.

[0038] The Bingham plastic model is used to fit the shear rate-shear stress of the magnetorheological fluids of examples 1-3 and comparative example 1, to obtain the yield stress of the magnetorheological fluids under different magnetic field intensities, as shown in Figure 2 . The yield stresses of the magnetorheological fluids of examples 1-3 are higher than that of comparative example 1, indicating that the rheological performance of examples 1-3 is better than that of comparative example 1.

[0039] The sedimentation analysis method is used to evaluate the anti-settling stability of the magnetorheological fluids of examples 1-3 and comparative example 1. Specifically, the magnetorheological fluids are poured into cuvettes respectively, the sedimentation of the magnetorheological fluids at different time points is observed at room temperature, the anti-settling stability of the magnetorheological fluids is evaluated by measuring the sedimentation distance and the corresponding sedimentation time, and the sedimentation volume ratio is defined by the percentage of the sedimentation distance relative to the height of the whole fluid, as shown in Figure 3 and Figure 4 . The anti-settling stability of examples 1-3 is better than that of comparative example 1.

[0040] The above-described embodiments are merely preferred examples of the present application and do not serve to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A magnetorheological fluid based on a eutectic mixture, characterized in that, The composition, by mass percentage, includes: 10-40 wt% nonionic hydrophobic eutectic solvent and 60-90 wt% soft magnetic particles.

2. The magnetorheological fluid based on a eutectic mixture according to claim 1, characterized in that, The nonionic hydrophobic eutectic solvent includes hydrogen bond donors and hydrogen bond acceptors.

3. The magnetorheological fluid based on a eutectic mixture according to claim 2, characterized in that, The hydrogen bond donor is thymol or lauric acid, and the hydrogen bond acceptor is menthol.

4. The magnetorheological fluid based on a eutectic mixture according to claim 2, characterized in that, The molar percentage of the hydrogen bond donor and the hydrogen bond acceptor is 1:0.5 to 1:

2.

5. The magnetorheological fluid based on a eutectic mixture according to claim 1, characterized in that, The soft magnetic particles are carbonyl iron powder, iron(III) oxide, or cobalt-nickel particles.

6. The magnetorheological fluid based on a eutectic mixture according to claim 5, characterized in that, The soft magnetic particles are carbonyl iron powder.

7. The magnetorheological fluid based on a eutectic mixture according to claim 6, characterized in that, The carbonyl iron powder particles have a particle size of 1-10 μm.

8. A method for preparing a magnetorheological fluid based on a eutectic mixture according to any one of claims 1-7, characterized in that, The preparation method specifically includes the following steps: Step 1: Prepare a nonionic hydrophobic eutectic solvent. Specifically, stir and mix the hydrogen bond donor and the hydrogen bond acceptor under heating to obtain a nonionic hydrophobic eutectic solvent. Step 2: Weigh the required amount of raw materials. Specifically, by mass percentage, weigh 10%~40wt% of nonionic hydrophobic eutectic solvent and 60%~90wt% of soft magnetic particles; mix the nonionic hydrophobic eutectic solvent and the soft magnetic particles uniformly according to a certain mass ratio to obtain the magnetorheological fluid.

9. The method for preparing a magnetorheological fluid based on a eutectic mixture according to claim 8, characterized in that, The hydrogen bond donor and hydrogen bond acceptor are mixed and stirred at 500-1000 rpm for 2-3 hours at 60-80°C until a transparent and homogeneous liquid is formed.

10. The method for preparing a magnetorheological fluid based on a eutectic mixture according to claim 8, characterized in that, The nonionic hydrophobic eutectic solvent and the soft magnetic particles are mixed and then dispersed by ultrasound, vortexing or stirring; the frequency of the ultrasound dispersion is 200~240W and the dispersion time is 10~20 minutes.

11. A magnetorheological fluid based on a eutectic mixture prepared by the preparation method according to any one of claims 8-10.

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