Magnetorheological fluid based on eutectic mixture and preparation method thereof

Abstract

The invention discloses magnetorheological fluid based on a eutectic mixture and a preparation method of the magnetorheological fluid. The magnetorheological fluid comprises nonionic hydrophobic eutectic solvent base fluid and soft magnetic particles, wherein the nonionic hydrophobic deep-eutectic solvent has rich non-covalent intermolecular acting force, the sedimentation rate of the soft magnetic particles in the base fluid can be remarkably improved, and the shear yield stress of the magnetorheological fluid is improved. The preparation method comprises the following steps in percentage by mass: 10-40wt% of a nonionic hydrophobic deep-eutectic solvent; and 60-90 wt% of soft magnetic particles. The magnetorheological fluid prepared by the invention has the advantages of low zero magnetic field viscosity, high shear yield stress in a saturated magnetic field, simple preparation method, good environmental adaptability and the like, and is suitable for the field of vibration reduction in severe environments such as aerospace and off-road vehicles.

Description

Technical Field

[0001] The invention relates to the technical field of magnetorheological fluid vibration reduction, and in particular to a magnetorheological fluid based on a low eutectic mixture and a preparation method thereof. Background Art

[0002] Magnetorheological Fluid (MRF) is a new type of smart material. In the absence of a magnetic field, magnetic particles are freely suspended in a base fluid, and the fluid exhibits normal fluidity 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 lines of force. The presence of these chain structures causes the viscosity of the liquid to increase dramatically, thereby increasing the friction inside the liquid. Since the chain structure formed by the magnetic particles increases the viscosity of the liquid, the liquid encounters greater resistance when passing through a pipe or through a shock absorber, thereby increasing the damping force.

[0003] In the prior art, due to the large difference in density between the magnetic particles and the base liquid, the magnetic particles may settle during long-term standing or storage, resulting in liquid stratification. In addition, the magnetic particles may agglomerate when there is no external magnetic field, affecting their arrangement in the magnetic field and the formation of chain structures. These phenomena will directly affect 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 will also bring about the problem of decreased magnetism of the magnetic particles, thereby reducing the magnetorheological effect of the magnetorheological fluid. Summary of the invention

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

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The invention provides a magnetorheological fluid based on a low eutectic mixture, which comprises, by weight percentage, 10-40 wt% of a non-ionic hydrophobic low eutectic solvent and 60-90 wt% of soft magnetic particles.

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

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

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

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

[0011] Furthermore, the soft magnetic particles are soft magnetic particles such as carbonyl iron powder, ferroferric oxide, cobalt nickel, etc.

[0012] Furthermore, the particle size of the carbonyl iron powder particles is 1-10 μm;

[0013] The present invention also provides a method for preparing a magnetorheological fluid based on a eutectic mixture, which specifically comprises the following steps:

[0014] Step 1, preparing a non-ionic hydrophobic deep eutectic solvent, specifically, stirring and dissolving a hydrogen bond donor and a hydrogen bond acceptor under heating to obtain a non-ionic hydrophobic deep eutectic solvent;

[0015] Step 2, weighing the required amount of raw materials, specifically, in terms of mass percentage, weighing 10% to 40wt% of a non-ionic hydrophobic low eutectic solvent and 60% to 90wt% of soft magnetic particles; uniformly mixing the non-ionic hydrophobic low eutectic solvent and the soft magnetic particles in a certain mass ratio to obtain the magnetorheological fluid.

[0016] Furthermore, the hydrogen bond donor and the hydrogen bond acceptor are mixed and stirred at 60-80° C. and 500-1000 rpm for 0.5-1 hour until a transparent and uniform liquid is formed.

[0017] Furthermore, the non-ionic hydrophobic low eutectic solvent and the soft magnetic particles are mixed and then dispersed using ultrasound; the frequency of the ultrasonic dispersion is 200 to 240 W, and the dispersion time is 10 to 20 minutes.

[0018] The magnetorheological fluid is prepared by using the above-mentioned method for preparing a magnetorheological fluid based on a low eutectic mixture.

[0019] The technical solution of the present invention has the following beneficial effects:

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

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

[0022] In order to more clearly illustrate the specific implementation of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the specific implementation or the prior art description. It should be understood that the drawings described below are only some implementations of the present invention. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work. In the drawings:

[0023] Figure 1 The graphs of shear stress of the magnetorheological fluids of Examples 1-3 and Comparative Example 1 as a function of shear rate are shown;

[0024] Figure 2 The graph showing the change of the yield stress of the magnetorheological fluid of Examples 1-3 and Comparative Example 1 with the magnetic field intensity;

[0025] Figure 3 This is a comparison diagram of Examples 1-3 and Comparative Example 1 after settling for 5 hours;

[0026] Figure 4 The graph of the sedimentation rate of the magnetorheological fluid of Examples 1-3 and Comparative Example 1 changing with time. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific implementation methods. It should be understood that these embodiments are only part of the embodiments of the present invention, rather than all of the embodiments.

[0028] The instruments, reagents and consumables used in the examples without indicating the manufacturer can all be purchased from commercial companies.

[0029] The carbonyl iron powder particles used in the examples and comparative examples were from BASF AG, Germany, with a particle size of 3-4 μm; the silicone oil was from Shin-Etsu Chemical Co., Ltd., with a particle size of 20 cst.

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

[0031] Table 1. Combinations of hydrogen bond donors and hydrogen bond acceptors in the non-ionic hydrophobic deep eutectic solvents of Examples 1-3.

[0032]

[0033] A method for preparing a magnetorheological fluid based on a low eutectic mixture comprises the following steps: step 1, preparing a non-ionic hydrophobic low eutectic solvent, specifically, stirring and dissolving a hydrogen bond donor and a hydrogen bond acceptor under heating at 80° C. as shown in Table 1 until a transparent and uniform liquid is formed to obtain a non-ionic hydrophobic low eutectic solvent; step 2, mixing carbonyl iron powder particles with the non-ionic hydrophobic low eutectic solvents of Examples 1-3 respectively and stirring them evenly to obtain the magnetorheological fluid, wherein the mass fraction of carbonyl iron powder particles in the magnetorheological fluid is 60wt%.

[0034] Comparative Example 1

[0035] The preparation method provided in this comparative example is the same as that in Examples 1-3, except that the base liquid in this comparative example is silicone oil.

[0036] Test Example 1

[0037] A parallel plate rheometer (MCR 302, Anton Paar) was used to test the shear stress τ of the magnetorheological fluid at different magnetic induction intensities as a function of shear rate. The test temperature is constant at 25°C, and the shear rate is set The range of variation is 0.1-100s -1 , steady-state shearing, current 0-2A increase by 0.2A, magnetic field strength 0-490mT, test results are as follows Figure 1 In zero magnetic field, the shear stress of Examples 1-3 and Comparative Example 1 is relatively close. In saturated magnetic field, the shear stress of the magnetorheological fluid of Examples 1-3 is higher than that of Comparative Example 1, indicating that the variable damping performance of Examples 1-3 is better than that of Comparative Example 1.

[0038] The shear rate-shear stress of the magnetorheological fluids of Examples 1-3 and Comparative Example 1 was fitted using the Bingham plasticity model to obtain the yield stress of the magnetorheological fluids under different magnetic field intensities, such as Figure 2 The yield stress of the magnetorheological fluids of Examples 1-3 is higher than that of Comparative Example 1, indicating that the rheological properties of Examples 1-3 are better than those of Comparative Example 1.

[0039] The sedimentation analysis method was used to evaluate the anti-sedimentation stability of the magnetorheological fluids of Examples 1-3 and Comparative Example 1. Specifically, the magnetorheological fluids were poured into cuvettes, and the sedimentation of the magnetorheological fluids at different time points was observed at room temperature. The anti-sedimentation stability of the magnetorheological fluids was evaluated by measuring the sedimentation distance and the corresponding sedimentation time. The sedimentation volume ratio was defined by the percentage of the sedimentation distance relative to the entire fluid height, such as Figure 3 and Figure 4 The anti-sedimentation stability performance of Examples 1-3 is better than that of Comparative Example 1.

[0040] The embodiments described above are only preferred examples of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A magnetorheological fluid based on a eutectic mixture, characterized in that: Calculated by weight percentage, it includes: 10-40wt% of non-ionic hydrophobic low eutectic solvent and 60-90wt% of soft magnetic particles.

2. A magnetorheological fluid based on a eutectic mixture according to claim 1, characterized in that: The non-ionic hydrophobic deep eutectic solvent includes a hydrogen bond donor and a hydrogen bond acceptor.

3. A magnetorheological fluid based on a eutectic mixture according to claim 1, characterized in that: The hydrogen bond donor is thymol or lauric acid, preferably thymol, and the hydrogen bond acceptor is menthol.

4. A magnetorheological fluid based on a eutectic mixture according to claim 1, 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, ferroferric oxide or cobalt nickel particles, preferably carbonyl iron powder.

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

7. A method for preparing a magnetorheological fluid based on a eutectic mixture according to claims 1-6, characterized in that: The preparation method specifically comprises the following steps: Step 1, preparing a non-ionic hydrophobic deep eutectic solvent, specifically, stirring and dissolving a hydrogen bond donor and a hydrogen bond acceptor under heating to obtain a non-ionic hydrophobic deep eutectic solvent; Step 2, weighing the required amount of raw materials, specifically, in terms of mass percentage, weighing 10% to 40wt% of a non-ionic hydrophobic low eutectic solvent and 60% to 90wt% of soft magnetic particles; uniformly mixing the non-ionic hydrophobic low eutectic solvent and the soft magnetic particles in a certain mass ratio to obtain the magnetorheological fluid.

8. The method for preparing a magnetorheological fluid based on a eutectic mixture according to claim 7, characterized in that: After the hydrogen bond donor and the hydrogen bond acceptor are mixed, they are stirred at 60-80° C. and 500-1000 rpm for 2-3 hours until a transparent and uniform liquid is formed.

9. The method for preparing a magnetorheological fluid based on a eutectic mixture according to claim 7, characterized in that: The nonionic hydrophobic low eutectic solvent and the soft magnetic particles are mixed and dispersed by ultrasound, vortex or stirring; the frequency of the ultrasonic dispersion is 200 to 240 W, and the dispersion time is 10 to 20 minutes.

10. A magnetorheological fluid based on a eutectic mixture prepared according to the method of any one of claims 1 to 9.

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