Preparation method of mineral oil-based magnetorheological fluid

Abstract

The present invention discloses a method for preparing a mineral oil-based magnetorheological fluid, which relates to the technical field of preparing damping and vibration reduction materials. The method comprises the following steps: 1: activating carbonyl iron powder micron particles in dilute HCl; 2: coating the carbonyl iron powder with a silane coupling agent in alcohol / water; 3: ball-milling and coating Fe / Co nanomagnetic particles with oleic acid; and 4: adding the coated carbonyl iron powder, coated Fe / Co particles, and hydrophobic nano-SiO2 to mineral oil in a certain mass ratio, followed by mechanical stirring, to prepare the mineral oil-based magnetorheological fluid. The high-dispersion stability magnetorheological fluid prepared by this method exhibits a sedimentation rate of less than 5% after standing for three months, exhibiting good dispersion stability and suitable for applications in vibration reduction, damping, military industry, aerospace, and other fields.

Description

Technical Field

[0001] The invention relates to the technical field of preparation of damping and vibration reduction materials, and in particular to a method for preparing a mineral oil-based magnetorheological fluid. Background Art

[0002] Magnetorheological fluid (MRF) is a new type of intelligent material that can instantly transform from a liquid to a near-solid state under the influence of an external magnetic field. Conventional variable damping and microfluidic devices typically adjust damping or flow by controlling the number or size of channels, which often results in significant hysteresis in their behavior. To overcome these limitations, the unique properties of MRF can be utilized to replace hydraulic oil in conventional variable damping vibration reduction and microfluidic devices, effectively achieving these functions and aligning with current trends in intelligent development.

[0003] Magnetorheological fluid is usually composed of three parts: micron-sized magnetic powder, base carrier fluid, and additives. Due to the large density difference between the magnetic powder and the base carrier fluid and the poor compatibility between the two, the magnetic powder is prone to agglomeration and sedimentation during use, which directly affects the rheological effect of the magnetorheological fluid and greatly reduces its application effect. This is also one of the key issues that need to be urgently solved in the current research on the preparation of magnetorheological fluid.

[0004] Patent CN1632891A uses a ball milling method to mix carbonyl iron powder particles, mineral oil, organic bentonite contact, surfactant, and solid phase lubricant in a certain proportion and then ball mill to prepare the product. Since it is difficult for the components to coat the particles through chemical reactions, the dispersion stability of the prepared magnetorheological fluid cannot meet long-term application requirements.

[0005] Patent CN107057810A describes heating polyalphaolefin synthetic oil, adding a thixotropic agent, organobentonite, and stirring evenly. A copolymer solution containing acidic groups is then added as a surfactant and stirred evenly. Graphite, an antiwear agent, and sodium nitrite, an antioxidant, are then added and stirred evenly. Carbonyl iron powder is then added and dispersed at high speed for 1 hour to produce the finished magnetorheological fluid. Due to the micron-sized particles, chemical coating between the particles by the surfactant is difficult, making it difficult for the surfactant to form a chemical coating. Consequently, the dispersion stability of the resulting magnetorheological fluid cannot meet the requirements of long-term application.

[0006] Patent CN114551022A, magnetic nanoparticles and thermosetting high molecular polymer material (magnetic particles, composite accumulation magnetic nanoparticles, base carrier liquid, dispersant, anti-settling agent, lubricant, thixotropic agent, surfactant) mix and heat cure, and with solidification, again the particle cluster of solidification is broken, put into the ball milling jar that base carrier liquid is housed and ball mill for a long time again, after ball milling finishes, suspension is everywhere, utilize magnet repeatedly large particle (composite accumulation magnetic nanoparticles) to be sucked away, until suspension does not undergo solid-liquid separation, finally wash large particle repeatedly with deionized water and promptly obtain required composite accumulation magnetic nanoparticles. Similarly, this method is in the preparation process, and surfactant and particle are to coat under heating, is difficult to realize stronger chemical coating, therefore, when solidified particle is difficult to be evenly dispersed in the base liquid after ball milling, is difficult to prepare the magnetorheological fluid that can disperse stably for a long time.

[0007] Patent CN113972061A uses an oxidative precipitation method to prepare Fe3O4 micron powder. The powder surface is chemically treated and then stirred to allow strong chemical adsorption with carboxylic acids with multiple carboxyl functional groups. The coated powder is then dispersed in a high-viscosity dispersant oil through stirring, ultrasound, and ball milling to prepare a magnetorheological fluid with high dispersion stability. The particles prepared in this invention patent contain nanometer-sized particles. The smaller the particle size, the more conducive it is to stable dispersion in the base fluid. Therefore, no stratification occurs after centrifugation, and no stratification occurs after sedimentation for one month. Reducing the particle size can also have adverse effects, namely, a decrease in the magnetic properties of the particles. This results in the shear yield stress of the prepared magnetorheological fluid being reduced in a magnetic field, which is unfavorable for application.

[0008] This suggests that MR fluids prepared by simple mechanical mixing and physical interaction of magnetic powders, non-magnetic powders, and various additives exhibit a high sedimentation rate after standing for a period of time, and their dispersion stability cannot meet the requirements for long-term vibration reduction and damping applications. Furthermore, improving the dispersion stability of the MR fluid does not significantly reduce its field-induced shear yield stress. Summary of the Invention

[0009] Based on the problem of poor dispersion stability of existing magnetorheological fluids caused by powder agglomeration and sedimentation as pointed out in the background art, the purpose of the present invention is to provide a method for preparing a mineral oil-based magnetorheological fluid with high dispersion stability. The magnetorheological fluid with high dispersion stability prepared by this preparation method has a sedimentation rate of less than 5% after standing for three months, has good dispersion stability, and can be used in vibration reduction, damping, military industry, aerospace and other fields.

[0010] The present invention is achieved through the following technical solutions:

[0011] In a first aspect, the present invention provides a method for preparing a mineral oil-based magnetorheological fluid, comprising the following steps:

[0012] Step 1: Activate the carbonyl iron powder micron particles in diluted HCl;

[0013] Step 2: Coating the carbonyl iron powder with a silane coupling agent in alcohol / water;

[0014] Step 3: ball milling and coating of Fe / Co nanomagnetic particles using surfactant oleic acid;

[0015] Step 4: Add coated carbonyl iron powder, coated Fe / Co particles and hydrophobic nano-SiO2 into mineral oil in a certain mass ratio and stir mechanically to prepare a mineral oil-based magnetorheological fluid.

[0016] The principle of this technical solution is:

[0017] First, mineral oil is selected as the base carrier liquid. The surface of the carbonyl iron powder is first activated by hydrochloric acid to attach a large number of -OH functional groups to its surface. Then, a silane coupling agent is used to chemically coat the particle surface in alcohol / water. Oleic acid is used to chemically coat the nano-Fe / Co particles under ball milling. Nano-SiO2 is added to the mineral oil to realize its own condensation reaction. Nanoparticles replace part of the micron particles, effectively improving the dispersion stability, so that the prepared mineral oil-based magnetorheological fluid has high dispersion stability.

[0018] As a better embodiment of the present application, the ratio of carbonyl iron powder to dilute hydrochloric acid added in step 1 is (10g~50g): (10ml~100ml); wherein the dilute hydrochloric acid is diluted as follows: hydrochloric acid with a mass concentration of 36% is diluted with ultrapure water in a volume ratio of (10~20): (200~400).

[0019] Wherein, the stirring rate in step 1 is 600 rpm, the stirring time is 20 min, the temperature of the activation reaction is 40° C., and the particle size of the carbonyl iron powder is 1 to 5 μm.

[0020] As a preferred embodiment of the present application, in step 2, the carbonyl iron powder is coated with a silane coupling agent in alcohol / water, and the mass ratio of the silane coupling agent to the carbonyl iron powder is 1:(1-5).

[0021] Wherein, the coating time in step 2 is 1 to 3 hours, and the stirring rate is 300 to 500 r / min.

[0022] As a preferred embodiment of the present application, in step 2, the volume ratio of alcohol to water is (10-100): (50-400).

[0023] As a preferred embodiment of the present application, in step 3, the mass ratio of oleic acid to Fe / Co nanomagnetic particles is (1-10):1.

[0024] The ball milling time in step 3 is 10 to 48 hours, and the steel balls used are 12.7 mm GCr19 standard steel balls.

[0025] As a preferred embodiment of the present application, the particle size distribution range of the nano-silicon dioxide added in step 4 is 50 nm to 500 nm.

[0026] As a better implementation method in the present application, the total mass proportion of the coated carbonyl iron powder, coated Fe / Co particles and hydrophobic nano-SiO2 in step 4 is 1% to 10%.

[0027] As a better embodiment of the present application, in terms of mass percentage, the coated carbonyl iron powder in step 4: coated Ee / Co particles: hydrophobic nano-SiO2 are (50% to 95%): (1% to 5%): (1% to 10%).

[0028] As a preferred embodiment of the present application, the mechanical stirring rate in step 4 is 1000-2000 r / min, the time is 10-24 h, and the temperature is 50-80° C. The mass ratio of the total mass of the coated mixed powder to the mineral oil is 50%-80%.

[0029] In a second aspect, the present invention provides a mineral oil-based magnetorheological fluid prepared by any of the above-mentioned preparation methods.

[0030] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0031] (1) The micron carbonyl iron powder and nano metal powder in the magnetorheological fluid prepared by the present invention are both chemically coated. Moreover, by using a portion of nano powder to replace the micron powder, the Brownian motion of the nano powder can be utilized. Therefore, the magnetorheological fluid prepared after dispersion has high dispersion stability.

[0032] (2) The magnetorheological fluid prepared by the present invention also uses nano-silicon dioxide, which forms a network structure by utilizing its self-condensation reaction in the solution, which can also promote the dispersion stability of the magnetorheological fluid;

[0033] (3) The magnetorheological fluid prepared by the present invention has a simple and safe preparation process, the required materials are easily available, and the equipment requirements are also very low. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the following briefly introduces the drawings required for use in the examples. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be considered as limiting the scope. A person of ordinary skill in the art can also derive other relevant drawings based on these drawings without inventive effort. In the drawings:

[0035] Figure 1 This is a SEM image of the uncoated carbonyl iron powder described in Example 1 of the present invention;

[0036] Figure 2 This is a SEM image of the coated carbonyl iron powder described in Example 1 of the present invention;

[0037] Figure 3 2. Schematic diagram of the magnetorheological fluid in Example 1 of the present invention before and after application of a magnetic field, (a) without application of a magnetic field, (b) with application of a magnetic field;

[0038] Figure 4 The graph shows the dispersion stability of the magnetorheological fluids prepared in Examples 1 to 3 and Comparative Examples 1 to 4 of the present invention after sedimentation for three months. From left to right are the samples of Example 1, Example 2, Example 3, Comparative Example 1, Comparative Example 2, Comparative Example 3, and Comparative Example 4. DETAILED DESCRIPTION

[0039] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings herein can be arranged and designed in various different configurations.

[0040] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are intended to fall within the scope of protection of the present invention.

[0041] Example 1

[0042] This embodiment provides a method for preparing a mineral oil-based magnetorheological fluid, which is carried out according to the following steps:

[0043] S1. Dilute hydrochloric acid with a mass concentration of 36% and ultrapure water in a volume ratio of 10 ml:300 ml, activate the carbonyl iron powder micron particles in the diluted HCl, and add the carbonyl iron powder to the diluted hydrochloric acid in a ratio of 20 g:80 ml. In addition, the stirring rate is 600 rpm, the stirring time is 20 minutes, the activation reaction temperature is 40°C, and the particle size of the carbonyl iron powder is 1 to 5 μm.

[0044] S2. The carbonyl iron powder was coated with a silane coupling agent (dodecyltrimethoxysilane) in alcohol / water. The mass ratio of dodecyltrimethoxysilane to carbonyl iron powder was 1:4, the volume ratio of alcohol:water was 20 ml:300 ml, the coating time was 2 hours, and the stirring rate was 300 r / min.

[0045] S3. The Fe / Co nanomagnetic particles were ball-milled and coated with oleic acid. The mass ratio of oleic acid to Fe / Co nanomagnetic particles was 1:1. The ball milling time was 24 hours. The steel balls used were 12.7 mm GCr19 standard steel balls.

[0046] S4. Add carbonyl iron powder: SiO2: Fe / Co in a ratio of 90%:5%:5% by mass to mineral oil, wherein the total mass of the coated carbonyl iron powder, coated Fe / Co particles and hydrophobic nano-SiO2 accounts for 5%, wherein the particle size distribution range of nano-silicon dioxide is 50nm~500nm, and mechanical stirring is performed to prepare a magnetorheological fluid with high dispersion stability, wherein the mechanical stirring rate is 1000r / min, the time is 10 hours, the temperature is 70°C, and the mass ratio of the total mass of the coated mixed powder to the mineral oil is 70%.

[0047] After the magnetorheological fluid prepared in Example 1 was left to stand for three months, the sedimentation rate was 4%. Figure 4 As shown, it shows that the prepared magnetorheological fluid has high dispersion stability.

[0048] like Figure 1 , which is a SEM image of the uncoated carbonyl iron powder in Example 1; it can be seen from the image that the surface of the uncoated carbonyl iron powder particles is smooth and there is no obvious agglomeration between the particles.

[0049] like Figure 2 As shown, this is an SEM image of the coated carbonyl iron powder in Example 1; it can be seen from the figure that obvious flocs appear on the surface of the coated carbonyl iron powder particles, and some particles agglomerate, which is caused by the action of the surfactant causing adhesion between the particles. Figure 1 and Figure 2 The comparison shows that the active agent is effectively coated on the surface of the particles.

[0050] like Figure 3Figures 2 and 3 show the magnetorheological fluid in Example 1 before and after a magnetic field is applied: (a) without a magnetic field, and (b) with a magnetic field. As shown in Figure (a), before the magnetic field is applied, the magnetorheological fluid appears as a black, flowing liquid, similar to a conventional black colloid. However, after the magnetic field is applied, the magnetorheological fluid's surface develops a transient, spiky structure, deteriorating its fluidity and approaching a semi-solid state. This transformation from a liquid to a near-solid state before and after the magnetic field is applied effectively addresses the turbine shaft vibration issue by utilizing this difference in rheological properties.

[0051] Example 2

[0052] This embodiment provides a method for preparing a mineral oil-based magnetorheological fluid, which is carried out according to the following steps:

[0053] S1. Dilute hydrochloric acid with a mass concentration of 36% and ultrapure water in a volume ratio of 20 ml:400 ml, activate the carbonyl iron powder micron particles in the diluted hydrochloric acid, and add the carbonyl iron powder to the diluted hydrochloric acid in a ratio of 40 g:50 ml. In addition, the stirring rate is 600 rpm, the stirring time is 20 minutes, the activation reaction temperature is 40°C, and the particle size of the carbonyl iron powder is 1 to 5 μm.

[0054] S2. The carbonyl iron powder was coated with a silane coupling agent (dodecyltrimethoxysilane) in alcohol / water. The mass ratio of dodecyltrimethoxysilane to carbonyl iron powder was 1:3, the volume ratio of alcohol:water was 20 ml:400 ml, the coating time was 3 hours, and the stirring rate was 400 r / min.

[0055] S3. Fe / Co nanomagnetic particles were ball-milled and coated with oleic acid. The mass ratio of oleic acid to Fe / Co nanomagnetic particles was 3:1. The ball-milling time was 48 hours. The steel balls used were 12.7 mm GCr19 standard steel balls.

[0056] S4. Add carbonyl iron powder: SiO2: Fe / Co in a ratio of 85%:5%:10% by mass to mineral oil, wherein the total mass of the coated carbonyl iron powder, coated Fe / Co particles and hydrophobic nano-SiO2 accounts for 1%, and the particle size distribution range of nano-silicon dioxide is 50nm~500nm, to prepare a magnetorheological fluid with high dispersion stability, wherein the mechanical stirring rate is 2000r / min, the time is 24 hours, the temperature is 80℃, and the mass ratio of the total mass of the coated mixed powder to the mineral oil is 80%.

[0057] After the magnetorheological fluid prepared in Example 2 was left to stand for three months, the sedimentation rate was 4.5%, indicating that the magnetorheological fluid prepared had high dispersion stability.

[0058] Example 3

[0059] This embodiment provides a method for preparing a mineral oil-based magnetorheological fluid, which is carried out according to the following steps:

[0060] S1. Dilute hydrochloric acid with a mass concentration of 36% and ultrapure water in a volume ratio of 15 ml:300 ml, activate the carbonyl iron powder micron particles in the diluted HCl, and add the carbonyl iron powder to the diluted hydrochloric acid in a ratio of 50 g:100 ml. In addition, the stirring rate is 600 rpm, the stirring time is 20 minutes, the activation reaction temperature is 40°C, and the particle size of the carbonyl iron powder is 1 to 5 μm.

[0061] S2. The carbonyl iron powder was coated with a silane coupling agent (dodecyltrimethoxysilane) in alcohol / water. The mass ratio of dodecyltrimethoxysilane to carbonyl iron powder was 1:1, the volume ratio of alcohol:water was 12 ml:300 ml, the coating time was 2 hours, and the stirring rate was 300 r / min.

[0062] S3. The Fe / Co nanomagnetic particles were coated by ball milling using oleic acid. The mass ratio of oleic acid to Fe / Co nanomagnetic particles was 5:1. The ball milling time was 25 hours. The steel balls used were 12.7 mm GCr19 standard steel balls.

[0063] S4. Add carbonyl iron powder: SiO2: Fe / Co into mineral oil in a ratio of 50%:1%:10% by mass, wherein the total mass of the coated carbonyl iron powder, coated Fe / Co particles and hydrophobic nano-SiO2 accounts for 10%, and the particle size distribution range of nano-silicon dioxide is 50nm~500nm. Mechanical stirring is carried out to prepare a magnetorheological fluid with high dispersion stability, wherein the mechanical stirring rate is 1500r / min, the time is 10 hours, the temperature is 50°C, and the mass ratio of the total mass of the coated mixed powder to the mineral oil is 50%.

[0064] After the magnetorheological fluid prepared in Example 3 was left to stand for three months, the sedimentation rate was 5%. Figure 4 As shown, it shows that the prepared magnetorheological fluid has high dispersion stability.

[0065] Example 4

[0066] This embodiment provides a method for preparing a mineral oil-based magnetorheological fluid. Unlike Example 1, the ratio of carbonyl iron powder to dilute hydrochloric acid in step S1 is 10 g:10 ml. Other steps and process conditions are the same as those in Example 1.

[0067] Follow these steps:

[0068] S1. Dilute hydrochloric acid with a mass concentration of 36% and ultrapure water in a volume ratio of 10 ml:300 ml, activate the carbonyl iron powder micron particles in the diluted HCl, and add the carbonyl iron powder in a ratio of 10 g:10 ml of dilute hydrochloric acid. In addition, the stirring rate is 600 rpm, the stirring time is 20 minutes, the activation reaction temperature is 40°C, and the particle size of the carbonyl iron powder is 1 to 5 μm.

[0069] S2. The carbonyl iron powder was coated with a silane coupling agent (dodecyltrimethoxysilane) in alcohol / water. The mass ratio of dodecyltrimethoxysilane to carbonyl iron powder was 1:4, the volume ratio of alcohol:water was 20 ml:300 ml, the coating time was 2 hours, and the stirring rate was 300 r / min.

[0070] S3. The Fe / Co nanomagnetic particles were coated by ball milling using oleic acid. The mass ratio of oleic acid to Fe / Co nanomagnetic particles was 10:1. The ball milling time was 24 hours. The steel balls used were 12.7 mm GCr19 standard steel balls.

[0071] S4. Add carbonyl iron powder: SiO2: Fe / Co in a ratio of 90%:5%:5% by mass to mineral oil, wherein the total mass of the coated carbonyl iron powder, coated Fe / Co particles and hydrophobic nano-SiO2 accounts for 5%, wherein the particle size distribution range of nano-silicon dioxide is 50nm~500nm, and mechanical stirring is performed to prepare a magnetorheological fluid with high dispersion stability, wherein the mechanical stirring rate is 1000r / min, the time is 10 hours, the temperature is 70°C, and the mass ratio of the total mass of the coated mixed powder to the mineral oil is 70%.

[0072] It was determined that the magnetorheological fluid prepared in this embodiment had a sedimentation rate of 4% after standing for three months, the same as that in Example 1, indicating that the magnetorheological fluid prepared in this embodiment had high dispersion stability.

[0073] Example 5

[0074] This embodiment provides a method for preparing a mineral oil-based magnetorheological fluid. The difference from Example 1 is that in step 2 of this embodiment, the mass ratio of the silane coupling agent to the carbonyl iron powder is 1:5. The other steps and process conditions are the same as those in Example 1. The following steps are performed:

[0075] S1. Dilute hydrochloric acid with a mass concentration of 36% and ultrapure water in a volume ratio of 10 ml:300 ml, activate the carbonyl iron powder micron particles in the diluted HCl, and add the carbonyl iron powder to the diluted hydrochloric acid in a ratio of 20 g:80 ml. In addition, the stirring rate is 600 rpm, the stirring time is 20 minutes, the activation reaction temperature is 40°C, and the particle size of the carbonyl iron powder is 1 to 5 μm.

[0076] S2. The carbonyl iron powder was coated with a silane coupling agent (dodecyltrimethoxysilane) in alcohol / water. The mass ratio of dodecyltrimethoxysilane to carbonyl iron powder was 1:5, the volume ratio of alcohol:water was 20 ml:300 ml, the coating time was 2 hours, and the stirring rate was 300 r / min.

[0077] S3. The Fe / Co nanomagnetic particles were coated by ball milling using oleic acid. The mass ratio of oleic acid to Fe / Co nanomagnetic particles was 8:1. The ball milling time was 24 hours. The steel balls used were 12.7 mm GCr19 standard steel balls.

[0078] S4. Add carbonyl iron powder: SiO2: Fe / Co in a ratio of 90%:5%:5% by mass to mineral oil, wherein the total mass of the coated carbonyl iron powder, coated Fe / Co particles and hydrophobic nano-SiO2 accounts for 5%, wherein the particle size distribution range of nano-silicon dioxide is 50nm~500nm, and mechanical stirring is performed to prepare a magnetorheological fluid with high dispersion stability, wherein the mechanical stirring rate is 1000r / min, the time is 10 hours, the temperature is 70°C, and the mass ratio of the total mass of the coated mixed powder to the mineral oil is 70%.

[0079] It was determined that the magnetorheological fluid prepared in this example had a sedimentation rate of 4.5% after standing for three months, the same as that in Example 2, indicating that the magnetorheological fluid prepared in this example had high dispersion stability.

[0080] Example 6

[0081] This example provides a method for preparing a mineral oil-based magnetorheological fluid. Unlike Example 1, the mass ratio of oleic acid to Fe / Co nanomagnetic particles in this example is 1:10. Other steps and process conditions are the same as those in Example 1. The following steps are performed:

[0082] S1. Dilute hydrochloric acid with a mass concentration of 36% and ultrapure water in a volume ratio of 10 ml:300 ml, activate the carbonyl iron powder micron particles in the diluted HCl, and add the carbonyl iron powder to the diluted hydrochloric acid in a ratio of 20 g:80 ml. In addition, the stirring rate is 600 rpm, the stirring time is 20 minutes, the activation reaction temperature is 40°C, and the particle size of the carbonyl iron powder is 1 to 5 μm.

[0083] S2. The carbonyl iron powder was coated with a silane coupling agent (dodecyltrimethoxysilane) in alcohol / water. The mass ratio of dodecyltrimethoxysilane to carbonyl iron powder was 1:4, the volume ratio of alcohol:water was 20 ml:300 ml, the coating time was 2 hours, and the stirring rate was 300 r / min.

[0084] S3. The Fe / Co nanomagnetic particles were coated by ball milling using oleic acid. The mass ratio of oleic acid to Fe / Co nanomagnetic particles was 6:1. The ball milling time was 24 hours. The steel balls used were 12.7 mm GCr19 standard steel balls.

[0085] S4. Add carbonyl iron powder: SiO2: Fe / Co in a ratio of 90%:5%:5% by mass to mineral oil, wherein the total mass of the coated carbonyl iron powder, coated Fe / Co particles and hydrophobic nano-SiO2 accounts for 5%, wherein the particle size distribution range of nano-silicon dioxide is 50nm~500nm, and mechanical stirring is performed to prepare a magnetorheological fluid with high dispersion stability, wherein the mechanical stirring rate is 1000r / min, the time is 10 hours, the temperature is 70°C, and the mass ratio of the total mass of the coated mixed powder to the mineral oil is 70%.

[0086] It was determined that the magnetorheological fluid prepared in this embodiment had a sedimentation rate of 5% after standing for three months, the same as that in Example 3, indicating that the magnetorheological fluid prepared in this embodiment had high dispersion stability.

[0087] Comparative Example 1

[0088] This comparative example provides a method for preparing a magnetorheological fluid. The specific preparation method is basically the same as that of Example 1. The difference between the two is that hydrochloric acid is not used to corrode the particles in step S1, and the conditions of the remaining steps are the same as those of Example 1.

[0089] The magnetorheological fluid prepared in Comparative Example 1 was left to stand for three months, and the sedimentation rate was as high as 22%. Figure 4 As shown, the dispersion stability of the prepared magnetorheological fluid is very poor.

[0090] Comparative Example 2

[0091] This comparative example provides a method for preparing a magnetorheological fluid. The specific preparation method is basically the same as that of Example 1. The difference between the two is that ethanol is not used in step S2, and the conditions of the other steps are the same as those of Example 1.

[0092] The magnetorheological fluid prepared in Comparative Example 2 was left to stand for three months, and the sedimentation rate was as high as 20%. Figure 4 As shown, the dispersion stability of the prepared magnetorheological fluid is very poor.

[0093] Comparative Example 3

[0094] This comparative example provides a method for preparing a magnetorheological fluid. The specific preparation method is basically the same as that of Example 1. The difference between the two is that oleic acid is not used for coating in step S3, and the conditions of the remaining steps are the same as those of Example 1.

[0095] The magnetorheological fluid prepared in Comparative Example 3 was left to stand for three months, and the sedimentation rate was as high as 18%. Figure 4 As shown, the dispersion stability of the prepared magnetorheological fluid is very poor.

[0096] Comparative Example 4

[0097] This comparative example provides a method for preparing a magnetorheological fluid. The specific preparation method is basically the same as that of Example 1. The difference between the two is that SiO2 is not added in step S4, and the conditions of the other steps are the same as those of Example 1.

[0098] The magnetorheological fluid prepared in Comparative Example 4 was left to stand for three months, and the sedimentation rate was as high as 21%. Figure 4 As shown, the dispersion stability of the prepared magnetorheological fluid is very poor.

[0099] from Figure 4 It can be seen from the sedimentation results of the embodiments and comparative examples shown in the table that the dispersion stability of the magnetorheological fluid prepared under different reaction conditions after sedimentation for three months showed obvious differences. Only by preparing according to the preparation method and process conditions in this application can a magnetorheological fluid with high dispersion stability be obtained, which not only improves the dispersion stability of the magnetorheological fluid, but also has a higher field-induced shear yield stress.

[0100] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a mineral oil-based magnetorheological fluid, characterized in that: The following steps are involved: Step 1: Activate the carbonyl iron powder micron particles in diluted HCl; Step 2: Coating the carbonyl iron powder with a silane coupling agent in alcohol / water; Step 3: ball milling and coating of Fe / Co nanomagnetic particles using surfactant oleic acid; Step 4: Add coated carbonyl iron powder, coated Fe / Co particles and hydrophobic nano-SiO2 into mineral oil in a certain mass ratio and mechanically stir to prepare a mineral oil-based magnetorheological fluid; The ratio of carbonyl iron powder to dilute hydrochloric acid added in step 1 is (10g~50g): (10ml~100ml); the dilute hydrochloric acid is diluted as follows: hydrochloric acid with a mass concentration of 36% is diluted with ultrapure water in a volume ratio of (10~20): (200~400); In step 2, the carbonyl iron powder is coated with a silane coupling agent in alcohol / water, and the mass ratio of the silane coupling agent to the carbonyl iron powder is 1:(1-5); In step 3, the mass ratio of surfactant oleic acid to Fe / Co nanomagnetic particles is (1-10):1; By mass percentage, the coated carbonyl iron powder in step 4: coated Fe / Co particles: hydrophobic nano-SiO2 are (50%~95%): (1%~5%): (1%~10%).

2. The method for preparing a mineral oil-based magnetorheological fluid according to claim 1, characterized in that: In step 2, the volume ratio of alcohol to water is (10~100):(50~400).

3. The method for preparing a mineral oil-based magnetorheological fluid according to claim 1, characterized in that: The particle size distribution range of the nano-silicon dioxide added in step 4 is 50nm~500nm.

4. The method for preparing a mineral oil-based magnetorheological fluid according to claim 1, characterized in that: In step 4, the total mass of the coated carbonyl iron powder, coated Fe / Co particles and hydrophobic nano-SiO2 accounts for 1% to 10%.

5. The method for preparing a mineral oil-based magnetorheological fluid according to claim 1, characterized in that: The mechanical stirring rate in step 4 is 1000-2000 r / min, the time is 10-24 h, and the temperature is 50-80°C.

6. A mineral oil-based magnetorheological fluid, characterized in that: The method is prepared according to any one of claims 1 to 5.

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