WO2022121774A1

WO2022121774A1 - Composite magnetorheological fluid

Info

Publication number: WO2022121774A1
Application number: PCT/CN2021/135148
Authority: WO
Inventors: 秦浩; 梁燕玲
Original assignee: 深圳博海新材料技术有限公司
Priority date: 2020-12-07
Filing date: 2021-12-02
Publication date: 2022-06-16
Also published as: CN112687446A

Abstract

A composite magnetorheological fluid, comprising: anisotropic magnetic particles, the content of which is in the range of 0.05-5% of the total weight of the composite magnetorheological fluid; isotropic magnetic particles of a micron scale, the content of which is in the range of 70-90% of the total weight of the composite magnetorheological fluid; and a carrier liquid and an additive added to the carrier liquid, the content of which is the balance of the composite magnetorheological fluid. The composite magnetorheological fluid retains excellent mechanical properties of the anisotropic magnetorheological fluid under a magnetic field, and also gives consideration to good fluidity of a traditional magnetorheological fluid under a zero magnetic field, the fluid has a stable and wide second Newton area, and the initial kinematic viscosity of the fluid is low, so that a control range of the magnetorheological device is wider and more stable.

Description

Composite magnetorheological fluid

This application claims the priority of the Chinese invention patent application "composite magnetorheological fluid" with the application number CN202011436456.4 filed in China on December 7, 2020, the entire contents of which are incorporated herein by reference Applying.

technical field

The present invention relates to the technical field of magnetorheological fluids. More specifically, the present invention relates to the preparation of composite magnetorheological fluids using a combination of isotropic and anisotropic magnetic powders.

Background technique

A magnetorheological fluid is a liquid whose viscosity changes with the application of a magnetic field. It is a stable suspension system composed of soft magnetic particles with high magnetic permeability and low remanence dispersed uniformly in a non-magnetic carrier liquid through the action of surfactants. The working principle of magnetorheological fluid is: under the action of an external magnetic field, each particle is polarized into a magnetic dipole, each dipole attracts each other, and the chain-like structure formed between the two magnetic pole plates crosses like a bridge. Between the plates, the normal flow of fluid is impeded, giving it a solid-like characteristic. When the external magnetic field is removed, the fluid returns to its original state, that is, the magnetorheological fluid undergoes rapid and reversible conversion between liquid and solid. The degree of solidification has a stable and reversible relationship with the current intensity, that is, by controlling the current intensity, the shear yield strength of the solidified magnetorheological fluid can be precisely controlled.

Magnetorheological fluids have been studied for many years and have been gradually applied to control damping force in various devices, such as shock absorbers, shock absorbers, human prostheses and elastic seats. The rheology of magnetorheological fluid under the action of a magnetic field is instantaneous and reversible, and its shear yield strength after rheology has a stable corresponding relationship with the magnetic field strength, which is very easy to realize intelligent control. Therefore, magnetorheological fluid is a kind of intelligent material with wide application and excellent performance, and the application field of magnetorheological fluid is expanding rapidly.

The traditional magnetorheological fluid has the phenomenon of remanence, and the magnetically responsive particles with residual magnetism dispersed in the magnetorheological fluid cannot completely return to the free-flowing state due to the residual magnetism of the particles after the magnetic field is removed, which interferes with the magnetic field. Control process of rheological fluid working devices. The existence of residual magnetism is a common problem in the existing technology, and this defect will become more prominent with the delay of use time, which will not only lead to poor performance of the magnetorheological fluid and its application equipment, but also cause the fluid or equipment. Control response performance and reliability are low, and there are also disadvantages of short service life.

In order to reduce the coercive force, conventional magnetorheological fluids tend to increase the particle size of the magnetic particles, such as set to micron scale, for example, see US Pat. Easy to settle in rheological fluids. The settling of the magnetic particles directly leads to the short service life, low reliability and ultimately the failure of the magnetorheological fluid.

In addition, the traditional magnetorheological fluid not only has poor anti-settling performance, but also its shear strength performance needs to be improved. Compared with No. 201510538070.7 and No. 201510537836.X and PCT application WO 2017036337 A1), under the same volume percentage of the magnetic powder particle content, the shear strength is lower than that of the nano-MR fluid invented by the inventor. Therefore, when applied to the electromagnetic suspension of automobiles, for example, the excitation coil of the magnetorheological fluid damping tube containing the traditional magnetorheological fluid must adopt the configuration of double coils, which makes the magnetorheological fluid damping tube not only difficult to Miniaturization and higher cost; if the single-coil configuration is used, the response time of the MRF damping tube to vibration is longer, which is suitable for MRF damping devices that need to respond quickly to vibration is unacceptable.

In the nano magnetorheological fluid invented by the inventor before, the anisotropic magnetic powder has a higher magnetic saturation and a faster response speed, so the anisotropic magnetic powder has a stronger binding force in the chain under the magnetic field, so the anisotropic magnetic powder has a stronger binding force. Magnetorheological fluids can provide stronger shear yield strength under the action of a magnetic field.

However, nano-MR fluids still have their inherent defects, such as long preparation time, complicated procedures, high environmental protection requirements, and higher material costs, resulting in higher costs than traditional MR fluids. In addition, the specific surface area (specific surface energy) of the anisotropic magnetic powder is large, so the magnetorheological fluid is thicker, the second Newton zone of the magnetorheological fluid is large, the initial force is large, and the controllable range is limited to a certain extent. Anisotropic magnetic powder may affect the flow performance of magnetorheological fluid at high shear rate under zero magnetic field because of its anisotropic shape, such as large aspect ratio, making the second Newton zone unstable under zero magnetic field, which is not conducive to device control and Vibration control. The so-called second Newtonian zone means that the non-Newtonian fluid will exhibit the properties of Newtonian fluid under high shear rate, that is, the viscosity is constant, the shear force increases linearly with the increase of the shear rate, and the second Newtonian zone is due to the constant kinematic viscosity. , which is beneficial to control, so it is the main control area of magnetorheological fluid.

In view of the foregoing and other concepts, the present invention has been made.

The information included in this Background section of the description of the invention, including any references cited herein and any description or discussion thereof, is included for technical reference purposes only and is not considered to be Subject matter that limits the scope of the invention.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above and other further concepts. The present invention aims to solve the above technical deficiencies and other problems.

In this regard, the present invention contemplates a better solution to the above technical problems, as well as other technical problems, by mixing different magnetic powders to prepare magnetorheological fluids to achieve more advantages, especially in terms of cost and overall performance advantages, and a wider range of application scenarios.

Anisotropic magnetic powder has higher magnetic saturation and faster response speed, so the chain of anisotropic magnetic powder has stronger binding force under the magnetic field, so the anisotropic magnetorheological fluid can provide stronger force under the action of magnetic field. However, the anisotropic magnetorheological fluid also has its shortcomings, such as material cost and process cost defects, the specific surface area (and specific surface energy) of the anisotropic magnetic powder is large, so the magnetorheological fluid is relatively Thick, the second Newton zone of the magnetorheological fluid is large, the initial force is large, and the controllable range is limited to a certain extent. Due to the anisotropy of the shape, the anisotropic magnetic powder has a large aspect ratio, which affects the high shear rate flow performance of the magnetorheological fluid under zero magnetic field, making the second Newton zone unstable under zero magnetic field, which is not conducive to control.

The present invention proposes that the composite magnetorheological fluid of the present invention is prepared by using a combination of anisotropic magnetic powder and common isotropic magnetic powder in a certain proportion, mixed with carrier liquid and other additives. In other words, the anisotropic magnetic powder can be added to the conventional magnetorheological fluid to obtain the composite magnetorheological fluid of the present invention, which can form a structure similar to "reinforced cement" or so-called "fiber-reinforced composite material" under a magnetic field. A structure in which anisotropic magnetic powders that can rapidly form chains (or "bridges") in the direction of magnetic lines of force under the action of a magnetic field are similar to "steel bars", and isotropic magnetic powders are similar to "cement". Under the magnetic field, the anisotropic magnetic powder in the composite magnetorheological fluid quickly forms a chain, and the isotropic magnetic powder and the adjacent isotropic magnetic powder are connected by magnetic attraction, forming a "interweaving" similar to the "reinforced cement" structure. Compared with the traditional magnetorheological fluid, its binding force is larger, the response to the magnetic field is faster, and the shape is more stable. And the magnetorheological fluid of the present invention can provide higher shear strength. At the same time, the magnetorheological fluid of the present invention can at least partially overcome the above-mentioned disadvantages of anisotropic magnetorheological fluids, and can at least partially maintain the advantages of conventional magnetorheological fluids compared with conventional magnetorheological fluids. Compared with the improved anti-settling.

According to an aspect of the present invention, a composite magnetorheological fluid is provided, comprising: anisotropic magnetic powder, the content of which is in the range of 0.05-5% of the total weight of the composite magnetorheological fluid; microns A scaled isotropic magnetic powder, the content of which is in the range of 70-90% of the total weight of the composite magnetorheological fluid; and a carrier liquid and an additive added to the carrier liquid, the content of which is the The balance of the composite magnetorheological fluid.

According to an embodiment, the isotropic magnetic powder is iron powder with a particle size in the range of about 0.1-50 microns, for example in the range of about 0.1-20 microns, 0.2-10 microns or 0.2-5 microns.

According to an embodiment, the anisotropic magnetic powder is selected from at least one of flake-shaped, strip-shaped, needle-shaped, rod-shaped, cylindrical, dendritic, spherical-like anisotropic magnetic powder and single-crystal anisotropic magnetic powder .

According to an embodiment, the anisotropic magnetic powder has an average particle size or a minimum single-dimensional size of less than 99 nanometers, for example in the range of 0.1-99 nanometers, preferably between 0.1-80 nanometers, more preferably between 0.2-50 nanometers between, more preferably between 0.5-20 nanometers.

According to an embodiment, the anisotropic magnetic powder has an average particle size or minimum single-dimensional dimension in the range of about 100-900 nanometers, such as 100-500 nanometers, or between 100-200 nanometers.

According to an embodiment, the material of the anisotropic magnetic powder is selected from iron, iron alloy, iron-cobalt alloy, iron-platinum alloy, iron oxide, iron nitride, iron carbide, carbonyl iron, nickel, cobalt, chromium dioxide , FePt, SmCo, NdFeB, stainless steel, silicon steel, or a combination of these materials.

According to an embodiment, the iron alloy is an iron-cobalt alloy or an iron-platinum alloy.

According to an embodiment, the carrier liquid is an organic liquid, such as white oil, alpha-olefin, silicone oil, or a combination thereof.

According to an embodiment, the content of the anisotropic magnetic powder is in the range of 0.1-3% of the total weight of the composite magnetorheological fluid, preferably in the range of 0.5-1%.

According to one embodiment, the additive comprises at least one of the following: surfactants, dispersants, anti-settling agents, organic thixotropic agents, thickeners, antioxidants, lubricants, viscosity modifiers, flame retardants, Organoclay-based rheological additives, sulfur-containing compounds, and any combination thereof.

According to an embodiment, the additive comprises at least one of the following: C16-18 alcohol polyoxyethylene ether, C12-14 alcohol and ethylene oxide condensate, isomeric tridecanol polyoxyethylene ether, isomeric ten Alcohol polyoxyethylene ether, oleyl alcohol polyoxyethylene ether, octadecyl alcohol polyoxyethylene ether, octylphenol polyoxyethylene ether, polyethylene glycol stearate, polyoxyethylene stearate, castor oil polyoxyethylene Vinyl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyethylene glycol, polypropylene glycol, polyoxyethylene polyoxypropylene, alkylphenol polyoxyethylene polyoxypropylene ether, allyl Alcohol polyoxyalkyl ether, polyoxyethylene-polyoxypropylene copolymer, methoxypolyethylene glycol, methoxypolypropylene glycol, fatty alcohol ether phosphate, phenol ether phosphate, isotridecyl phosphate, lauryl Ethyl phosphate, fatty alcohol ether phosphate potassium salt, fatty alcohol ether phosphate potassium salt, phenol ether phosphate potassium salt, isotridecyl ether phosphate potassium salt, lauryl phosphate potassium salt, dodecylamine polyoxyethylene ether, stearylamine polyoxyethylene ether, tallow amine polyoxyethylene ether, fatty acid diethanolamide, coconut fatty acid diethanolamide, styrene phenol, glycerol polyether, castor oil phosphate, tripolyglycerol oleate, ( Z)-9-octadecenoic acid-1,2,3-propanetriyl ester, pentaerythritol oleate, trimethylolpropane oleate, nonylphenol polyoxyethylene ether sulfate amine salt, styrene phenol polymer Ammonium oxyethylene ether sulfate, polyether modified silicone oil and fluorocarbon surfactant.

According to an embodiment, the additive comprises at least one of the following: 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, hindered amine, 2,6--dihydroquinoline tert-Butyl-4-methylphenol, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, β-(3,5- Di-tert-butyl-4-hydroxyphenyl) propionate n-octadecyl ester, tris(2,4-di-tert-butylphenyl) phosphite, tetrakis[beta-(3,5-di-tert-butyl) -4-Hydroxyphenyl)propionic acid] pentaerythritol ester, isooctyl oleate, trimellitate, neopentyl polyol ester, dipentaerythritol ester, neopentyl glycol dioleate, diisosebacate Octyl Ester, Diisooctyl Adipate, Trimethylolpropane Cocoate, Diethyl Phthalate, Trioctyl Phosphate, Dioctyl Phosphate, Diethyl Adipate, Epoxidized Soybean Oil , polyol benzoate, dioctyl terephthalate and dioctyl phthalate.

According to an embodiment, the anisotropic magnetic powder is shape anisotropic and/or magnetocrystalline and/or stress magnetotropic.

According to an embodiment, the composite magnetorheological fluid does not undergo significant sedimentation during at least one week of standing at room temperature.

The main advantage of the present invention is that the composite magnetorheological fluid of the present invention not only retains the excellent mechanical properties of the anisotropic magnetorheological fluid under the magnetic field, but also has the good flow of the traditional magnetorheological fluid under the zero magnetic field. The fluid has a stable and broad second Newtonian zone, and the initial kinematic viscosity of the fluid is low, so that the control range of the magnetorheological device is wider and more stable, and so on. At the same time, compared with the traditional magnetorheological fluid, the present invention also improves the anti-settling performance of the fluid.

More embodiments of the present invention can also achieve other advantageous technical effects that are not listed one by one. These other technical effects may be partially described below, and those skilled in the art may be able to read the present invention. expected and understood.

This "Summary" section is intended to introduce concepts and selections in a simplified form that are further described below in the "Detailed Description" to help the reader better understand the invention. This Summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. All of the above-mentioned features are to be understood as exemplary only, and further features and objects regarding process steps can be gleaned from the present disclosure. A more complete presentation of the features, details, applicability, and advantages of the invention will be provided in the following written description of various embodiments of the invention, illustrated in the accompanying drawings, and defined in the appended claims. Accordingly, many of the limiting interpretations of the present disclosure may not be understood without further reading of the entire specification, as well as the claims and drawings.

Description of drawings

In order to illustrate the technical solutions in the embodiments of the present invention more clearly, the following briefly describes the accompanying drawings that are required to be used in the description of the embodiments or the prior art.

The above-described features and advantages and other features and advantages of these embodiments, and the manner in which they are achieved, will be more apparent, and embodiments of the present invention may be better understood, by reference to the following description in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic diagram schematically showing the form of an embodiment of the composite magnetorheological fluid of the present invention after applying a magnetic field.

FIG. 2 schematically shows the magnetic field sweep stress curves (shear rate 0.1-s) of the composite magnetorheological fluids of the present invention with different anisotropic magnetic powder contents.

3 schematically shows the relationship between the shear strength of the composite magnetorheological fluid of the present invention and the anisotropic magnetic powder content in the composite magnetorheological fluid under a magnetic field of 800 mT (shear rate 0.1- s).

Figure 4 schematically shows the various composite magnetorheological fluids of the present invention with different anisotropic magnetic powder contents (higher) and traditional magnetic fluids under different shear rates at zero magnetic field and 40°C temperature. Comparative test results for shear strength of variable fluids.

Figure 5 schematically shows the various composite magnetorheological fluids of the present invention with different anisotropic magnetic powder contents (lower) and traditional magnetorheological fluids at a zero magnetic field and a temperature of 40°C under different shear rates. Comparative test results for shear strength of fluids.

Figure 6 shows the zero magnetic field viscosity of the composite magnetorheological fluid with uniform addition of 2% of different types of anisotropic magnetic powders in the conventional magnetorheological fluid.

FIG. 7 shows a comparison of shear stress (ie, shear strength) testing of composite magnetorheological fluids in which 2% of different types of anisotropic magnetic powders are uniformly added to conventional magnetorheological fluids under a magnetic field.

Figure 8 shows the comparison of the anti-settling performance test of the composite magnetorheological fluid obtained by adding 0.5% anisotropic magnetic powder to the traditional magnetorheological fluid and the traditional magnetorheological fluid.

Detailed ways

The details of one or more embodiments of the invention are set forth in the accompanying drawings and the detailed description below. Other features, objects and advantages of the present invention will be apparent from the description, drawings and claims.

It should be understood that the illustrated and described embodiments are not limited in application to the details of construction and the arrangement of components set forth in the following description or illustrated in the accompanying drawings. The illustrated embodiments are capable of other embodiments and of being implemented or carried out in various ways. The examples are provided by way of explanation and not limitation of the disclosed embodiments.

In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the various embodiments of the present invention without departing from the scope or spirit of the present disclosure. For example, features illustrated or described as part of one embodiment can be used with another embodiment to still yield a further embodiment. Accordingly, the present disclosure covers such modifications and variations as fall within the scope of the appended claims and their equivalents.

Also, it is to be understood that the phraseology and phraseology used herein is for the purpose of description and should not be regarded as limiting. For example, the use of "including", "having" or "having" and variations thereof herein is intended to be open-ended to include the items listed thereafter and their equivalents as well as additional items.

The present invention will be explained and described in more detail below with reference to the specific embodiments of the present invention in conjunction with the accompanying drawings.

Common magnetic powders, ie common isotropic magnetic powders, may be, for example, those disclosed in conventional magnetorheological fluids, eg, see US Pat. No. 6,203,717 B1, which is incorporated herein by reference. Typical isotropic magnetic powders generally have a generally spherical shape, obtainable by, for example, a water atomization process, and generally have a particle size on the micrometer scale, eg, on the order of 1 micrometer. Some other patents related to general magnetorheological fluids and magnetic powders and related can also be found in, for example, US Patent Applications 2,575,360, 2,661,825, 2,886,151, 5,645,752, 7,393,463B2, 6,203,717B1, and 2006/0033069A1, the relevant contents of which are also incorporated herein by reference. application, as described in the application. Of course, in the present invention, the particle size of the common isotropic magnetic powder is not limited to the above, but can have a larger or smaller range of particle size, for example, in the range of about 0.1-50 microns, such as in Varies in the range of about 0.1-20 microns, 0.2-10 microns, 0.2-5 microns.

Anisotropic magnetic powder can be obtained, for example, from Chinese patent applications No. 201510538070.7, No. 201510537836.X and PCT application WO 2017036337 A1 previously invented by the inventor, and the relevant contents of these patent applications are also incorporated into the present application by reference, as in as described in the application. The anisotropic magnetic powder may for example have dimensions on the nanometer scale, for example its average particle size or smallest single dimension is generally less than 99 nanometers, for example in the range of 0.1-99 nanometers, for example between 0.1-80 nanometers, in the range of 0.2-50 nanometers between 0.5-20 nanometers, and so on. However, in the present invention, the size of the anisotropic magnetic powder is not limited to the above-mentioned nanoscale range, but can have a larger particle size or particle size range, for example, the average particle size or the minimum single-dimensional size is about 0.1-900 nanometers, in the range of 0.1-500 nanometers, 0.1-200 nanometers, etc.

The composite magnetorheological fluid of the present invention and its preparation process will be described below with reference to specific examples.

Example I

To prepare the carrier liquid of the composite magnetorheological fluid, the carrier liquid can use white oil, alpha-olefin or silicone oil, etc., which can be purchased from the market.

Additives for preparing composite magnetorheological fluid, optional additives include but are not limited to organoclay, molybdenum disulfide, fumed silica, etc., which can be purchased from the market.

The steps of a preparation process of the composite magnetorheological fluid are as follows.

Process step 1. Disperse the additives

The process that can be adopted in this step can be selected from one of the following:

1. Add the organic clay and fumed silica at room temperature to the container of the ultrasonic mixer (for example, the model is JM-1018), and use the stirring frequency of about 30 Hz to carry out ultrasonic stirring and dispersion treatment for about 20 minutes;

2. Add the organic clay and fumed silica at room temperature to the circulating sanding equipment (for example, the model is YSN-0.2L), carry out sand grinding and stirring and dispersing (rotation speed 500 rpm, linear speed 12m/s) about 30 minutes; and

3. Add the organic clay and fumed silica at room temperature to a high-speed centrifugal dispersion device (for example, the model is TFS-2.2) for dispersion treatment for about 5 minutes, wherein the linear speed of the centrifugal rotation is 12m/s～37m/s between.

Process Step 2, Liquid Dosing and Mixing Treatment

Provide anisotropic magnetic powder in a certain proportion (eg 0.5%, 1%, 1.5%, 2%, 2.5%, 3%, 5%) of the total weight of the magnetorheological fluid, such as nanoscale sheet-like anisotropic Magnetic powder, dendritic anisotropic magnetic powder, spherical anisotropic magnetic powder, as the anisotropic magnetic powder added to the carrier liquid.

The basic composition of the carrier liquid is formulated with 12% by weight of white oil, 5% by weight of alpha-olefin, and about 2% by weight of other various types of additives. . Examples of additives include anti-settling agents, dispersants, lubricants, antioxidants, and the like.

The anti-settling agent and dispersing agent in the additive can include C16-18 alcohol polyoxyethylene ether, C12-14 alcohol and ethylene oxide condensate, isomeric tridecanol polyoxyethylene ether, isomeric ten alcohol polyoxyethylene ether , oleyl alcohol polyoxyethylene ether, octadecanol polyoxyethylene ether, octylphenol polyoxyethylene ether, polyethylene glycol stearate, polyoxyethylene stearate, castor oil polyoxyethylene ether, dehydration Sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyethylene glycol, polypropylene glycol, polyoxyethylene polyoxypropylene, alkylphenol polyoxyethylene polyoxypropylene ether, allyl alcohol polyoxyalkylene Ether, polyoxyethylene-polyoxypropylene copolymer, methoxypolyethylene glycol, methoxypolypropylene glycol, fatty alcohol ether phosphate, phenol ether phosphate, isotridecyl phosphate, lauryl phosphate, fat Alcohol ether phosphate potassium salt, fatty alcohol ether phosphate potassium salt, phenol ether phosphate potassium salt, isotridecyl ether phosphate potassium salt, lauryl phosphate potassium salt, dodecylamine polyoxyethylene ether, stearylamine Polyoxyethylene ether, tallow amine polyoxyethylene ether, fatty acid diethanolamide, coconut fatty acid diethanolamide, styrene phenol, glycerol polyether, castor oil phosphate, triglycerol oleate, (Z)-9- Octadenoic acid-1,2,3-propanetriyl ester, pentaerythritol oleate, trimethylolpropane oleate, nonylphenol polyoxyethylene ether sulfate amine salt, styrene phenol polyoxyethylene ether ammonium sulfate At least one of salt, polyether modified silicone oil, and fluorocarbon surfactant.

Antioxidants and lubricants in additives may include 6-ethoxy-2,2,4-trimethyl-1,2-dihydroquinoline, hindered amines, 2,6--di-tert-butyl-4- methylphenol, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl)hexanediamine, β-(3,5-di-tert-butyl-4 -Hydroxyphenyl) propionate n-octadecyl ester, tris(2,4-di-tert-butylphenyl) phosphite, tetrakis[beta-(3,5-di-tert-butyl-4-hydroxyphenyl) ) propionate] pentaerythritol ester, isooctyl oleate, trimellitate, neopentyl polyol ester, dipentaerythritol ester, neopentyl glycol dioleate, diisooctyl sebacate, adipic acid Diisooctyl, Trimethylolpropane Cocoate, Diethyl Phthalate, Trioctyl Phosphate, Dioctyl Phosphate, Diethyl Adipate, Epoxidized Soybean Oil, Polyol Benzoate , at least one of dioctyl terephthalate and dioctyl phthalate.

After stirring the above-mentioned carrier liquid with a stirrer at low speed for about 10 minutes, use a closed vibration feeder whose model is GZVF, for example, slowly add the weighed balance of solid additive organoclay 1.5%, gas-phase dioxide at low speed. Silicon, etc., after the addition is completed, the carrier liquid is dispersed at a high speed for about 30 to 60 minutes with the shaking feeder to obtain the configured carrier liquid.

Put the prepared carrier liquid into a low-speed stirring device (for example, JB200-D), and add the anisotropic magnetic powder while stirring slowly at a low speed. in liquid.

Thereafter, ordinary magnetic powder, such as isotropic iron powder, having a particle size in the range of about 0.1-1 micron is added using an oscillatory feeder. For example, it can be added slowly and uniformly at first, and as the iron powder is added, the rotational speed of the oscillating feeder can be gradually increased.

After the addition of all the magnetic powders is completed, the linear speed of the stirring of the low-speed stirring device is increased to a high speed of, for example, about 7-10 m/s, and the stirring is carried out at the high speed for 2 hours.

Finally, for the carrier liquid added with magnetic powder, vacuum bake in a vacuum oven (for example, model 202-0B) at a temperature of about 40-60° C. for 5 hours, and discharge the air mixed in the process.

After that, the composite magnetorheological fluid product of the present invention is obtained by weighing and packaging.

Example II

The preparation process, steps, equipment, raw materials, components, parameters, etc. of this example are basically the same as those of Example I, the difference is that the anisotropic magnetic powder adopts single-crystal anisotropic magnetic powder, and the added single-crystal anisotropic magnetic powder is The anisotropic magnetic powder accounts for 2% of the total weight of the magnetorheological fluid.

test

1. Anti-sedimentation test

1. Description of the Settlement System

The root cause of the MRF sedimentation problem is the large density difference between the dispersed phase (take carbonyl iron powder as an example, the density is 7.8g/mL) and the continuous phase (carrier liquid, 1g/mL). Under the action of gravity, the particles continue to sink to the bottom of the container. A transparent (or non-transparent, depending on the properties of the carrier liquid) supernatant liquid area containing only carrier liquid generally appears in the upper part of the container, and a clear demarcation line is formed in the lower part, which is called "mud line". Immediately below the mud line, the particle concentration remains unchanged for a period of time at the beginning, so it is called the "initial concentration area". At the bottom of the container, the particles continue to accumulate, and after a certain period of time, they are pressed against each other under the force of gravity to harden and harden, forming a deposition area with the largest concentration and uniform distribution. Obviously, there must be a transition zone between the initial concentration zone and the deposition zone, called "variable concentration zone", the concentration of which will change significantly with time and height. The dividing line between the initial concentration area and the variable concentration area is named "gel line", as the name implies, because the variable concentration area looks like a very viscous "gel state". The boundary between the variable concentration zone and the deposition zone is named "deposition line", which characterizes the starting line from which the deposition zone is formed downward.

2. Visual measurement scheme for anti-settling test of magnetorheological fluids

Take a 15ml test tube, pour 10ml of traditional magnetorheological fluid and 10ml of composite magnetorheological fluid with anisotropic magnetic powder, and let it stand vertically. Observe and record the scale of the mud line every 7 days, and observe continuously for about 1 month, and draw the mud line settlement curve.

As shown in Figure 8, the height of the transparent layer can be determined by measuring the distance from the bottom of the test tube to the top of the fluid-liquid level, and measuring the distance from the bottom of the test tube to the top of the settled magnetic powder-the height of the settled magnetic powder. And, using the following equation, the sedimentation rate (Ratio) can be calculated:

Sedimentation rate Ratio=(liquid level height (cm)-settled magnetic powder height (cm))/liquid level height (cm)×100%

The visual test results are shown in Figure 8. Figure 8 shows the test results and data comparison of the anti-settling performance of the composite magnetorheological fluid obtained by adding 0.5% anisotropic magnetic powder to the traditional magnetorheological fluid and the traditional magnetorheological fluid. As shown in Figure 8, the test results show that in all the anti-settling tests of 7 days, 14 days, 21 days and 28 days, the sedimentation rate of the composite magnetorheological fluid is lower than that of the traditional magnetorheological fluid, that is, the The anti-settling performance of the composite magnetorheological fluid is slightly better than that of the traditional magnetorheological fluid. That is to say, adding an appropriate amount of anisotropic magnetic powder to the traditional magnetorheological fluid can also properly improve the anti-settling performance of the traditional magnetorheological fluid.

2. Zero Magnetic Field Viscosity Test

The zero magnetic field viscosity detection and the shear stress detection under the magnetic field of the composite magnetorheological fluid of the present invention all use the rheometer of the model MCR302 produced by Anton-Paar Company, and the detection system is a parallel plate type detection system, and the model is PP20/MRD/TI , the upper heating unit in the detection unit is the semiconductor heating unit and the water bath circulation unit model is MRD170+H-PTD200, the lower heating unit in the detection unit is the oil bath circulation unit model is VT2, the magnetic field unit in the detection unit is the external magnetic field unit model is PS-DC/MR/1T.

For the zero magnetic field viscosity detection, take 2ml of the sample and place it in the flat sample tank of the parallel plate detection system, and scan the kinematic viscosity at 40°C under 0-1200-s.

As can be seen from Figure 4, the magnetic powder concentration of the traditional magnetorheological fluid and the composite magnetorheological fluid added with 1% anisotropic magnetic powder is about 81%, and the magnetic powder concentration of the magnetorheological fluid prepared from pure anisotropic magnetic powder with comparable mechanical properties. The magnetic powder concentration is about 65%. However, the kinematic viscosity of the anisotropic magnetorheological fluid at 65% magnetic powder concentration is much larger than that of conventional and composite magnetorheological fluids at about 81% magnetic powder concentration—this is because the magnetic flow of pure anisotropic magnetic powder The particle size of the anisotropic magnetic powder in the variable fluid is generally nanoscale, which affects the initial force of the damper and the control range of the damper.

Figure 5 schematically shows the various composite magnetorheological fluids of the present invention with different anisotropic magnetic powder contents (lower) and traditional magnetorheological fluids at a zero magnetic field and a temperature of 40°C under different shear rates. Comparative test results for shear strength of fluids. As shown in Figure 5, in the present invention, the composite magnetorheological fluid obtained by adding a small amount of anisotropic magnetic powder to the traditional magnetorheological fluid has little change in the kinematic viscosity of the traditional magnetorheological fluid under zero magnetic field, In this way, the composite magnetorheological fluid of the present invention can not only maintain the excellent physical and chemical properties of traditional magnetorheological fluids, such as kinematic viscosity properties, and have better fluidity under zero magnetic field, but also provide superior mechanical properties, such as in Shear strength after applying a magnetic field, etc.

Figure 6 shows the zero magnetic field viscosity of the composite magnetorheological fluid with uniform addition of 2% of different types of anisotropic magnetic powders in the conventional magnetorheological fluid. As shown in Figure 6, it has been tested that there is no substantial correlation or influence between the zero-field viscosity and the type of anisotropic magnetic powder added. However, in general, the flake anisotropic magnetic powder has the greatest influence on the zero magnetic field viscosity, and the dendritic anisotropic magnetic powder has the least influence on the zero magnetic field viscosity, but these effects are not substantial and do not affect the composite type of the present invention. Practical industrial applications of magnetorheological fluids.

3. Detection of shear strength under magnetic field

This patent uses the rheometer of model MCR302 produced by Anton-Paar for the detection of viscosity in zero magnetic field and the detection of shear strength under magnetic field. It is the semiconductor heating unit and the water bath circulation unit model MRD170+H-PTD200, the lower heating unit in the detection unit is the oil bath circulation unit model VT2, the magnetic field unit in the detection unit is the external magnetic field unit The model is PS-DC/MR/1T .

For the detection of shear strength under the magnetic field, take 2ml of the sample and place it in the flat sample tank of the parallel plate detection system.

As shown in Figure 2, it is shown that the shear strength of the composite magnetorheological fluid with different proportions of anisotropic magnetic powders is improved under the magnetic field.

As shown in Figure 3, it shows the effect of adding different proportions of anisotropic magnetic powder on the shear stress of the magnetorheological fluid under the magnetic field. The test in Figure 3 is a mechanical test comparison of the composite magnetorheological fluid obtained by adding anisotropic magnetic powder to the traditional magnetorheological fluid under a magnetic field. It can be seen from the test results that in the composite magnetorheological fluid of the present invention, the amount of the anisotropic magnetic powder added ranges from more than 0% to about 0.1% to about 0.3% to about 0.5% of the total weight of the magnetorheological fluid. %, the shear strength performance of the composite magnetorheological fluid under the magnetic field gradually rises to the highest peak value. Then, with the addition of anisotropic magnetic powder, the shear strength performance of the composite magnetorheological fluid under magnetic field decreased gradually from about 0.5% to 1%, until about 1% anisotropy With the addition of magnetic powder, the shear strength is comparable to that of about 0.1%. Thereafter, the shear strength of the composite magnetorheological fluid under a magnetic field remained substantially unchanged with an increase from about 1% to about 2% of anisotropic magnetic powder addition until an increase from about 2% to about 3% When the addition amount of anisotropic magnetic powder is higher, the overall shear strength has a small increase. That is to say, when the amount of the anisotropic magnetic powder added is increased from more than 0% to about 3% of the total weight of the magnetorheological fluid, the shear strength of the composite magnetorheological fluid under a magnetic field is greater than that of the conventional magnetorheological fluid. rheological fluid.

Figure 7 shows the shear strength test of the composite magnetorheological fluid in which 2% of different types of anisotropic magnetic powders are uniformly added to the conventional magnetorheological fluid under a magnetic field. As shown in Fig. 7, the shear strength under the magnetic field is tested, and the results show that the type of anisotropic magnetic powder has a great influence on the shear strength of the magnetorheological fluid under the magnetic field. Among them, the addition of dendritic anisotropic magnetic powder has higher shear strength, and the addition of single crystal anisotropic magnetic powder has lower shear force. In a word, no matter what type of anisotropic magnetic powder is added to the traditional magnetorheological fluid, some properties of the traditional magnetorheological fluid, such as the shear strength performance, can be substantially improved.

The foregoing description of several embodiments of the present invention has been presented for purposes of illustration. The foregoing description is not intended to be exhaustive or to limit the invention to the precise features and/or forms disclosed.

Obviously, many modifications and variations can be made in light of the above teachings, which fall within the scope of the present invention. The scope of the present invention is limited only by the appended claims. The appended claims are intended to cover all such modifications and variations.

Claims

A composite magnetorheological fluid, comprising:

anisotropic magnetic powder, the content of which is in the range of 0.05-5% of the total weight of the composite magnetorheological fluid;

a micron-scale isotropic magnetic powder in an amount in the range of 70-90% of the total weight of the composite magnetorheological fluid; and

The content of the carrier liquid and the additives added to the carrier liquid is the balance of the composite magnetorheological fluid.
The composite magnetorheological fluid according to claim 1, wherein the isotropic magnetic powder is iron powder, and its particle size is in the range of about 0.1-50 microns, such as about 0.1-20 microns, 0.2- 10 microns or in the range of 0.2-5 microns.
The composite magnetorheological fluid according to claim 1 or 2, wherein the anisotropic magnetic powder is selected from the group consisting of flakes, strips, needles, rods, cylinders, dendrites, and spherical anisotropic At least one of magnetic powder and single crystal anisotropic magnetic powder.
The composite magnetorheological fluid according to any one of claims 1-3, wherein the anisotropic magnetic powder has an average particle size or minimum single-dimensional dimension of less than 99 nanometers, for example in the range of 0.1-99 nanometers , preferably between 0.1-80 nanometers, more preferably between 0.2-50 nanometers, further preferably between 0.5-20 nanometers.
The composite magnetorheological fluid of any one of claims 1-3, wherein the anisotropic magnetic powder has an average particle size or a minimum single-dimensional dimension in the range of about 100-900 nanometers, such as 100 nanometers -500nm, or between 100-200nm.
The composite magnetorheological fluid according to any one of the preceding claims, wherein the material of the anisotropic magnetic powder is selected from the group consisting of iron, iron alloys, iron-cobalt alloys, iron-platinum alloys, iron oxides, nitrides Iron, iron carbide, carbonyl iron, nickel, cobalt, chromium dioxide, FePt, SmCo, NdFeB, stainless steel, silicon steel, or a combination of these materials.
The composite magnetorheological fluid according to claim 6, wherein the iron alloy is an iron-cobalt alloy or an iron-platinum alloy.
A composite magnetorheological fluid according to any preceding claim, wherein the carrier liquid is an organic liquid such as white oil, alpha-olefin, silicone oil or a combination thereof.
The composite magnetorheological fluid according to any one of the preceding claims, wherein the content of the anisotropic magnetic powder is in the range of 0.1-3% of the total weight of the composite magnetorheological fluid, It is preferably in the range of 0.5-1%.
The composite magnetorheological fluid according to any one of the preceding claims, wherein the additive comprises at least one of the following: a surfactant, a dispersant, an anti-settling agent, an organic thixotropic agent, a thickener , antioxidants, lubricants, viscosity modifiers, flame retardants, organoclay-based rheological additives, sulfur-containing compounds, and any combination thereof.
The composite magnetorheological fluid of any preceding claim, wherein the additive comprises at least one of the following: C16-18 alcohol polyoxyethylene ether, C12-14 alcohol condensed with ethylene oxide compound, isotridecanol polyoxyethylene ether, isomeric decahydric polyoxyethylene ether, oleyl alcohol polyoxyethylene ether, octadecyl alcohol polyoxyethylene ether, octylphenol polyoxyethylene ether, polyethylene glycol stearin acid ester, polyoxyethylene stearate, castor oil polyoxyethylene ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyethylene glycol, polypropylene glycol, polyoxyethylene polyoxyethylene Propylene, alkylphenol polyoxyethylene polyoxypropylene ether, allyl alcohol polyoxyalkylene ether, polyoxyethylene-polyoxypropylene copolymer, methoxypolyethylene glycol, methoxypolypropylene glycol, fatty alcohol ether phosphoric acid Esters, phenol ether phosphate, isotridecyl phosphate, lauryl phosphate, fatty alcohol ether phosphate potassium salt, fatty alcohol ether phosphate potassium salt, phenol ether phosphate potassium salt, isotridecyl ether phosphate potassium Salt, potassium lauryl phosphate, dodecylamine polyoxyethylene ether, stearylamine polyoxyethylene ether, tallow amine polyoxyethylene ether, fatty acid diethanolamide, coconut fatty acid diethanolamide, styrene phenol, glycerol poly ether, castor oil phosphate, triglycerol oleate, (Z)-9-octadecenoic acid-1,2,3-propanetriyl ester, pentaerythritol oleate, trimethylolpropane oleate, Nonylphenol polyoxyethylene ether sulfate amine salt, styrene phenol polyoxyethylene ether sulfate ammonium salt, polyether modified silicone oil and fluorocarbon surfactant.
The composite magnetorheological fluid of any preceding claim, wherein the additive comprises at least one of the following: 6-ethoxy-2,2,4-trimethyl-1,2 -Dihydroquinoline, hindered amine, 2,6--di-tert-butyl-4-methylphenol, N,N'-bis-(3-(3,5-di-tert-butyl-4-hydroxyphenyl) ) propionyl) hexamethylenediamine, n-octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, tris(2,4-di-tert-butylphenyl) phosphite Esters, tetrakis[beta-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester, isooctyl oleate, trimellitate, neopentyl polyol ester, dipentaerythritol ester , Neopentyl Glycol Dioleate, Diisooctyl Sebacate, Diisooctyl Adipate, Trimethylolpropane Cocoate, Diethyl Phthalate, Trioctyl Phosphate, Phosphoric Acid Dioctyl ester, diethyl adipate, epoxidized soybean oil, polyol benzoate, dioctyl terephthalate, and dioctyl phthalate.
A composite magnetorheological fluid according to any preceding claim, wherein the anisotropic magnetic powder is shape anisotropic and/or magnetocrystalline anisotropic and/or stress magnetotropic heterosexual.
The composite magnetorheological fluid according to any one of the preceding claims, wherein the composite magnetorheological fluid does not undergo significant settling during a period of at least 1 week at room temperature.