CN106571206A - Micro-nano magnetorheological fluid and preparation method thereof - Google Patents

Abstract

The invention discloses a micro-nano magnetorheological fluid, which comprises the following raw materials in mass fractions: carbonyl iron powder 48-80, magnetic Fe ₃ O ₄ 2.4-18, carrier liquid 10-40, surfactant 1-4, inorganic Thixotropic agent 0.5‑1, antioxidant 0.5‑1, antiwear agent 0.5‑1 and absolute ethanol 15% vol, the particle size of the carbonyl iron powder is 0.5um～10um; the magnetic _Fe3O The particle size of ₄ is 50nm-300um, and the average particle size is 60nm; the invention also discloses the preparation method of the micro-nano magnetorheological fluid. The micro-nano magnetorheological fluid of the present invention improves the stability of the magnetorheological fluid by adding an appropriate amount of nano-scale magnetic Fe ₃ O ₄ to the carrier fluid, and exhibits better external performance under the condition of an external magnetic field. Mechanical properties, with high normal stress.

Description

A kind of micronano magnetorheological fluid and preparation method thereof

technical field

The invention belongs to the technical field of intelligent materials, and in particular relates to a micro-nano magnetorheological fluid and a preparation method thereof.

Background technique

Magnetorheological fluid is a new type of controllable fluid mainly composed of carrier liquid, magnetic particles with high magnetic permeability and low hysteresis, and additives. It is an important branch of current smart material research. Under the action of a magnetic field, the magnetorheological fluid can be continuously and reversibly transformed into a Bingham fluid with high viscosity and low fluidity in milliseconds, which has mechanical properties similar to solids. When the external magnetic field is removed, the magnetorheological fluid Therefore, magnetorheological fluid is used in many important engineering and cutting-edge technical fields because of its continuous, reversible, easy-to-control and rapid response characteristics. The density of magnetic particles in magnetorheological fluid is generally 7-8g/cm ³ , which is 7-8 times the density of carrier fluid. The sedimentation of magnetic particles caused by this has always been the bottleneck of developing high-performance magnetorheological fluid. At present, there are two methods commonly used to improve the stability of magnetorheological fluids: 1) surface modification of magnetic particles, thereby improving the compatibility and dispersibility of polar magnetic metals and non-polar carrier fluids. 2) Adding nanoparticles or nanowires. This method improves the microstructure of the flux linkage under the action of a magnetic field by adjusting the composition and collocation of the dispersed phase, so as to achieve the purpose of improving the magnetorheological effect.

Experts and scholars at home and abroad have done a lot of research in order to obtain high-performance magnetorheological fluids. Among them, Ngatu et al. added different proportions of rod-shaped nanofibers to conventional magnetorheological fluids, and obtained a long-term Magnetorheological fluids that maintain a better dispersed state over time [Reference: G.T.Ngatu, N.M.Wereley, J.O.Karli, et al.Dimorphicmagnetorheological fluids Exploiting partial substitution of microspheres bynanowires[J].Smart Materials and Structures,2008,17(4): 045022]; Lopez et al. have significantly improved the mechanical properties of magnetorheological fluids by adding cobalt nanowires and steel nanowires to magnetorheological fluids [Reference: M.T.Lopez, G.Vertelov, G.Bossis, et al.New magnetorheological fluids based on magnetic fibers[J].Journal of Materials Chemistry,2007,17(36):3839-3844]; Dodbiba et al. mixed carbonyl iron powders with two different particle sizes (7μm and 1.1μm) into an ionic In the carrier liquid, the experimental results show that when the mass fraction of large particles is 60%, the performance of the magnetorheological fluid is the best [reference: G.Dodbiba, H.S.Park, K.Okaya, et al.Investigating magnetorheological properties of a mixture of twotypes of carbonyl iron powders suspended in an ionic liquid[J].Journal ofMagnetism and Magnetic Materials, 2008,320(7):1322-1327.]; Osama Ashour et al. obtained an average particle diameter of 28nm pure iron particles are mixed with micron-sized carbonyl iron particles to obtain a magnetorheological fluid with good stability and strong rheological effect [Ref: Ashour O, et al. Manufacturing and characterization of MR fiuids. SPIE, 1997 ,3040:174-175.]; Wereley et al. added nano-scale silica particles to the magnetorheological fluid, which improved the sedimentation stability of the magnetorheological fluid [reference: Wereley N M, Chaudhur A, e tal.Bidisperse magneto-rheological fluids using Fe particles at nanometer andmicron scale[J].Intelligent Material Systems and Structures,2006,17(5):393-401.].

In addition, some scholars use organic polymers to coat magnetic particles, which strengthens the combination of dispersed phase and continuous phase, and can improve the stability of magnetorheological fluids. However, since the surface of magnetic particles is covered with non-magnetic organic polymers, it will not only The magnetization of the magnetorheological fluid will decrease, and the magnetic saturation of the magnetic particles will decrease significantly, and the coercive force will increase instead. damping force characteristics, Smart Materials and Structures, 22, (2013); HHSim, SHKwon, HJ Choi, Xanthan gum-coated softmagnetic carbonyl iron composite particles and their magnetorheology, ColloidPolym Sci, 963 (2013).]; some scholars use composite magnetic particles to Reduce the density difference between the magnetic particles and the base liquid to improve the stability of the magnetorheological fluid, that is, combine the magnetic particles with the microporous material, and make the surface of each magnetic particle covered with a certain thickness of binder through the polymerization reaction, and Solidified to obtain composite magnetic particles, however, due to the intervention of non-magnetic microporous materials, the magnetization of magnetorheological fluid will decrease [Reference: Feng Jun, Guan Jianguo, Cheng Haibin, Zhang Qingjie. Modified carbon-based ferromagnetic with coFeZo ₄ nanoparticles Rheological Fluids.[J].Functional Materials,2006,37(5):713-715.]. However, the addition of an appropriate amount of nano-scale substances [Reference: Cuan Hongliang, Zhang Jinqiu, Kong Yanan, Zhang Jian, Effect of Nano-Fe ₃ O ₄ on the Properties of Magnetorheological Fluid for Armored Vehicles, Magnetic Materials and Devices, 42(3), 34 (2011); Bong Jun Park, Kang Hyun Song, Hyoung JinChoi.Magnetic carbonyl iron nanoparticle based magnetotheological suspension and its characteristics[J].Materials Letters,2009,63(15):1350-1352.], making it common with the base fluid The density of the dispersed medium is increased, which reduces the density difference between the base liquid and the magnetic particles, and improves the stability of the magnetorheological fluid. Among the structural defects formed in the liquid, the magnetorheological fluid forms a denser chain structure under the condition of an applied magnetic field, so that the magnetorheological fluid can perform better to the outside under the condition of an applied magnetic field. mechanical properties. Therefore, adding an appropriate amount of nano-scale magnetic materials to the magnetorheological fluid can effectively improve the stability of the magnetorheological fluid, and at the same time make the mechanical properties of the magnetorheological fluid more superior and more uniform.

Contents of the invention

The invention provides a micro-nano magnetorheological fluid, aiming to obtain a magnetorheological fluid with good anti-sedimentation agglomeration and high normal stress, by selecting micron-scale carbonyl iron powder and nano-scale magnetic _{Fe3O 4} The mixed particles are used as the dispersed phase to prepare high-performance micro-nano magnetorheological fluid.

Technical scheme of the present invention is as follows:

A micro-nano magnetorheological fluid, comprising the following raw materials in mass fractions:

The particle size of the carbonyl iron powder is 0.5um-10um; the particle size of the magnetic Fe ₃ O ₄ is 50nm-300um, and the average particle size is 60nm.

Preferably, the carrier liquid is simethicone or silicone oil.

Preferably, the surfactant is sodium dodecylbenzenesulfonate or polyethylene glycol.

Preferably, the inorganic thixotropic agent is diatomaceous earth.

Preferably, the antioxidant is benzoic acid.

Preferably, the antiwear agent is graphite or silicon dioxide.

The present invention also discloses a method for preparing the above-mentioned micro-nano magnetorheological fluid, which includes the following steps:

(1) In the reaction device, add the surface-treated carbonyl iron powder and the magnetic Fe ₃ O ₄ , mix and then add the surfactant, the inorganic thixotropic agent and the The dehydrated alcohol described above, and through high-speed dispersion treatment;

(2) Take it out and put it in a vacuum drying oven to dry, and mix it with the carrier liquid, the antioxidant and the anti-wear agent, and then undergo high-speed grinding and dispersion treatment to obtain the micro-nano-scale magnetic rheological fluid

Compared with the prior art, the beneficial effects of the present invention are as follows:

1. In the micro-nano magnetorheological fluid of the present invention, by adding an appropriate amount of nano-scale magnetic Fe ₃ O ₄ to the carrier liquid, the density of the dispersion medium composed of it and the carrier liquid is increased, thereby reducing the density of the carrier liquid. The density difference between magnetic particles improves the stability of magnetorheological fluid;

2. The nano-scale magnetic Fe ₃ O ₄ of a micro-nano magnetorheological fluid of the present invention can be filled into the structural defects formed by the micron-scale carbon-based iron powder particles dispersed in the carrier liquid, so that the magnetorheological fluid Under the condition of applying an external magnetic field, a denser chain structure is formed, so that the magnetorheological fluid can exhibit better mechanical properties to the outside under the condition of an external magnetic field;

3. A micro-nano magnetorheological fluid of the present invention, because the nano-scale magnetic Fe ₃ O ₄ has superparamagnetism, it can be magnetized under the application of an external magnetic field, so the magnetic interaction with micron-scale carbonyl iron powder particles can enhance the magnetic flux. Rheological effect, with higher normal stress.

Description of drawings

Fig. 1 is a micro-nano magnetorheological fluid prepared in Example 1 of the present invention-a schematic diagram of the relationship between normal stress and magnetic induction in static mode;

Fig. 2 is a micro-nano magnetorheological fluid prepared in Example 1 of the present invention - a schematic diagram of the relationship between normal stress and magnetic induction in a stable shear mode;

Fig. 3 is a schematic diagram of the relationship between the normal stress and the magnetic induction intensity of the micro-nano magnetorheological fluid made of different mass fractions of magnetic Fe ₃ O ₄ .

detailed description

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention, not to limit the protection scope of the present invention. Improvements and adjustments made by those skilled in the art according to the present invention in practical applications still belong to the protection scope of the present invention.

A micro-nano magnetorheological fluid, comprising the following raw materials in mass fractions:

The particle size of the carbonyl iron powder is 0.5um-10um; the particle size of the magnetic Fe ₃ O ₄ is 50nm-300um, and the average particle size is 60nm.

In order to maintain a good stability of the magnetorheological fluid, it is generally necessary to add a certain amount of additives to the magnetorheological fluid to prevent the aggregation and precipitation of magnetic particles in the base fluid; such as: magnetorheological surfactant, generally It is an oligomer with an amphiphilic group or a high polymer with a strong dispersion effect, which is conducive to the dispersion of magnetic particles; the thixotropic agent is mainly used to solve the problem of excessive sedimentation of magnetic particles in the carrier liquid due to the action of gravity Problem; In addition, since the magnetorheological fluid has different degrees of friction between the magnetic particles in the actual work, adding a certain amount of anti-wear agent is to improve the lubrication effect between the magnetic particles and improve the wear resistance of the magnetic particles There are other stabilizer additives that can form a thixotropic structure on the surface of magnetic particles, which can change the zero-field viscosity of the magnetorheological fluid while improving the sedimentation stability of the particles, thus affecting the mechanical properties of the magnetorheological fluid.

The micro-nano magnetorheological fluid of the present invention is compared with the magnetorheological fluid prepared by nano-scale coated magnetic particles and nano-scale composite magnetic particles in the prior art. An appropriate amount of nano-scale magnetic Fe ₃ O ₄ is added, on the one hand, it makes The density of the dispersion medium composed of it and the carrier liquid is increased, which reduces the density difference between the carrier liquid and the magnetic particles, thereby improving the stability of the magnetorheological fluid. On the other hand, under the application of an external magnetic field, due to Nano-Fe ₃ O ₄ magnetic particles can be magnetized, so that the magnetic interaction with micron-sized carbonyl iron powder can enhance the magnetorheological effect. Inside the conventional micron-scale magnetorheological fluid, when there is no external magnetic field, the two particles are in a freely dispersed state; after the magnetic field is applied, the two magnetic particles will be magnetized and arranged along the direction of the magnetic field line to form a chain; the micron magnetic flow The working mode of the variable fluid is mainly a pure shear mode between two magnetic particles. However, after nano-magnetic particles are added to the micron magnetorheological fluid, the above-mentioned working mode has changed greatly, from the previous pure shearing mode to a more complex rotation and shearing composite working mode, which improves the magnetic field. The normal stress of the rheological fluid under the action of a magnetic field. Therefore, the magnetorheological fluid developed by the present invention using micron-sized carbonyl iron powder and nano-sized Fe ₃ O ₄ magnetic particles as the dispersed phase not only has good stability, but also has relatively high normal stress.

The present invention also discloses a method for preparing the above-mentioned micro-nano magnetorheological fluid. The micro-nano magnetorheological fluid is prepared by the carrier liquid replacement method, which specifically includes the following steps:

(1) In the reaction device, add the surface-treated carbonyl iron powder and the magnetic Fe ₃ O ₄ , mix and then add the surfactant, the inorganic thixotropic agent and the The dehydrated alcohol described above, and through high-speed dispersion treatment;

(2) After taking it out, place it in a vacuum drying oven to dry at 60-80°C, mix it with the carrier liquid, the antioxidant and the anti-wear agent, and then undergo high-speed grinding and dispersion treatment to obtain the Micro-nano magnetorheological fluid.

Example 1

The preparation method of a kind of micro-nano magnetorheological fluid of the present invention specifically comprises the following steps:

(1) In a 500mL stainless steel container, add 220g of the surface-treated carbonyl iron powder and the magnetic Fe ₃ O _44g , add 12.8g of sodium dodecylbenzenesulfonate after mixing (surface active agent), diatomaceous earth 3.1g (inorganic thixotropic agent) and 75mL of absolute ethanol, and subjected to high-speed dispersion treatment for 8 hours;

(2) Take it out and place it in a vacuum drying oven for drying at 60-80°C to purify or activate the surface of the magnetic particles, and introduce active polar groups on the surface to achieve amphiphilic treatment and improve magnetorheological properties. Then the suspension phase mixture after the above-mentioned vacuum drying and the weighed simethicone oil 33.75g (carrier liquid), benzoic acid 3.1g (antioxidant) and graphite 3.1g (anti-wear agent) are added in the stainless steel grinding tank and mixed, After high-speed grinding and dispersion for 12 hours, the micro-nano-scale magnetorheological fluid was obtained.

In order to study the mechanical properties of the micro-nano magnetorheological fluid in Example 1 under the static mode and the stable shear mode, the present invention uses a magnetorheological fluid normal force testing device to carry out experimental research on it. The results show that in the static mode, the normal force of the magnetorheological fluid will increase with the increase of the magnetic induction intensity and reach the maximum value, then there will be a downward trend and finally stabilize, as shown in Figure 1; In the steady shear mode, the normal force of the magnetorheological fluid increases with the increase of the magnetic induction intensity and reaches the maximum value, then has a downward trend and finally stabilizes, as shown in Figure 2. In the stage of increasing normal stress, for the magnetorheological fluid used in the experiment, the relationship between the normal force and the magnetic induction can be described by the formula F _N =4667*B ^2.48 . The research results have extremely important theoretical significance for the further development of corresponding magnetorheological fluid devices, such as magnetorheological fluid dampers and drivers, and for expanding the application of magnetorheological fluids in mechanical vibration control.

Example 2

The preparation process and steps of a micro-nano magnetorheological fluid in this Example 2 are the same as those in the above-mentioned Example 1, except that the sampling amount of each component raw material is different, and the specific amount of each component raw material is shown in Table 1.

Example 3

The preparation process and steps of a micro-nano magnetorheological fluid in this Example 3 are the same as those in the above-mentioned Example 1, except that the sampling amount of each component raw material is different, and the specific amount of each component raw material is shown in Table 1.

Example 4

The preparation process and steps of a micro-nano magnetorheological fluid in this embodiment 4 are the same as those in the above-mentioned embodiment 1, except that the sampling amount of each component raw material is different, and the specific amount of each component raw material is shown in Table 1.

Example 5

The preparation process and steps of a micro-nano magnetorheological fluid in Example 5 are the same as those in Example 1 above, except that the sampling amount of each component raw material is different, and the specific amount of each component raw material is shown in Table 1.

In addition, the present invention also tested Examples 1-5, under the external magnetic induction intensity, the influence of different mass fractions of magnetic Fe ₃ O ₄ on the normal stress of micro-nano magnetorheological fluid, see Table 1 and Figure 3.

Table 1 Effect of different mass fractions of magnetic Fe ₃ O ₄ on the normal stress of micro-nano magnetorheological fluid

Figure 3 is the relationship between the normal stress and the applied magnetic induction B of micro-nano magnetorheological fluids made of different mass fractions (0%, ₄ %, 7%, 12%, 16%) nano-magnetic _Fe3O4 It can be seen from Fig. 3 that the normal stress and the magnetic induction intensity of each magnetorheological fluid are basically in a linear relationship. When the applied magnetic induction intensity is small (B<1.5T), the normal stress of each micronano magnetorheological fluid has little difference; but with the increase of the applied magnetic induction intensity, the normal stress of each micronano magnetorheological fluid sample The difference appears to be growing. It can also be seen from Figure 3 that the normal stress of the micro-nano magnetorheological fluid increases with the increase of the mass fraction of the nanomagnetic Fe ₃ O ₄ dispersed phase, and is greater than that of the magnetorheological fluid without nanoparticles; but when When the content of magnetic Fe ₃ O ₄ is 7%, the growth rate of normal stress with the change of magnetic induction reaches the maximum. It can be seen that the content of nano-Fe ₃ O ₄ particles is not as good as possible.

The preferred embodiments of the invention disclosed above are only to help illustrate the invention. The preferred embodiments are not exhaustive in all detail, nor are the inventions limited to specific embodiments described. Obviously, many modifications and variations can be made based on the contents of this specification. This description selects and specifically describes these embodiments in order to better explain the principle and practical application of the present invention, so that those skilled in the art can well understand and utilize the present invention. The invention is to be limited only by the claims, along with their full scope and equivalents.

Claims (7)

1. A micro-nano magnetorheological fluid, characterized in that, comprising the raw materials of the following mass fractions: The particle size of the carbonyl iron powder is 0.5um-10um; the particle size of the magnetic Fe ₃ O ₄ is 50nm-300um, and the average particle size is 60nm. 2. A micro-nano magnetorheological fluid according to claim 1, wherein said carrier liquid is simethicone or silicone oil. 3. a kind of micro-nano magnetorheological fluid according to claim 1, described tensio-active agent is sodium dodecylbenzenesulfonate or polyethylene glycol. 4. A kind of micro-nano magnetorheological fluid according to claim 1, wherein said inorganic thixotropic agent is diatomaceous earth. 5. a kind of micro-nano magnetorheological fluid according to claim 1, described antioxidant is benzoic acid. 6. A kind of micro-nano magnetorheological fluid according to claim 1, wherein said anti-wear agent is graphite or silicon dioxide. 7. A method for preparing a micro-nano magnetorheological fluid according to any one of claims 1 to 6, characterized in that it comprises the following steps: (1) In the reaction device, add the surface-treated carbonyl iron powder and the magnetic Fe ₃ O ₄ , mix and then add the surfactant, the inorganic thixotropic agent and the The dehydrated alcohol described above, and through high-speed dispersion treatment; (2) Take it out and put it in a vacuum drying oven to dry, and mix it with the carrier liquid, the antioxidant and the anti-wear agent, and then undergo high-speed grinding and dispersion treatment to obtain the micro-nano-scale magnetic rheological fluid.