A metal liquid-based intelligent hydraulic transmission medium, its preparation method and application

Abstract

The present invention relates to a metal liquid-based intelligent hydraulic transmission medium, its preparation method and application, belonging to the technical field of fluid transmission and control. The metal liquid-based intelligent hydraulic transmission medium is composed of 90.2-99.5% of a metal base liquid, 0.5-9.8% of magnetic core-shell nanoparticles and a mixture of low-dimensional nano-additives, wherein the magnetic core-shell nanoparticles and the low-dimensional nano-additives are prepared according to a volume ratio of 1:1. The present invention uses a gallium-based alloy as the base liquid of the medium, which has stable high-temperature properties and almost no evaporation loss; the viscosity is little affected by temperature and pressure, improving the control characteristics of the hydraulic system from normal temperature to high temperature; the thermal expansion rate is low, which can weaken the deformation of pipelines and components caused by positive pressure due to the thermal expansion of the medium, and is beneficial to the application of closed systems; it has a magnetohydrodynamic effect under high flow velocity conditions, improving the problem of shear thinning during operation of the magnetic fluid as a hydraulic transmission medium.

Description

Technical Field

[0001] The present invention relates to a metal liquid-based intelligent hydraulic transmission medium, a preparation method thereof and an application, and belongs to the technical field of fluid transmission and control. Background Art

[0002] Magnetorheological fluid (also known as magnetic liquid, ferrofluid) is a suspension formed by strong magnetic particles with a scale of 1-100 nm dispersed in a base liquid, which has both the fluidity of a liquid and the magnetism of a magnetic material. Compared with magnetorheological fluid with a particle size of micrometers, the performance of magnetorheological fluid is more stable, and it is not easy to agglomerate or precipitate to cause system blockage. It has the characteristics of good fluidity, sealing performance and lubricity, and meets the basic performance requirements of hydraulic transmission. The intelligent characteristic of magnetorheological fluid is reflected in that its flow state can be continuously and reversibly controlled by a magnetic field: under the condition of no magnetic field, the magnetorheological fluid presents a free flow state of Newtonian fluid. Under the action of an external magnetic field, its viscosity will increase within several milliseconds, and increase with the increase of the external magnetic field and decrease with the decrease of the external magnetic field. Using magnetorheological fluid as a hydraulic transmission medium to develop new hydraulic components and systems with characteristics such as intelligence, low energy consumption, fast response speed and low working noise has many advantages.

[0003] In the prior art, the base liquids of magnetorheological fluid hydraulic transmission media have not deviated from the categories of water and oil: (1) Water has problems such as scaling and boiling at high temperatures, and oil has problems such as aging, decomposition, flammability and carbonization at high temperatures, and cannot work under high temperature conditions; (2) The viscosities of water and oil are sensitive to temperature. The viscosity of pure water drops by 56% at 40-70 °C, and the viscosity of mineral hydraulic oil drops by more than 80% at 40-70 °C, resulting in a decrease in lubricity and sealing performance, aggravating wear and leakage, causing a decrease in volumetric efficiency, and deteriorating the working efficiency and control accuracy of the system; (3) The evaporation losses of water and oil are large, and evaporation will cause an increase in the nanoparticle concentration of magnetorheological fluid, changing the dispersion system and magnetic properties, seriously affecting the working stability and intelligent control characteristics of the medium; (4) Under the action of a certain external magnetic field, the apparent viscosity of water-based and oil-based magnetorheological fluids will decrease with the increase of the shear rate, that is, there is a phenomenon of shear thinning, seriously affecting the control accuracy of hydraulic components and systems; (5) When the flowing magnetorheological fluid medium is under the action of an external magnetic field, there is magneto-viscous dissipation, and the consumed energy is converted into heat energy, causing a large temperature rise of the medium. The thermal conductivities of water and oil are low, and the heat dissipation performance is poor; (6) For a hydraulic transmission system using water-based and oil-based liquids as working media, its energy recovery methods are traditional electric and hydraulic methods, and it is difficult to recover the throttling loss of the hydraulic system. The throttling loss is finally dissipated in the form of heat energy of the hydraulic medium; (7) Under high pressure, water-based and oil-based hydraulic media show obvious compressibility, increasing the control error of the high-pressure system.

[0004] The authorized patent "A preparation method of a water-based magnetorheological hydraulic transmission medium", with the authorization number CN102041154B, and the authorized patent "A preparation method of an oil-based magnetorheological hydraulic transmission medium", with the authorization number CN102031187B, respectively provide a preparation method of a water-based magnetorheological hydraulic transmission medium and an oil-based magnetorheological hydraulic transmission medium.

[0005] The liquid metal-based base fluid is prepared by alloying low-melting-point metals such as gallium, bismuth, indium, tin, and zinc. It has both metallicity and room-temperature fluidity, and has the characteristics of good fluidity, good thermal conductivity, good electrical conductivity, low saturated vapor pressure, environmental protection and non-toxicity, small temperature-viscosity change, and low thermal expansion rate. Moreover, it has an MHD (magnetohydrodynamic effect) magneto-induced flow resistance controlled by a magnetic field: the flowing liquid metal cuts the magnetic field to generate an induced current inside it, and the interaction between the induced current and the magnetic field generates a Lorentz body force opposite to the flow direction to inhibit the flow, which is the MHD flow resistance. The magnitude of the MHD flow resistance is related to the magnetic field strength and the flow velocity: when the flow velocity is constant, the MHD flow resistance increases with the increase of the magnetic field; when the magnetic field is constant, the MHD flow resistance increases with the increase of the flow velocity.

[0006] Liquid metals have problems such as low viscosity, poor lubricity, and easy occurrence of turbulence. Traditional hydraulic transmission media improve the characteristics of the base fluid through additives to meet the requirements of hydraulic transmission. However, liquid metals are essentially different from fluids such as water and oil. It can be regarded as a mixture composed of positive ion fluids and free electron gases, belonging to the category of atomic fluids. Therefore, conventional hydraulic medium additives cannot meet the performance regulation requirements of liquid metals.

[0007] The prior art proposes to use micro-nano particles as additives for the liquid metal matrix: the authorized patent "Liquid metal lubricant with micro-nano powder as additive, its preparation and application", with the authorization number CN109022110B, provides a liquid metal lubricant with non-magnetic or magnetic micro-nano powder as additive. It uses paste-like liquid metal as the base fluid, lipid-based, with high viscosity and insufficient fluidity, and is not suitable as a hydraulic transmission medium. The published patent "Hydraulic transmission device based on liquid metal", with the publication number CN107587473A, proposes to use gallium-based or bismuth-based liquid metals as hydraulic transmission media to design a hydraulic transmission device, and gives a scheme of doping magnetic particles with a particle size of 1 - 900nm. However, directly using liquid metal as a hydraulic medium has problems such as low viscosity, poor lubrication performance, and easy component wear; particles with a sub-micron particle size greater than 100nm are likely to cause sticking, jamming, and severe wear of key friction pairs such as plungers, spool valves, and hydraulic cylinder pistons, seriously affecting the component performance and service life; magnetic particles will react with liquid metal to cause a decrease or even disappearance of the magnetic properties of the medium. Micro-nano particles will increase electron scattering, resulting in a decrease in the electrical conductivity of the medium and affecting the functional characteristics.

[0008] The magnetic core-shell nanoparticles are composed of a core of magnetic material and a shell coated on the outside, and the core and the shell are connected to each other through physical and chemical interactions. Using a non-metallic material as the shell can prevent the magnetic material from failing due to alloying reaction with the liquid metal-based alloy.

[0009] Graphene is a material in which carbon atoms connected by sp 2 hybridization are closely packed into a single-layer two-dimensional honeycomb lattice structure. It has an ultra-thin sheet structure, is easy to enter the friction contact surface, its layers are easy to slide, the shear strength is low, and it has good self-lubricating performance. Moreover, graphene has excellent high-temperature stability, good compatibility with liquid metal-based alloys, and its electrical and thermal conductivity are both better than those of liquid metal-based alloys. Using single-layer or few-layer graphene as an additive can improve the stability, lubricity, heat dissipation, electrical conductivity, and regulation of medium viscosity of the liquid metal-based hydraulic medium.

[0010] To achieve the dispersion of solid-phase particles in liquid metal: The authorized patent "A Method for Doping Micro-Nano Particles into Liquid Metal and Its Application", authorization number CN108085519B, this method adds micro-nano particles and liquid metal with a mass ratio of 1:9 to 19 to an acidic, alkaline or conductive solution and stirs. By means of an auxiliary metal and an external power source, the wettability of the liquid metal is changed so that the micro-nano particles are doped into the liquid metal. The external power source has problems such as high energy consumption and great preparation difficulty, and introducing an auxiliary metal will affect the purity of the liquid metal.

[0011] Based on the above problems, the present invention proposes a liquid metal-based intelligent hydraulic transmission medium and a preparation method thereof, which use magnetic core-shell nanoparticles and low-dimensional nano materials as additives with liquid metal as the base fluid. Summary of the Invention

[0012] The technical problem to be solved by the present invention is to provide a liquid metal-based intelligent hydraulic transmission medium and a preparation method thereof to solve the problems of insufficient high-temperature working performance of the existing magneto-fluid hydraulic transmission medium, the problem of shear thinning of the magneto-fluid hydraulic transmission medium during work, and improve the dispersion stability and functional characteristics of the liquid metal-based nano-magneto-fluid.

[0013] The technical solution of the present invention is: A liquid metal-based intelligent hydraulic transmission medium is composed of 90.2-99.5% of a metal base fluid, 0.5-9.8% of a mixture of magnetic core-shell nanoparticles and low-dimensional nano additives, wherein the magnetic core-shell nanoparticles and the low-dimensional nano additives are prepared in a volume ratio of 1:1, and the metal base fluid is prepared by alloying two or more metals among gallium, indium, tin, zinc, silver, and aluminum.

[0014] The composition of the metal base fluid is Ga 94.5 Ag 5.5 (melting point 26.0 °C), GaAl0.9 (Melting point 25.0 °C), Ga 96.3 Zn 3.7 (Melting point 24.7 °C), GaSn 13.4 (Melting point 21.0 °C), Ga 82 Sn 12 Zn6 (Melting point 17.0 °C), Ga 75.5 In 24.5 (Melting point 15.7 °C), Ga 77 In 21.4 (Melting point 15.4 °C), Ga 68.5 In 21.5 Sn 10 (Melting point 13.2 °C), Ga 67 In 29 Zn4 (Melting point 13.0 °C), Ga 67 In 20.5 Sn 12.5 (Melting point 10.5 °C), Ga 61 In 25 Sn 13 Zn1 (Melting point 7.6 °C), Ga 67.98 In 20.01 Sn 10.5 Ag 1.51 (Melting point < 4 °C), Ga 61 In 25 Sn 13 Zn1 (Melting point 3.0 °C).

[0015] The magnetic core-shell nanoparticles adopt a core-shell structure and are composed of an inner core of ferrite nano-magnetic particles with a relatively high Curie temperature and a SiO2 outer shell that is resistant to high temperatures and does not react with the Ga-based alloy.

[0016] The core-shell structure adopted by the magnetic core-shell nanoparticles is one or more of Fe3O4@SiO2, NiFe2O4@SiO2, Ni 0.5 Zn 0.5 Fe2O4@SiO2.

[0017] The particle size of the magnetic core-shell nanoparticles is 1 - 100 nm to meet the requirements of hydraulic transmission for the fluidity, lubricity and stability of the medium, where the diameter of the inner core of the magnetic nanoparticles is 1 - 90 nm and the thickness of the outer shell is 5% - 90% of the particle size of the magnetic nanoparticles.

[0018] The low-dimensional nano-additive is one of the following with good lubrication performance and relatively good dispersion stability: few-layer graphene (FLG-Ls) with a lamellar thickness of 0.5 - 3.0 nm, a diameter of 0.1 - 5 μm, and a purity > 99%, or nano monolayer graphene (GNFs) with a lamellar thickness of 0.5 - 1.2 nm, a diameter of 100 - 500 nm, and a purity > 99%.

[0019] A preparation method of a metal liquid-based intelligent hydraulic transmission medium, the specific steps are as follows:

[0020] Step1: Add a mixture of magnetic core-shell nanoparticles and low-dimensional nano-additives with a volume fraction of 0.5 - 15% to an acidic aqueous solution. Under the condition of a constant temperature water bath at 45 - 50 °C, mechanically stir and ultrasonically disperse for 30 - 120 min, with a stirring speed of 200 - 1000 r / min, to obtain a stably dispersed binary mixed nano-solution;

[0021] Step2: Add the metal base liquid to the acidic aqueous solution, with a volume ratio of the metal base liquid to the acidic aqueous solution of 1:5 - 9. React for 30 - 60 min to remove the oxide layer on the outer surface of the metal base liquid. Under the condition of a constant temperature water bath at 45 - 50 °C, mechanically stir and ultrasonically disperse for 30 - 120 min, with a stirring speed of 200 - 1000 r / min, so that the metal base liquid is dispersed into the acidic solution with a micron-sized particle size to obtain a metal droplet dispersion;

[0022] Step3: Add the binary mixed nano-solution obtained in Step1 to the metal droplet dispersion obtained in Step2. Under the condition of a constant temperature water bath at 45 - 50 °C, mechanically stir and ultrasonically disperse for 30 - 120 min, with a stirring speed of 500 - 1200 r / min, and apply a pulsed magnetic field with a magnetic field intensity range of 0 - 300 mT and a frequency of 10 - 50 Hz to obtain a ternary mixed solution;

[0023] Step4: Apply a constant magnetic field with a strength of 30 - 60 mT on the upper layer of the ternary mixed solution prepared in Step3 to collect the remaining magnetic core-shell nanoparticles. Let it stand for 8 - 24 h under a constant temperature water bath at 30 °C - 40 °C. After the solution is completely stratified, remove the remaining magnetic core-shell nanoparticles and low-dimensional nano-additives on the upper layer of the solution, collect the lower layer liquid and perform vacuum drying treatment to obtain the metal liquid-based intelligent hydraulic transmission medium.

[0024] Store the prepared metal liquid-based intelligent hydraulic transmission medium sample in a storage liquid, and the storage liquid is a weakly acidic solvent.

[0025] The acidic aqueous solution is a hydrochloric acid aqueous solution with a pH of 0.7 - 1.0.

[0026] The storage liquid is an acetic acid aqueous solution with a pH of 3.0 - 4.5.

[0027] The present invention also provides an application of the metal-based intelligent hydraulic transmission medium in hydraulic components. When the metal-based intelligent hydraulic transmission medium of the present invention is applied to traditional hydraulic components, special magnetic fluid hydraulic components or magnetorheological control components: when applied to traditional hydraulic components, the upper limit of the working temperature of the hydraulic components can be increased, the control error caused by the temperature-viscosity change of the traditional transmission medium can be improved, and the lubrication characteristics of the flow distribution pair of the hydraulic pump, the piston-cylinder wall friction pair of the hydraulic cylinder, and the spool-valve sleeve friction pair of the hydraulic valve can be improved, and a self-repairing effect can be achieved; when applied to a high-speed hydraulic cylinder with nano-magnetic fluid clearance seal (CN113803322A), the control accuracy of the high-speed hydraulic cylinder with nano-magnetic fluid clearance seal can be improved, the buffering force can be increased, and the upper limit of the working temperature can be increased; when applied to a magnetic fluid hydraulic pump station (CN114001023A), the upper limit of the working temperature can be increased, and the temperature rise rate of alternating magnetic field heating can be increased. When applied to various magnetorheological valves, the upper limit of the working temperature can be increased, the shear thinning of the magnetorheological valves under high-pressure and high-flow velocity conditions can be solved, the control accuracy of the magnetorheological valves can be improved, and the magnetorheological valves can be applied to high-pressure and large-flow hydraulic systems.

[0028] The hydraulic components are traditional hydraulic components, special magnetic fluid hydraulic components or magnetorheological control components.

[0029] The special magnetic fluid hydraulic components are high-speed hydraulic cylinders with nano-magnetic fluid clearance seals or magnetic fluid hydraulic pump stations, and the magnetorheological control components include various magnetorheological valves.

[0030] The preparation principle and working principle of the present invention are as follows:

[0031] (1) The preparation and dispersion principle of the medium: The preparation adopts a process of "dispersing first and then mixing". The mixture of magnetic core-shell nanoparticles and low-dimensional nano-additives (as shown in Figure 17 ) is uniformly dispersed into an acidic aqueous solution through mechanical stirring and ultrasonic waves to form a binary nano-solution. The presence of the magnetic core-shell nanoparticles changes the exfoliation state and interlayer distance of graphene, improving the dispersion stability; through ultrasonic waves, the metal-based liquid is dispersed in the acidic aqueous solution in the form of micron-sized micro-droplets (as shown in Figure 18 ), increasing the specific surface area of the metal-based liquid; the binary nano-solution and the micro-droplet dispersion of the metal-based liquid are dispersed and mixed through mechanical stirring and ultrasonic waves under a pulsed magnetic field. The micro-droplets of the metal-based liquid generate induced current and become charged when cutting the magnetic induction lines during the high-speed movement, significantly enhancing the wettability of the micro-droplets of the metal-based liquid. The magnetic core-shell nanoparticles and low-dimensional nano-additives collide with the micron-sized charged micro-droplets of the metal-based liquid and are wetted and endocytosed, thus preparing a metal-based intelligent hydraulic transmission medium with uniform dispersion and good stability. A pulsed magnetic field is used instead of a constant magnetic field to reduce the aggregation of the magnetic core-shell nanoparticles under the action of the constant magnetic force. The whole preparation process is carried out in an acidic aqueous solution to prevent the metal-based liquid from being oxidized by air.

[0032] (2) Principle of performance regulation of the medium: The low-dimensional nano-additive graphene has high electrical conductivity and good thermal conductivity, which can significantly improve the electrical conductivity and thermal conductivity of the medium, thereby enhancing the electromagnetic functional properties and heat dissipation of the medium. The SiO2 shell of the magnetic core-shell nanoparticles has good temperature resistance, corrosion resistance, thermal shock resistance, electrical conductivity and excellent chemical inertness, and the wettability of the gallium-based alloy on SiO2 is better than that of carbon. The magnetic core-shell nanoparticles can easily penetrate into the graphene aggregates during the dispersion process, destroying the formation of graphene clusters, thereby improving the dispersion stability of the medium. Adding magnetic core-shell nanoparticles and low-dimensional nano-additives can regulate the viscosity of the medium, improve the problem that the metal-based liquid is prone to turbulence due to its large density and small viscosity, making the flow tend to a stable laminar state and improving the system control characteristics.

[0033] (3) Principle of high temperature resistance of the medium: The metal-based liquid uses a gallium-based alloy, which has almost no evaporation at high temperatures, a low thermal expansion rate, and excellent temperature-viscosity characteristics; the low-dimensional nano-additive graphene has excellent high-temperature stability, with a melting point as high as 4125K and good compatibility with the gallium-based alloy; the magnetic core-shell nanoparticles use SiO2 as the coating layer, with stable high-temperature properties and good compatibility with the gallium-based alloy, and the ferrite nano-magnetic material used in its core has a high Curie temperature and a small decay of magnetic properties at high temperatures. It can meet the requirements of hydraulic transmission for use from room temperature to 400°C.

[0034] (4) Principle of anti-wear and friction reduction of the medium: The low-dimensional nano-additive graphene has an ultra-thin lamellar structure, which is easy to enter the friction contact surface. Its interlayer is easy to slip, with low shear strength and good self-lubricating performance; the magnetic core-shell nanoparticles have a "micro-rolling bearing" effect on the surface of the friction pair and can be controlled by a magnetic field. Utilizing the unique lubrication advantages of low-dimensional nano-additives and magnetic core-shell nanoparticles to exert a synergistic lubrication effect: during the friction process, (1) the magnetic core-shell nanoparticles roll and squeeze the low-dimensional nano-additive graphene, and the graphene undergoes interlayer slip, further reducing the frictional resistance; (2) the magnetic core-shell nanoparticles share part of the load, improving the load-bearing capacity of the low-dimensional nano-additive graphene; (3) the deposition of the magnetic core-shell nanoparticles on the low-dimensional nano-additive graphene reduces the interlayer van der Waals force and enhances the anti-shear ability; (4) the magnetic core-shell nanoparticles and the low-dimensional nano-additive graphene enter the worn surface and form a composite protective film to repair the wear.

[0035] (5) Principle of energy recovery based on MHD: As Figure 2As shown, the metal liquid-based intelligent hydraulic transmission medium passes through a magnetic field perpendicular to the flow direction at a certain speed, cuts the magnetic force lines to generate electromotive force, and thus generates electric energy, which is stored in the battery. This energy recovery method has no relatively moving or rotating components, directly converts heat energy into electric energy, can reduce system heat generation, and has a high energy conversion efficiency. It can recover the throttling energy losses of components such as the damping flow channel of the magnetorheological valve and the buffer device of the magnetohydrodynamic cylinder.

[0036] (6) Shear-thinning compensation principle of the medium: As Figure 3As shown in the figure, the intelligent control principle of the metal liquid-based intelligent hydraulic transmission medium is different from that of ordinary magnetorheological fluids and general conductive fluids. Under the action of a magnetic field, both magnetorheological effects and magnetohydrodynamic effects exist: (1) At low flow rates, the magnetorheological effect plays a dominant role. The magnetic core-shell nanoparticles in the metal liquid-based intelligent hydraulic transmission medium are affected by the applied magnetic field and form a relatively stable chain-like structure. The stable chain-like structure has a large hindrance effect on the medium flow and can be described based on magnetorheological mathematical models such as the Bingham model and Herschel-Bulkley model; (2) At medium flow rates, the magnetorheological effect and magnetohydrodynamic effect (MHD) act together. The magnetic core-shell nanoparticles in the metal liquid-based intelligent hydraulic transmission medium are affected by the applied magnetic field to form a chain-like structure. The medium flow rate destroys the stability of the chain-like structure (macroscopically manifested as shear thinning). The chain-like structure still has a certain hindrance effect on the medium flow. At the same time, under medium flow rate conditions, the metal liquid, as a conductive fluid, cuts the magnetic induction lines to generate an induced current. The induced current interacts with the magnetic field to generate a reverse Lorentz force, which also has a certain hindrance effect on the medium flow. The Lorentz force compensates for the shear thinning. It can be described based on magnetorheological mathematical models such as the Bingham model and Herschel-Bulkley model and magnetohydrodynamic equations; (3) At high flow rate conditions, the magnetohydrodynamic effect (MHD) plays a dominant role. The high flow rate completely breaks through the chain-like structure. The magnetorheological effect has no hindrance effect on the medium flow. At high flow rate conditions, the metal liquid, as a conductive fluid, cuts the magnetic induction lines to generate an induced current. The induced current interacts with the magnetic field to generate a large reverse Lorentz force, which also has a strong hindrance effect on the medium flow and can be described based on magnetohydrodynamic equations. The Lorentz force compensates for the shear thinning and solves the key technical problem of shear thinning of existing magnetorheological fluids. The magnetohydrodynamic effect of the metal-based liquid compensates for the shear thinning of traditional magnetorheological fluids at high flow rates, and the magnetorheological effect of magnetic core-shell nanoparticles makes up for the problem that traditional conductive fluids have weak magnetohydrodynamic effects and small MHD flow resistance at low flow rates, solving the key technical problem of shear thinning of existing magnetorheological fluids. Based on the above principle, the viscosity and fluid resistance of the medium can be continuously and reversibly controlled by using a magnetic field, and the lubrication state control, flow rate and pressure control, start-up and buffering process control of key friction pairs of hydraulic components, and compensation of the temperature-viscosity characteristics of the compensation medium can be realized by applying a magnetic field.

[0037] (VII) Intelligent control principle of the medium: As Figure 4As shown, the schematic diagram of the intelligent control applicable to the magnetorheological valve is given, including a shear thinning compensation module and a magnetorheological pressure drop control module, which can solve the shear thinning of the magnetorheological valve under high-pressure and high-flow conditions. The inlet / outlet pressures of the magnetorheological valve are measured by a pressure sensor, the pressure difference between the inlet and outlet is judged by a pressure calculator, and the DC power supply is controlled by a control algorithm, so as to adjust the magnetic induction intensity value of the electromagnetic coil. The metal-based intelligent hydraulic transmission medium undergoes magnetorheological effect and magnetohydrodynamic effect under the action of a magnetic field, thereby realizing the intelligent control of the pressure drop of the magnetorheological valve. Among them, for the switching of the control algorithm, the instantaneous flow rate at the inlet of the magnetorheological valve is measured by a flow sensor, and the flow velocity is judged by an arithmetic unit. If the flow velocity is low, the MR control algorithm is used; if the flow velocity is medium, the MR and MHD control algorithms are used; if the flow velocity is high, the MHD control algorithm is used.

[0038] The beneficial effects of the present invention are as follows:

[0039] (1) The present invention uses a gallium-based alloy as the base liquid of the medium, which has stable high-temperature properties, almost no evaporation loss; the viscosity is little affected by temperature and pressure, improving the control characteristics of the hydraulic system from normal temperature to high temperature; it has a low coefficient of thermal expansion, which can weaken the deformation of pipelines and components caused by positive pressure due to the thermal expansion of the medium, facilitating the application of closed-loop systems; its compressibility is much lower than that of water and oil, which is beneficial to improving the control accuracy of high-pressure systems; when there is a leak in the system, the gallium-based alloy can form a high-viscosity oxide film at the sealing interface to inhibit leakage and improve the sealing performance of components; it is safe, non-toxic and environmentally friendly.

[0040] (2) For the metal-based intelligent hydraulic transmission medium of the present invention, the magnetic core-shell nanoparticles used have stable high-temperature magnetic properties; the low-dimensional nano-additive graphene has stable high-temperature properties, excellent lubricity, good electrical conductivity and thermal conductivity.

[0041] (3) The present invention adopts a preparation process of "dispersing first and then mixing", with uniform dispersion. The magnetohydrodynamic effect generated under the magnetic field is used to charge the micro-droplets of the metal base liquid to enhance wettability, without the need for a power supply and auxiliary electrodes, and the purity of the metal base liquid is ensured.

[0042] (4) For the metal-based intelligent hydraulic transmission medium of the present invention, the MHD effect compensates for shear thinning, with a wide controllable range and stable control. It can realize continuous, stepless and intelligent control of relatively high pressures and flows, with small demagnetization errors and high control accuracy, meeting the long-term use requirements of hydraulic transmission at room temperature to 400 °C.

[0043] (5) For the metal-based intelligent hydraulic transmission medium of the present invention, the energy throttled and lost by the damping flow channel of the magnetorheological valve, the magnetic fluid hydraulic cylinder buffer device, etc. can be recovered based on the MHD power generation principle, with high energy efficiency.

[0044] (6) The intelligent hydraulic transmission medium based on metal liquid of the present invention can be driven by an electromagnetic pump, with good sealing performance, stable transmission and good noise reduction performance.

[0045] (7) The intelligent hydraulic transmission medium based on metal liquid of the present invention has excellent fire resistance, which can improve the battlefield survival ability of military hydraulic equipment.

[0046] (8) The intelligent hydraulic transmission medium based on metal liquid of the present invention can work at a lower temperature by setting a heating device. Description of the Drawings

[0047] Figure 1 is the preparation flow chart of the intelligent hydraulic transmission medium based on metal liquid of the present invention;

[0048] Figure 2 is the schematic diagram of the MHD energy recovery principle of the present invention;

[0049] Figure 3 is the schematic diagram of the shear thinning compensation principle of the intelligent hydraulic transmission medium based on metal liquid of the present invention;

[0050] Figure 4 is the schematic diagram of the intelligent control method of the intelligent hydraulic transmission medium based on metal liquid of the present invention;

[0051] Figure 5 is the comparison chart of the viscosity reduction rate of the intelligent hydraulic transmission medium based on metal liquid of the present invention in Example 1 and the existing hydraulic transmission medium at 40-100 °C;

[0052] Figure 6 is the comparison chart of the thermogravimetric curves of the intelligent hydraulic transmission medium based on metal liquid of the present invention in Example 1 and the existing hydraulic transmission medium at 0-500 °C;

[0053] Figure 7 is the magneto-viscosity characteristic curve of the intelligent hydraulic transmission medium based on metal liquid of the present invention in Example 1;

[0054] Figure 8 is the comparison chart of the viscosity reduction rate of the intelligent hydraulic transmission medium based on metal liquid of the present invention in Example 2 and the existing hydraulic transmission medium at 40-100 °C;

[0055] Figure 9 is the comparison chart of the thermogravimetric curves of the intelligent hydraulic transmission medium based on metal liquid of the present invention in Example 2 and the existing hydraulic transmission medium at 0-500 °C;

[0056] Figure 10 is the magneto-viscosity characteristic curve of the intelligent hydraulic transmission medium based on metal liquid of the present invention in Example 2;

[0057] Figure 11 is the comparison chart of the viscosity reduction rate of the intelligent hydraulic transmission medium based on metal liquid of the present invention in Example 3 and the existing hydraulic transmission medium at 40-100 °C;

[0058] Figure 12 is the comparison chart of the thermogravimetric curves of the intelligent hydraulic transmission medium based on metal liquid of the present invention in Example 3 and the existing hydraulic transmission medium at 0-500 °C;

[0059] Figure 13 is the magnetic-viscous property curve of Embodiment 3 of the present invention;

[0060] Figure 14 is the nano-Ni used in the embodiments of the present invention 0.5 Zn 0.5 TEM image of the microscopic morphology of Fe2O4@SiO2 particles;

[0061] Figure 15 is the nano-Ni used in the embodiments of the present invention 0.5 Zn 0.5 XRD pattern of Fe2O4@SiO2 particles;

[0062] Figure 16 is the nano-Ni used in the embodiments of the present invention 0.5 Zn 0.5 Hysteresis loop diagram of Fe2O4@SiO2 particles;

[0063] Figure 17 is the TEM image of the mixture of few-layer graphene and nano-Ni 0.5 Zn 0.5 Fe2O4@SiO2 particles;

[0064] Figure 18 SEM image of micro-nano metal droplets in the metal droplet dispersion of the embodiments of the present invention;

[0065] Figure 19 is the physical image of the metal-based intelligent hydraulic transmission medium sample of the embodiments of the present invention under the action of a magnetic field. Detailed implementation manners

[0066] The present invention will be further described below in conjunction with the accompanying drawings and specific implementation manners.

[0067] Embodiment 1: As Figure 1 shown, a metal-based intelligent hydraulic transmission medium (Embodiment 1) is composed of a Ga 77 In 21.4 metal base fluid, Ni 0.5 Zn 0.5 Fe2O4@SiO2 magnetic core-shell nanoparticles and few-layer graphene (FLG-Ls) low-dimensional nano-additives.

[0068] Its preparation method is as follows:

[0069] Step1: Ni with a volume fraction of 5.0% 0.5 Zn 0.5The mixture of Fe2O4@SiO2 magnetic core-shell nanoparticles and few-layer graphene (FLG-Ls) low-dimensional nano-additives was added to an acidic aqueous solution. Under the condition of a constant temperature water bath at 47 °C, it was mechanically stirred and ultrasonically dispersed for 60 min at a stirring speed of 500 r / min to obtain a stably dispersed binary mixed nano-solution;

[0070] Step2: Add Ga 77 In 21.4 The metal base liquid was added to the acidic aqueous solution with a volume ratio of the metal base liquid to the acidic aqueous solution of 1:7. After reacting for 45 min to remove the oxide layer on the outer surface of the metal base liquid, under the condition of a constant temperature water bath at 45 °C, it was mechanically stirred and ultrasonically dispersed for 60 min at a stirring speed of 500 r / min to disperse the metal base liquid into the acidic solution with a micron-sized particle size, obtaining a metal droplet dispersion;

[0071] Step3: Add the binary mixed nano-solution obtained in Step1 to the metal droplet dispersion obtained in Step2. Under the condition of a constant temperature water bath at 47 °C, it was mechanically stirred and ultrasonically dispersed for 45 min at a stirring speed of 700 r / min, and a pulsed magnetic field was applied with a magnetic field intensity range of 0 - 300 mT and a frequency of 20 Hz to obtain a ternary mixed solution;

[0072] Step4: Apply a constant magnetic field with a strength of 50 mT on the upper layer of the ternary mixed solution prepared in Step3 to collect the remaining Ni 0.5 Zn 0.5 Fe2O4@SiO2 magnetic core-shell nanoparticles. After standing for 12 h in a constant temperature water bath at 35 °C, after the solution was completely stratified, the remaining Ni 0.5 Zn 0.5 Fe2O4@SiO2 magnetic core-shell nanoparticles and few-layer graphene (FLG-Ls) low-dimensional nano-additives were removed from the upper layer of the solution. The lower layer liquid was collected and subjected to vacuum drying treatment to obtain the metal liquid-based intelligent hydraulic transmission medium of Example 1. After testing, the metal liquid-based intelligent hydraulic transmission medium of Example 1 was composed of 97.6% metal base liquid, 2.4% magnetic core-shell nanoparticles and low-dimensional nano-additive mixture;

[0073] Perform performance tests on the metal liquid-based intelligent hydraulic transmission medium sample prepared in Example 1, and the results are shown in Table 1:

[0074]

[0075] Table 1: Comparison of basic performance parameters between Example 1 and existing hydraulic transmission media

[0076] As can be seen from Table 1, the boiling point of the metal-based intelligent hydraulic transmission medium sample (Example 1) is >1300 °C, much higher than that of several other hydraulic transmission media; the melting point is 11.0 °C, which can be applied to a normal-temperature hydraulic transmission system; the viscosity of the metal-based intelligent hydraulic transmission medium sample (Example 1) is between that of water and mineral oil, with good fluidity; the thermal conductivity is much higher than that of existing hydraulic media, which is beneficial to the heat dissipation of the system; the conductivity is as high as 3.0·10 6 μS / cm, having the MHD functional characteristics of a conductive fluid, which are not possessed by other hydraulic transmission media.

[0077] As Figure 5 shown, the viscosity decline rate of several traditional high-temperature hydraulic transmission media is >50% at 40 - 100 °C, while that of the metal-based intelligent hydraulic transmission medium (Example 1) is about 21%, indicating that the viscosity of the metal-based intelligent hydraulic transmission medium (Example 1) changes little with temperature, which is beneficial to improving the control stability of the hydraulic system.

[0078] As Figure 6 shown, pure water completely evaporates within 150 °C, and several hydrocarbon-based hydraulic medium base fluids decompose successively in the range of 100 - 270 °C, and completely decompose when the temperature exceeds 400 °C. However, within the range of 30 - 500 °C, the mass of the metal-based intelligent hydraulic transmission medium sample (Example 1) does not decay, indicating that its evaporability is extremely low and its thermal stability is good in this temperature range.

[0079] As Figure 7 shown, under an 80 mT magnetic field, the viscosity of the sample increases to 312 mPas at 25 °C, indicating that the metal-based intelligent hydraulic transmission medium (Example 1) has a large magneto-viscous regulation range; the viscosity increases to 262 mPas at 220 °C, indicating that the metal-based intelligent hydraulic transmission medium (Example 1) also has good magneto-viscous characteristics at high temperatures, with less demagnetization at high temperatures and being able to be used normally at high temperatures.

[0080] The present invention also provides an application of a metal - based intelligent hydraulic transmission medium in hydraulic components. When the metal - based intelligent hydraulic transmission medium of the present invention (Example 1) is applied to traditional hydraulic components, special hydraulic components for magnetorheological fluids, or magnetorheological control components: when applied to traditional hydraulic components, it can increase the upper limit of the working temperature of the hydraulic components, improve the control error caused by the temperature - viscosity change of traditional transmission media, improve the lubrication characteristics of the flow - distribution pair of hydraulic pumps, the piston - cylinder wall friction pair of hydraulic cylinders, and the spool - valve sleeve friction pair of hydraulic valves, and play a self - repair role; when applied to a high - speed hydraulic cylinder with nano - magnetorheological fluid clearance seal (CN113803322A), it can improve the control accuracy of the high - speed hydraulic cylinder with nano - magnetorheological fluid clearance seal, increase the buffer force, and increase the upper limit of the working temperature; when applied to a magnetorheological fluid hydraulic pump station (CN114001023A), it can increase the upper limit of the working temperature and the temperature rise rate of alternating - magnetic - field heating. When applied to various magnetorheological valves, it can increase the upper limit of the working temperature, solve the shear - thinning problem of magnetorheological valves under high - pressure and high - flow - rate conditions, improve the control accuracy of magnetorheological valves, and enable magnetorheological valves to be applied to high - pressure and large - flow hydraulic systems.

[0081] Example 2: As Figure 1 shown, a metal - based intelligent hydraulic transmission medium (Example 2) is composed of a Ga 77 In 21.4 metal base fluid, Ni 0.5 Zn 0.5 Fe2O4@SiO2 magnetic core - shell nanoparticles, and few - layer graphene (FLG - Ls) low - dimensional nano - additives.

[0082] Its preparation method is as follows:

[0083] Step1: Add a mixture of Ni 0.5 Zn 0.5 Fe2O4@SiO2 magnetic core - shell nanoparticles and few - layer graphene (FLG - Ls) low - dimensional nano - additives with a volume fraction of 1.2% to an acidic aqueous solution. Under the condition of a constant - temperature water bath at 45°C, mechanically stir and ultrasonically disperse for 30 min, with a stirring speed of 200 r / min, to obtain a stably dispersed binary mixed nano - solution;

[0084] Step2: Add the Ga 77 In 21.4 metal base fluid to an acidic aqueous solution, with a volume ratio of the metal base fluid to the acidic aqueous solution of 1:5. React for 30 min to remove the oxide layer on the outer surface of the metal base fluid. Under the condition of a constant - temperature water bath at 47°C, mechanically stir and ultrasonically disperse for 30 min, with a stirring speed of 200 r / min, so that the metal base fluid is dispersed into the acidic solution with a micron - sized particle size to obtain a metal droplet dispersion;

[0085] Step 3: Add the binary hybrid nano-solution obtained in Step 1 into the metal droplet dispersion obtained in Step 2. Under the condition of a constant temperature water bath at 47 °C, stir mechanically and disperse ultrasonically for 30 min, with a stirring speed of 500 r / min, and apply a pulsed magnetic field with a magnetic field strength ranging from 0 to 300 mT and a frequency of 10 Hz to obtain a ternary hybrid solution;

[0086] Step 4: Apply a constant magnetic field with a strength of 30 mT on the upper layer of the ternary hybrid solution prepared in Step 3 to collect the remaining Ni 0.5 Zn 0.5 Fe2O4@SiO2 magnetic core-shell nanoparticles. Let it stand for 8 h in a constant temperature water bath at 30 °C. After the solution is completely stratified, remove the remaining Ni 0.5 Zn 0.5 Fe2O4@SiO2 magnetic core-shell nanoparticles and few-layer graphene (FLG-Ls) low-dimensional nano-additives. Collect the lower layer of the liquid and perform vacuum drying treatment to obtain the metal-based intelligent hydraulic transmission medium of Example 2. After testing, the metal-based intelligent hydraulic transmission medium of Example 2 is composed of 99.5% metal base fluid, 0.5% magnetic core-shell nanoparticles and a mixture of low-dimensional nano-additives;

[0087] Perform performance tests on the metal-based intelligent hydraulic transmission medium sample prepared in Example 2, and the results are shown in Table 2:

[0088]

[0089] Table 2: Comparison of basic performance parameters between Example 2 and existing hydraulic transmission media

[0090] As can be seen from Table 2, the boiling point of the metal-based intelligent hydraulic transmission medium sample (Example 2) > 1300 °C, which is much higher than several other hydraulic transmission media; the melting point is 11.0 °C, which can be applied to a normal temperature hydraulic transmission system; the viscosity of the metal-based intelligent hydraulic transmission medium sample (Example 2) is between that of water and mineral oil, with good fluidity; the thermal conductivity is much higher than that of existing hydraulic media, which is beneficial to system heat dissipation; the conductivity is as high as 2.7·10 6 μS / cm, with the MHD functional characteristics of a conductive fluid, which other hydraulic transmission media do not have.

[0091] As Figure 8 shown, the viscosity decline rates of several traditional high-temperature hydraulic transmission media at 40 - 100 °C are all > 50%, while that of the metal-based intelligent hydraulic transmission medium (Example 2) is about 17.2%, indicating that the viscosity of the metal-based intelligent hydraulic transmission medium (Example 2) changes little with temperature, which is beneficial to improving the control stability of the hydraulic system.

[0092] As Figure 9As shown, pure water completely evaporates within 150 °C, and several hydrocarbon-based hydraulic medium base fluids decompose successively in the range of 100 - 270 °C. When the temperature exceeds 400 °C, they all completely decompose. In the range of 30 - 500 °C, the metal-based intelligent hydraulic transmission medium sample (Example 2) has no mass attenuation, indicating that its evaporability is extremely low and its thermal stability is good in this temperature range.

[0093] As Figure 10 shown, under an 80 mT magnetic field, the viscosity of the sample increases to 312 mPas at 25 °C, indicating that the metal-based intelligent hydraulic transmission medium (Example 2) has a large magneto-viscous regulation range; the viscosity increases to 262 mPas at 220 °C, indicating that the metal-based intelligent hydraulic transmission medium (Example 2) also has good magneto-viscous properties at high temperatures, with less demagnetization at high temperatures and being able to be used normally at high temperatures.

[0094] The present invention also provides an application of the metal-based intelligent hydraulic transmission medium in hydraulic components. When the metal-based intelligent hydraulic transmission medium of the present invention (Example 2) is applied to traditional hydraulic components, special hydraulic components for magnetic fluids, or magnetorheological control components: when applied to traditional hydraulic components, it can increase the upper limit of the working temperature of the hydraulic components, improve the control error caused by the temperature-viscosity change of traditional transmission media, improve the lubrication characteristics of the flow distribution pair of hydraulic pumps, the piston-cylinder wall friction pair of hydraulic cylinders, and the spool-valve sleeve friction pair of hydraulic valves, and play a self-repairing role; when applied to a high-speed hydraulic cylinder with nano-magnetic fluid clearance seal (CN113803322A), it can improve the control accuracy of the high-speed hydraulic cylinder with nano-magnetic fluid clearance seal, increase the buffering force, and increase the upper limit of the working temperature; when applied to a magnetic fluid hydraulic pump station (CN114001023A), it can increase the upper limit of the working temperature and the temperature rise rate of alternating magnetic field heating. When applied to various magnetorheological valves, it can increase the upper limit of the working temperature, solve the shear thinning of magnetorheological valves under high-pressure and high-flow velocity conditions, improve the control accuracy of magnetorheological valves, and enable magnetorheological valves to be applied to high-pressure and large-flow hydraulic systems.

[0095] Example 3: As Figure 1 shown, a metal-based intelligent hydraulic transmission medium (Example 3) consists of a Ga 77 In 21.4 metal base fluid, Ni 0.5 Zn 0.5 Fe2O4@SiO2 magnetic core-shell nanoparticles, and few-layer graphene (FLG-Ls) low-dimensional nano-additives.

[0096] Its preparation method is as follows:

[0097] Step1: Ni with a volume fraction of 15.0% 0.5 Zn 0.5The mixture of Fe2O4@SiO2 magnetic core-shell nanoparticles and few-layer graphene (FLG-Ls) low-dimensional nano-additives was added to an acidic aqueous solution. Under the condition of a constant water bath at 50 °C, mechanical stirring and ultrasonic dispersion were carried out for 120 min at a stirring speed of 1000 r / min to obtain a stably dispersed binary mixed nano-solution;

[0098] Step2: Add Ga 77 In 21.4 The metal base liquid was added to the acidic aqueous solution with a volume ratio of the metal base liquid to the acidic aqueous solution of 1:9. The reaction was carried out for 60 min to remove the oxide layer on the outer surface of the metal base liquid. Under the condition of a constant water bath at 50 °C, mechanical stirring and ultrasonic dispersion were carried out for 120 min at a stirring speed of 1000 r / min to disperse the metal base liquid into the acidic solution with a micron-sized particle diameter to obtain a metal droplet dispersion;

[0099] Step3: The binary mixed nano-solution obtained in Step1 was added to the metal droplet dispersion obtained in Step2. Under the condition of a constant water bath at 50 °C, mechanical stirring and ultrasonic dispersion were carried out for 120 min at a stirring speed of 1200 r / min, and a pulsed magnetic field was applied with a magnetic field intensity range of 0 - 300 mT and a frequency of 50 Hz to obtain a ternary mixed solution;

[0100] Step4: A constant magnetic field with a strength of 60 mT was applied to the upper layer of the ternary mixed solution prepared in Step3 to collect the remaining Ni 0.5 Zn 0.5 Fe2O4@SiO2 magnetic core-shell nanoparticles. After standing for 24 h in a constant water bath at 40 °C, after the solution was completely stratified, the remaining Ni 0.5 Zn 0.5 Fe2O4@SiO2 magnetic core-shell nanoparticles and few-layer graphene (FLG-Ls) low-dimensional nano-additives were removed. The lower layer of the liquid was collected and subjected to vacuum drying treatment to obtain the metal liquid-based intelligent hydraulic transmission medium of Example 3. After testing, the metal liquid-based intelligent hydraulic transmission medium of Example 3 was composed of 90.2% metal base liquid, 9.8% magnetic core-shell nanoparticles and low-dimensional nano-additive mixture;

[0101] The performance of the metal liquid-based intelligent hydraulic transmission medium sample prepared in Example 3 was tested, and the results are shown in Table 3:

[0102]

[0103] Table 3: Comparison of basic performance parameters between Example 3 and existing hydraulic transmission media

[0104] As can be seen from Table 3, the boiling point of the intelligent hydraulic transmission medium based on liquid metal is >1300 °C, much higher than that of several other hydraulic transmission media; the melting point is 11.0 °C, which can be applied to normal-temperature hydraulic transmission systems; the viscosity of the intelligent hydraulic transmission medium based on liquid metal is close to that of 46# mineral hydraulic oil, showing good fluidity; the thermal conductivity is much higher than that of existing hydraulic media, which is beneficial to the heat dissipation of the system; the conductivity is as high as 2.6·10 6 μS / cm, having the MHD functional characteristics of a conductive fluid, which are not possessed by other hydraulic transmission media.

[0105] As Figure 11 shown, the viscosity reduction rates of several traditional high-temperature hydraulic transmission media are all >50% at 40 - 100 °C, while that of the intelligent hydraulic transmission medium based on liquid metal is about 28%, indicating that the viscosity of the intelligent hydraulic transmission medium based on liquid metal changes little with temperature, which is beneficial to improving the control stability of the hydraulic system.

[0106] As Figure 12 shown, pure water completely evaporates within 150 °C, and several hydrocarbon-based hydraulic medium base fluids decompose successively in the range of 100 - 270 °C, and completely decompose when the temperature exceeds 400 °C. However, within the range of 30 - 500 °C, the intelligent hydraulic transmission medium based on liquid metal samples has no mass attenuation, indicating that its evaporability is extremely low and its thermal stability is good at this temperature range.

[0107] As Figure 13 shown, under an 80 mT magnetic field, the viscosity of the sample increases to 312 mPas at 25 °C, indicating that the intelligent hydraulic transmission medium based on liquid metal has a large magneto-viscous regulation range; the viscosity increases to 262 mPas at 220 °C, indicating that the intelligent hydraulic transmission medium based on liquid metal also has good magneto-viscous characteristics at high temperatures, with less demagnetization at high temperatures and can be used normally at high temperatures.

[0108] The present invention also provides an application of a metal liquid-based intelligent hydraulic transmission medium in hydraulic components. When the metal liquid-based intelligent hydraulic transmission medium of the present invention (Example 3) is applied to traditional hydraulic components, special hydraulic components for magnetorheological fluids or magnetorheological control components: when applied to traditional hydraulic components, it can increase the upper limit of the working temperature of the hydraulic components, improve the control error caused by the temperature-viscosity change of traditional transmission media, improve the lubrication characteristics of the flow distribution pair of hydraulic pumps, the piston-cylinder wall friction pair of hydraulic cylinders, and the spool-valve sleeve friction pair of hydraulic valves, and play a self-repairing role; when applied to a high-speed hydraulic cylinder with nano-magnetorheological fluid clearance seal (CN113803322A), it can improve the control accuracy of the high-speed hydraulic cylinder with nano-magnetorheological fluid clearance seal, increase the buffering force, and increase the upper limit of the working temperature; when applied to a magnetorheological fluid hydraulic pump station (CN114001023A), it can increase the upper limit of the working temperature and the temperature rise rate of alternating magnetic field heating. When applied to various magnetorheological valves, it can increase the upper limit of the working temperature, solve the shear thinning of magnetorheological valves under high-pressure and high-flow-rate conditions, improve the control accuracy of magnetorheological valves, and enable magnetorheological valves to be applied to high-pressure and large-flow hydraulic systems.

[0109] The specific embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A preparation method of a metal liquid-based intelligent hydraulic transmission medium, characterized in that: Step1: Add a mixture of magnetic core-shell nanoparticles and low-dimensional nano-additives with a volume fraction of 0.5-15% to an acidic aqueous solution. Under the condition of a constant temperature water bath at 45-50 °C, mechanically stir and ultrasonically disperse for 30-120 min, with a stirring speed of 200-1000 r / min, to obtain a stably dispersed binary mixed nano-solution; Step2: Add the metal base liquid to the acidic aqueous solution, with the volume ratio of the metal base liquid to the acidic aqueous solution being 1:5-9. React for 30-60 min to remove the oxide layer on the outer surface of the metal base liquid. Under the condition of a constant temperature water bath at 45-50 °C, mechanically stir and ultrasonically disperse for 30-120 min, with a stirring speed of 200-1000 r / min, so that the metal base liquid is dispersed into the acidic solution with a micron-sized particle size, obtaining a metal droplet dispersion; Step3: Add the binary mixed nano-solution obtained in Step1 to the metal droplet dispersion obtained in Step2. Under the condition of a constant temperature water bath at 45-50 °C, mechanically stir and ultrasonically disperse for 30-120 min, with a stirring speed of 500-1200 r / min, and apply a pulsed magnetic field with a magnetic field strength range of 0-300 mT and a frequency of 10-50 Hz to obtain a ternary mixed solution; Step4: Apply a constant magnetic field with a strength of 30-60 mT on the upper layer of the ternary mixed solution prepared in Step3 to collect the remaining magnetic core-shell nanoparticles. Let it stand for 8-24 h under a constant temperature water bath at 30 °C - 40 °C. After the solution is completely stratified, remove the remaining magnetic core-shell nanoparticles and low-dimensional nano-additives on the upper layer of the solution, collect the lower layer of the liquid and perform vacuum drying treatment to obtain the metal liquid-based intelligent hydraulic transmission medium; The metal liquid-based intelligent hydraulic transmission medium is composed of 90.2-99.5% of the metal base liquid, 0.5-9.8% of the mixture of magnetic core-shell nanoparticles and low-dimensional nano-additives, and the magnetic core-shell nanoparticles and low-dimensional nano-additives are prepared according to a volume ratio of 1:1; The low-dimensional nano-additive is one of few-layer graphene FLG-Ls with a thickness of 0.5-3.0 nm, a diameter of 0.1-5 µm, and a purity > 99% or nano-monolayer graphene GNFs with a thickness of 0.5-1.2 nm, a diameter of 100-500 nm, and a purity > 99%; 2. The preparation method of the metal liquid-based intelligent hydraulic transmission medium according to claim 1, wherein: The metal base liquid is prepared by alloying two or more metals among gallium, indium, tin, zinc, silver, and aluminum; 3. The preparation method of the intelligent hydraulic transmission medium based on molten metal according to claim 2, characterized in that: The composition of the metal base liquid is Ga 94.5 Ag 5.5 , GaAl 0.9 、Ga 96.3 Zn 3.7 、GaSn 13.4 、Ga 82 Sn 12 Zn6、Ga 75.5 In 24.5 、Ga 77 In 21.4 、Ga 68.5 In 21.5 Sn 10 、Ga 67 In 29 Zn4、Ga 67 In 20.5 Sn 12.5 、Ga 61 In 25 Sn 13 Zn1、Ga 67.98 In 20.01 Sn 10.5 Ag 1.51 、Ga 61 In 25 Sn 13 One of Zn1.

4. The preparation method of the intelligent hydraulic transmission medium based on molten metal according to claim 1, wherein: The magnetic core-shell nanoparticles adopt a core-shell structure and are composed of a ferrite nano-magnetic particle inner core and a SiO2 outer shell that does not react with the Ga-based alloy; 5. The preparation method of the intelligent hydraulic transmission medium based on molten metal according to claim 4, wherein: The core-shell structure adopted by the magnetic core-shell nanoparticles is one or more of Fe3O4@SiO2, NiFe2O4@SiO2, Ni 0.5 Zn 0.5 Fe2O4@SiO2.

6. The preparation method of the metal liquid-based intelligent hydraulic transmission medium according to claim 4 or 5, characterized in that: The particle size of the magnetic core-shell nanoparticles is 1-100 nm, where the diameter of the magnetic nano-particle inner core is 1-90 nm, and the thickness of the outer shell is 5%-90% of the particle size of the magnetic nano-particles; 7. An application of the metal liquid-based intelligent hydraulic transmission medium according to any one of claims 1-6 in hydraulic components.

8. The application according to claim 7, wherein: The hydraulic components are traditional hydraulic components, magnetic fluid special hydraulic components, or magnetorheological control components.

9. The application according to claim 8, characterized in that: The special hydraulic components for magnetic fluid are high-speed hydraulic cylinders with nano-magnetic fluid clearance seals or magnetic fluid hydraulic pumping stations, and the magnetorheological control components include various magnetorheological valves.

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