A method for reducing friction and wear of a water-based lubricating liquid based on magnetic field regulation of nanochain

Abstract

This invention provides a method for reducing friction and wear in a water-based lubricant based on magnetic field-controlled nanochains, belonging to the field of water-based lubricant technology. The invention utilizes magnetic Fe3O4 nanoparticles as raw materials and employs a silanization reaction to achieve magnetic field-assisted self-assembly of one-dimensional Fe3O4@SiO2 nanochains. These nanochains are then dispersed in deionized water or other basic lubricants to form a nanochain water-based lubricant. During lubrication, the one-dimensional nanochains are aligned perpendicular to the sliding direction using a magnetic field, achieving controllable orientation and forming a uniformly oriented rolling bearing structure on the contact area of ​​the friction pair. This significantly reduces the coefficient of friction and wear rate. The method is simple, uses environmentally friendly materials, and allows for real-time control of the lubrication state. It can be widely applied to friction reduction and wear resistance in mechanical transmissions, water-lubricated bearings, flexible device interface protection, and micro-precision moving parts.

Description

Technical Field

[0001] This invention relates to the field of water-based lubricant technology, and in particular to a method for reducing friction and wear resistance based on magnetic field-controlled nanochain water-based lubricants. Background Technology

[0002] In critical sectors such as aerospace, automotive manufacturing, and biomedicine—fields vital to national welfare and high-tech development—friction and wear are prevalent and have become key factors leading to mechanical component failure, shortened equipment lifespan, and increased maintenance costs. Water-based lubricants, with their environmental friendliness, zero pollutant emissions, and excellent cooling performance, better meet the demands of modern industrial green development compared to traditional oil-based lubricants, thus attracting widespread attention from research and industry and becoming a hot research area. However, water-based lubricants have inherent drawbacks. Their viscosity is generally low, and their oil film carrying capacity is poor. Under complex conditions such as high speed, heavy load, and precision contact, they struggle to form a stable and robust lubricating film, often resulting in severe wear, scratches, and even seizing failure on the friction surfaces, significantly limiting their application in high-precision machinery.

[0003] To effectively improve the lubrication performance, load-bearing capacity, and friction-reducing and anti-wear effects of water-based lubricants, nanoparticles, due to their unique size, surface, and interface effects, have been widely used as functional additives for water-based lubricants, becoming an important research path for solving this problem. However, traditional nanoparticles still face many application bottlenecks in water-based lubrication systems: on the one hand, nanoparticles themselves have high specific surface area and surface energy, making them prone to aggregation during lubrication, forming large particle aggregates. This not only fails to exert their nanoscale lubrication effect but may also become abrasive particles, exacerbating the wear of the friction pair; on the other hand, the motion state of nanoparticles in the friction contact area is disordered, unable to act directionally and stably on the friction interface, making it difficult to form a continuous and efficient lubrication protection mechanism, which greatly limits the further improvement of lubrication effect. Although existing research has shown that spherical nanoparticles can generate a "micro-bearing" effect during friction by utilizing their rolling properties, which can reduce the coefficient of friction and wear to a certain extent, how to achieve uniform dispersion and directional arrangement of nanoparticles in the lubrication system and thus achieve more efficient friction reduction and wear resistance through nanoparticle structural design (such as controlling particle morphology, size, and surface modification) combined with external field control (such as magnetic field, electric field, and ultrasonic field) to achieve more efficient friction reduction and wear resistance remains a key research challenge and focus in the field of water-based lubricants. Summary of the Invention

[0004] The purpose of this invention is to provide a friction reduction and wear resistance method based on magnetic field-controlled nanochain water-based lubricant. The method provided by this invention controls the Fe3O4@SiO2 one-dimensional nanochains in the nanochain water-based lubricant to align perpendicular to the sliding direction during the lubrication process by using a magnetic field. This achieves an orientation similar to a "rolling log" effect at the friction interface, thereby converting sliding friction into rolling friction and significantly reducing the friction coefficient and wear rate.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for reducing friction and wear based on a magnetic field-controlled nanochain water-based lubricant, comprising the following steps: (1) After mixing the iron source, the first solvent, the dispersant and the auxiliary agent, the solvothermal reaction and the first post-treatment were carried out in sequence to obtain Fe3O4 nanoparticles; (2) The Fe3O4 nanoparticles obtained in step (1) are dispersed in a portion of deionized water, and the remaining deionized water, silicon source, second solvent and catalyst are added. Under the action of an external magnetic field, a self-assembly-coating reaction is carried out. After the second post-treatment, Fe3O4@SiO2 one-dimensional nanochains are obtained. (3) Disperse the Fe3O4@SiO2 one-dimensional nanochains obtained in step (2) in a base lubricant to obtain a nanochain water-based lubricant; (4) Place the nano-chain water-based lubricant obtained in step (3) in the contact area of ​​the friction pair, apply an external magnetic field during the friction process, and use the magnetic field to control the arrangement direction of the Fe3O4@SiO2 one-dimensional nano-chains in the nano-chain water-based lubricant to be perpendicular to the friction sliding direction, so as to achieve friction reduction and wear resistance.

[0006] Preferably, the average particle size of the Fe3O4 nanoparticles in step (1) is 0.1~0.3 μm.

[0007] Preferably, in step (2), the silicon source is at least one of tetraethyl orthosilicate and methyl orthosilicate; the solvent is isopropanol; and the catalyst is ammonium hydroxide.

[0008] Preferably, in step (2), the ratio of the mass of Fe3O4 nanoparticles, the volume of some deionized water, the volume of the remaining deionized water, the volume of the second solvent, the volume of the catalyst, and the volume of the silicon source is (28~55) mg: 4 mL; 400 μL: 1 mL: (27~54) μL: (12~35) μL.

[0009] Preferably, the strength of the external magnetic field in step (2) is 300~400 Oe.

[0010] Preferably, the reaction time of the self-assembly-coating reaction in step (2) is 6~12h, and the reaction temperature of the self-assembly-coating reaction is room temperature.

[0011] Preferably, in step (2), the average length of the Fe3O4@SiO2 one-dimensional nanochain is 50~70μm, the average diameter of the Fe3O4@SiO2 one-dimensional nanochain is 0.1~0.3μm, and the outer surface of the Fe3O4@SiO2 one-dimensional nanochain is coated with an amorphous silicon dioxide layer with an average thickness of 30~40 nm.

[0012] Preferably, the mass fraction of Fe3O4@SiO2 one-dimensional nanochains in the nanochain water-based lubricant in step (3) is 0.5wt%~2wt%.

[0013] Preferably, the direction of the external magnetic field in step (4) is perpendicular to the friction sliding direction, so that the Fe3O4@SiO2 one-dimensional nanochains in the nanochain water-based lubricant form a vertical arrangement structure of rolling bearing in the contact area of ​​the friction pair.

[0014] Preferably, the contact area of ​​the friction pair in step (4) is the contact area of ​​the mechanical friction pair.

[0015] This invention provides a friction-reducing and wear-resistant method based on a water-based lubricant using magnetically controlled nanochains. First, magnetic Fe3O4 nanoparticles are prepared via a solvothermal method. Then, magnetic field-assisted self-assembly of one-dimensional Fe3O4@SiO2 nanochains is achieved using a silanization reaction. These Fe3O4@SiO2 one-dimensional nanochains have a core-shell structure, and the silica layer on their surface not only connects the magnetic Fe3O4 nanoparticles to form chains but also provides good chemical stability. The obtained Fe3O4@SiO2 one-dimensional nanochains are dispersed in deionized water or other basic lubricants. During lubrication, the one-dimensional nanochains in the water-based lubricant are aligned perpendicular to the sliding direction using a magnetic field, achieving controllable orientation of the one-dimensional nanochains. This forms a uniformly oriented rolling bearing structure on the surface of the contact area of ​​the friction pair. By controlling the relative angle between the chain and the friction direction, the coefficient of friction and wear rate can be significantly reduced. Compared to deionized water lubrication, the method provided by this invention can reduce the coefficient of friction by 45% to 55% and the wear rate by 70% to 80%. Compared to simple Fe3O4 nanoparticles or parallel-arranged chains, the vertically arranged one-dimensional nanochains in this invention exhibit superior friction reduction and wear resistance, avoiding severe abrasive wear and ploughing phenomena. The vertically arranged one-dimensional nanochains can effectively bear loads, making the friction surface smoother and significantly reducing surface plastic deformation and oxidative wear. The water-based lubricant of this invention has advantages such as simple preparation method, environmentally friendly materials, and real-time controllable lubrication state, and can be widely used in mechanical transmission, water-lubricated bearings, interface protection of flexible devices, and friction reduction and wear resistance of micro-precision moving parts. Attached Figure Description

[0016] Figure 1 These are microscopic morphology images of the Fe3O4 nanoparticles and Fe3O4@SiO2 one-dimensional nanochains prepared in Example 1 of this invention; wherein, Figure 1 The image in the middle left is a SEM image of Fe3O4 particles. Figure 1 The middle right image shows SEM images of multiple Fe3O4@SiO2 one-dimensional nanochains; Figure 2 The image shows the microstructure of a single Fe3O4@SiO2 nanochain prepared in Example 1 of this invention and a schematic diagram of the magnetic field assembly device. Figure 2 The image in the middle left shows a SEM image of a single Fe3O4@SiO2 one-dimensional nanochain. Figure 2 The lower left corner of the middle left image shows the length distribution statistics of the Fe3O4@SiO2 one-dimensional nanochains prepared in Example 1. Figure 2 The right figure in the middle is a schematic diagram of the magnetic field assembly device formed by placing the reaction vessel between two magnets with a size of 15×10×5 cm in step (2) of Example 1; Figure 3The diagrams show the magnetic field control and frictional sliding directions in Embodiment 1 and Comparative Examples 1 and 2 of the present invention, as well as the different arrangement directions of Fe3O4 nanoparticles (hereinafter referred to as nanoparticles) and Fe3O4@SiO2 one-dimensional nanochains under magnetic field control in Embodiment 1. Figure 3 The left-middle image is a schematic diagram of magnetic field control and frictional sliding direction. Figure 3 The right-middle figure shows different arrangement directions of Fe3O4 nanoparticles and Fe3O4@SiO2 one-dimensional nanochains under magnetic field control in Example 1. The long axis arrangement directions of the Fe3O4@SiO2 one-dimensional nanochains in Example 1 and Comparative Examples 1 and 2 are perpendicular to the friction sliding direction (referred to as perpendicularly arranged chains), parallel to the friction sliding direction (referred to as horizontally arranged chains), and randomly arranged (referred to as nanochains), respectively. Figure 4 This is a statistical graph showing the friction coefficients under different lubrication conditions in Embodiment 1 and Comparative Examples 1-4 of the present invention, wherein... Figure 4 The left-middle figure shows the variation of the coefficient of friction with the number of sliding cycles under different lubrication conditions in Example 1 and Comparative Examples 1-4. Figure 4 The top right corner of the left-middle image shows actual images of deionized water lubricant, a 1wt% Fe3O4 nanoparticle dispersion lubricant (referred to as nanoparticles), and a nanochain water-based lubricant (referred to as nanochains). Figure 4 The right-middle figure is a comparison of the average friction coefficients of different lubricants in Example 1 and Comparative Examples 1-4. Example 1 is a vertically arranged chain, Comparative Example 1 is a horizontally arranged chain, Comparative Example 2 is a randomly arranged chain (referred to as nano-chain), Comparative Example 3 is Fe3O4 nanoparticles (referred to as nanoparticles), and Comparative Example 4 is deionized water. Figure 5 These are images showing the wear surface morphology and wear profile under different lubrication conditions in Embodiment 1 and Comparative Examples 1-4 of the present invention, wherein... Figure 5 The image in the middle left shows the morphology of the worn surface. Figure 5 The right-middle figure is a wear profile diagram. Example 1 is a vertically arranged chain, Comparative Example 1 is a horizontally arranged chain, Comparative Example 2 is a randomly arranged chain (referred to as nanochain), Comparative Example 3 is nanoparticles, and Comparative Example 4 is deionized water. Figure 6 The figures show the wear volume and wear rate under different lubrication conditions in Example 1 and Comparative Examples 1 to 4 of the present invention. In Example 1, the chain is arranged vertically; in Comparative Example 1, the chain is arranged horizontally; in Comparative Example 2, the chain is arranged randomly (referred to as nanochain); in Comparative Example 3, the chain is nanoparticles; and in Comparative Example 4, the chain is deionized water. Detailed Implementation

[0017] This invention provides a method for reducing friction and wear based on a magnetic field-controlled nanochain water-based lubricant, comprising the following steps: (1) After mixing the iron source, the first solvent, the dispersant and the auxiliary agent, the solvothermal reaction and the first post-treatment were carried out in sequence to obtain Fe3O4 nanoparticles; (2) The Fe3O4 nanoparticles obtained in step (1) are dispersed in a portion of deionized water, and the remaining deionized water, silicon source, second solvent and catalyst are added. Under the action of an external magnetic field, a self-assembly-coating reaction is carried out. After the second post-treatment, Fe3O4@SiO2 one-dimensional nanochains are obtained. (3) Disperse the Fe3O4@SiO2 one-dimensional nanochains obtained in step (2) in a base lubricant to obtain a nanochain water-based lubricant; (4) Place the nano-chain water-based lubricant obtained in step (3) in the contact area of ​​the friction pair, apply an external magnetic field during the friction process, and use the magnetic field to control the arrangement direction of the Fe3O4@SiO2 one-dimensional nano-chains in the nano-chain water-based lubricant to be perpendicular to the friction sliding direction, so as to achieve friction reduction and wear resistance.

[0018] Unless otherwise specified, all raw materials used in this invention are commercially available products in the art.

[0019] In this invention, an iron source, a first solvent, a dispersant, and an auxiliary agent are mixed and then subjected to a solvothermal reaction and a first post-treatment in sequence to obtain Fe3O4 nanoparticles.

[0020] In this invention, the iron source is preferably at least one of FeCl3 and FeCl2·4H2O. In this invention, the first solvent is preferably at least one of ethylene glycol and diethylene glycol. In this invention, the dispersant is preferably at least one of sodium citrate and sodium polyacrylate. In this invention, the auxiliary agent is preferably at least one of anhydrous sodium acetate, ammonium acetate, and sodium hydroxide. In this invention, the temperature of the solvothermal reaction is 180~220℃, and the time of the solvothermal reaction is 8~12h. By controlling the temperature and time of the solvothermal reaction within the above ranges, FeCl3 can be fully reduced to Fe3O4 in reducing solvents such as ethylene glycol, achieving sufficient crystal growth and avoiding the possibility of Fe3O4 crystals being damaged by excessively low temperatures or short reaction times. 3+Insufficient reduction and poor Fe3O4 crystallinity, coupled with the risk of excessive particle growth or agglomeration due to excessively high temperatures or prolonged reaction times, necessitate careful control of the solvothermal reaction temperature and time. This allows for the preparation of Fe3O4 nanoparticles with good dispersibility, strong superparamagnetism, and narrow particle size distribution, providing an ideal magnetic core material for subsequent SiO2 shell coating. In this invention, the average particle size of the Fe3O4 nanoparticles is 0.1–0.3 μm. By controlling the average particle size within this range, the prepared Fe3O4 nanoparticles possess both good superparamagnetism and a suitable specific surface area. This avoids insufficient magnetic response strength due to excessively small particle size, which is detrimental to magnetic separation and subsequent coating operations. Conversely, excessively large particle size leads to sedimentation and agglomeration, affecting the uniform coating of the SiO2 shell and potentially weakening the superparamagnetism. Therefore, controlling the average particle size within the range of 0.1–0.3 μm is the preferred solution, balancing magnetic properties and dispersion stability. In this invention, the first post-processing preferably includes: sequentially performing solid-liquid separation, washing, and drying on the product of the solvothermal reaction to obtain Fe3O4 nanoparticles. In this invention, the solid-liquid separation is preferably centrifugal separation. In this invention, the washing is preferably performed sequentially with ethanol and deionized water. In this invention, the number of ethanol and deionized water washes is independently 2 to 4 times. In this invention, the drying is preferably performed overnight at 60°C.

[0021] After obtaining Fe3O4 nanoparticles, the present invention disperses the Fe3O4 nanoparticles in a portion of deionized water, adds the remaining deionized water, silicon source, second solvent and catalyst, and carries out a self-assembly-coating reaction under the action of an external magnetic field. After a second post-treatment, Fe3O4@SiO2 one-dimensional nanochains are obtained.

[0022] In this invention, the silicon source is preferably at least one of tetraethyl orthosilicate and methyl orthosilicate; the second solvent is preferably isopropanol; and the catalyst is preferably ammonium hydroxide (i.e., ammonia monohydrate). In this invention, the preferred ratio of the mass of the Fe3O4 nanoparticles, the volume of a portion of the deionized water, the volume of the remaining deionized water, the volume of the second solvent, the volume of the catalyst, and the volume of the silicon source is (28~55) mg: 4 mL; 400 μL: 1 mL: (27~54) μL: (12~35) μL, more preferably (30~50) mg: 4 mL; 400 μL: 1 mL: (30~50) μL: (15~30) μL, and even more preferably 40 mg: 4 mL; 400 μL: 1 mL: 40 μL: 20 μL. This invention controls the ratio of the mass of Fe3O4 nanoparticles, the volume of partially deionized water, the volume of the remaining deionized water, the volume of the second solvent, the volume of the catalyst, and the volume of the silicon source within the aforementioned range. This facilitates the uniform coating and controllable thickness of the SiO2 shell on the surface of the Fe3O4 nanoparticles, ensuring that the Fe3O4 nanoparticles can orderly self-assemble into a one-dimensional nanochain structure along the magnetic field direction under magnetic field induction. Simultaneously, it avoids excessive silicon source leading to an overly thick shell that weakens the magnetic response performance, or insufficient silicon source leading to incomplete coating and particle agglomeration. In this invention, the external magnetic field is preferably applied by symmetrically placing magnets on both sides of the iron source, so that the direction of the generated magnetic field is along the line connecting the two magnets; the strength of the external magnetic field is 300~400 Oe, more preferably 350 Oe. In this invention, the reaction time of the self-assembly-coating reaction is preferably 6~12 h, more preferably 7~10 h; the reaction temperature of the self-assembly-coating reaction is preferably room temperature. This invention controls the reaction time and temperature of the self-assembly-coating reaction within the aforementioned range, which is beneficial for Fe3O4 nanoparticles to fully arrange themselves into ordered one-dimensional nanochains under magnetic field induction. Simultaneously, it ensures uniform TEOS hydrolysis-condensation reaction, and the SiO2 shell solidifies synchronously on the surface of the Fe3O4 nanoparticles and at particle contact points, stabilizing and fixing the chain structure. This avoids incomplete chain structure due to excessively short reaction time or side reactions and excessive particle agglomeration due to excessively long reaction time. Room temperature conditions simplify the process, reduce energy consumption, and maintain a mild and uniform reaction system, avoiding excessively rapid SiO2 deposition and uneven coating caused by high-temperature accelerated TEOS hydrolysis. In this invention, the second post-treatment includes: sequentially washing the product of the self-assembly-coating reaction and drying it overnight at 60°C to obtain Fe3O4@SiO2 one-dimensional nanochains. In this invention, the washing is preferably performed sequentially with ethanol and deionized water. In this invention, the number of ethanol and deionized water washings is independently 2 to 4 times.

[0023] In this invention, the average length of the Fe3O4@SiO2 one-dimensional nanochains is preferably 50-70 μm. The average diameter of the Fe3O4@SiO2 one-dimensional nanochains is preferably 0.1-0.3 μm. By controlling the average length of the Fe3O4@SiO2 one-dimensional nanochains to be 50-70 μm and the average diameter to be 0.1-0.3 μm, this invention avoids the weakening of magnetic response performance due to excessively short chains or the easy agglomeration and sedimentation due to excessively long chains, thereby achieving a balance between dispersion stability and magnetic manipulation efficiency, and thus achieving better lubrication effect. In this invention, the outer surface of the Fe3O4@SiO2 one-dimensional nanochains is coated with an amorphous silicon dioxide layer with an average thickness of 30-40 nm. This invention controls the average length, average diameter, and thickness of the amorphous silica layer of the Fe3O4@SiO2 one-dimensional nanochains within the aforementioned ranges. This not only firmly coats and bonds adjacent Fe3O4 nanoparticles to maintain the stability of the chain structure and prevent nanoparticle detachment or chain breakage, but also provides effective anti-oxidation protection for the magnetic Fe3O4 core, preventing the iron(III) oxide from being oxidized in air and reducing the saturation magnetization. At the same time, the shell thickness ensures that the chain has good superparamagnetic and magnetic response properties, facilitating magnetic separation and directional manipulation.

[0024] After obtaining the Fe3O4@SiO2 one-dimensional nanochains, the present invention disperses the Fe3O4@SiO2 one-dimensional nanochains in a base lubricant to obtain a nanochain water-based lubricant.

[0025] In this invention, the base lubricant is at least one of deionized water and hyaluronic acid solution. In this invention, the mass fraction of Fe3O4@SiO2 one-dimensional nanochains in the nanochain water-based lubricant is preferably 0.5wt%~2wt%, more preferably 0.8wt%~1.2wt%, and even more preferably 1wt%. By controlling the mass fraction of Fe3O4@SiO2 one-dimensional nanochains in the nanochain water-based lubricant within the above range, this invention ensures magnetic manipulation efficiency, avoids the aggregation of Fe3O4@SiO2 one-dimensional nanochains, and thus achieves better lubrication.

[0026] After obtaining the nano-chain water-based lubricant, the present invention places the nano-chain water-based lubricant in the contact area of ​​the friction pair, applies an external magnetic field during the friction process, and uses the magnetic field to control the arrangement direction of the Fe3O4@SiO2 one-dimensional nano-chains in the nano-chain water-based lubricant to be perpendicular to the friction sliding direction, thereby achieving friction reduction and wear resistance.

[0027] In this invention, the direction of the external magnetic field is preferably perpendicular to the friction sliding direction, so that the Fe3O4@SiO2 one-dimensional nanochains in the nanochain water-based lubricant form a vertically arranged structure resembling a rolling bearing in the contact area of ​​the friction pair. In this invention, the contact area of ​​the friction pair is preferably a mechanical friction pair contact area.

[0028] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0029] Unless otherwise specified, all experiments were repeated three times, and the results are expressed as averages.

[0030] Example 1 A method for reducing friction and wear based on magnetic field-controlled nanochain water-based lubricant, comprising the following steps: (1) Dissolve 3.25 g FeCl3 in 100 mL ethylene glycol and stir magnetically for 0.5 h. Then slowly add 2 g sodium citrate and 12 g anhydrous sodium acetate and stir for 0.5 h until completely dissolved to obtain a mixed solution. Transfer the mixed solution to a stainless steel autoclave lined with polytetrafluoroethylene and heat at 200 °C for a solvothermal reaction for 10 h. After the reaction is completed, centrifuge and wash with ethanol and deionized water alternately, and dry at 60 °C overnight to obtain Fe3O4 nanoparticles with an average particle size of 0.1~0.3 μm.

[0031] (2) Disperse 40 mg of the Fe3O4 nanoparticles obtained in step (1) in 4 mL of deionized water and disperse them evenly using ultrasound. Then, add 400 μL of deionized water, 1 mL of isopropanol, 40 μL of ammonium hydroxide and 20 μL of tetraethyl orthosilicate. After stirring thoroughly, place the reaction vessel between two magnets with dimensions of 15 × 10 × 5 cm (e.g., Figure 2 As shown in the middle right figure, magnets are placed symmetrically on both sides of the iron source so that the direction of the generated magnetic field is along the line connecting the two magnets. The strength of the external magnetic field is 350 Oe. After the self-assembly-coating reaction is carried out for 8 h, the product of the self-assembly-coating reaction is washed alternately with deionized water and alcohol, and dried at 60℃ overnight to obtain Fe3O4@SiO2 one-dimensional nanochains. The SEM image of the Fe3O4@SiO2 one-dimensional nanochain obtained by SEM detection shows that its length is 64.62±0.99 μm, its diameter is 0.2 μm, and its outer surface is covered with an amorphous silicon dioxide layer with an average thickness of 30~40 nm. The ratio of the mass of the Fe3O4 nanoparticles, the volume of some deionized water, the volume of the remaining deionized water, the volume of isopropanol, the volume of ammonium hydroxide, and the volume of tetraethyl orthosilicate is 40 mg: 4 mL; 400 μL: 1 mL: 40 μL: 20 μL. (3) Disperse the Fe3O4@SiO2 one-dimensional nanochains obtained in step (2) in deionized water to prepare a nanochain water-based lubricant with a concentration of 1 wt% of Fe3O4@SiO2 one-dimensional nanochains. (4) The friction coefficient was tested using a pin-disc friction and wear tester. The nano-chain water-based lubricant obtained in step (3) was placed in the contact area of ​​the friction pair. The pin sample was PEEK (polyether ether ketone), and the disc sample was 6061 aluminum alloy. The test conditions were: load 1 N, speed 120 mm / s, frequency 10 Hz. During the test, the orientation of the nanochains was controlled by adjusting the position of the magnets. The magnetic field regulated the long axis alignment of the Fe3O4@SiO2 one-dimensional nanochains in the water-based lubricant to be perpendicular to the friction and sliding direction, thereby achieving friction reduction and wear resistance.

[0032] Comparative Example 1 The friction reduction and wear resistance were carried out according to the method of Example 1. The difference from Example 1 is that in step (4), the long axis of the Fe3O4@SiO2 one-dimensional nanochain in the magnetic field-controlled nanochain water-based lubricant is parallel to the friction sliding direction.

[0033] Comparative Example 2 Friction reduction and wear resistance were performed according to the method of Example 1. The difference from Example 1 is that no magnetic field was applied, and the Fe3O4@SiO2 one-dimensional nanochains in the nanochain water-based lubricant were randomly arranged.

[0034] Comparative Example 3 Fe3O4 nanoparticles were prepared according to step (1) of Example 1. 0.1 mg of the prepared Fe3O4 nanoparticles were mixed with 9.9 mL of deionized water to obtain a dispersion of Fe3O4 nanoparticles with a concentration of 1 wt% as a lubricant. The friction coefficient of the Fe3O4 nanoparticles was tested according to step (4) of Example 1. The experiment was conducted five times, and the average friction coefficient was 1.23.

[0035] Comparative Example 4 Deionized water was used as the lubricant, and the coefficient of friction of the deionized water was tested according to the method of step (4) described in Example 1.

[0036] Figure 1 These are microscopic morphology images of the Fe3O4 nanoparticles and Fe3O4@SiO2 one-dimensional nanochains prepared in Example 1 of this invention; wherein, Figure 1The image in the middle left is a SEM image of Fe3O4 particles. Figure 1 The middle right image shows SEM images of multiple Fe3O4@SiO2 one-dimensional nanochains. Figure 1 It can be seen that the Fe3O4 nanoparticles prepared in Example 1 are spherical or near-spherical with uniform particle size distribution; the Fe3O4@SiO2 one-dimensional nanochains prepared in Example 1 are assembled by connecting multiple Fe3O4 nanoparticles end to end along the same axis.

[0037] Figure 2 The image shows the microstructure of a single Fe3O4@SiO2 nanochain prepared in Example 1 of this invention and a schematic diagram of the magnetic field assembly device. Figure 2 The image in the middle left shows a SEM image of a single Fe3O4@SiO2 one-dimensional nanochain. Figure 2 The lower left corner of the middle left image shows the length distribution statistics of the Fe3O4@SiO2 one-dimensional nanochains prepared in Example 1. Figure 2 The right-hand figure is a schematic diagram of the magnetic field assembly device formed by placing the reaction vessel between two magnets with dimensions of 15×10×5 cm in step (2) of Example 1. Figure 2 It can be seen that the average length of the Fe3O4@SiO2 one-dimensional nanochains prepared in Example 1 is 64.62±0.99 μm, and the chain structure is complete, the shape is straight and the dispersion is good. The SiO2 shell is uniformly coated on the particle surface and particle connection.

[0038] Figure 3 The diagrams show the magnetic field control and frictional sliding directions in Embodiment 1 and Comparative Examples 1 and 2 of the present invention, as well as the different arrangement directions of Fe3O4 nanoparticles (hereinafter referred to as nanoparticles) and Fe3O4@SiO2 one-dimensional nanochains under magnetic field control in Embodiment 1. Figure 3 The left-middle image is a schematic diagram of magnetic field control and frictional sliding direction. Figure 3 The right-hand figure shows different arrangement directions of Fe3O4 nanoparticles and Fe3O4@SiO2 one-dimensional nanochains under magnetic field control in Example 1. In Example 1 and Comparative Examples 1 and 2, the long axis arrangement of the Fe3O4@SiO2 one-dimensional nanochains is perpendicular to the friction sliding direction (referred to as perpendicularly arranged chains), parallel to the friction sliding direction (referred to as horizontally arranged chains), and randomly arranged (referred to as nanochains), respectively. Figure 3It can be seen that when the magnetic field direction is perpendicular to the friction sliding direction, the nanochains are vertically aligned; when the magnetic field direction is parallel to the friction sliding direction, the nanochains are horizontally aligned; and under no magnetic field conditions, the nanochains are randomly distributed. This fully demonstrates that the directional alignment of Fe3O4@SiO2 one-dimensional nanochains at the friction interface can be achieved with the help of an external magnetic field, providing a structural basis for subsequent research on the influence of different alignment directions on lubrication performance. At the same time, compared with Fe3O4 nanoparticles under no magnetic field conditions, the nanochains formed by magnetic field-induced assembly have a clear long axis orientation, demonstrating the effective control of the magnetic field on the assembly behavior and alignment direction of nanoparticles.

[0039] Figure 4 This is a statistical graph showing the friction coefficients under different lubrication conditions in Embodiment 1 and Comparative Examples 1-4 of the present invention, wherein... Figure 4 The left-middle figure shows the variation of the coefficient of friction with the number of sliding cycles under different lubrication conditions in Example 1 and Comparative Examples 1-4. Figure 4 The top right corner of the middle left image shows actual images of deionized water lubricant, a 1wt% Fe3O4 nanoparticle dispersion lubricant (referred to as nanoparticles), and a nanochain water-based lubricant. Figure 4 The right-hand figure shows a comparison of the average friction coefficients of different lubricants in Example 1 and Comparative Examples 1-4. Example 1 uses vertically arranged chains, Comparative Example 1 uses horizontally arranged chains, Comparative Example 2 uses randomly arranged chains (referred to as nanochains), Comparative Example 3 uses Fe3O4 nanoparticles (referred to as nanoparticles), and Comparative Example 4 uses deionized water. Figure 4 It can be seen that the average friction coefficients of different lubricants for deionized water, nanoparticles, nanochains, vertically arranged chains, and horizontally arranged chains are 1.23, 0.69, 0.83, 0.63, and 0.70, respectively. In Example 1, the average friction coefficient of the vertically arranged chain is the lowest, which is 48.51% lower than that of deionized water in Comparative Example 4, and the curve is stable.

[0040] Figure 5 These are images showing the wear surface morphology under different lubrication conditions in Embodiment 1 and Comparative Examples 1-4 of the present invention. Embodiment 1 uses vertically arranged chains, Comparative Example 1 uses horizontally arranged chains, Comparative Example 2 uses randomly arranged chains (referred to as nanochains), Comparative Example 3 uses nanoparticles, and Comparative Example 4 uses deionized water. Figure 5 It was found that the sample lubricated with deionized water exhibited the largest wear volume. Compared to deionized water, the wear volume of the four lubricant samples (nanoparticles, nanochains, vertically arranged chains, and horizontally arranged chains) was reduced by 32.43%, 20.46%, 73.55%, and 35.52%, respectively. Fe3O4 nanoparticles can provide additional support points between sliding contacts, facilitating the separation of friction surfaces and thus reducing the wear volume accordingly; and the vertically arranged nanochains showed the best friction-reducing effect.

[0041] Figure 6 This is a statistical chart showing the wear volume and wear rate under different lubrication conditions in Example 1 and Comparative Examples 1-4 of the present invention. Example 1 uses vertically arranged chains, Comparative Example 1 uses horizontally arranged chains, Comparative Example 2 uses randomly arranged chains (referred to as nanochains), Comparative Example 3 uses nanoparticles, and Comparative Example 4 uses deionized water. Figure 6 It can be seen that the wear volume under different lubrication conditions in Example 1 and Comparative Examples 1-4 is 5.18 × 10⁻⁶. -6 μm 3 3.50×10 -6 μm 3 4.12×10 -6 μm 3 1.37×10 -6 μm 3 3.34×10 -6 μm 3 The wear rates were 1.44 × 10⁻⁶. -7 μm 3 / N·m, 9.71×10 -8 μm 3 / N·m, 1.14×10 -7 μm 3 / N·m, 3.80×10 -8 μm 3 / N·m, 9.27×10 -8 μm 3 / N·m, the wear rate of vertically arranged chains was reduced by 73.55% compared to deionized water.

[0042] In summary, compared with pure deionized water, Fe3O4 nanoparticles, horizontally arranged chains, and randomly arranged nanochains, the nanochain water-based lubricant of Example 1 of this invention, which incorporates vertically arranged Fe3O4@SiO2 one-dimensional nanochains, exhibits the best lubricating effect. Compared to simple Fe3O4 nanoparticles or parallel-arranged chains, the vertically arranged one-dimensional nanochains in this invention demonstrate superior friction reduction and wear resistance, avoiding severe abrasive wear and ploughing. The vertically arranged one-dimensional nanochains can effectively bear loads, resulting in a smoother friction surface and significantly reducing surface plastic deformation and oxidative wear. The Fe3O4@SiO2 one-dimensional nanochains prepared in this invention, combined with vertical magnetic field orientation technology, can significantly improve the tribological properties of water-based lubricants, showing broad application prospects in polar underwater equipment, flexible electronic devices, and mechanical engineering.

[0043] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for reducing friction and wear of a nanochain water-based lubricating fluid based on magnetic field regulation, characterized by, Includes the following steps: (1) After mixing the iron source, the first solvent, the dispersant and the auxiliary agent, the solvothermal reaction and the first post-treatment were carried out in sequence to obtain Fe3O4 nanoparticles; (2) The Fe3O4 nanoparticles obtained in step (1) are dispersed in a portion of deionized water, and the remaining deionized water, silicon source, second solvent and catalyst are added. Under the action of an external magnetic field, a self-assembly-coating reaction is carried out. After the second post-treatment, Fe3O4@SiO2 one-dimensional nanochains are obtained. (3) Disperse the Fe3O4@SiO2 one-dimensional nanochains obtained in step (2) in a base lubricant to obtain a nanochain water-based lubricant; (4) Place the nano-chain water-based lubricant obtained in step (3) in the contact area of ​​the friction pair, apply an external magnetic field during the friction process, and use the magnetic field to control the arrangement direction of the Fe3O4@SiO2 one-dimensional nano-chains in the nano-chain water-based lubricant to be perpendicular to the friction sliding direction, so as to achieve friction reduction and wear resistance.

2. The antifriction wear reducing method of claim 1 wherein, The average particle size of the Fe3O4 nanoparticles in step (1) is 0.1~0.3 μm.

3. The antifriction wear reducing method of claim 1 wherein, In step (2), the silicon source is at least one of tetraethyl orthosilicate and methyl orthosilicate; the second solvent is isopropanol; and the catalyst is ammonium hydroxide.

4. The antifriction wear reducing method of claim 1 wherein, In step (2), the ratio of the mass of Fe3O4 nanoparticles, the volume of some deionized water, the volume of the remaining deionized water, the volume of the second solvent, the volume of the catalyst, and the volume of the silicon source is (28~55) mg: 4 mL; 400 μL: 1 mL: (27~54) μL: (12~35) μL.

5. The antifriction wear reducing method of claim 1 wherein, The strength of the external magnetic field in step (2) is 300~400 Oe.

6. The antifriction wear reducing method of claim 1 wherein, The reaction time for the self-assembly-coating reaction in step (2) is 6~12h, and the reaction temperature for the self-assembly-coating reaction is room temperature.

7. The antifriction wear reducing method of claim 1 wherein, In step (2), the average length of the Fe3O4@SiO2 one-dimensional nanochain is 50~70μm, the average diameter of the Fe3O4@SiO2 one-dimensional nanochain is 0.1~0.3μm, and the outer surface of the Fe3O4@SiO2 one-dimensional nanochain is coated with an amorphous silicon dioxide layer with an average thickness of 30~40 nm.

8. The antifriction wear reducing method of claim 1 wherein, In step (3), the mass fraction of Fe3O4@SiO2 one-dimensional nanochains in the nanochain water-based lubricant is 0.5wt%~2wt%.

9. The antifriction wear reducing method of claim 1 wherein, In step (4), the direction of the external magnetic field is perpendicular to the direction of friction and sliding, so that the Fe3O4@SiO2 one-dimensional nanochains in the nanochain water-based lubricant form a vertical arrangement structure of rolling bearing in the contact area of ​​the friction pair.

10. The friction reduction and wear resistance method according to claim 1, characterized in that, In step (4), the contact area of ​​the friction pair is the contact area of ​​the mechanical friction pair.

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