High-durability two-dimensional material nano-lubricating coating and preparation method thereof

Abstract

This invention discloses a highly durable two-dimensional material nano-lubricating coating, comprising an adhesive layer, a composite lubricating layer, and a surface layer sequentially disposed on a substrate. The composite lubricating layer is formed by spraying a composite lubricating slurry onto the adhesive layer. The composite lubricating slurry is prepared from modified molybdenum disulfide powder, SiO2 nanoparticles, and polyamide-imide resin. This invention also discloses its preparation method, including S1 substrate pretreatment; S2 adhesive layer preparation; S3 composite lubricating layer preparation; and S4 surface layer preparation. The lubricating coating of this invention exhibits strong interfacial bonding, high density, strong load-bearing capacity, and excellent overall performance. It is also suitable for complex working conditions and has a simple preparation process.

Description

Technical Field

[0001] This invention relates to the field of lubrication coating technology, and in particular to a highly durable two-dimensional material nano-lubricating coating and its preparation method. Background Technology

[0002] Lubricating coatings are a core technology for solving friction and wear in mechanical parts and extending equipment service life, and are widely used in industrial manufacturing, aerospace, and precision instruments. Two-dimensional materials such as graphene, molybdenum disulfide, and hexagonal boron nitride, due to their unique layered slip structure and low shear resistance, have become core functional fillers in nano-lubricating coatings, exhibiting far superior performance in friction reduction and wear resistance compared to traditional materials. Existing technologies for two-dimensional material nano-lubricating coatings each have their shortcomings, which can be specifically divided into three categories: The first type is lubricating coatings made of a single two-dimensional material. For example, patent application CN107793888 proposes a method for preparing a corrosion-resistant nano-MoS2-RGO-epoxy composite coating, which is prepared using a high-pressure spraying process and relies on the layered structure of molybdenum disulfide to achieve friction reduction. However, the load-bearing capacity of a single material is limited, and the layered structure is easily crushed under high load and high speed conditions, resulting in rapid decay of lubrication performance. Furthermore, if the coating prepared by the spraying process is not optimized and modified, it has a high porosity and is prone to peeling and cracking in humid environments, significantly shortening its service life.

[0003] The second category is two-dimensional material composite lubricating coatings. For example, utility model patent CN221371117 discloses a graphene lubricating layer structure that improves the dispersibility of graphene through structural design, belonging to a single graphene material system; invention patent CN106544619 describes a solid lubricating ball bearing equipped with a composite coating of Ni-coated micron-sized graphite and graphene, prepared by plasma spraying. These solutions still have significant drawbacks: the bonding force between the two-dimensional material and the substrate is weak, making it prone to detachment under friction and high-pressure conditions; the coating density is low, making it susceptible to damage from abrasive particles and corrosive media; and the plasma spraying process suffers from high equipment investment and operational difficulty, making it unsuitable for coating large areas and irregularly shaped components.

[0004] The third category is multi-component composite lubricating coatings. For example, patent application CN118237587 discloses a self-lubricating composite coating, its preparation method, and its application, utilizing the plastic deformation of copper alloys to buffer pressure impacts and improve load-bearing capacity; patent CN114892142 optimizes the structure of a molybdenum disulfide composite film, balancing lubricity and wear resistance; and patent CN112574800 uses ball milling pretreatment to obtain a nano-roll structure of two-dimensional nanosheets encapsulating nanoparticles, creating a composite super-lubricating coating with a friction coefficient below 0.01. However, these solutions generally suffer from complex structures and stringent preparation process requirements, and struggle to balance temperature resistance, corrosion resistance, and lubrication performance. They are prone to oxidation and decomposition at temperatures above 200℃, resulting in a sharp drop in lubrication performance and failing to meet the comprehensive performance requirements of complex operating conditions.

[0005] In summary, existing two-dimensional material nano-lubricating coating technologies all suffer from one or more defects, such as weak interfacial bonding, low density, limited load-bearing capacity, complex processes, or poor adaptability to operating conditions. These defects make it difficult to meet the requirements of coating durability and service stability under harsh operating conditions such as high pressure, high speed, high temperature, and corrosion. Summary of the Invention

[0006] The purpose of this invention is to provide a highly durable two-dimensional material nano-lubricating coating and its preparation method, so as to solve the technical problems mentioned in the background art. To achieve the above objectives, the present invention adopts the following technical solution: A highly durable two-dimensional material nano-lubricating coating, comprising an adhesive layer, a composite lubricating layer, and a surface layer sequentially disposed on a substrate; the composite lubricating layer is formed by spraying a composite lubricating slurry onto the adhesive layer, the composite lubricating slurry being prepared from modified molybdenum disulfide powder, SiO2 nanoparticles, and polyamide-imide resin.

[0007] Furthermore, the preparation method of the composite lubricating slurry includes the following steps: S1: Take modified molybdenum disulfide powder and put it into a reaction vessel. Add anhydrous ethanol at a solid-liquid ratio of 1g:100mL. Place the vessel in an ultrasonic cleaner and ultrasonically disperse it for 30min at an ultrasonic power of 800W. Then transfer the reaction vessel to a stirrer and add SiO2 nanoparticles. The mass ratio of SiO2 nanoparticles to modified molybdenum disulfide powder particles is 1:5. Stir the reaction at 400r / min for 4h to obtain a molybdenum disulfide-SiO2 composite system. S2: Place the molybdenum disulfide-SiO2 composite system into a reaction vessel, add polyamide-imide resin, and the mass ratio of the solid content of polyamide-imide resin to the molybdenum disulfide-SiO2 composite system is 2:1. Then add N-methylpyrrolidone to adjust the solid content of the system to 30%, and then place it in an ultrasonic cleaner and ultrasonically disperse it for 20 minutes at a power of 500W. S3: Place the ultrasonically dispersed mixture into a vacuum degassing machine and degas for 20 minutes at a vacuum degree of 0.09 MPa to obtain the composite lubricating slurry.

[0008] Furthermore, the modified molybdenum disulfide powder is made from the following raw materials: molybdenum disulfide nanosheets, anhydrous ethanol, and silane coupling agent.

[0009] Furthermore, the method for preparing the modified molybdenum disulfide powder includes the following steps: S1: Place molybdenum disulfide nanosheets into a reaction vessel, add anhydrous ethanol at a solid-liquid ratio of 1g:100mL, stir at 400r / min for 30min to form a uniform suspension; then add silane coupling agent, the mass ratio of silane coupling agent to molybdenum disulfide nanosheets is 1:10, continue stirring for 10min, and add glacial acetic acid during stirring to adjust the pH of the system to between 4 and 5; S2: After the reaction is complete, the reaction vessel is transferred to an oil bath, the oil bath is heated to 70°C, and the reflux condenser is turned on. The mixture is stirred at 300 r / min for 4 hours to obtain a suspension. S3: Transfer the suspension to a centrifuge and centrifuge at 8000 r / min for 10 min. Collect the precipitate at the bottom, wash the precipitate with anhydrous ethanol, and centrifuge again under the same conditions. Repeat this process several times. S4: Place the precipitate after the last centrifugation into a drying oven and dry it at 60℃ for 12 hours. After drying, take it out, grind it, and sieve it to obtain modified molybdenum disulfide powder.

[0010] A method for preparing a highly durable two-dimensional material nano-lubricating coating includes the following steps: S1 Substrate Pretreatment: The substrate is placed in an ultrasonic cleaner and ultrasonically cleaned for 15 minutes each with acetone, anhydrous ethanol and deionized water. Then, the substrate surface is roughened by sandblasting. After the sandblasting roughening is completed, the substrate is placed in an ultrasonic cleaner again and cleaned for 10 minutes each with anhydrous ethanol and deionized water to obtain the pretreated substrate. S2 adhesive layer preparation: The pretreated substrate is placed in a magnetron sputtering device, a working gas is introduced, and the Ni target is sputtered and deposited on the surface of the pretreated substrate to form an adhesive layer, thus obtaining a substrate with an adhesive layer. Preparation of S3 composite lubricating layer: The substrate with the adhesive layer is placed in the spraying equipment, and the composite lubricating slurry is sprayed onto the surface of the substrate with the adhesive layer through the spray gun of the spraying equipment; after the spraying is completed, the substrate is placed in the box furnace, pre-cured by heating once, and then cured by heating a second time to form a composite lubricating layer, thus obtaining a substrate with the adhesive layer and the composite lubricating layer. S4 Surface Preparation: The substrate with the adhesive layer and the composite lubricating layer is placed in a magnetron sputtering device. First, working gas is introduced and bias voltage is applied for etching. Then, the graphite target is sputtered and deposited on the surface of the composite lubricating layer to form a surface layer, and finally the high-durability two-dimensional material nano-lubricating coating is obtained.

[0011] Furthermore, in S1, the sandblasting pressure for the roughening treatment is 0.4 MPa, the distance between the nozzle of the sandblasting equipment and the substrate surface is maintained at 15 cm, and the substrate surface is uniformly sandblasted at a 45° angle for 30 s / surface.

[0012] Furthermore, in S2, the working gas is argon, the working pressure is 0.8 Pa, the sputtering power is 150 W, the deposition temperature is 150 °C, and the deposition time is 30 min.

[0013] Furthermore, in S3, the spray gun nozzle diameter is 0.8mm, the spraying distance is 20cm, the spraying pressure is 0.3MPa, and the spray gun moving speed is 20cm / s.

[0014] Furthermore, in S3, the temperature for the first heating is 100℃, and the pre-curing time is 30min; during the second heating, high-purity nitrogen is introduced into the box furnace, maintaining a nitrogen flow rate of 5L / min, and the temperature is raised to 200℃ at a heating rate of 5℃ / min, and then cured at a constant temperature for 2h.

[0015] Furthermore, in S4, during the etching process, the working gas is argon, the working pressure is 2 Pa, the applied bias voltage is -500 W, and the etching time is 15 min; during sputtering deposition, the working gas is argon, the working pressure is 1.0 Pa, the sputtering power is 200 W, the deposition temperature is 150 °C, and the deposition time is 60 min.

[0016] The functions and principles of each structural layer in this invention are as follows: Adhesive layer: Its core function is to strengthen the interfacial bonding strength between the coating and the metal substrate, reduce the risk of peeling and detachment of the coating during dynamic friction and vibration, and provide a solid and stable adhesion foundation for the entire coating system.

[0017] Composite lubrication layer: The two-dimensional material molybdenum disulfide in this layer is modified by a silane coupling agent, and nanoparticles are uniformly dispersed in the layer to form a special composite structure in which two-dimensional nanosheets encapsulate or support nanoparticles. It achieves excellent lubrication effect by relying on the low friction characteristics of the two-dimensional material, and significantly improves the wear resistance and load-bearing performance of the coating through the nanoparticles, thus achieving the dual functions of lubrication and wear resistance.

[0018] Surface layer: This is a dense protective layer made of diamond-like carbon film, which can effectively block external corrosive media and high-temperature environments from eroding and damaging the internal composite lubricating layer. At the same time, it reduces the loss of lubricating material, further improves the coating's corrosion resistance, temperature resistance and surface density, and extends the effective service life of the coating.

[0019] Through the functional design of the three-layer structure and the synergistic effect between each layer, the two-dimensional material nano-lubricating coating has excellent interfacial bonding strength, high density, strong load-bearing capacity and good temperature and corrosion resistance, providing reliable protection for substrate lubrication and protection under complex working conditions.

[0020] The advantages of this invention compared to the prior art are as follows: 1. This invention utilizes a gradient functionalized structure design of a bottom layer, a composite lubricating layer, and a surface layer. By combining the synergistic effect of two-dimensional material surface modification and nanoparticle reinforcement, the coating achieves strong interfacial bonding, high density, strong load-bearing capacity, and a low coefficient of friction. It also exhibits excellent temperature resistance, maintaining a stable coefficient of friction even at 200°C. This allows it to withstand the influence of complex dynamic friction conditions such as high pressure, high speed, high temperature, and corrosion, meeting the requirements of harsh industrial environments for coating durability and service stability.

[0021] 2. In the composite lubrication layer of this invention, the two-dimensional material is modified to improve its compatibility with the resin matrix and forms a special structure in which two-dimensional nanosheets encapsulate / carry nanoparticles. This achieves low-friction lubrication by relying on the layered sliding characteristics of the two-dimensional material, and solves the problems of limited load-bearing capacity and easy decay of lubrication performance of a single two-dimensional material by using nanoparticle-reinforced phase. This significantly reduces frictional loss of metal substrates, reduces equipment failure rate, and effectively extends the service life of substrates such as moving parts of industrial machinery and precision transmission components.

[0022] 3. The metal substrate of this invention is roughened by sandblasting to form a rough surface, which forms a mechanical engagement with the underlying metal bonding layer. The underlying layer provides a solid foundation for the composite lubrication layer and the surface layer. The three layers are tightly bonded through mechanical interlocking and chemical bonding, which fundamentally solves the problem of traditional coatings being prone to peeling and falling off under friction and high pressure conditions, and ensures that the coating has structural integrity and stable performance during long-term dynamic friction.

[0023] 4. The overall preparation process of this invention is clear and the parameters are controllable. It does not require high-cost special equipment and can be achieved through conventional processes such as electroplating / magnetron sputtering, spraying / spin coating, etc. It can also be adapted to uniform coating of large-area metal substrates and irregularly shaped components. At the same time, the raw material cost is controllable, the operation of each link is standardized and smooth, the coating formation rate is high and the quality is stable, and it is easy to promote and apply industrially.

[0024] 5. The coating of this invention can be applied to the surface of various metal substrates that require lubrication and protection by means of coating, pasting, etc. It is primarily adapted to moving parts of industrial machinery, precision transmission components, and irregularly shaped metal components in the fields of metallurgy, machinery, water conservancy and power. It can effectively improve the lubrication and protection effect of various substrates, ensure the stable and efficient operation of equipment under complex working conditions, and has significant technical practicality and application value. Attached Figure Description

[0025] Figure 1 This is an electron microscope image of the composite lubricating layer of the present invention; Figure 2 These are FT-IR images of molybdenum disulfide powder before and after modification according to this invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments. However, it should be noted that many details listed in the specification are merely to provide the reader with a thorough understanding of one or more aspects of the invention, and these aspects of the invention can be achieved even without these specific details.

[0027] A highly durable two-dimensional material nano-lubricating coating, comprising an adhesive layer, a composite lubricating layer, and a surface layer sequentially disposed on a substrate; the composite lubricating layer is formed by spraying a composite lubricating slurry onto the adhesive layer.

[0028] The preparation method of the composite lubricating slurry includes the following steps: S1: Place 2g of molybdenum disulfide nanosheets into a three-necked flask equipped with a stir bar, add 200mL of anhydrous ethanol, and then place the three-necked flask on a magnetic stirrer. Stir at 400r / min for 30min to form a uniform suspension. Then add 0.2g of KH-550 silane coupling agent and continue stirring for 10min. During the stirring process, add glacial acetic acid to adjust the pH of the system to between 4 and 5. S2: After the reaction is complete, the three-necked flask is transferred to an oil bath. The oil bath is heated to 70°C and the reflux condenser is turned on. The mixture is stirred at 300 r / min for 4 h to allow the silane coupling agent to fully react with the hydroxyl groups on the surface of molybdenum disulfide to obtain a suspension. S3: Transfer the suspension to a centrifuge and centrifuge at 8000 r / min for 10 min. Collect the bottom precipitate, wash the precipitate with anhydrous ethanol, and centrifuge again at 8000 r / min for 8 min. Repeat the washing and centrifugation several times to completely remove unreacted silane coupling agent. S4: Place the precipitate after the last centrifugation into a drying oven and dry it at 60°C for 12 hours. After drying, take it out, grind it, and pass it through a 200-mesh sieve to obtain modified molybdenum disulfide powder. By using a silane coupling agent to modify the two-dimensional material, the compatibility between the two-dimensional material and the subsequent resin matrix can be significantly improved.

[0029] Take a small amount of molybdenum disulfide powder before and after modification, and compare the characteristic peak of hydroxyl group (3400 cm⁻¹) by FT-IR test. -1 (Nearby) intensity, such as Figure 2 As shown, the hydroxyl peak was significantly weakened after modification, indicating that KH-550 was successfully grafted.

[0030] S5: Take 2g of modified molybdenum disulfide powder and put it into a beaker. Add 200mL of anhydrous ethanol and place it in an ultrasonic cleaner. At an ultrasonic power of 800W, use intermittent ultrasonic dispersion with a 5s on and 2s off setting for 30min to break up the agglomeration of nanoparticles and two-dimensional materials. Then transfer the beaker to a stirrer and add 0.4g of SiO2 nanoparticles while stirring at 400r / min. After the addition is complete, continue stirring for 4h so that the SiO2 nanoparticles are uniformly attached to the surface of molybdenum disulfide through electrostatic adsorption and chemical bonding, forming a composite structure in which molybdenum disulfide nanosheets support SiO2 nanoparticles, thus obtaining a molybdenum disulfide-SiO2 composite system. S6: Take 2.4g of molybdenum disulfide-SiO2 composite system and put it into a beaker. Add 4.8g of polyamide-imide resin (PAI, solid content of 50%) to make the mass ratio of composite system to PAI solid 1:2. Then add 12g of N-methylpyrrolidone to adjust the solid content of the system to 30%. Then place it in an ultrasonic cleaner and ultrasonically disperse it for 20min at a power of 500W to make the composite system uniformly dispersed in the resin matrix to obtain a mixed slurry. S7: Place the ultrasonically dispersed mixed slurry into a vacuum degassing machine and degas for 20 minutes at a vacuum degree of 0.09MPa to remove the air bubbles generated by stirring and ultrasonication in the slurry, thus obtaining the composite lubricating slurry.

[0031] A method for preparing a highly durable two-dimensional material nano-lubricating coating includes the following steps: S1 Substrate Pretreatment: Place the 45# steel substrate in an ultrasonic cleaner and sequentially ultrasonically clean it for 15 minutes each with acetone, anhydrous ethanol, and deionized water. After each cleaning, blot the surface with clean filter paper to remove residual liquid, oil, dust, and other impurities. After cleaning, place the substrate in a sandblasting machine using corundum abrasive as the sandblasting medium. Adjust the sandblasting pressure to 0.4 MPa, maintain a nozzle distance of 15 cm from the substrate surface, and uniformly sandblast the substrate surface at a 45° angle for 30 seconds per side to ensure the substrate... The surface is fully covered; after sandblasting roughening treatment, a roughness meter is used to test to ensure that the surface roughness Ra is about 3μm, which improves the mechanical interlocking effect between the substrate and the bottom layer and strengthens the subsequent interlayer bonding force; then it is placed in an ultrasonic cleaner again, and cleaned with anhydrous ethanol and deionized water for 10 minutes each to thoroughly remove oil, rust, sandblasting residue and other impurities from the substrate surface; finally, it is dried with high-purity nitrogen at a flow rate of 30L / min to obtain a clean, dry and rough pretreated substrate, which provides a good adhesion foundation for subsequent coating deposition; S2 Adhesive Layer Preparation: The pretreated substrate was placed in the chamber of the magnetron sputtering coating machine, and the Ni target was then mounted on the target holder, ensuring that the substrate surface and the target surface were parallel, with a spacing of 8 cm. The chamber was then closed, and the vacuum pump was started. First, a low vacuum was evacuated to below 1 Pa, then the high vacuum system was switched to evacuate the chamber to a base vacuum of 5 × 10⁻⁶ Pa. -4 Pa; Argon gas was introduced as the working gas, and the working gas pressure was adjusted to 0.8 Pa. The sputtering power was set to 150 W, the deposition temperature to 150 °C, and the deposition time to 30 min. The sputtering power supply was started to sputter and deposit the Ni target material onto the surface of the pretreated substrate to form a bonding layer. After deposition, the sputtering power supply was turned off, and the substrate was allowed to cool naturally to room temperature while maintaining the argon gas supply to obtain a substrate with a bonding layer. The thickness of the Ni bonding layer was measured to be approximately 200 nm using a micrometer. Preparation of S3 Composite Lubricating Layer: Place the substrate with the adhesive layer on the worktable of the spraying equipment. Pour the composite lubricating slurry into the material tank of the spraying equipment. Adjust the spray gun nozzle diameter to 0.8mm, the spraying distance to 20cm, the spraying pressure to 0.3MPa, and the spray gun moving speed to 20cm / s. Spray the composite lubricating slurry onto the surface of the substrate with the adhesive layer in a uniform reciprocating motion to ensure that the composite lubricating slurry evenly covers the substrate surface. After spraying, let it stand for 5 minutes. Repeat the spraying process twice. After spraying, place the substrate in a programmed temperature rise box oven. First, heat it to 100℃ for pre-curing for 30 minutes to remove the solvent in the slurry and allow the coating to initially form, avoiding sagging and deformation during the subsequent high-temperature curing process. Then, introduce high-purity nitrogen into the oven, maintaining a nitrogen flow rate of 5L / min and a nitrogen flow rate of 5℃ / min. The heating rate was increased to 200℃, and the mixture was kept at a constant temperature for 2 hours. During this time, nitrogen gas was continuously introduced to prevent high-temperature oxidation of molybdenum disulfide, so that the slurry could be fully cross-linked and cured to form a composite lubricating layer, thus obtaining a substrate with an adhesive layer and a composite lubricating layer. The thickness of the composite lubricating layer was measured to be approximately 15μm using a micrometer. S4 Surface Preparation: The substrate with the adhesive layer and composite lubricating layer is placed in the chamber of the magnetron sputtering coating machine. The graphite target is then mounted on the target holder, ensuring the substrate surface is parallel to the target surface with a spacing of 8 cm. The chamber is then closed, and the vacuum pump is started. First, a low vacuum is evacuated to below 1 Pa, then the high vacuum system is switched to evacuate the chamber to a base vacuum of 3 × 10⁻⁶ Pa. -3 Argon gas was introduced as the working gas, and a bias voltage of -500V was applied to perform argon ion etching on the surface of the composite lubricating layer for 15 minutes to remove surface impurities and oxide layers, thereby improving the adhesion between the surface layer and the composite lubricating layer. After etching, the working argon gas pressure was adjusted to 1.0 Pa, the sputtering power was 200W, the deposition temperature was 150℃, and the deposition time was 60 minutes. The sputtering power supply was started to sputter and deposit the graphite target on the surface of the composite lubricating layer to deposit a diamond-like carbon film, forming the surface layer. After deposition, the sputtering power supply was turned off, and the surface was allowed to cool naturally to room temperature while maintaining the argon gas supply. Finally, a highly durable two-dimensional material nano-lubricating coating with a three-layer structure of Ni bonding layer, molybdenum disulfide-SiO2 / PAI composite lubricating layer, and diamond-like carbon film surface layer was obtained. The surface layer thickness was measured to be approximately 200 nm with a micrometer, and the total coating thickness was approximately 15.4 μm.

[0032] The prepared two-dimensional nano-lubricating coating was observed using SEM, such as... Figure 1 As shown, the molybdenum disulfide-SiO2 composite system has good compatibility with the resin, and the SiO2 nanoparticles are uniformly distributed on the surface of molybdenum disulfide without obvious agglomeration.

[0033] Comparative Example 1 It uses a single molybdenum disulfide coating with the commercially available brand model Everlube 620C.

[0034] 1. Performance Testing 1.1 Friction Coefficient and Wear Rate Test Test method: The products of Example 1 and Comparative Example 1 were tested using a ball-disc friction and wear tester. The test conditions were as follows: GCr15 steel balls with a diameter of 6 mm were used as the mating parts, the load was 5 N, the rotation speed was set to 200 r / min, the friction radius was 5 mm, the test duration was 30 min, and the dry friction test was carried out in an ambient temperature environment. The results are shown in Table 1.

[0035] Table 1. Experimental results of friction coefficient and wear rate As can be seen from Table 1, the average coefficient of friction for Example 1 is 0.038, and the average wear rate is 2.10 × 10⁻⁶. -6 mm 3 N -1 m -1 The coefficient of friction for Comparative Example 1 was 0.131, and the wear rate was 12.81 × 10⁻⁶. -6 mm 3 N -1 m -1 Compared with Comparative Example 1, Example 1 showed a 71.0% reduction in friction coefficient and an 83.6% reduction in wear rate, demonstrating that the present application significantly improves the friction reduction and wear resistance of the coating through a three-layer gradient functionalized structure design and surface modification process.

[0036] This application employs a silane coupling agent to modify the surface of molybdenum disulfide, which significantly improves the interfacial compatibility between the two-dimensional material and the polyamide-imide resin matrix, allowing MoS2 to be uniformly dispersed in the resin without agglomeration, thereby reducing interfacial friction resistance. At the same time, SiO2 nanoparticles adhere to the surface of the modified molybdenum disulfide, forming a composite structure in which two-dimensional nanosheets encapsulate nanoparticles, further reducing the coefficient of friction.

[0037] 1.2 Coating Bond Strength Test Test method: The bonding strength of the coatings in Example 1 and Comparative Example 1 was determined using a scratch tester. A diamond indenter with a diameter of 200 μm was used, and the load was gradually increased to 100 N at a loading rate of 50 N / min. The load corresponding to the first peeling or cracking of the coating was defined as the critical load. The results are shown in Table 2.

[0038] Table 2. Experimental results of coating adhesion strength As can be seen from Table 2, the critical load of Example 1 is 81.7 N, and the critical load of Comparative Example 1 is 34.9 N. The bonding strength of Example 1 is 134% higher than that of Comparative Example 1, indicating that this application significantly enhances the interfacial bonding strength between the coating and the metal substrate, and achieves strong adhesion of the coating.

[0039] This is because, during the preparation process, the metal substrate was first roughened by sandblasting, and then a Ni metal bonding layer was deposited using magnetron sputtering. This bottom layer not only forms a metallic bond with the steel substrate but also fills the micro-pits on the rough surface, constituting a dual interface strengthening mechanism of mechanical and chemical structures. Furthermore, the polyamide-imide resin and silane-modified molybdenum disulfide in the composite lubricating layer further enhance the interlayer adhesion through chemical bonding.

[0040] 1.3 Salt spray corrosion test Test method: The product of Example 1 was tested according to the GB / T 10125-2021 neutral salt spray test standard. A 5% sodium chloride solution was used, the pH value was adjusted to 6.5~7.2, and the product was sprayed continuously for 200 hours at 35℃. After the test, the blistering, corrosion and peeling of the coating surface were observed and recorded. The results are shown in Table 3.

[0041] Table 3 Results of Salt Spray Corrosion Test As can be seen from Table 3, after 200 hours of continuous salt spray testing, there was no blistering or rust on the surface of Example 1, indicating that the present application significantly enhances the corrosion resistance of the coating through surface protection design and high-density structure, meeting the long-term protection requirements in harsh and humid environments.

[0042] This is because this application uses a diamond-like carbon film as a dense protective surface layer, which has excellent chemical inertness and extremely low porosity, effectively preventing corrosive media from penetrating into the interior. At the same time, the resin in the composite lubricating layer is fully cross-linked and cured, forming a dense bulk phase structure with low porosity, eliminating corrosion channels. In addition, the Ni metal bonding underlayer not only enhances interfacial bonding but also prevents interlayer delamination caused by corrosive media penetrating along the interface.

[0043] 1.4 High-Temperature Friction Performance Test Test method: The products of Example 1 and Comparative Example 1 were tested using a high-temperature friction and wear testing machine. The samples were heated to 200℃ and held for 30 minutes before the test was started. The mating part was a GCr15 steel ball with a diameter of 6mm. The test parameters were a load of 5 N, a rotation speed of 200 rpm, and a test time of 30 minutes. The stable friction coefficient at high temperature was recorded during the test. The results are shown in Table 4.

[0044] Table 4. Experimental results of high-temperature friction properties As can be seen from Table 4, the average friction coefficient of Example 1 at 200℃ is 0.073, while that of Comparative Example 1 at 200℃ is 0.184. The friction coefficient of Example 1 is reduced by 60.3% compared to Comparative Example 1, indicating that this application significantly improves the high-temperature stability of the coating through surface protection and process optimization.

[0045] This is because the diamond-like carbon (DLC) film surface layer prepared by magnetron sputtering in Example 1 has excellent thermal stability and barrier properties. Meanwhile, the polyamide-imide resin (PAI) in the composite lubricating layer itself has high thermal stability, and nitrogen gas is introduced for protection during the curing process. Furthermore, SiO2 nanoparticles, as a thermal barrier phase, reduce the transfer of frictional heat to the resin matrix, maintaining the integrity of the lubricating structure.

[0046] 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 highly durable two-dimensional material nano-lubricating coating, characterized in that, The two-dimensional material nano-lubricating coating includes an adhesive layer, a composite lubricating layer, and a surface layer sequentially disposed on a substrate; the composite lubricating layer is formed by spraying a composite lubricating slurry onto the adhesive layer, and the composite lubricating slurry is prepared from modified molybdenum disulfide powder, SiO2 nanoparticles, and polyamide-imide resin.

2. The high-durability two-dimensional material nano-lubricating coating according to claim 1, characterized in that: The preparation method of the composite lubricating slurry includes the following steps: S1: Take modified molybdenum disulfide powder and put it into a reaction vessel. Add anhydrous ethanol at a solid-liquid ratio of 1g:100mL. Place the vessel in an ultrasonic cleaner and ultrasonically disperse it for 30min at an ultrasonic power of 800W. Then transfer the reaction vessel to a stirrer and add SiO2 nanoparticles while stirring at a speed of 400r / min. The mass ratio of SiO2 nanoparticles to modified molybdenum disulfide powder is 1:

5. After the addition is complete, continue stirring for 4h to obtain a molybdenum disulfide-SiO2 composite system. S2: Place the molybdenum disulfide-SiO2 composite system into a reaction vessel, add polyamide-imide resin, and the mass ratio of the solid content of polyamide-imide resin to the molybdenum disulfide-SiO2 composite system is 2:

1. Then add N-methylpyrrolidone to adjust the solid content of the system to 30%, and then place it in an ultrasonic cleaner and ultrasonically disperse it for 20 minutes at a power of 500W. S3: Place the ultrasonically dispersed mixture into a vacuum degassing machine and degas for 20 minutes at a vacuum degree of 0.09 MPa to obtain the composite lubricating slurry.

3. The high-durability two-dimensional material nano-lubricating coating according to claim 1, characterized in that: The modified molybdenum disulfide powder is made from the following raw materials: molybdenum disulfide nanosheets, anhydrous ethanol, and silane coupling agent.

4. The high-durability two-dimensional material nano-lubricating coating according to claim 3, characterized in that: The method for preparing the modified molybdenum disulfide powder includes the following steps: S1: Place molybdenum disulfide nanosheets into a reaction vessel, add anhydrous ethanol at a solid-liquid ratio of 1g:100mL, stir at 400r / min for 30min to form a uniform suspension; then add silane coupling agent, the mass ratio of silane coupling agent to molybdenum disulfide nanosheets is 1:10, continue stirring for 10min, and add glacial acetic acid during stirring to adjust the pH of the system to between 4 and 5; S2: After the reaction is complete, the reaction vessel is transferred to an oil bath, the oil bath is heated to 70°C, and the reflux condenser is turned on. The mixture is stirred at 300 r / min for 4 hours to obtain a suspension. S3: Transfer the suspension to a centrifuge and centrifuge at 8000 r / min for 10 min. Collect the bottom precipitate, wash the precipitate with anhydrous ethanol, and centrifuge again at 8000 r / min for 8 min. Repeat this process several times. S4: Place the precipitate after the last centrifugation into a drying oven and dry it at 60℃ for 12 hours. After drying, take it out, grind it, and sieve it to obtain modified molybdenum disulfide powder.

5. The method for preparing a high-durability two-dimensional material nano-lubricating coating according to claim 1, characterized in that, Includes the following steps: S1 Substrate Pretreatment: The substrate is placed in an ultrasonic cleaner and ultrasonically cleaned for 15 minutes each with acetone, anhydrous ethanol and deionized water. Then, the substrate surface is roughened by sandblasting. After the sandblasting roughening is completed, the substrate is placed in an ultrasonic cleaner again and cleaned for 10 minutes each with anhydrous ethanol and deionized water. Then, it is dried to obtain the pretreated substrate. S2 adhesive layer preparation: The pretreated substrate is placed in a magnetron sputtering device, a working gas is introduced, and the Ni target is sputtered and deposited on the surface of the pretreated substrate to form an adhesive layer, thus obtaining a substrate with an adhesive layer. S3 composite lubricating layer preparation: The substrate with the adhesive layer is placed in the spraying equipment, and the composite lubricating slurry is sprayed onto the surface of the substrate with the adhesive layer through the spray gun of the spraying equipment; After the coating is completed, the substrate is placed in a box oven, pre-cured by heating once, and then cured by heating a second time to form a composite lubricating layer, thus obtaining a substrate with an adhesive layer and a composite lubricating layer. S4 Surface Preparation: The substrate with the adhesive layer and the composite lubricating layer is placed in a magnetron sputtering device. First, working gas is introduced and bias voltage is applied for etching. Then, the graphite target is sputtered and deposited on the surface of the composite lubricating layer to form a surface layer, and finally the high-durability two-dimensional material nano-lubricating coating is obtained.

6. The method for preparing a high-durability two-dimensional material nano-lubricating coating according to claim 5, characterized in that: In S1, the sandblasting pressure for the roughening treatment is 0.4 MPa, the distance between the nozzle of the sandblasting equipment and the substrate surface is kept at 15 cm, and the substrate surface is uniformly sandblasted at a 45° angle for 30 seconds per surface.

7. The method for preparing a high-durability two-dimensional material nano-lubricating coating according to claim 5, characterized in that: In S2, the working gas is argon, the working pressure is 0.8 Pa, the sputtering power is 150 W, the deposition temperature is 150 °C, and the deposition time is 30 min.

8. The method for preparing a high-durability two-dimensional material nano-lubricating coating according to claim 5, characterized in that: In S3, the spray gun nozzle diameter is 0.8mm, the spraying distance is 20cm, the spraying pressure is 0.3MPa, and the spray gun moving speed is 20cm / s.

9. The method for preparing a high-durability two-dimensional material nano-lubricating coating according to claim 5, characterized in that: In S3, the temperature for the first heating is 100℃, and the pre-curing time is 30min. During the second heating, high-purity nitrogen is introduced into the box furnace at a flow rate of 5L / min, and the temperature is raised to 200℃ at a rate of 5℃ / min, and then cured at a constant temperature for 2h.

10. The method for preparing a high-durability two-dimensional material nano-lubricating coating according to claim 5, characterized in that: In S4, during etching, the working gas is argon, the working pressure is 2 Pa, the applied bias voltage is -500 W, and the etching time is 15 min; during sputtering deposition, the working gas is argon, the working pressure is 1.0 Pa, the sputtering power is 200 W, the deposition temperature is 150 °C, and the deposition time is 60 min.

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