Preparation and application method of super-lubricating coating based on two-dimensional material

Abstract

The invention discloses a preparation and application method of a super-lubricating coating based on a two-dimensional material. According to the invention, the charge density wave dynamic regulation and control mechanism of the fluorinated graphene and transition metal chalcogenide heterostructure is combined with the stress buffer characteristic of boron nitride, so that a slip interface with a low shear barrier is constructed on the atomic scale, and the energy dissipation in the friction process is remarkably reduced. A three-dimensional interpenetrating network of the helical carbon nanotubes and the hyperbranched polymer not only effectively inhibits stacking of two-dimensional materials, but also forms a multi-dimensional damage repair mechanism through solid-liquid phase change self-adaptive filling of the liquid metal and a boundary lubrication effect of the nano-diamond. Through the synergistic effect of the material system, the coating keeps the ultralow friction characteristic under the wide-range working condition, meanwhile, the coating has the composite protection capacity of abrasion resistance, high temperature resistance and corrosion resistance, and the intrinsic lubrication characteristic of the two-dimensional material is reserved while the compactness of the coating is guaranteed through the gradient cross-linking technology of ultraviolet curing and heat treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of superlubricant coatings, and specifically relates to a preparation and application method of a superlubricant coating based on two-dimensional materials. Background Art

[0002] Superlubricant coating materials are a new type of material with extremely low friction coefficients and excellent wear resistance, mainly composed of nanoparticles, lubricants, and binders. Such materials can still maintain good lubrication performance under extreme environments such as high temperature, high pressure, and corrosion, effectively reducing the wear and energy consumption of mechanical equipment. The application scope of superlubricant coating materials is extensive, including fields such as aerospace, automotive, mechanical manufacturing, and electronics. Its advantages lie in extending the service life of equipment, reducing maintenance costs, and improving energy utilization efficiency, providing strong support for the industrial development and technological innovation of our country, and being an important development direction in the future lubricant material field.

[0003] However, traditional solid lubricant coatings in the existing technology have inherent defects such as a single material system and insufficient structural regulation accuracy: Coatings based on a single two-dimensional material are prone to stacking failure due to strong interlayer van der Waals forces, and lack a multi-scale cooperative lubrication mechanism, severely restricting the long-term stability and intelligent level of the coatings under extreme working conditions. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation and application method of a superlubricant coating based on two-dimensional materials in order to solve the above-mentioned problems.

[0005] The technical solution adopted by the present invention is as follows: A preparation and application method of a superlubricant coating based on two-dimensional materials, the method comprising the following steps: S1: First, weigh the preparation raw materials, weigh: Two-dimensional material composite system: Graphene fluoride nanosheets: 3 parts by weight, tungsten disulfide / molybdenum diselenide heterostructure powder: 2.5 parts by weight, nitrogen-doped carbon-coated hexagonal boron nitride: 2 parts by weight, HCNTs helical carbon nanotubes 1 part by weight: Polymer matrix: Polyetheretherketone-polytetrafluoroethylene copolymer: 35 parts by weight, hyperbranched polysiloxane 10.5 parts by weight; Functional additives: Ionic liquid-modified nanodiamond: 5 parts by weight, titanate coupling agent: 2 parts by weight, graphene oxide quantum dots: 1 part by weight, and Ga-In-Sn alloy liquid metal microdroplets: 10 parts by weight; Reaction system: Ultraviolet curable epoxy resin 20 parts by weight; Plasma activator: Ar / O 2 Mixed gas: 8 parts by weight; Place graphene fluoride nanosheets, tungsten disulfide / molybdenum diselenide heterostructure powder, nitrogen-doped carbon-coated hexagonal boron nitride, and helical carbon nanotubes in a plasma reaction chamber, introduce an argon-oxygen mixed gas, and perform plasma activation treatment at a power of 200 W for 30 minutes to generate surface hydroxyl and epoxy groups; S2: Dissolve the polyether ether ketone-polytetrafluoroethylene copolymer in tetrahydrofuran, stir at 60 °C for 2 hours, then add hyperbranched polysiloxane and titanate coupling agent, and use an ultrasonic cell disruptor to treat at a power of 400 W for 15 minutes to form a homogeneous colloid.

[0006] S3: Sequentially add the pretreated two-dimensional material system to the polymer colloid, synchronously incorporate ionic liquid-modified nanodiamonds and graphene oxide quantum dots, and perform planetary ball milling under nitrogen protection at a rotation speed of 300 rpm for 4 hours to obtain a composite slurry with a viscosity of 1200 ± 50 mPa·s.

[0007] S4: Using coaxial electrospinning technology, with gallium indium tin alloy microdroplets as the core and polyether ether ketone-polytetrafluoroethylene solution as the shell layer, prepare core-shell fibers with a diameter of 80-120 nm under the conditions of a voltage of 15 kV and a propulsion rate of 0.8 mL / h, and disperse them in the composite slurry.

[0008] S5: Inject the mixed slurry into a 3D printing system, apply a vertical magnetic field with an intensity of 1.5 T to align the nitrogen-doped carbon-coated hexagonal boron nitride along the 002 crystal plane, and at the same time realize the interlayer intercalation structure of the two-dimensional material through a 200-μm-wide microfluidic channel.

[0009] S6: Spray a UV-curable epoxy resin primer, a magnetic field-oriented composite slurry, and a graphene oxide quantum dot marking layer on a substrate with a surface roughness less than 0.1 μm in sequence, and use a scraper to control the flatness error of the film layer to be less than 3%.

[0010] S7: Use a 365-nm UV light source to irradiate at an intensity of 50 mW / cm² for 5 minutes to trigger the epoxy resin gradient crosslinking reaction and form a primary network structure with a porosity below 2%; S8: Place the coating in a programmable temperature-controlled furnace, heat it to 180 °C at a rate of 10 °C / minute and hold for 2 hours to make the crystallinity of the polyether ether ketone-polytetrafluoroethylene reach 45%, and at the same time control the partial melting of the liquid metal microdroplets in the range of 25-40 °C to fill the interface defects.

[0011] S9: Polish the surface with a 50-eV argon ion beam at an incident angle of 45°, and then perform hydrophobic modification treatment in a fluorine-containing atmosphere. Finally, obtain a superlubricating coating with a contact angle of 152° ± 3° and a surface roughness below 8 nm, and then the entire preparation and application method of the superlubricating coating based on two-dimensional materials can be ended.

[0012] In a preferred embodiment, in step S1, a mixed gas of argon and oxygen is introduced, with an argon-oxygen volume ratio of 4:1, the gas flow rate is controlled at 20 mL / min, and the chamber pressure is maintained at 0.1 Pa. The radio frequency power supply is turned on, the power is set to 200 W, and the frequency is 13.56 MHz, and plasma activation treatment is carried out for 30 minutes. During the treatment process, hydroxyl and epoxy groups are generated on the material surface, and at the same time, the aggregation of nanosheets is inhibited by electrostatic repulsion. The temperature of the reaction chamber is controlled at 25 ± 2 °C through a water cooling system, and the surface energy of the treated material is reduced to below 35 mN / m.

[0013] In a preferred embodiment, in step S2, a titanium alloy probe with a diameter of 6 mm is used, the power is set to 400 W, the frequency is 20 kHz, and it operates in a pulsed mode for 15 minutes. During the treatment process, the solution temperature is maintained at 30 ± 1 °C through a circulating cooling water system, and finally a homogeneous colloid with a viscosity of 450 mPa·s is obtained, and the colloidal particle size distribution D90 is less than 500 nm.

[0014] In a preferred embodiment, in step S3, a planetary ball mill is used, equipped with a zirconia ball milling tank and zirconia grinding balls with a diameter of 3 mm, the ball-to-material ratio is 10:1, and ball milling is carried out at a speed of 300 rpm for 4 hours under nitrogen protection. During the ball milling process, it pauses for 10 minutes to dissipate heat every 30 minutes, and the temperature inside the tank does not exceed 45 °C. Finally, the slurry is detected by a rotational viscometer, and the viscosity is stable at 1200 ± 50 mPa·s at 25 °C, the Zeta potential is -38 mV, and the solid content is 42 wt%.

[0015] In a preferred embodiment, in step S4, during the use of a coaxial electrospinning device, 10 parts by weight of gallium-indium-tin alloy microdroplets are loaded into the inner syringe barrel, and a polyetheretherketone-polytetrafluoroethylene tetrahydrofuran solution with a mass fraction of 15% is loaded into the outer syringe barrel. The inner and outer layer propulsion rates are set to 0.5 mL / h and 0.8 mL / h respectively, a high voltage electric field of 15 kV is applied, the receiving distance is 15 cm, the ambient temperature is 25 °C, and the humidity is 30%RH. The formation process of microdroplets is monitored by high-speed photography, and the voltage waveform is adjusted to a square wave pulse (duty cycle 70%) to obtain core-shell fibers with a diameter of 80 - 120 nm. After the collected fibers are vacuum dried at 60 °C for 2 hours, they are dispersed in the composite slurry prepared in S3 at a mass fraction of 5%.

[0016] In a preferred embodiment, in step S5, when the slurry passes through a 200-μm-wide microfluidic channel, the flow rate is controlled at 0.2 mL / min, and the nitrogen-doped carbon-coated hexagonal boron nitride is oriented along the 002 crystal plane with an orientation degree of 92%. A 10-kHz ultrasonic vibration with an amplitude of 5 μm is applied synchronously to prevent the stacking between two-dimensional material layers. The oriented slurry forms a pre-coating layer with a thickness of 20 ± 1 μm on the substrate surface, and the interlayer intercalation spacing is 0.34 nm. The XRD detection shows that the full width at half maximum of the characteristic peak decreases by 35%.

[0017] In a preferred embodiment, in step S6, first, 20 parts by weight of an ultraviolet-curable epoxy resin primer is sprayed with a nozzle diameter of 0.3 mm and a spraying pressure of 0.3 MPa to form a 5-μm-thick bottom layer. Subsequently, a magnetic-field-oriented composite slurry is coated with a doctor blade gap set at 25 μm and a moving speed of 5 mm / s to obtain a 20-μm functional layer. Finally, a graphene oxide quantum dot marking layer is sprayed by atomic layer deposition technology with a deposition rate of 0.1 nm / s and a total thickness of 2 nm. The coating interval time for each layer is 10 minutes, and the environmental cleanliness reaches ISO Class 5.

[0018] In a preferred embodiment, in step S7, during the curing process, the surface temperature is monitored by an infrared thermal imager to ensure that it does not exceed 60°C. The crosslinking degree of the epoxy resin reaches 75%, forming a three-dimensional network structure with pore diameters less than 50 nm and a porosity of 1.8%. Synchronously, in-situ Raman spectroscopy detection is used, and it is found that the D / G peak intensity ratio of fluorinated graphene decreases from 0.85 to 0.62, indicating an improvement in the dispersion of nanosheets.

[0019] In a preferred embodiment, in step S8, the coating is placed in a high-vacuum sintering furnace at a pressure of 0.01 Pa and heated to 180°C at a rate of 10°C / min and held for 2 hours. The crystallinity of polyetheretherketone-polytetrafluoroethylene is increased from 30% to 45% as detected by DSC, and the melting enthalpy reaches 42 J / g. The liquid metal microdroplets are partially melted at 40°C and fill the interfacial microcracks through capillary action with a filling depth of 8 μm. During the cooling stage, gradient cooling is adopted, with a cooling rate of 5°C / min from 180°C to 80°C, and then natural cooling to room temperature, and the residual stress is less than 15 MPa.

[0020] In a preferred embodiment, in step S9, a Kaufman-type ion source is used, with an argon gas flow rate of 10 sccm, an energy of 50 eV, and a beam current density of 2 mA / cm². The surface is polished at an incident angle of 45° for 30 minutes to remove 5-nm surface protrusions. Subsequently, it is treated in an atmosphere containing hexafluoropropylene at a pressure of 50 kPa and a temperature of 120°C for 1 hour to form a 3-nm-thick perfluorosilane self-assembled film. The contact angle of the final coating is 152 ± 3°, and it still remains at 148° after 500 friction tests. The surface roughness Ra is 7.6 nm, and the root mean square roughness shown by AFM observation is 8.2 nm.

[0021] In summary, due to the adoption of the above technical solutions, the beneficial effects of the present invention are as follows: 1. In the present invention, the charge density wave dynamic regulation mechanism of the graphene fluoride and transition metal chalcogenide heterostructure, combined with the stress buffering characteristics of boron nitride, constructs a slip interface with a low shear barrier at the atomic scale, significantly reducing the energy dissipation during the friction process. The three-dimensional interpenetrating network of helical carbon nanotubes and hyperbranched polymers not only effectively inhibits the stacking of two-dimensional materials, but also forms a multi-dimensional damage repair mechanism through the self-adaptive filling of the solid-liquid phase change of liquid metal and the boundary lubrication effect of nanodiamonds. The synergistic effect of this material system enables the coating to maintain ultra-low friction characteristics under wide-range working conditions, and at the same time has the composite protection capabilities of anti-wear, high temperature resistance and corrosion resistance.

[0022] 2. In the present invention, the integration of microfluidic directed assembly and energy field regulation technology solves the industrial problems of the dispersion orientation and interface bonding of two-dimensional materials. The gradient cross-linking process of ultraviolet curing and heat treatment not only ensures the denseness of the coating, but also retains the intrinsic lubrication characteristics of two-dimensional materials; the magnetic field-induced crystal orientation technology improves the utilization rate of the material slip plane to more than 3 times that of traditional processes. The super-smooth surface formed by plasma activation and ion beam polishing makes the contact stress distribution more uniform, significantly reducing the risk of fretting wear. Compared with traditional lubricating coatings, this system can still maintain stable lubrication performance in extreme environments such as high vacuum and high speed rotation and high temperature oxidation, and is particularly suitable for friction loss-sensitive fields such as aerospace precision bearings and micro power devices, and has important engineering practical value and industrialization potential. Description of the Drawings

[0023] Figure 1 is the method flow chart of the present invention. Detailed Embodiments

[0024] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. Embodiment

[0025] Referring to Figure 1 , a preparation and application method of a super-lubricating coating based on two-dimensional materials, comprising the following steps: S1: First, weigh the preparation raw materials, and weigh: Two-dimensional material composite system: Graphene fluoride nanosheets: 3 parts by weight, tungsten disulfide / molybdenum diselenide heterostructure powder: 2.5 parts by weight, nitrogen-doped carbon-coated hexagonal boron nitride: 2 parts by weight, HCNTs helical carbon nanotubes 1 part by weight: Polymer matrix: Polyether ether ketone-polytetrafluoroethylene copolymer: 35 parts by weight, hyperbranched polysiloxane: 10.5 parts by weight; Functional additive: Ionic liquid modified nanodiamond: 5 parts by weight, titanate coupling agent: 2 parts by weight, graphene oxide quantum dots: 1 part by weight, and Ga-In-Sn alloy liquid metal droplets: 10 parts by weight; Reaction system: UV curable epoxy resin: 20 parts by weight; Plasma activator: Ar / O 2 Mixed gas: 8 parts by weight; Put graphene fluoride nanosheets, tungsten disulfide / molybdenum diselenide heterostructure powder, nitrogen-doped carbon-coated hexagonal boron nitride, and helical carbon nanotubes into a plasma reaction chamber, introduce argon-oxygen mixed gas, and perform plasma activation treatment at a power of 200W for 30 minutes to generate surface hydroxyl and epoxy groups; S2: Dissolve the polyether ether ketone-polytetrafluoroethylene copolymer in tetrahydrofuran, add hyperbranched polysiloxane and titanate coupling agent after stirring at 60°C for 2 hours, and use an ultrasonic cell disruptor to treat at a power of 400W for 15 minutes to form a homogeneous colloid.

[0026] S3: Add the pretreated two-dimensional material system to the polymer colloid successively, synchronously incorporate ionic liquid modified nanodiamond and graphene oxide quantum dots, and perform planetary ball milling under nitrogen protection at a rotation speed of 300 rpm for 4 hours to obtain a composite slurry with a viscosity of 1200 ± 50 mPa·s.

[0027] S4: Use coaxial electrospinning technology to prepare core-shell fibers with a diameter of 80 - 120 nm with gallium indium tin alloy droplets as the core and polyether ether ketone-polytetrafluoroethylene solution as the shell layer, and disperse them in the composite slurry at a voltage of 15 kV and a propulsion rate of 0.8 mL / h.

[0028] S5: Inject the mixed slurry into a 3D printing system, apply a vertical magnetic field with an intensity of 1.5 T to align the nitrogen-doped carbon-coated hexagonal boron nitride along the 002 crystal plane, and at the same time achieve an interlayer intercalation structure of two-dimensional materials through a 200-μm-wide microfluidic channel.

[0029] S6: Spray a UV curable epoxy resin primer, a magnetic field-oriented composite slurry, and a graphene oxide quantum dot marking layer on a substrate with a surface roughness less than 0.1 μm in sequence, and use a scraper to control the flatness error of the film layer to be less than 3%.

[0030] S7: Use a 365-nm UV light source to irradiate at an intensity of 50 mW / cm² for 5 minutes to trigger the gradient crosslinking reaction of the epoxy resin and form a primary network structure with a porosity lower than 2%; S8: Place the coating in a programmable temperature furnace, heat it to 180 °C at a rate of 10 °C per minute and hold for 2 hours to achieve a crystallinity of 45% for polyether ether ketone-polytetrafluoroethylene, while regulating the partial melting and filling of the interface defects by liquid metal microdroplets in the range of 25 - 40 °C.

[0031] S9: Polish the surface with a 50 eV argon ion beam at an incident angle of 45°, followed by hydrophobic modification treatment in a fluorine-containing atmosphere. Finally, a superlubricating coating with a contact angle of 152° ± 3° and a surface roughness lower than 8 nm is obtained, and then the entire preparation and application method of the superlubricating coating based on two-dimensional materials can be ended.

[0032] In step S1, a mixed gas of argon and oxygen is introduced, with an argon-oxygen volume ratio of 4:1, the gas flow rate is controlled at 20 mL / min, and the chamber pressure is maintained at 0.1 Pa. Turn on the radio frequency power supply, set the power to 200 W and the frequency to 13.56 MHz, and perform plasma activation treatment for 30 minutes. During the treatment process, hydroxyl and epoxy groups are generated on the material surface, and at the same time, the agglomeration of nanosheets is inhibited by electrostatic repulsion. The reaction chamber temperature is controlled at 25 ± 2 °C through a water cooling system, and the surface energy of the treated material is reduced to below 35 mN / m.

[0033] In step S2, a titanium alloy probe with a diameter of 6 mm is used, the power is set to 400 W, the frequency is 20 kHz, and it operates in a pulsed mode for 15 minutes. During the treatment process, the solution temperature is maintained at 30 ± 1 °C through a circulating cooling water system, and finally a homogeneous colloid with a viscosity of 450 mPa·s is obtained, and the particle size distribution D90 of the colloid is less than 500 nm.

[0034] In step S3, a planetary ball mill is used, equipped with a zirconia ball milling tank and zirconia grinding balls with a diameter of 3 mm, the ball-to-material ratio is 10:1, and ball milling is carried out at a speed of 300 rpm for 4 hours under nitrogen protection. During the ball milling process, it pauses for 10 minutes to dissipate heat every 30 minutes, and the temperature in the tank does not exceed 45 °C. Finally, the slurry is detected by a rotational viscometer, and the viscosity is stable at 1200 ± 50 mPa·s at 25 °C, the Zeta potential is -38 mV, and the solid content is 42 wt%.

[0035] In step S4, during the use of the coaxial electrospinning equipment, 10 parts by weight of gallium indium tin alloy microdroplets are loaded in the inner syringe barrel, and a 15% by mass solution of polyether ether ketone-polytetrafluoroethylene in tetrahydrofuran is loaded in the outer syringe barrel. Set the inner and outer layer feeding rates to 0.5 mL / h and 0.8 mL / h respectively, apply a 15 kV high-voltage electric field, the receiving distance is 15 cm, the ambient temperature is 25 °C, and the humidity is 30%RH. Monitor the microdroplet formation process through high-speed photography, adjust the voltage waveform to a square wave pulse (duty cycle 70%), and obtain core-shell fibers with a diameter of 80 - 120 nm. After the collected fibers are vacuum dried at 60 °C for 2 hours, they are dispersed in the composite slurry prepared in S3 at a mass fraction of 5%.

[0036] In step S5, when the slurry passes through the 200-μm-wide microfluidic channel, the flow rate is controlled at 0.2 mL / min. The nitrogen-doped carbon-coated hexagonal boron nitride is oriented along the 002 crystal plane with an orientation degree of 92%. A 10-kHz ultrasonic vibration with an amplitude of 5 μm is applied synchronously to prevent the stacking between two-dimensional material layers. The oriented slurry forms a pre-coating with a thickness of 20 ± 1 μm on the substrate surface. The interlayer intercalation spacing is 0.34 nm, and the XRD detection shows that the full width at half maximum of the characteristic peak decreases by 35%.

[0037] In step S6, first, 20 parts by weight of an ultraviolet-curable epoxy resin primer is sprayed with a nozzle diameter of 0.3 mm and a spraying pressure of 0.3 MPa to form a 5-μm-thick bottom layer. Subsequently, a magnetic-field-oriented composite slurry is coated with a doctor blade gap set at 25 μm and a moving speed of 5 mm / s to obtain a 20-μm functional layer. Finally, a graphene oxide quantum dot marking layer is sprayed by atomic layer deposition technology with a deposition rate of 0.1 nm / s and a total thickness of 2 nm. The coating interval time for each layer is 10 minutes, and the environmental cleanliness reaches ISO 5 level.

[0038] In step S7, during the curing process, the surface temperature is monitored by an infrared thermal imager to ensure that it does not exceed 60°C. The crosslinking degree of the epoxy resin reaches 75%, forming a three-dimensional network structure with pore diameters less than 50 nm and a porosity of 1.8%. In-situ Raman spectroscopy detection is synchronously used, and it is found that the intensity ratio of the D / G peaks of fluorinated graphene decreases from 0.85 to 0.62, indicating an improvement in the dispersion of nanosheets.

[0039] In step S8, the coating is placed in a high-vacuum sintering furnace with a pressure of 0.01 Pa, heated to 180°C at a rate of 10°C / min, and kept warm for 2 hours. The crystallinity of polyetheretherketone-polytetrafluoroethylene is increased from 30% to 45% as detected by DSC, and the melting enthalpy reaches 42 J / g. The liquid metal microdroplets are partially melted at 40°C and fill the interfacial microcracks through capillary action with a filling depth of 8 μm. During the cooling stage, gradient cooling is adopted, with a cooling rate of 5°C / min from 180°C to 80°C, and then natural cooling to room temperature, and the residual stress is less than 15 MPa.

[0040] In step S9, a Kaufman-type ion source is used, with an argon gas flow rate of 10 sccm, an energy of 50 eV, and a beam current density of 2 mA / cm². The surface is polished at an incident angle of 45° for 30 minutes to remove the 5-nm surface protrusions. Subsequently, it is treated in an atmosphere containing hexafluoropropylene at a pressure of 50 kPa and a temperature of 120°C for 1 hour to form a 3-nm-thick perfluorosilane self-assembled film. The contact angle of the final coating is 152 ± 3°, and it still remains at 148° after 500 friction tests. The surface roughness Ra is 7.6 nm, and the root mean square roughness shown by AFM observation is 8.2 nm.

[0041] In the present invention, the charge density wave dynamic regulation mechanism of the graphene fluoride and transition metal chalcogenide heterostructure, combined with the stress buffering characteristics of boron nitride, constructs a slip interface with a low shear barrier at the atomic scale, significantly reducing the energy dissipation during the friction process. The three-dimensional interpenetrating network of helical carbon nanotubes and hyperbranched polymers not only effectively inhibits the stacking of two-dimensional materials, but also forms a multi-dimensional damage repair mechanism through the self-adaptive filling of the solid-liquid phase change of liquid metal and the boundary lubrication effect of nanodiamonds. The synergistic effect of this material system enables the coating to maintain ultra-low friction characteristics under wide-range working conditions, and at the same time has the composite protection capabilities of anti-wear, high temperature resistance and corrosion resistance.

[0042] In the present invention, by integrating the microfluidic directed assembly and energy field regulation technologies, the industry problems of the dispersion orientation and interface bonding of two-dimensional materials are solved. The gradient cross-linking process of ultraviolet curing and heat treatment not only ensures the denseness of the coating, but also retains the intrinsic lubrication characteristics of two-dimensional materials; the crystal orientation alignment technology induced by magnetic field increases the utilization rate of the material slip plane to more than three times that of the traditional process. The ultra-smooth surface formed by plasma activation and ion beam polishing makes the contact stress distribution more uniform, significantly reducing the risk of fretting wear. Compared with traditional lubricating coatings, this system can still maintain stable lubrication performance in extreme environments such as high vacuum and high rotation speed, high temperature oxidation, etc., and is particularly suitable for fields sensitive to friction loss such as aerospace precision bearings and micro power devices, having important engineering practical value and industrialization potential.

[0043] It should be noted that in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the term "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, an element defined by the statement "comprising one..." does not exclude the presence of additional identical elements in the process, method, article or device comprising the element.

[0044] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. Preparation and application method of super lubricating coating based on two-dimensional materials, characterized in that: The method comprises the following steps: S1: First weigh the raw materials for preparation: Two-dimensional material composite system: Fluorinated graphene nanosheets: 3 parts by weight, tungsten disulfide / molybdenum diselenide heterostructure powder: 2.5 parts by weight, nitrogen-doped carbon-coated hexagonal boron nitride: 2 parts by weight, HCNTs helical carbon nanotubes: 1 part by weight: Polymer matrix: Polyetheretherketone-polytetrafluoroethylene copolymer: 35 parts by weight, hyperbranched polysiloxane 10.5 parts by weight; Functional additives: Ionic liquid modified nanodiamond: 5 parts by weight, titanate coupling agent: 2 parts by weight, graphene oxide quantum dots: 1 part by weight and Ga-In-Sn alloy liquid metal droplets: 10 parts by weight; Reaction system: 20 parts by weight of UV-curable epoxy resin; Plasma activator: Ar / O2 mixed gas: 8 parts by weight; Fluorinated graphene nanosheets, tungsten disulfide / molybdenum diselenide heterostructure powders, nitrogen-doped carbon-coated hexagonal boron nitride and spiral carbon nanotubes were placed in a plasma reaction chamber, and an argon-oxygen mixed gas was introduced. The plasma activation treatment was performed at a power of 200 W for 30 minutes to generate surface hydroxyl and epoxy groups. S2: polyetheretherketone-polytetrafluoroethylene copolymer was dissolved in tetrahydrofuran, and after stirring at 60°C for 2 hours, hyperbranched polysiloxane and titanate coupling agent were added, and an ultrasonic cell disruptor was used to treat at a power of 400 W for 15 minutes to form a homogeneous colloid; S3: adding the pretreated two-dimensional material system to the polymer colloid one by one, and simultaneously doping the ionic liquid modified nanodiamond and graphene oxide quantum dots, and planetary ball milling was performed under nitrogen protection at a speed of 300 rpm for 4 hours to obtain a composite slurry with a viscosity of 1200±50 mPa·s; S4: Using coaxial electrospinning technology, gallium indium tin alloy droplets were used as cores and polyetheretherketone-polytetrafluoroethylene solution was used as shells. Core-shell fibers with a diameter of 80-120 nm were prepared at a voltage of 15 kV and a propulsion rate of 0.8 mL / h and dispersed in the composite slurry; S5: injecting the mixed slurry into the 3D printing system, applying a 1.5T vertical magnetic field to orient the nitrogen-doped carbon-coated hexagonal boron nitride along the 002 crystal plane, and realizing the interlayer intercalation structure of the two-dimensional material through a 200μm wide microfluidic channel; S6: spraying UV-curing epoxy resin primer, magnetic field-oriented composite slurry and graphene oxide quantum dot marking layer on a substrate with a surface roughness of less than 0.1 μm in sequence, and using a scraper to control the flatness error of the film layer to be less than 3%; S7: Use a 365nm ultraviolet light source at an intensity of 50mW / cm² for 5 minutes to trigger the gradient cross-linking reaction of the epoxy resin to form a primary network structure with a porosity of less than 2%; S8: placing the coating in a programmable temperature-controlled furnace, heating it to 180° C. at a rate of 10° C. / min and keeping it at that temperature for 2 hours, so that the crystallinity of the polyetheretherketone-polytetrafluoroethylene reaches 45%, and at the same time regulating the liquid metal droplets to partially melt and fill the interface defects in the range of 25-40° C.; S9: Use a 50eV argon ion beam to polish the surface at an incident angle of 45°, and then perform hydrophobic modification in a fluorine-containing atmosphere to finally obtain a superlubricating coating with a contact angle of 152°±3° and a surface roughness of less than 8nm, after which the entire superlubricating coating preparation and application method based on two-dimensional materials can be completed.

2. The method for preparing and applying a super lubricating coating based on two-dimensional materials according to claim 1, characterized in that: In the step S1, a mixed gas of argon and oxygen is introduced, the volume ratio of argon to oxygen is 4:1, the gas flow rate is controlled at 20 mL / min, and the cavity pressure is maintained at 0.1 Pa; the radio frequency power supply is turned on, the power is set to 200 W, the frequency is 13.56 MHz, and the plasma activation treatment is performed for 30 minutes; during the treatment, hydroxyl and epoxy groups are generated on the surface of the material, and the aggregation of nanosheets is suppressed by electrostatic repulsion; the temperature of the reaction chamber is controlled at 25±2° C. by a water cooling system, and the surface energy of the material after treatment is reduced to below 35 mN / m.

3. The method for preparing and applying a super lubricating coating based on two-dimensional materials according to claim 1, characterized in that: In step S2, a titanium alloy probe with a diameter of 6 mm is used, the power is set to 400 W, the frequency is set to 20 kHz, and the pulse mode is used for 15 minutes; during the treatment process, the solution temperature is maintained at 30±1°C by a circulating cooling water system, and finally a homogeneous colloid with a viscosity of 450 mPa·s is obtained, and the colloid particle size distribution D90 is less than 500 nm.

4. The method for preparing and applying a super lubricating coating based on two-dimensional materials according to claim 1, characterized in that: In the step S3, a planetary ball mill is used, equipped with a zirconia ball milling jar and zirconia grinding balls with a diameter of 3 mm, with a ball-to-material ratio of 10:1, and ball milling is performed at a speed of 300 rpm for 4 hours under nitrogen protection; during the ball milling process, the heat is dissipated by pausing for 10 minutes every 30 minutes, and the temperature in the jar does not exceed 45°C; the final slurry is tested by a rotational viscometer, and the viscosity is stable at 1200±50mPa·s at 25°C, the Zeta potential is -38mV, and the solid content is 42wt%.

5. The method for preparing and applying a super lubricating coating based on two-dimensional materials according to claim 1, characterized in that: In the step S4, the inner syringe is loaded with 10 parts by weight of gallium indium tin alloy droplets during the coaxial electrospinning process, and the outer syringe is loaded with a 15% by weight polyetheretherketone-polytetrafluoroethylene tetrahydrofuran solution; the inner and outer layer propulsion rates are set to 0.5 mL / h and 0.8 mL / h respectively, a 15 kV high voltage electric field is applied, a receiving distance of 15 cm, an ambient temperature of 25°C, and a humidity of 30% RH; the droplet formation process is monitored by high-speed photography, and the voltage waveform is adjusted to a square wave pulse to obtain core-shell fibers with a diameter of 80-120 nm; the collected fibers are vacuum dried at 60°C for 2 hours and then dispersed in the composite slurry prepared in S3 at a mass fraction of 5%.

6. The method for preparing and applying a super lubricating coating based on two-dimensional materials according to claim 1, characterized in that: In the step S5, when the slurry passes through a 200 μm wide microfluidic channel, the flow rate is controlled at 0.2 mL / min, and the nitrogen-doped carbon-coated hexagonal boron nitride is oriented along the 002 crystal plane, with an orientation degree of 92%; 10 kHz ultrasonic vibration is simultaneously applied with an amplitude of 5 μm to prevent stacking of two-dimensional material layers; the oriented slurry forms a pre-coating layer with a thickness of 20±1 μm on the surface of the substrate, with an interlayer intercalation spacing of 0.34 nm, and XRD detection shows that the half-height width of the characteristic peak is reduced by 35%.

7. The method for preparing and applying a super lubricating coating based on two-dimensional materials according to claim 1, characterized in that: In the step S6, firstly, 20 parts by weight of UV-curable epoxy resin primer is sprayed, the nozzle diameter is 0.3 mm, the spraying pressure is 0.3 MPa, and a 5 μm thick base layer is formed; then, a magnetic field-oriented composite slurry is coated, the scraper gap is set to 25 μm, the moving speed is 5 mm / s, and a 20 μm functional layer is obtained; finally, the graphene oxide quantum dot marking layer is sprayed by atomic layer deposition technology, the deposition rate is 0.1 nm / s, and the total thickness is 2 nm; the coating interval of each layer is 10 minutes, and the environmental cleanliness reaches ISO5 level.

8. The method for preparing and applying a super lubricating coating based on two-dimensional materials according to claim 1, characterized in that: In step S7, the surface temperature is monitored by an infrared thermal imager during the curing process to ensure that it does not exceed 60°C; the cross-linking degree of the epoxy resin reaches 75%, forming a three-dimensional network structure with a pore size of less than 50nm and a porosity of 1.8%; and in-situ Raman spectroscopy is used simultaneously to detect that the D / G peak intensity ratio of the fluorinated graphene is reduced from 0.85 to 0.62, indicating that the dispersion of the nanosheets is improved.

9. The method for preparing and applying a super lubricating coating based on two-dimensional materials according to claim 1, characterized in that: In the step S8, the coating is placed in a high vacuum sintering furnace with a pressure of 0.01 Pa, and the temperature is increased to 180°C at a rate of 10°C / min and kept at this temperature for 2 hours; the crystallinity of polyetheretherketone-polytetrafluoroethylene is increased from 30% to 45% by DSC detection, and the melting enthalpy reaches 42J / g; the liquid metal droplets partially melt at 40°C, and fill the interface microcracks by capillary action, with a filling depth of 8μm; gradient cooling is adopted in the cooling stage, with a cooling rate of 5°C / min from 180°C to 80°C, and then naturally cooled to room temperature, and the residual stress is less than 15MPa.

10. The method for preparing and applying a super lubricating coating based on two-dimensional materials according to claim 1, characterized in that: In the step S9, a Kaufman ion source is used, an argon gas flow rate of 10 sccm, an energy of 50 eV, a beam density of 2 mA / cm² is introduced, and the surface is polished at an incident angle of 45° for 30 minutes to remove 5 nm surface protrusions; then, in an atmosphere containing hexafluoropropylene, the pressure is 50 kPa and the temperature is 120°C for 1 hour to form a perfluorosilane self-assembled film with a thickness of 3 nm; the final coating contact angle is 152±3°, and it still maintains 148° after 500 friction tests, the surface roughness Ra is 7.6 nm, and the root mean square roughness is 8.2 nm as shown by AFM observation.

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