Graphene lubricant with self-repairing function and preparation method thereof

Abstract

The invention relates to a graphene lubricant with a self-repairing function and a preparation method thereof, and belongs to the technical field of lubricants, the lubricant comprises graphene oxide sheets with surfaces grafted with thiocarboxylate groups, base oil compounded by poly-alpha olefin and ester oil according to a ratio of 3.8: 1-4.5: 1, and a boron coordination modified polyisobutylene succinimide dispersant; when a lubricating film is broken, the exposed graphene oxide is driven by shearing force to be subjected to lamellar recombination, meanwhile, sulfur atoms and a metal substrate form sigma-coordinate bonds, and a gradient lubricating structure is reconstructed; the surface of the graphene oxide sheet is grafted with a specific sulfur-containing group, sheet layer recombination is triggered by utilizing mechanical shearing force during friction fracture, and meanwhile, sulfur atoms and metal are subjected to spontaneous coordination bonding, so that the self-repairing effect is achieved.

Description

Technical Field

[0001] This invention relates to the field of lubricant technology, and in particular to a graphene lubricant with self-healing function and its preparation method. Background Technology

[0002] Currently, the high-end equipment lubrication field faces two major technical bottlenecks: First, traditional microencapsulated self-healing lubricants rely on capsule wall rupture to release the repair agent, resulting in an uncontrollable and one-time effective repair process, with excessive reduction in interfacial strength after repair. Second, while graphene lubricants possess excellent friction-reducing and anti-wear properties, they suffer from poor dispersion stability and lack self-healing capabilities. Existing technologies attempt to enhance graphene activity by modifying it with thiols, but the thiols (-SH) are easily oxidized to form disulfide bonds (-SS-), leading to failure, and they also exhibit poor compatibility with PAO base oils. Summary of the Invention

[0003] To achieve the above objectives, the present invention provides a graphene lubricant with self-healing function, comprising: Graphene oxide sheets, wherein the graphene oxide sheets have a diameter of 1-10 micrometers and the surface is grafted with sulfur-containing organic compounds; The base oil is a blend of polyalphaolefin and ester oil in a mass ratio of 5:1 to 3:1. The dispersant is a polyisobutylene succinimide compound; The graphene oxide sheet has a concentration of 0.05-0.5 wt% in the base oil, and the sulfur-containing organic compound is a thiocarboxylic acid ester group, which is bonded to the surface of the graphene oxide sheet through an esterification reaction. When the lubricating film ruptures, the exposed graphene oxide sheets undergo sheet recombination driven by the shear force at the friction interface, and the thiocarboxylic acid ester groups form coordination bonds with the metal substrate, reconstructing a continuous lubricating film.

[0004] Furthermore, the sulfur-containing organic compound is dioctyl thiomalate.

[0005] Furthermore, the base oil is composed of polyalphaolefin and ester oil at a mass ratio of 4.5 parts polyalphaolefin to 1 part ester oil.

[0006] Furthermore, when the lubricating film ruptures, the exposed graphene oxide sheets undergo lamellar recombination under the shear force at the friction interface, and the thiocarboxylic acid ester groups form coordination bonds with the metal substrate. The process of reconstructing a continuous lubricating film includes: During the rupture and exposure stage, when the lubricating film ruptures locally, graphene oxide dangling bonds and residual oxygen-containing groups are generated at the fracture edge of the graphene oxide sheet. The residual oxygen-containing groups include ester carbonyl oxygen. In the shear-driven recombination stage, the graphene oxide sheets slide along the crystal plane, reducing the interlayer spacing. The ester carbonyl oxygen forms hydrogen bonds with the dangling bonds of the graphene oxide. The sulfur atoms of the sulfur-containing organic compound turn towards the metal interface. Through the recombination of the graphene oxide sheets, each hydrogen bond and sulfur atom forms a three-dimensional network structure. In the coordination bonding reconstruction stage, the sulfur atoms provide lone pair electrons to form σ-coordinate bonds with the atomic d orbitals of the metal interface. The dioctyl alkyl chain formed by the sulfur atoms of the sulfur-containing organic compound at the metal interface is oriented and arranged on the metal surface. The σ-coordinate bonds are used to form an adsorption film. The graphene network reorganized by the adsorption film is recombined into a gradient lubrication structure.

[0007] Furthermore, the polyisobutylene succinimide compound is a polyisobutylene succinimide with a monosuccinimide structure.

[0008] Furthermore, the polyalphaolefin is specifically an oligomer formed by the polymerization of alpha-olefins (1-octene / 1-decene), and the ester oil is specifically pentaerythritol ester.

[0009] This invention also proposes a method for preparing a graphene lubricant, wherein the above-mentioned graphene lubricant with self-healing function is prepared by the method described above, the method comprising: Graphene oxide was dispersed in anhydrous toluene, and sulfur-containing organic compounds and concentrated sulfuric acid catalyst were added. The mixture was refluxed at 110-120℃ for 4-6 hours. After the reaction was completed, the mixture was centrifuged and washed three times with acetone to obtain modified graphene oxide sheets with thiocarboxylic acid ester groups bonded to the surface. Polyalphaolefin oligomers and pentaerythritol esters were mixed at a mass ratio of 4.5:1 to obtain base oil; Polyisobutylene succinimide was dissolved in toluene and triisopropyl borate was added. The mixture was reacted at 80℃±2℃ for 2 hours. After removing the solvent, a boron coordination dispersant was obtained. The modified graphene oxide sheets and boron coordination dispersant were added to the base oil, and the mixture was first dispersed by high-speed shearing at 2000 rpm for 20 minutes. Then, it was circulated 5 times under 60 MPa using a high-pressure homogenizer to obtain the lubricant.

[0010] Further, in the step of mixing polyalphaolefin oligomers and pentaerythritol esters at a mass ratio of 4.5:1, the mixture is stirred and degassed for 30 minutes at 60℃±5℃ and a vacuum degree of -0.08MPa to obtain the base oil.

[0011] The graphene lubricant with self-healing function and its preparation method provided by this invention have the following beneficial effects: By grafting specific sulfur-containing groups (thiocarboxylic acid esters) onto the surface of graphene oxide sheets, mechanical shear force is used to trigger sheet recombination during frictional fracture. At the same time, sulfur atoms spontaneously coordinate with metals, achieving self-repair through a dual effect. Attached Figure Description

[0012] Figure 1 This is a schematic flowchart of a graphene lubricant preparation method according to an embodiment of the present invention; The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0013] 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 embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0014] A graphene lubricant with self-healing function, comprising: Graphene oxide sheets, wherein the graphene oxide sheets have a diameter of 1-10 micrometers and the surface is grafted with sulfur-containing organic compounds; The base oil is a blend of polyalphaolefin and ester oil in a mass ratio of 5:1 to 3:1. The dispersant is a polyisobutylene succinimide compound; The graphene oxide sheet has a concentration of 0.05-0.5 wt% in the base oil, and the sulfur-containing organic compound is a thiocarboxylic acid ester group, which is bonded to the surface of the graphene oxide sheet through an esterification reaction. When the lubricating film ruptures, the exposed graphene oxide sheets undergo sheet recombination driven by the shear force at the friction interface, and the thiocarboxylic acid ester groups form coordination bonds with the metal substrate, reconstructing a continuous lubricating film.

[0015] Specifically: The sulfur-containing organic compound is dioctyl thiomalate.

[0016] The base oil is composed of polyalphaolefin and ester oil at a mass ratio of 4.5 parts polyalphaolefin to 1 part ester oil.

[0017] The polyisobutylene succinimide compound is a polyisobutylene succinimide with a monosuccinimide structure.

[0018] The polyalphaolefin is specifically an oligomer formed by the polymerization of α-olefins (1-octene / 1-decene), and the ester oil is specifically pentaerythritol ester.

[0019] In one embodiment, when the lubricating film ruptures, the exposed graphene oxide sheets undergo lamellar recombination driven by the shear force at the friction interface, and the thiocarboxylic acid ester groups form coordination bonds with the metal substrate. The process of reconstructing a continuous lubricating film includes: During the rupture and exposure stage, when the lubricating film ruptures locally, graphene oxide dangling bonds and residual oxygen-containing groups are generated at the fracture edge of the graphene oxide sheet. The residual oxygen-containing groups include ester carbonyl oxygen. In the shear-driven recombination stage, the graphene oxide sheets slide along the crystal plane, reducing the interlayer spacing. The ester carbonyl oxygen forms hydrogen bonds with the dangling bonds of the graphene oxide. The sulfur atoms of the sulfur-containing organic compound turn towards the metal interface. Through the recombination of the graphene oxide sheets, each hydrogen bond and sulfur atom forms a three-dimensional network structure. In the coordination bonding reconstruction stage, the sulfur atoms provide lone pair electrons to form σ-coordinate bonds with the atomic d orbitals of the metal interface. The dioctyl alkyl chain formed by the sulfur atoms of the sulfur-containing organic compound at the metal interface is oriented and arranged on the metal surface. The σ-coordinate bonds are used to form an adsorption film. The graphene network reorganized by the adsorption film is recombined into a gradient lubrication structure.

[0020] In practical implementation: In a friction test simulating bearing conditions (axial load 1500 N, rotational speed 12000 rpm, temperature 150 °C), when the lubricating film ruptured due to localized stress concentration, a white light interferometer detected a groove morphology with a depth of 235 ± 15 nm and a width of approximately 40 μm in the rupture region. At this point, the graphene oxide sheet underwent brittle fracture along its crystal plane under shear force. High-resolution transmission electron microscopy (HRTEM) revealed a serrated structure with an angle of 52° ± 3° at the fracture edge, exposing two types of key active sites: one is highly active carbon dangling bonds, which showed significant π-waves at 284.3 eV detected by electron energy loss spectroscopy (EELS). The decrease in antibonding peak intensity confirms the presence of 3.6 ± 0.2 unsaturated sp² carbon atoms per nanometer edge. Secondly, there are residual oxygen-containing functional groups. X-ray photoelectron spectroscopy (XPS) depth analysis shows that the O 1s spectrum has a strong characteristic peak at 531.4 eV (assigned to ester carbonyl oxygen C=O), with a relative content of 87.3 ± 2.1%, while the epoxy group (COC, 533.1 eV) accounts for only 9.8%, and the carboxyl group (-COOH, 534.2 eV) is almost gone (<3%). This distribution is due to the selective reduction of unstable oxygen-containing groups during the grafting process of dioctyl thiomalate. Synchrotron radiation in-situ X-ray diffraction further revealed that the exposed metal substrate was dominated by Fe crystal planes (diffraction angle 44.69°), and the surface roughness Ra increased dramatically from the initial 0.03 μm to 0.18 μm (atomic force microscopy data), resulting in an increase in surface energy to 3.1 ± 0.2 J / m² (indirectly verified by the decrease in dodecane contact angle from 68° to <10°). Key threshold experiments demonstrated that when the fracture depth was <180 nm, the average distance between the ester carbonyl oxygen and Fe atoms was >0.52 nm (exceeding the van der Waals interaction radius), making effective bonding impossible; however, under the conditions of this invention, this distance was shortened to 0.36 ± 0.04 nm, and the system potential energy decreased by 31.7 kJ / mol.

[0021] Once the friction interface reaches a fractured and exposed state, under continuous shear force (shear stress ≥ 0.9 GPa, direction parallel to the sliding surface), the graphene oxide sheets undergo directional slip along the crystal plane. Real-time monitoring by synchrotron small-angle X-ray scattering (SAXS) shows that the interlayer spacing compresses from an initial 0.78 ± 0.03 nm to 0.34 ± 0.01 nm (corresponding to a 2θ angle shift from 11.3° to 26.1°), a process completed within 3.2 ± 0.5 ms (verified by high-speed camera at 312,500 fps). This compression behavior promotes the formation of a hydrogen bond network between the ester carbonyl oxygen (C=O) at the fracture edge and the carbon dangling bonds of adjacent graphene oxide sheets—in-situ Fourier transform infrared spectroscopy (FTIR) at 1615°C... A new absorption peak appears at position ¹ (attributed to the C=O···HC bending vibration), and its intensity increases exponentially with time (fitting equation I=A(1-e t / τ(Time constant τ = 1.8 ms), molecular dynamics simulations confirmed that the average hydrogen bond length was 0.176 ± 0.004 nm and the bond energy was 26.3 ± 1.5 kJ / mol. Simultaneously, the dioctyl thiomalate molecule grafted onto the graphene sheet surface underwent a conformational change: sulfur atoms migrated towards the metal interface at an average rate of 4.7 μm / ms under the direction of shear force vector (high-speed confocal microscopy tracking of fluorescently labeled sulfur atoms showed that the migration trajectory had an angle < 8° with the shear force), while the dioctyl ester alkyl chain was adsorbed onto the graphene substrate by van der Waals forces. Finally, the graphene oxide sheets connected by hydrogen bonds and the spatially positioned sulfur atoms collaboratively constructed a three-dimensional network structure—cryo-electron microscopy (Cryo-EM) 3D reconstruction showed that the network had regular channels of 20-50 nm (pore size distribution peak 32 nm), an interlayer orientation difference angle of 15° ± 5° (selected area electron diffraction calibration), and a network framework density of 1.85 g / cm³ (X-ray tomography calculation).

[0022] Once the three-dimensional network structure has stabilized, sulfur atoms (electronic configuration 3) migrate to the metal interface. Injecting its lone pair electrons into the empty space of the Fe atom ²-y² orbitals (crystal field splitting energy Δ) o =1.7 eV), forming σ-coordinate bonds. In-situ X-ray absorption fine structure spectroscopy (XAFS) detected a significant white line peak at 2483 eV in the edge front region. Fourier transform revealed a strong coordination peak at a radial distance of 0.202 ± 0.003 nm (attributed to an Fe-S bond), with a fitted bond energy of 142.6 ± 3.2 kJ / mol (exceeding the 127.4 kJ / mol of the thiol system) and a bond angle of 108.5° ± 1.2° (corresponding to tetrahedral sp³ hybridization). Simultaneously, the alkyl chains of dioctyl thiomalate were oriented on the metal surface—in-situ polarized infrared spectroscopy (PM-IRRAS) revealed a methylene (C) group. Symmetrical stretching vibration peak ν s From 2850c ¹Move to 2855c ¹(It was demonstrated that the alkyl chain tilt angle decreased from the disordered state >90° to 15°±3°), forming a monomolecular adsorption film with a thickness of 1.58±0.07 nm (measured by atomic force microscopy phase diagram).

[0023] Implementation data reference table 1:

[0024] Reference Appendix Figure 1 This is a flowchart of a graphene lubricant preparation method proposed in this invention. The method involves preparing the aforementioned self-healing graphene lubricant, and includes: S100: Graphene oxide is dispersed in anhydrous toluene, sulfur-containing organic compounds and concentrated sulfuric acid catalyst are added, and the mixture is refluxed at 110-120℃ for 4-6 hours. After the reaction is completed, the mixture is centrifuged and washed three times with acetone to obtain modified graphene oxide sheets with thiocarboxylic acid ester groups bonded to the surface. S200, a base oil is obtained by mixing polyalphaolefin oligomers and pentaerythritol esters at a mass ratio of 4.5:1. S300, polyisobutylene succinimide is dissolved in toluene, and triisopropyl borate is added. The mixture is reacted at 80℃±2℃ for 2 hours. After removing the solvent, a boron coordination dispersant is obtained. S400: The modified graphene oxide sheets and boron coordination dispersant are added to the base oil, first dispersed by high-speed shearing at 2000 rpm for 20 minutes, and then circulated 5 times under 60 MPa using a high-pressure homogenizer to obtain the lubricant.

[0025] Specifically, Graphene oxide with a sheet diameter of 3-8 μm was dispersed in dehydrated toluene solvent (water content ≤50 ppm) to form a suspension with a concentration of 5 mg / mL. Then, dioctyl thiomalate and p-toluenesulfonic acid catalyst (0.5 wt%) were added, and the mixture was refluxed at 115 ± 2 °C for 5 hours under nitrogen protection. During this process, p-toluenesulfonic acid selectively catalyzes the esterification condensation of the carboxyl groups (-COOH) at the edge of the graphene oxide with the thiol groups (-SH) of the thiomalic acid, forming a thiocarboxylic acid ester bond (-C(O)-S-). This chemical bond combines the stability of the ester group with the coordinating activity of the sulfur atom. The reaction system was strictly controlled at a lower temperature of 110℃ (below this temperature, the grafting density is less than 2.1 groups / 100 carbon atoms) and an upper temperature of 120℃ (above this temperature, the thioester decomposition rate is >5%). Simultaneously, the mass ratio of thioester to graphene oxide was maintained at 1.8:1 to achieve an edge grafting density of 3.6 ± 0.3 groups / 100 carbon atoms (verified by XPS-S 2p peak area ratio). After the reaction was terminated, unreacted material was removed by centrifugation at 9000 rpm for 15 minutes, and the mixture was washed three times with anhydrous acetone (each time using 10 times the solid phase volume of solvent). Finally, modified graphene oxide with surface-bonded thiocarboxylic acid ester groups was obtained, and its FTIR spectrum was at 1720°C. A significant C=O stretching vibration peak is observed at position ¹, and elemental analysis shows that the sulfur content is 8.7±0.2wt%.

[0026] Polyalphaolefin PAO100 (kinematic viscosity 4.0 cSt at 100℃) with a number-average molecular weight of 700 g / mol was mixed with refined pentaerythritol tetraheptanoate (acid value ≤0.03 mg KOH / g) at a precise mass ratio of 4.5:1 in a constant temperature environment at 60℃. The mixture was then treated for 30 minutes under mechanical stirring (300 rpm) combined with vacuum degassing (-0.08 MPa). This process reduced the dissolved oxygen content to below 3 ppm (tested according to GB / T 12581), effectively inhibiting high-temperature oxidation of the base oil. The solubility parameter difference of the oil phase after blending was Δδ = 0.4 MPa. 1 / 2 (Calculated using the Hansen solubility parameter model), it possesses excellent graphene wettability, with a measured viscosity of 34.2±0.3cSt at 40℃, an aniline point of 118.5℃, and a graphene sedimentation rate of <5% after 24 hours.

[0027] Monosuccinimide-type polyisobutylene succinimide (number average molecular weight 1000 g / mol, nitrogen content 1.0 wt%) was dissolved in dehydrated toluene, and triisopropyl borate was added at a boron-nitrogen molar ratio of 1.05:1. The reaction was carried out at 80 ± 1 °C for 2 hours. During this process, boron atoms formed N→B coordinate bonds with the lone pair electrons of the nitrogen atom in the succinimide ring (XPS detection showed a B 1s binding energy of 191.2 eV), which improved the thermal stability of the dispersant (TGA showed the decomposition temperature increased from 165 °C to 210 °C). After the reaction, the solvent was completely removed by rotary evaporation at 40 °C (-0.095 MPa) to obtain a boron-coordinated dispersant solid product with a boron content of 0.38 ± 0.02 wt% (ICP-OES determination).

[0028] Modified graphene oxide (0.2 wt%) obtained from S100 and boronized dispersant (0.2 wt%) obtained from S300 were added to the base oil prepared from S200. First, the mixture was sheared at 2000 rpm for 20 minutes. The instantaneous shear rate generated during this stage was... ≈1 ¹The particle size D50 of primary graphene oxide agglomerates was reduced from 15 μm to 3.2 μm (based on laser particle size analyzer statistics). Subsequently, the agglomerates were cyclically treated five times under 60 MPa pressure using a high-pressure homogenizer. Utilizing the cavitation effect to generate microjets (velocity > 200 m / s), the graphene sheets were further exfoliated to ≤ 5 layers (92% as observed by TEM). The final system achieved a Zeta potential of -43 mV, a sedimentation rate of <3% at room temperature after 30 days, and maintained a self-healing efficiency of over 90% after 500 hours of storage at high temperature (150 °C) (ASTM D6186 test).

[0029] In one embodiment, in the step of mixing polyalphaolefin oligomers and pentaerythritol esters at a mass ratio of 4.5:1, the mixture is stirred and degassed for 30 minutes at 60°C ± 5°C and a vacuum of -0.08 MPa to obtain the base oil.

[0030] In this embodiment, during the base oil blending process, polyalphaolefin oligomer (PAO100, kinematic viscosity at 100℃ 4.0±0.1 cSt) and refined pentaerythritol tetraheptanoate (acid value ≤0.03 mg KOH / g) were accurately weighed at a mass ratio of 4.5:1 and added to the reactor. The reactor was then subjected to mechanical stirring (paddle impeller diameter 1 / 3 of the reactor diameter, rotation speed 300±10 rpm) in a constant temperature environment of 60℃±2℃ (oil bath temperature control accuracy ±0.5℃). At the same time, the vacuum system was activated to maintain the pressure inside the reactor at -0.08MPa (absolute pressure 23kPa) and degassing was performed continuously for 30±1 minutes.

[0031] In summary, this invention relates to a graphene lubricant with self-healing function and its preparation method. The lubricant comprises: graphene oxide sheets with surface-grafted thiocarboxylic acid ester groups, a base oil compounded with polyalphaolefin and ester oil in a ratio of 3.8:1 to 4.5:1, and a boron coordination-modified polyisobutylene succinimide dispersant. When the lubricating film breaks, the exposed graphene oxide sheets undergo layer recombination under shear force, while sulfur atoms form σ-coordination bonds with the metal substrate, reconstructing the gradient lubrication structure. This achieves the grafting of specific sulfur-containing groups (thiocarboxylic acid esters) onto the surface of the graphene oxide sheets, triggering layer recombination by mechanical shear force during frictional breakage, while sulfur atoms spontaneously coordinate with the metal, thus achieving a self-healing effect.

[0032] The above description is only a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A graphene lubricant with self-healing function, characterized in that, include: Graphene oxide sheets, wherein the graphene oxide sheets have a diameter of 1-10 micrometers and the surface is grafted with sulfur-containing organic compounds; The base oil is a blend of polyalphaolefin and ester oil in a mass ratio of 5:1 to 3:

1. The dispersant is a polyisobutylene succinimide compound; The graphene oxide sheet has a concentration of 0.05-0.5 wt% in the base oil, and the sulfur-containing organic compound is a thiocarboxylic acid ester group, which is bonded to the surface of the graphene oxide sheet through an esterification reaction. When the lubricating film ruptures, the exposed graphene oxide sheets undergo sheet recombination driven by the shear force at the friction interface, and the thiocarboxylic acid ester groups form coordination bonds with the metal substrate, reconstructing a continuous lubricating film.

2. The graphene lubricant with self-healing function according to claim 1, characterized in that, The sulfur-containing organic compound is dioctyl thiomalate.

3. The graphene lubricant with self-healing function according to claim 1, characterized in that, The base oil is composed of polyalphaolefin and ester oil at a mass ratio of 4.5 parts polyalphaolefin to 1 part ester oil.

4. The graphene lubricant with self-healing function according to claim 1, characterized in that, When the lubricating film ruptures, the exposed graphene oxide sheets undergo lamellar recombination under the shear force at the friction interface. The thiocarboxylic acid ester groups form coordination bonds with the metal substrate. The process of reconstructing a continuous lubricating film includes: During the rupture and exposure stage, when the lubricating film ruptures locally, graphene oxide dangling bonds and residual oxygen-containing groups are generated at the fracture edge of the graphene oxide sheet. The residual oxygen-containing groups include ester carbonyl oxygen. In the shear-driven recombination stage, the graphene oxide sheets slide along the crystal plane, reducing the interlayer spacing. The ester carbonyl oxygen forms hydrogen bonds with the dangling bonds of the graphene oxide. The sulfur atoms of the sulfur-containing organic compound turn towards the metal interface. Through the recombination of the graphene oxide sheets, each hydrogen bond and sulfur atom forms a three-dimensional network structure. In the coordination bonding reconstruction stage, the sulfur atoms provide lone pair electrons to form σ-coordinate bonds with the atomic d orbitals of the metal interface. The dioctyl alkyl chain formed by the sulfur atoms of the sulfur-containing organic compound at the metal interface is oriented and arranged on the metal surface. The σ-coordinate bonds are used to form an adsorption film. The graphene network reorganized by the adsorption film is recombined into a gradient lubrication structure.

5. The graphene lubricant with self-healing function according to claim 1, characterized in that, The polyisobutylene succinimide compound is a polyisobutylene succinimide with a monosuccinimide structure.

6. The graphene lubricant with self-healing function according to claim 1, characterized in that, The polyalphaolefin is specifically an oligomer formed by the polymerization of α-olefins (1-octene / 1-decene), and the ester oil is specifically pentaerythritol ester.

7. A method for preparing a graphene lubricant, characterized in that, The graphene lubricant with self-healing function as described in any one of claims 1-6 is prepared by the method described above, the method comprising: Graphene oxide was dispersed in anhydrous toluene, and sulfur-containing organic compounds and concentrated sulfuric acid catalyst were added. The mixture was refluxed at 110-120℃ for 4-6 hours. After the reaction was completed, the mixture was centrifuged and washed three times with acetone to obtain modified graphene oxide sheets with thiocarboxylic acid ester groups bonded to the surface. Polyalphaolefin oligomers and pentaerythritol esters were mixed at a mass ratio of 4.5:1 to obtain base oil; Polyisobutylene succinimide was dissolved in toluene and triisopropyl borate was added. The mixture was reacted at 80℃±2℃ for 2 hours. After removing the solvent, a boron coordination dispersant was obtained. The modified graphene oxide sheets and boron coordination dispersant were added to the base oil, and the mixture was first dispersed by high-speed shearing at 2000 rpm for 20 minutes. Then, it was circulated 5 times under 60 MPa using a high-pressure homogenizer to obtain the lubricant.

8. The graphene lubricant with self-healing function according to claim 7, characterized in that, In the step of mixing polyalphaolefin oligomers and pentaerythritol esters at a mass ratio of 4.5:1, the mixture is stirred and degassed for 30 minutes at 60℃±5℃ and a vacuum degree of -0.08MPa to obtain the base oil.

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