Modified fluorinated graphene, preparation method, application and modified fluorinated graphene-based lubricating oil

Abstract

This invention relates to the field of lubricating oil technology, specifically to a modified fluorinated graphene, its preparation method, its application, and a modified fluorinated graphene-based lubricating oil. The modified fluorinated graphene is obtained by modifying fluorinated graphene with a modifier solution; the modifier is selected from at least one of ODA, PVDF, and PIB. This invention also provides a method for preparing modified fluorinated graphene, comprising the following steps: mixing and reacting fluorinated graphene with a modifier solution to obtain modified fluorinated graphene. This invention also provides an application of modified fluorinated graphene in lubricating oils. This invention further provides a modified fluorinated graphene-based lubricating oil, comprising a base oil and the modified fluorinated graphene obtained by the aforementioned preparation method; the base oil is selected from pentaerythritol esters. This invention solves the problems of poor dispersibility and easy agglomeration and sedimentation of existing fluorinated graphene.

Description

Technical Field

[0001] This invention relates to the field of lubricating oil technology, specifically to a modified fluorinated graphene, its preparation method, its application, and a modified fluorinated graphene-based lubricating oil. Background Technology

[0002] Friction and wear are major factors contributing to global energy consumption and mechanical system failure. Statistics show that approximately 30-50% of primary energy consumption worldwide is lost due to friction, and wear accounts for about 70-80% of mechanical part failures in industrial sectors. This not only causes significant economic losses but also exacerbates energy waste and environmental pollution. Therefore, effective lubrication is a core means to reduce energy loss from friction pairs and improve the performance of mechanical systems. The use of high-performance lubricating media typically lowers the coefficient of friction, reducing energy consumption from friction pairs and effectively improving the working performance of mechanical systems. Practice has shown that using a rationally optimized lubrication scheme can save 5-10% on diesel engine fuel consumption and over 7% on hydraulic systems. Furthermore, the combined application of high-performance lubricating media and nano-additives can further extend equipment lifespan by 20-30%.

[0003] The core of lubricating oil lies in its lubricating additives, often referred to as the "chip" of lubricating oil. With the development of science and technology, equipment is constantly being upgraded, but the resulting operating conditions are becoming increasingly demanding, placing higher requirements on the extreme pressure anti-wear properties, chemical stability, and reliability of lubricating oils. Fluorinated graphene, due to its excellent chemical stability, extreme pressure lubrication, and anti-wear properties, can be added as an additive to lubricating oils to prepare fluorinated graphene-based lubricating oils, significantly improving the combat and technical performance of equipment and contributing to high reliability and long service life. However, fluorinated graphene exhibits poor dispersibility in base oils and is prone to agglomeration and sedimentation, which to some extent severely hinders its engineering application in the lubrication field. Therefore, there is an urgent need to develop a new type of modified fluorinated graphene to promote its application in high-end equipment lubrication systems. Summary of the Invention

[0004] In view of this, the purpose of this invention is to provide a modified fluorinated graphene, its preparation method, its application, and a modified fluorinated graphene-based lubricating oil, so as to solve the problems of poor dispersibility and easy agglomeration and sedimentation of existing fluorinated graphene.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A modified fluorinated graphene is obtained by modifying fluorinated graphene with a modifier solution. The modifier is selected from at least one of octadecylamine (ODA), polyvinylidene fluoride (PVDF), polyisobutylene (PIB), and 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6).

[0006] Based on the above technical means, by using at least one of ODA (octadecylamine), PVDF (polyvinylidene fluoride), PIB (polyisobutylene), and [BMIM]PF6 (butyltrimethylhexafluorophosphate) to perform surface grafting modification and ionic liquid modification on fluorinated graphene, the problems of poor dispersibility and easy aggregation and sedimentation of existing fluorinated graphene are fundamentally solved through molecular structure design and multi-scale synergistic mechanism.

[0007] Among them, octadecylamine (ODA) undergoes a chemical grafting reaction with the residual oxygen-containing functional groups on the surface of fluorinated graphene through an amino group, and its long-chain alkyl groups form a steric barrier to generate a steric hindrance effect, thereby improving dispersion stability; polyvinylidene fluoride (PVDF) relies on the strong similarity and compatibility between the main chain fluorine atoms and the CF bonds of fluorinated graphene to achieve physical coating through hydrophobic-hydrophobic interactions and π-π stacking, which not only enhances the interfacial bonding force but also blocks the interlayer van der Waals forces, thereby improving dispersion stability; polyisobutylene (PIB) is adsorbed on the surface in a flexible long-chain entanglement manner, and the entropy repulsion effect of the polymer chain significantly expands the interlayer spacing, thereby improving dispersion stability; the ionic liquid [BMIM]PF6 is anchored to the negatively charged region of fluorinated graphene through the electrostatic interaction of imidazole cations, and its hexafluorophosphate anions generate specific fluorine-fluorine recognition with the surface fluorine atoms, while forming an electric double layer in the solvent to provide electrostatic repulsion, thereby improving dispersion stability.

[0008] This invention also provides a method for preparing modified fluorinated graphene as described herein, comprising the following steps: Modified fluorinated graphene is obtained by mixing and reacting fluorinated graphene with a modifier solution.

[0009] Efficient modification is achieved through solution-phase molecular-level assembly. The modifier is formulated into a solution, allowing its molecules to pre-dissociate and uniformly disperse in the solvent. Driven by concentration gradients and Brownian motion, it achieves sufficient contact with the modified fluorinated graphene. The liquid environment significantly reduces molecular diffusion resistance, enabling the functional groups of the modifier to migrate directionally to defect sites or high-energy regions on the surface of the modified fluorinated graphene. In-situ grafting and self-assembly occur simultaneously through chemical bonding or physical adsorption, with reaction kinetics significantly superior to solid-phase mixing. Solvent molecules act as "temporary spacers," intercalating into the interlayer spaces of the modified fluorinated graphene sheets, effectively pre-expanding the interlayer spacing and creating access channels for the modifier molecules. Simultaneously, the fluid properties of the solution system facilitate real-time control of key parameters such as reaction temperature, concentration, and pH, achieving precise control over modification density and graft chain length. The method thermodynamically avoids high-temperature and high-pressure conditions, preserving the intrinsic structure of fluorinated graphene to the greatest extent. Furthermore, the process is simple, energy-efficient, and easily scaled up, possessing the triple advantages of uniform reaction, mild conditions, and industrial feasibility.

[0010] Preferably, when the modifier is selected from 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) or polyisobutylene (PIB), the following steps are included: Fluorinated graphene was added to an organic solvent to obtain a fluorinated graphene dispersion. 1-Butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) is dissolved in an organic solvent to obtain a modifier solution; or, polyisobutylene (PIB) and azobisisobutyronitrile (AIBN) are dissolved in an organic solvent to obtain a modifier solution. The modifier solution was added to the fluorinated graphene dispersion, and the mixture was heated and stirred to react, resulting in modified fluorinated graphene (FG-[BMIM]PF6) or modified fluorinated graphene (FG-PIB).

[0011] By pre-dispersing modified fluorinated graphene, solvation can be used to exfoliate aggregates and expand interlayer spacing, exposing more active edges and defect sites, creating "molecular channels" for subsequent modifier incorporation. Pre-dissolving the modifier ensures that its molecules / ions are uniformly dissociated in the solvent and reach a uniform concentration, avoiding localized concentration inconsistencies in direct solid-solid mixing. Using a solution dropwise addition method can establish a controllable concentration gradient, allowing modifier molecules to migrate directionally to the surface of fluorinated graphene under the drive of concentration difference, achieving layer-by-layer adsorption and orderly assembly. Heating and stirring provide molecular thermal energy, significantly reducing the reaction activation energy and enhancing the collision frequency and orientation matching probability between the modifier and the matrix. This is particularly crucial for the PIB system, activating the AIBN initiator to generate free radicals and inducing surface grafting reactions. This process simultaneously completes efficient mass transfer, controllable reaction, and uniform coating in a liquid-phase reaction field, ensuring both modifier utilization and grafting density, and achieving green recycling through solvent recovery.

[0012] Preferably, the heating reaction is carried out at a temperature of 40°C to 70°C for 4 hours to 6 hours.

[0013] Preferably, the heating reaction is carried out at a temperature of 60°C for 6 hours.

[0014] Preferably, the mass ratio of the fluorinated graphene to the 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) is 3~7:1, or the mass ratio of the fluorinated graphene, polyisobutylene (PIB) and azobisisobutyronitrile (AIBN) is 8~12:8~12:3.

[0015] Preferably, the mass ratio of the fluorinated graphene to the 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) is 4:1, or the mass ratio of the fluorinated graphene, polyisobutylene (PIB), and azobisisobutyronitrile (AIBN) is 10:10:3.

[0016] Preferably, the organic solvent is selected from one or both of N,N-dimethylformamide (DMF) and N,N-diethylformamide (DEF).

[0017] Preferably, the organic solvent is selected from N,N-dimethylformamide (DMF).

[0018] Preferably, after the heating and stirring reaction, the process further includes: centrifugation, collection of the precipitate, washing, and vacuum drying to obtain the modified fluorinated graphene FG-[BMIM]PF6 or modified fluorinated graphene FG-PIB.

[0019] Preferably, when the modifier is selected from octadecylamine (ODA), the following steps are included: Octadecylamine (ODA) is added to an organic mixed solvent to obtain a modifier solution; Fluorinated graphene was added to a modifier solution and subjected to ultrasonic treatment to obtain modified fluorinated graphene FG-ODA.

[0020] Efficient grafting modification is achieved through the synergistic effect of solvent system optimization and ultrasonic field enhancement: the use of organic mixed solvents allows for precise control of the system's polarity and solubility parameters, enabling the octadecylamine molecular chains to fully extend and the amino functional groups to be fully activated, forming a stable homogeneous solution and avoiding local concentration unevenness; adding fluorinated graphene to the ODA solution, rather than the reverse order, allows the amino molecules to immediately surround and "occupy" the graphene sheet surface, effectively suppressing its own aggregation tendency through the "first-mover advantage" occupancy effect; the cavitation effect introduced by ultrasonic treatment generates microjets and shock waves that can strongly strip the interlayer stacking of fluorinated graphene, significantly increasing the specific surface area and exposing edge defect sites. At the same time, ultrasonic energy reduces the reaction activation energy of amino groups and oxygen-containing functional groups on the surface, accelerating chemical grafting kinetics and achieving simultaneous completion of molecular-level dispersion and surface modification. Finally, a dense and regularly oriented octadecyl steric barrier layer is constructed on the surface of fluorinated graphene, giving it excellent solvation stabilization ability.

[0021] Preferably, the ultrasonic treatment is performed at room temperature for 30 to 60 minutes.

[0022] Preferably, the ultrasonic treatment time is 40 minutes.

[0023] Preferably, the mass ratio of the fluorinated graphene to the octadecylamine is 2~5:1.

[0024] Preferably, the mass ratio of the fluorinated graphene to the octadecylamine (ODA) is 2:1.

[0025] Preferably, the organic mixed solvent is selected from a mixture of N,N-dimethylformamide (DMF) and tetrahydrofuran.

[0026] Preferably, after the ultrasonic treatment, the process further includes: centrifugation, collection of the precipitate, and vacuum drying to obtain the modified fluorinated graphene FG-ODA.

[0027] Preferably, when the modifier is selected from polyvinylidene fluoride (PVDF), the following steps are included: Polyvinylidene fluoride (PVDF) is added to an organic solvent to obtain a modified solution; The modified solution was added to fluorinated graphene and subjected to ultrasonic treatment to obtain an intermediate. The intermediate was heat-treated to obtain modified fluorinated graphene FG-PVDF.

[0028] Through a three-step synergistic mechanism of "solution pre-assembly - ultrasonic strengthening - heat treatment curing", PVDF achieves specific coating of fluorinated graphene. The CF bonds rich in the PVDF backbone generate a "fluorine-fluorine recognition" effect with fluorine atoms on the surface of fluorinated graphene. Based on the principle of similar compatibility, it spontaneously undergoes molecular-level selective adsorption in solution. The dipole moment of its β-crystal chain segments can form strong π-π stacking and van der Waals interactions with the graphene sheets. The cavitation microjets generated by ultrasonic treatment not only peel off the stacked sheets and increase the specific surface area, but more importantly, they provide energy to promote the transformation of PVDF molecular chains from random coils to an extended conformation on the surface of fluorinated graphene, achieving molecular rearrangement and tight adhesion. The subsequent heat treatment removes residual solvent and induces partial crystallization of PVDF, forming a stable, dense, and continuous physical coating layer on the surface of fluorinated graphene. At the same time, the heat energy promotes chain segment movement, further filling surface micro-defects and enhancing the interfacial bonding strength. Finally, a strong interaction network of "fluorine affinity" is constructed, which both prevents sheet aggregation and retains the intrinsic properties of fluorinated graphene.

[0029] Preferably, the ultrasonic treatment is performed at room temperature for 40 minutes.

[0030] Preferably, the mass ratio of the fluorinated graphene to the polyvinylidene fluoride is 2~5:1.

[0031] Preferably, the mass ratio of the fluorinated graphene to the polyvinylidene fluoride (PVDF) is 2:1.

[0032] Preferably, the heat treatment temperature is 150℃~300℃ and the time is 45min~75min.

[0033] Preferably, the heat treatment is performed at a temperature of 200°C for 1 hour.

[0034] Preferably, the organic solvent is selected from N,N-dimethylformamide (DMF).

[0035] Preferably, after ultrasonic treatment, the process further includes: centrifugation, collection of the precipitate, and vacuum drying to obtain the intermediate; Preferably, after the heat treatment, the process further includes washing and vacuum drying to obtain the modified fluorinated graphene FG-PVDF.

[0036] The present invention also provides an application of the modified fluorinated graphene prepared by the preparation method of the present invention in lubricating oil.

[0037] The present invention also provides a modified fluorinated graphene-based lubricating oil, comprising a base oil and modified fluorinated graphene obtained by the preparation method; wherein the base oil is selected from pentaerythritol ester.

[0038] By forming hydrogen bonds and dipole interactions between the polar ester groups of pentaerythritol ester base oil and the amine groups, ionic liquids, or polymer segments grafted onto the surface of modified fluorinated graphene, a stable "anchoring-solventization" structure is constructed. This ensures that the nanoparticles achieve thermodynamic compatibility and long-term kinetic dispersion in the oil phase, avoiding agglomeration and sedimentation. During friction, the layered structure of modified fluorinated graphene is directionally adsorbed and spread on the metal surface under the synergistic effect of pentaerythritol ester molecular chains. Its fluorine atoms undergo micro-regional chemical reactions with the matrix to generate a low-shear-strength FeF2 / FeF3 ceramic film, which couples with the inherent physical adsorption film of ester oil to form a "chemical-physical composite lubricating film." At the same time, the nanosheets exert a "ball bearing" effect to transform sliding friction into rolling friction. The high viscosity index of pentaerythritol ester ensures the stability of the lubricating film thickness over a wide temperature range. Ultimately, this synergistic effect achieves a superposition of four functions: anti-wear and friction reduction, extreme pressure bearing capacity, self-repair, and long-term stability. This gives the lubrication system the super-lubricating properties of nano-additives and the comprehensive performance advantages of ester synthetic oils.

[0039] The beneficial effects of this invention are: The modified fluorinated graphene of the present invention uses at least one of ODA (octadecylamine), PVDF (polyvinylidene fluoride), PIB (polyisobutylene), and [BMIM]PF6 (butyltrimethylhexafluorophosphate) to perform surface grafting modification and ionic liquid modification on fluorinated graphene. Through molecular structure design and multi-scale synergistic mechanism, the dispersion stability of fluorinated graphene is effectively improved, solving the problems of poor dispersibility and easy agglomeration and sedimentation of existing fluorinated graphene.

[0040] The method for preparing modified fluorinated graphene of this invention achieves efficient modification through solution-phase molecular-level assembly. The modifier is formulated into a solution, allowing its molecules to pre-dissociate and uniformly disperse in the solvent. Sufficient contact with the modified fluorinated graphene is achieved through concentration gradient and Brownian motion. The liquid environment significantly reduces molecular diffusion resistance, enabling the functional groups of the modifier to migrate directionally to defect sites or high-energy regions on the surface of the modified fluorinated graphene. In-situ grafting and self-assembly occur simultaneously through chemical bonding or physical adsorption, resulting in reaction kinetics significantly superior to solid-phase mixing. Solvent molecules act as "temporary spacers," intercalating into the interlayer spaces of the modified fluorinated graphene, effectively pre-expanding the interlayer spacing and creating access channels for the modifier molecules. Simultaneously, the fluid characteristics of the solution system facilitate real-time control of key parameters such as reaction temperature, concentration, and pH, achieving precise control over the modification density and graft chain length. The method thermodynamically avoids high-temperature and high-pressure conditions, preserving the intrinsic structure of the fluorinated graphene to the greatest extent. Furthermore, the process is simple, energy-efficient, and easily scaled up, possessing the triple advantages of uniform reaction, mild conditions, and industrial feasibility. The modified fluorinated graphene-based lubricating oil of this invention utilizes hydrogen bonds and dipole interactions formed between the polar ester groups of the pentaerythritol ester base oil and the amine groups, ionic liquids, or polymer segments grafted onto the surface of the modified fluorinated graphene. This constructs an "anchoring-solventization" stable structure, ensuring thermodynamic compatibility and long-term kinetic dispersion of nanoparticles in the oil phase, thus preventing agglomeration and sedimentation. During friction, the layered structure of the modified fluorinated graphene is directionally adsorbed and spread on the metal surface under the synergistic effect of the pentaerythritol ester molecular chains, and its fluorine atoms undergo micro-interaction with the matrix. A chemical reaction generates a low-shear-strength FeF2 / FeF3 ceramic film, which couples with the inherent physical adsorption film of ester oils to form a "chemical-physical composite lubricating film." Simultaneously, the nanosheets exert a "ball bearing" effect, converting sliding friction into rolling friction. The high viscosity index of pentaerythritol ester ensures stable lubricating film thickness across a wide temperature range. Ultimately, this synergistic process achieves a four-fold superposition of anti-wear and friction reduction, extreme pressure bearing capacity, self-repair, and long-term stability, giving the lubrication system both the super-lubricating properties of nano-additives and the comprehensive performance advantages of ester synthetic oils. This technology has significant potential for widespread application in the field of lubricant technology. Attached Figure Description

[0041] Figure 1 This is a photograph of the modified fluorinated graphene powder FG-[BMIM]PF6 prepared in Example 1; Figure 2 A photograph of the pentaerythritol ester base oil used in Example 5; Figure 3 The images are SEM images, where (a) is the SEM image of FG before modification, (b) is the SEM image of FG-ODA, (c) is the SEM image of FG-PVDF, (d) is the SEM image of FG-PIB, and (e) is the SEM image of FG-[BMIM]PF6. Figure 4 This is an FT-IR spectrum; Figure 5 AFM test image of FG before modification; Figure 6 AFM test chart for FG-ODA; Figure 7 AFM test pattern for FG-PVDF; Figure 8 AFM test chart for FG-PIB; Figure 9 AFM test diagram for FG-[BMIM]PF6; Figure 10 XPS full spectra of FG, FG-ODA, FG-PIB, FG-PVDF and FG-[BMIM]PF6 before modification; Figure 11 XPS fine spectra of the C1s orbitals of FG, FG-ODA, FG-PIB, FG-PVDF and FG-[BMIM]PF6 before modification; Figure 12 XPS fine spectra of the O1s orbitals of FG, FG-ODA, FG-PIB, FG-PVDF and FG-[BMIM]PF6 before modification; Figure 13 XPS fine spectra of the F1s orbitals of FG, FG-ODA, FG-PIB, FG-PVDF and FG-[BMIM]PF6 before modification; Figure 14 XPS fine spectra of the N1s orbitals of FG, FG-ODA, FG-PIB, FG-PVDF and FG-[BMIM]PF6 before modification; Figure 15 The figures show a comparison of the dispersion of novel lubricating oils with different contents of modified fluorinated graphene at different time periods. (a) shows the dispersion after ultrasonic dispersion, (b) after standing for 72 hours, (c) after standing for 168 hours, and (d) after standing for 720 hours. Figure 16 The graph shows the real-time friction coefficient results of novel lubricating oils with different contents of modified fluorinated graphene. Figure 17 The average friction coefficient results for novel lubricating oils with different contents of modified fluorinated graphene are shown in the figure. Figure 18 The surface morphology of the steel ball wear marks of novel lubricating oils with different contents of modified fluorinated graphene is shown in the image. Figure 19 The figure shows the average wear scar diameter of novel lubricating oils with different contents of modified fluorinated graphene. Figure 20A 3D profile of the wear marks on a steel ball under pure base oil lubrication; Figure 21 The image shows the corresponding wear depth of the steel ball under pure base oil lubrication. Figure 22 and Figure 23 3D profile of the wear track on the steel ball under lubrication of a sample with the optimal concentration of FG-[BMIM]PF6 added to the lubricating oil; Figure 24 Image showing the wear depth of steel ball wear under lubrication with the optimal concentration of FG-[BMIM]PF6 in the lubricating oil; Figures 25 to 28 SEM micrograph and EDS spectrum of the wear track on the surface of the steel ball. Detailed Implementation

[0042] The following description, with reference to preferred embodiments, illustrates the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are merely illustrative of the present invention and not intended to limit the scope of protection of the present invention. Example 1

[0043] A method for preparing modified fluorinated graphene includes the following steps: S1. Pretreatment: Fluorinated graphene (FG) powder is placed in a vacuum drying oven and dried at 60°C for 12 hours to remove any moisture that may be adsorbed on the surface, thus obtaining dried FG powder. S2. Preparation of FG dispersion: Accurately weigh 0.2g of the dry FG powder obtained in S1 and add it to 100mL of DMF. Place it in an ultrasonic cleaner and ultrasonically disperse it for 40 minutes to make the FG roughly uniformly dispersed, thus obtaining the FG dispersion. S3. Preparation of modifier solution: Dissolve 0.05g of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) in 20mL of DMF and stir until completely dissolved to form a homogeneous solution, thus obtaining the [BMIM]PF6 solution, which is the modifier solution. S4. Preparation of modified fluorinated graphene: The [BMIM]PF6 solution obtained in S3 was slowly added dropwise to the FG dispersion obtained in S2. The addition process was carried out under magnetic stirring, and the addition rate was controlled at 1 drop / second. After the addition was completed, the mixture was stirred continuously at 60℃ for 6 hours to obtain a mixture. The mixture was then cooled to room temperature and transferred to a centrifuge tube. It was centrifuged at 9000 rpm for 10 minutes, the supernatant was filtered off, and the precipitate was collected. The precipitate was then washed three times with anhydrous ethanol to remove unreacted [BMIM]PF6 and impurities. Subsequently, it was dried in a vacuum drying oven at 60℃ for 12 hours to obtain modified fluorinated graphene powder FG-[BMIM]PF6. The physical image of modified fluorinated graphene powder FG-[BMIM]PF6 is shown below. Figure 1 As shown. Example 2

[0044] A method for preparing modified fluorinated graphene includes the following steps: S1. Pretreatment: Fluorinated graphene (FG) powder is placed in a vacuum drying oven and dried at 60°C for 12 hours to remove any moisture that may be adsorbed on the surface, thus obtaining dried FG powder. S2. Preparation of modifier solution: Add 50 mL of DMF solvent and 50 mL of tetrahydrofuran solvent to a dry beaker, then add 0.1 g of octadecylamine (ODA), stir well to obtain ODA solution, i.e. modifier solution; S3. Preparation of modified fluorinated graphene: 0.2g of the dried FG powder obtained in S1 was slowly added to the modifier solution obtained in S2. The mixture was ultrasonically dispersed for 40 minutes at room temperature using an ultrasonic cleaner to ensure that FG and ODA were in full contact and reacted to obtain a mixture. The mixture was then centrifuged at 9000 rpm for 10 minutes. The supernatant was discarded, and the precipitate was collected. The precipitate was washed three times with anhydrous ethanol to ensure that impurities were completely removed. The solid product after centrifugation was then placed in a vacuum drying oven and dried at 60℃ for 12 hours to obtain modified fluorinated graphene powder FG-ODA. Example 3

[0045] A method for preparing modified fluorinated graphene includes the following steps: S1. Pretreatment: Fluorinated graphene (FG) powder is placed in a vacuum drying oven and dried at 60°C for 12 hours to remove any moisture that may be adsorbed on the surface, thus obtaining dried FG powder. S2. Preparation of modifier solution: Add 100mL of DMF solvent to a dry and clean beaker, weigh 0.1g of polyvinylidene fluoride (PVDF) powder, slowly add it to the beaker and stir until it is completely dissolved to form a uniform and transparent solution, thus obtaining the PVDF solution, i.e., the modifier solution. S3. Preparation of modified fluorinated graphene: 0.2g of the dried FG powder obtained in S1 was added to a clean beaker. The PVDF solution obtained in S2 was slowly added to the clean beaker and mixed with the FG powder. The mixture was ultrasonically dispersed for 40 minutes to ensure that the FG was uniformly dispersed in the solution, resulting in a mixed solution. The mixed solution was then centrifuged at 9000 rpm for 10 minutes, the supernatant was filtered off, and the precipitate was collected. The precipitate was then dried in a vacuum drying oven at 60°C for 10 minutes to remove excess solvent, resulting in an intermediate. The intermediate was then transferred to a drying oven and heat-treated at 200°C for 1 hour to promote the adhesion and curing of PVDF on the FG surface. The heat-treated product was then cooled to room temperature and immersed in anhydrous ethanol solution for 10-15 minutes to remove unattached PVDF and impurities. The product was then placed in a vacuum drying oven and dried at 60°C for 12 hours to obtain the modified fluorinated graphene FG-PVDF. Example 4

[0046] A method for preparing modified fluorinated graphene includes the following steps: S1. Pretreatment: Fluorinated graphene (FG) powder is placed in a vacuum drying oven and dried at 60°C for 12 hours to remove any moisture that may be adsorbed on the surface, thus obtaining dried FG powder. S2. Preparation of FG dispersion: Accurately weigh 0.2g of the dry FG powder obtained in S1 and add it to 100mL of DMF. Place it in an ultrasonic cleaner and ultrasonically disperse it for 40 minutes to make the FG roughly uniformly dispersed, thus obtaining the FG dispersion. S3. Preparation of modifier solution: Dissolve 0.2g of polyisobutylene (PIB) and 0.06g of azobisisobutyronitrile (AIBN) in 50 mL of DMF to obtain a mixed solution of PIB and AIBN, which is the modifier solution. S4. The mixed solution of PIB and AIBN obtained in S3 is slowly added dropwise to the FG dispersion obtained in S2. The dropwise addition is carried out under magnetic stirring, and the dropwise addition rate is controlled at 1 drop / second. After the dropwise addition is completed, the mixture is stirred continuously at 60℃ for 6 hours to obtain a mixed solution. Then, the mixed solution is cooled to room temperature and transferred to a centrifuge tube. It is centrifuged at 9000 rpm for 10 minutes, the supernatant is filtered off, and the precipitate is collected. The precipitate is then washed three times with anhydrous ethanol to remove unreacted PIB, AIBN and impurities. Subsequently, it is dried in a vacuum drying oven at 60℃ for 12 hours to obtain modified fluorinated graphene powder FG-PIB. Example 5

[0047] A novel method for preparing a lubricating oil includes the following steps: The modified fluorinated graphene powder FG-[BMIM]PF6 obtained in Example 1 was dried in an oven at 60°C for 12 hours, and then added to the sample as shown in the picture. Figure 2 The pentaerythritol base oil shown was ultrasonically dispersed to prepare a new type of lubricating oil with the following mass percentages of modified fluorinated graphene powder FG-[BMIM]PF6: 0.005%, 0.01%, 0.015%, 0.03%, 0.05%, 0.07%, 0.09%, 0.12%, and 0.15%, respectively.

[0048] Detection and Analysis 1) SEM characterization of modified fluorinated graphene The morphology of the unmodified fluorinated graphene and the modified fluorinated graphene prepared in Examples 1 to 4 were observed using a Zeiss Gemini Sigma 300 VP SEM at a magnification of 500,000. The results are as follows: Figure 3 As shown.

[0049] from Figure 3 As shown in (a), the unmodified FG exhibits a layered structure with numerous lamellae and severe stacking and aggregation. This is because FG itself contains CF and CC bonds, resulting in strong molecular forces, small interlamellar spacing, and numerous wrinkles. Figure 3 In (b), (c), (d), and (e), it can be observed that the lamellar opening of FG-ODA, FG-PVDF, FG-PIB, and FG-[BMIM]PF6 is better than that of the unmodified FG, and the thickness is significantly reduced. In particular, FG-[BMIM]PF6 forms a uniform lamellar morphology, which proves that the functional modification of FG by ionic liquid modification method better inhibits the self-aggregation of FG.

[0050] 2) FT-IR characterization of modified fluorinated graphene Infrared spectroscopy analysis was performed on the unmodified fluorinated graphene and the modified fluorinated graphene prepared in Examples 1 to 4 using an IRTracer 100 Fourier transform infrared spectrometer. The results are as follows: Figure 4 As shown.

[0051] from Figure 4 Analysis shows that it appears at 3500cm −1 The nearby peaks correspond to the OH stretching vibration (characteristic vibrational broad peak) in each sample, appearing at 1700 cm⁻¹. -1 The nearby peaks correspond to the C=O stretching vibrations at the edges of each sample. FG-ODA, FG-PVDF, FG-PIB, and FG-[BMIM]PF6 show peaks at 1312 cm⁻¹. -1 A CN peak appears nearby. FG-[BMIM]PF6 peaks at 867 cm⁻¹. -1 A -CF2 peak appeared nearby. This indicates that all four modified fluorinated graphenes were successfully modified. FG-ODA and FG-PVDF incorporated long carbon chains and nitrogen elements to enhance oil solubility. FG-PIB itself does not contain nitrogen elements, which may have been introduced by mixing in a certain amount of organic solvent when adding C=C unsaturated double bonds. FG-[BMIM]PF6 incorporates -CF2 bonds on the basis of FG, which enhances the surface activity of FG.

[0052] 3) AFM characterization of modified fluorinated graphene Atomic force microscopy (AFM) was used to capture images and analyze the layer thickness of the unmodified fluorinated graphene and the modified fluorinated graphene prepared in Examples 1 to 4. The results are as follows: Figures 5 to 9 As shown.

[0053] from Figure 5 As can be seen, the thickness of the unmodified FG sheets ranges from 0 to 100 nm, and the thickness distribution is uneven. From... Figure 6 As can be seen, the thickness of the FG-ODA sheets has decreased, ranging from 0 to 5 nm, but the sample surface is relatively rough with a large amount of particulate matter. From... Figure 7 As can be seen, the FG-PVDF sheets are relatively thick, ranging from 0 to 15 nm, and exhibit severe aggregation. From... Figure 8 As can be seen from this, the thickness of FG-PIB sheets ranges from 0 to 300 nm, and they are granular. From... Figure 9 As can be seen from the data, the sheet thickness of FG-[BMIM]PF6 is between 0 and 5 nm, and the surface morphology is gentle, mostly exhibiting a single-layer sheet structure. This is basically consistent with the conclusions drawn from the SEM images above.

[0054] 4) XPS characterization of modified fluorinated graphene X-ray photoelectron spectroscopy (XPS) was used to analyze the unmodified fluorinated graphene and the modified fluorinated graphene prepared in Examples 1 to 4. The results are as follows: Figures 10 to 14 As shown.

[0055] from Figures 10 to 14 Analysis revealed that all four modified samples—FG (unmodified), FG-ODA, FG-PIB, FG-PVDF, and FG-[BMIM]PF6—exhibited a distinct N1s peak. FG-PIB, FG-PVDF, and FG-[BMIM]PF6 samples were attributed to surface-grafted N elements, while FG-PIB was introduced during C=C grafting, but this did not affect the assessment of the modification effect. All four samples also exhibited a distinct O1s peak, indicating the presence of grafted elements. The FG-[BMIM]PF6 sample showed both F1s and P2p peaks, suggesting surface-active modification of FG, which preserved the F element while enhancing its oil dispersibility. This conclusion is largely consistent with the aforementioned FTIR analysis images.

[0056] 5) Dispersibility test of modified fluorinated graphene in base oil The pentaerythritol ester base oil from Example 5 and the novel lubricating oils with different contents of modified fluorinated graphene were left to stand at room temperature for 72 h, 168 h, and 720 h to observe their dispersibility. The results are as follows: Figure 15 As shown.

[0057] Figure 15 In the text, 1 to 9 represent new types of lubricating oils with a mass percentage content of modified fluorinated graphene powder FG-[BMIM]PF6 of 0.005%, 0.01%, 0.015%, 0.03%, 0.05%, 0.07%, 0.09%, 0.12%, and 0.15%, respectively.

[0058] from Figure 15 Analysis of (a) to (d) shows that after standing for 72 hours, the oil samples of the two new lubricating oils with FG-[BMIM]PF6 mass percentages of 0.005% and 0.01% showed slight color changes, while the other oil samples did not show obvious stratification and had uniform color. After standing for 168 hours, the oil samples with FG-[BMIM]PF6 mass percentages of 0.015%, 0.09%, and 0.12% began to show sedimentation at the bottom, with the 0.01% oil sample showing more obvious stratification. After standing for 720 hours, the oil samples with FG-[BMIM]PF6 mass percentages of 0.03%, 0.05%, and 0.07% showed the best oil solubility and did not show clear liquid, while the 0.15% oil sample showed clear liquid at the top, but the color of the middle and bottom was uniform. Furthermore, the stratification of all oil samples was not a solid precipitate; slight shaking of the bottle could disperse the suspended matter.

[0059] In summary, as the concentration of FG-[BMIM]PF6 increases, the dispersibility of fluorinated graphene-based lubricating oil is better at lower concentrations than at higher concentrations. This may be because FG-[BMIM]PF6 forms a lubrication system with the lubricating oil, maintaining a stable suspension state. When the concentration is too high, the system cannot maintain the dispersion state of FG-[BMIM]PF6, causing it to form suspended agglomerates, thus affecting the dispersibility of the lubricating oil. Furthermore, the quality of dispersibility directly affects the physicochemical properties and tribological properties of the oil sample.

[0060] 6) Viscosity-temperature performance test The viscosity of the pentaerythritol ester base oil in Example 5 and the novel lubricating oils with different contents of modified fluorinated graphene were measured according to GB / T265-1988 standard. The method was as follows: a glass capillary viscometer containing the oil sample was vertically installed in a constant temperature bath at 40°C. After 15 minutes of constant temperature, the time it took for the oil sample to flow through a calibrated glass capillary viscometer under gravity was recorded. The product of the capillary constant and the flow time was the kinematic viscosity of the liquid. To ensure that the sample passage time through the capillary viscometer was no less than 200 seconds and the flow time of a 0.4 mm inner diameter viscometer was no less than 350 seconds, a suitable viscometer (viscosity constant 0.1206) was selected.

[0061] The specific operating steps are as follows: At the start of the test, use a rubber bulb to draw a certain volume of oil sample into the viscometer. Immerse the viscometer containing the oil sample in a pre-prepared constant temperature bath, ensuring that the oil sample is completely submerged in the bath during the test. The viscometer should be adjusted to be perpendicular to the liquid surface. During the measurement, record the time it takes for the oil sample to flow from mark a to mark b, accurate to 0.1 s. Repeat the measurement at least three times, and then calculate the average flow time of the oil sample according to formula (Ⅰ). In formula (Ⅰ), Indicates kinematic viscosity (mm) 2 / s), c represents the viscometer constant (mm). 2 / s 2 ), where t represents the average flow time of the oil sample (s). The results are shown in Table 1.

[0062] Table 1 shows the kinematic viscosity results of the new lubricating oil. As shown in Table 1, the kinematic viscosity measured at 40℃ indicates that, at the same temperature, the kinematic viscosity of oil samples with different FG-[BMIM]PF6 concentrations is not significantly different, all ranging from 26 to 27 mm.2 Between / s, it conforms to the original base oil report standards.

[0063] 7) Corrosion performance test The acid values ​​of the pentaerythritol ester base oil in Example 5 and the novel lubricating oils with different contents of modified fluorinated graphene were determined according to GB / T264-1983 standard. First, acidic substances in the oil sample were extracted using boiling ethanol, and then titrated with potassium hydroxide ethanol solution. The acid value of the oil sample was calculated from the volume of potassium hydroxide ethanol solution used in the titration, and the result was expressed as mgKOH / g.

[0064] The specific experimental steps are as follows: Weigh approximately 10g of oil sample into a conical flask; add 50mL of 75% ethanol to another clean, anhydrous conical flask and place it in a reflux condenser. While continuously shaking, boil the 95% ethanol for 10 minutes to remove CO2 dissolved in the 95% ethanol; add 0.5mL of Basic Blue 6B solution to the boiled 95% ethanol, and while hot, neutralize with 0.05mol / L potassium hydroxide ethanol solution until the solution changes from blue to light red; pour the neutralized 95% ethanol into the conical flask containing the oil sample and place it in a reflux condenser. Add 0.5mL of Basic Blue 6B solution to the boiled mixture, and titrate while hot with 0.05mol / L potassium hydroxide ethanol solution until the 95% ethanol layer changes from blue to light red; the heating time should not exceed 3 minutes during each titration, until the titration reaches the endpoint. Calculate the acid value using formula (II): In formula (II), X represents the acid value, expressed in mgKOH / g; V represents the volume of potassium hydroxide ethanol solution consumed during titration, in mL; c represents the molar concentration of the potassium hydroxide ethanol solution, in mol / L; m represents the weight of the oil sample, in g; and M represents the molar mass of potassium hydroxide, in g / mol. The results are shown in Table 2.

[0065] Table 2 shows the acid value results of the new lubricating oil. As shown in Table 2, the acid values ​​of oil samples with different FG-[BMIM]PF6 concentrations remained basically unchanged, all less than 0.05, which meets the original base oil reporting standards.

[0066] 8) Low-temperature flow performance test The pour points of the pentaerythritol ester base oil in Example 5 and the novel lubricating oils with different contents of modified fluorinated graphene were determined according to GB / T510-2018 Petroleum Products Determination of Pour Point.

[0067] The specific operating steps are as follows: 1. Attach a cork or silicone rubber stopper to the thermometer, ensuring the stopper fits tightly against the opening of the freezing point test tube and remains stationary, with the mercury bulb approximately 10mm from the bottom of the tube. Then, set the water bath temperature to 50°C. After heating the oil sample to this temperature, allow it to stand at room temperature until the oil sample in the test tube cools to 35°C ± 5°C. Then, place this instrument into the aperture of the low-temperature measuring instrument. The coolant temperature of the cooling environment should be 8°C lower than the expected temperature of the oil sample. 2. When the oil sample temperature cools to the expected freezing point, tilt the test tube and sleeve (not submerged in the coolant) at a 45° angle and maintain this tilt for 1 minute, ensuring the oil sample portion of the test tube and sleeve remains submerged in the coolant. 3. When the liquid level changes, when removing the test tube from the sleeve, place the test tube containing the oil sample and thermometer at room temperature. After the oil sample temperature rises to 20℃, heat the test tube again until the oil sample reaches 50℃±1℃. Let the oil sample stand at room temperature until the temperature inside the test tube drops to 35℃. Then, repeat the measurement using a temperature 4℃ lower than the previous test temperature until a certain test temperature keeps the liquid level constant. 4. When the liquid level does not move, remove the test tube from the sleeve and reheat it to 50℃. Then, let it stand at room temperature until the oil sample in the test tube cools to 35℃±5℃. Repeat the measurement using a temperature 4℃ higher than the previous test temperature or another higher temperature until a certain test temperature causes the liquid level to move. After determining the temperature range of the freezing point, repeat the test using a temperature 2℃ lower than the temperature that caused the movement, or a temperature 2℃ higher than the temperature that did not cause the movement. The experiment was repeated until a certain temperature was determined that would keep the oil sample level still, while raising the temperature by 2°C would cause the surface to move. The temperature at which the surface remained still was then taken as the pour point of the oil sample. The results are shown in Tables 3 to 12.

[0068] Table 3 shows the pour point temperatures of the new lubricating oil. As analyzed in Table 3, the pour point of oil samples with different FG-[BMIM]PF6 concentrations was around -47℃, which meets the original base oil reporting standards.

[0069] 9) Friction reduction performance test The friction coefficient was tested using a four-ball friction tester according to the SH / T 0762 standard, and the average wear scar diameter was tested according to the SH / T 0189 standard.

[0070] The specific operating steps are as follows: Four clean, dry steel balls (12.7 mm in diameter) were taken out and placed into the four-ball oil box and clamped. Approximately 10 mL of the pentaerythritol ester base oil from Example 5 and the novel lubricating oil with different contents of modified fluorinated graphene were added to each ball, ensuring that three of the steel balls were submerged in the oil box. Another steel ball was used as the upper ball. The debugging software was then opened, the test force friction was cleared, and the instrument was zeroed. The four-ball oil pump was turned on for preheating for 30 minutes. Then, the oil box rise button was pressed, and the test force was applied in the software, causing the upper steel ball to clamp with the three lower steel balls to form a three-point contact. The test force knob was then manually adjusted to apply a load of 392 N (40 kgf) at a speed of 1200 rpm, and the operation was carried out in this mode for 1 hour. After the operation, the lubricating oil was drained and the steel balls were cleaned. The wear scar diameter of each of the three lower steel balls was then observed and measured using a microscope, and the average wear scar diameter was obtained by taking the average value.

[0071] All friction tests were performed three times under identical conditions to ensure repeatability and reliability. The average coefficient of friction and average wear rate were calculated based on the repeated tests. Furthermore, the relative deviation of the tests should be less than 5%. However, due to the accuracy of the testing equipment, some tests used to calculate the average wear rate may exceed 5%, which can be used to reflect the frictional performance of fluorinated graphene-based lubricants and the impact of FG content on the lubricant. Results are as follows... Figures 16 to 19 As shown.

[0072] Figure 16 Real-time friction coefficient images obtained after testing oil samples containing different concentrations of the novel FG-[BMIM]PF6 lubricating oil in long-term grinding mode on a four-ball mill. From Figure 16 Analysis revealed that both the FG-[BMIM]PF6 new lubricating oil sample and the original base oil exhibited varying degrees of rapid increases in friction coefficient during testing. The 0.07% FG-[BMIM]PF6 new lubricating oil remained stable between 0 and 1600 s, then experienced a sharp increase in friction coefficient between 1600 and 1800 s, before finally stabilizing within a certain range. This may be because initially, sufficient surface contact and uniform frictional distribution led to a stable friction coefficient. The subsequent sharp increase could be due to uneven distribution of the lubricating flakes or the influence of the flake structure during friction, resulting in a sudden increase in shear force and friction, and increased surface damage. The final stabilization likely occurred because the lubrication system material was sufficient, achieving a new lubrication equilibrium, and the interaction between frictional force and surface properties stabilized again.

[0073] Figure 17 The average coefficient of friction of FG-[BMIM]PF6 novel lubricating oil samples with different concentrations is shown in the test. From Figure 17Analysis shows that the higher the content of FG-[BMIM]PF6 in the base oil, the more the average friction coefficient initially decreases and then increases. It reaches a minimum of 0.0605 at a concentration of 0.05% and a maximum of 0.0962 at 0.15%, compared to 0.0909 for the original base oil. This may be because initially, at lower concentrations, the thin film of FG-[BMIM]PF6 forms a lubricating film between the upper and lower steel balls, effectively reducing the contact area and ultimately minimizing wear. However, as the concentration increases further, FG-[BMIM]PF6 tends to agglomerate. As friction continues, these agglomerates act as abrasive particles, causing discontinuities in the lubricating film and consequently increasing wear. Compared with the original base oil, the friction coefficient of the oil sample containing 0.05% FG-[BMIM]PF6 was reduced by about 33.4%. Except for the 0.15% FG-[BMIM]PF6 oil sample which showed increased wear, the friction coefficients of the other concentrations of oil samples were effectively reduced.

[0074] Figure 18 Schematic diagram of the wear scar diameter of steel balls in long-term grinding mode for different concentrations of FG-[BMIM]PF6 new lubricating oil. Figure 18 In the table, (a) to (j) represent the original base oil and a new type of lubricating oil sample containing 0.005%, 0.01%, 0.015%, 0.03%, 0.05%, 0.07%, 0.09%, 0.12%, and 0.15% FG-[BMIM]PF6, respectively. From... Figure 18 The comparison shows that all oil samples have certain black particles on the surface of the wear marks. This is because the steel ball was worn during the tribological experiment, and FG-[BMIM]PF6 entered the worn surface and continued to resist pressure and reduce friction with the lubricating oil, thus reducing the wear on the steel ball. Figure 18 In (a), the friction surface is relatively rough and there is a more obvious ploughing phenomenon, indicating that the lubricating oil cannot meet the requirements well during the friction process, resulting in more severe wear of the upper and lower steel balls. Figure 18 The friction surfaces in samples (b) to (j) are relatively smooth, with no abnormal wear. This indicates that the addition of FG-[BMIM]PF6 improves the performance of the lubricating oil and plays an anti-wear and friction-reducing role in the base oil. In particular, the 0.05% FG-[BMIM]PF6 oil sample has the smoothest friction surface, with virtually no cracks or grooves, indicating that the concentration of the additive also plays a dominant role in the lubricating effect of the lubricating oil.

[0075] Figure 19 This is a schematic diagram showing the average wear scar diameter of oil samples of the novel FG-[BMIM]PF6 lubricating oil at different concentrations. From... Figure 19The results show that the wear scar diameter initially decreases and then increases, reaching a minimum of 0.44 mm in the 0.005% FG-[BMIM]PF6 new lubricant and a maximum of 0.77 mm in the 0.15% FG-[BMIM]PF6. The original base oil has a smaller diameter (0.76 mm) than the 0.15% FG-[BMIM]PF6 sample. This may be because the high concentration of FG-[BMIM]PF6 resulted in large particles, leading to dry friction in the friction experiment and thus increased wear. This demonstrates that the average wear scar diameter corresponds to the average coefficient of friction; the higher the average coefficient of friction, the larger the average wear scar diameter.

[0076] 10) Wear resistance test The linear roughness, surface profile, wear scar depth, and hole volume of the steel ball in the tribological performance experiment were measured and analyzed using a SuperView WM100 optical 3D surface profiler.

[0077] The specific operating steps are as follows: Start the machine to warm up and open the software while waiting for the machine to reset. Then place the steel ball to be tested on the worktable, with the wear mark on the ball at the top, ensuring that the interference light covers the wear mark. Adjust the Z-axis downwards until the lower surface of the lens is close to the surface of the workpiece, and set the ZSTOP value. Manually adjust the focus so that the upper and lower limits are focused on the area where the wear mark is clearest. Then select autofocus, and once the machine has focused, you can begin the measurement.

[0078] Preprocessing: After measurement, the first step is to apply a leveling algorithm to ensure parallel image analysis. Then, peak denoising is selected to reduce the impact of some friction peaks on the average roughness during the experiment.

[0079] Experimental Analysis: After preprocessing, select surface roughness application to first analyze the surface roughness range and area; then select line roughness, set two points, draw lines perpendicular to the wear mark, obtain the linear roughness between wear marks, and output CSV data; next, select profile analysis to obtain the vertical distance between points, output CSV data, and analyze the wear mark profile and depth; then select hole volume, uncheck hole, select all data application to ensure complete measurement of the wear mark volume of the lower steel ball.

[0080] Data Export: Click on Process Statistics to export detailed data, and then rename it for easy analysis and application later.

[0081] The results are as follows Figures 20-24 As shown.

[0082] Figures 20-243D profiles and corresponding wear track depths of steel ball wear tracks were obtained for pure base oil and lubricating oil samples lubricated with the optimal concentration (0.15%) of FG-[BMIM]PF6. The comparison revealed that the pure base oil produced a maximum wear track depth of approximately 7.581 μm and an RMS (surface roughness) of 5.378 μm, indicating significant roughness, numerous surface grooves, and poor track smoothness, failing to provide adequate lubrication. In contrast, the base oil with added FG-[BMIM]PF6 exhibited significantly reduced wear track depths, all controlled at approximately 6.079 μm, with the RMS decreasing to 4.469 μm. This resulted in reduced roughness and a smoother wear surface. This further demonstrates that the addition of FG-[BMIM]PF6 effectively enhances the anti-wear and friction-reducing properties of the lubricating oil.

[0083] 11) Friction mechanism analysis To further investigate the interaction mechanism of fluorinated graphene particles on the friction pair surface, SEM and EDS were used to analyze the wear surface characteristics and anti-wear mechanism of the steel ball, such as... Figures 25 to 28 As shown.

[0084] Figure 25 and Figure 26 SEM images and EDS spectra of FG-based lubricating oil after friction testing. Figure 27 and Figure 28 SEM images and EDS spectra of FG-[BMIM]PF6-based lubricating oil after friction testing.

[0085] After the four-ball friction test, the surface of the steel balls showed clear wear marks, obvious ploughing effect and deformation marks. Figure 27 Compared to Figure 25 The wear track spacing and wear track width decreased slightly. EDS analysis of the worn surface... Figure 26 The presence of compounds containing C and Fe indicates that the accumulated particles on the wear tracks are indeed residues of FG. Figure 26 The results showed a significant increase in C concentration, a decrease in Fe concentration, and the presence of compounds containing N and P, indicating the presence of FG-[BMIM]PF6 on the surface of the steel ball. This also provided better lubrication, hindering direct contact between the grinding head and the metal steel ball, and protecting the steel ball together with the lubricating oil.

[0086] In summary, lubricating oils containing FG-[BMIM]PF6 exhibit better tribological properties than pure base oils. Wear surfaces lubricated with pure base oil show wider wear tracks, with an average track volume of 6478621 μm. 3 Furthermore, irregular pits were present near the wear tracks. In contrast, the wear tracks lubricated with FG-[BMIM]PF6-based lubricant were narrower, the surface wear was smoother, and the average wear volume was 5073843 μm.3 Compared to pure base oil, it decreased by 21.7%. According to EDS analysis of the wear tracks, [BMIM]PF6 and fluorinated graphene produce a synergistic effect in the lubricating oil, forming a chemical film on the surface of the steel ball wear tracks, resulting in better lubrication than pure base oil. It can be seen that the addition of fluorinated graphene is indeed beneficial to improving the performance of lubricating oil.

[0087] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A modified fluorinated graphene, characterized in that, Fluorinated graphene was modified using a modifier solution to obtain modified fluorinated graphene; The modifier is selected from at least one of octadecylamine, polyvinylidene fluoride, polyisobutylene, and 1-butyl-3-methylimidazolium hexafluorophosphate.

2. A method for preparing modified fluorinated graphene as described in claim 1, characterized in that, Includes the following steps: Modified fluorinated graphene is obtained by mixing and reacting fluorinated graphene with a modifier solution.

3. The method for preparing modified fluorinated graphene according to claim 2, characterized in that, When the modifier is selected from 1-butyl-3-methylimidazolium hexafluorophosphate or polyisobutylene, the following steps are included: Fluorinated graphene was added to an organic solvent to obtain a fluorinated graphene dispersion. 1-Butyl-3-methylimidazolium hexafluorophosphate is dissolved in an organic solvent to obtain a modifier solution; or, polyisobutylene and azobisisobutyronitrile are dissolved in an organic solvent to obtain a modifier solution. The modifier solution was added to the fluorinated graphene dispersion, and the mixture was heated and stirred to react, thus obtaining modified fluorinated graphene.

4. The method for preparing modified fluorinated graphene according to claim 3, characterized in that, The heating reaction is carried out at a temperature of 40℃ to 70℃ for a duration of 4h to 6h. And / or, the mass ratio of the fluorinated graphene to the 1-butyl-3-methylimidazolium hexafluorophosphate is 3~7:1, or the mass ratio of the fluorinated graphene, polyisobutylene and azobisisobutyronitrile is 8~12:8~12:3; And / or, the organic solvent is selected from one or both of N,N-dimethylformamide (DMF) and N,N-diethylformamide (DEF); And / or, after the heating and stirring reaction, the process further includes: centrifugation, collection of the precipitate, washing, and vacuum drying to obtain the modified fluorinated graphene. Or FG-PIB.

5. The method for preparing modified fluorinated graphene according to claim 2, characterized in that, When the modifier is selected from octadecylamine, the following steps are included: Octadecylamine was added to an organic mixed solvent to obtain a modifier solution; Fluorinated graphene was added to a modifier solution and subjected to ultrasonic treatment to obtain modified fluorinated graphene FG-ODA.

6. The method for preparing modified fluorinated graphene according to claim 5, characterized in that, The ultrasonic treatment was performed at room temperature for 30 to 60 minutes. And / or, the mass ratio of the fluorinated graphene to the octadecylamine is 2~5:1; And / or, the organic mixed solvent is selected from a mixture of N,N-dimethylformamide and tetrahydrofuran; And / or, after the ultrasonic treatment, the process further includes: centrifugation, collecting the precipitate, and vacuum drying to obtain the modified fluorinated graphene FG-ODA.

7. The method for preparing modified fluorinated graphene according to claim 2, characterized in that, When the modifier is selected from polyvinylidene fluoride, the following steps are included: Polyvinylidene fluoride is added to an organic solvent to obtain a modified solution; The modified solution was added to fluorinated graphene and subjected to ultrasonic treatment to obtain an intermediate. The intermediate was heat-treated to obtain modified fluorinated graphene FG-PVDF.

8. The method for preparing modified fluorinated graphene according to claim 7, characterized in that, The ultrasonic treatment was performed at room temperature for 40 minutes. And / or, the mass ratio of the fluorinated graphene to the polyvinylidene fluoride is 2~5:1; And / or, the heat treatment temperature is 150℃~300℃, and the time is 45min~75min; And / or, the organic solvent is selected from N,N-dimethylformamide; And / or, after ultrasonic treatment, the process further includes: centrifugation, collection of the precipitate, and vacuum drying to obtain the intermediate; And / or, after the heat treatment, the process further includes: washing, vacuum drying, to obtain the modified fluorinated graphene FG-PVDF.

9. The application of modified fluorinated graphene prepared by the preparation method according to any one of claims 2 to 8 in lubricating oil.

10. A modified fluorinated graphene-based lubricating oil, characterized in that, Includes base oil and modified fluorinated graphene prepared by the preparation method according to any one of claims 2 to 8; The base oil is selected from pentaerythritol ester.

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