Energy-saving and environment-friendly nano-graphite lubricant and preparation method thereof

Abstract

The application discloses an energy-saving and environment-friendly nano-graphite lubricant and a preparation method thereof, and relates to the technical field of inorganic nanometer materials. The lubricant comprises three-layer structure composite particles, a dispersing agent, an anti-wear extreme pressure agent and base oil. The three-layer structure composite particles are constructed by taking nano-graphite as a core, transition metal oxide as an intermediate layer and self-lubricating inorganic nano-particles as an outer shell. The stable combination of the layers is formed. The nano-graphite core provides basic lubrication support by relying on its own structure. The transition metal oxide intermediate layer builds a rigid support framework for the composite particles, and maintains the integrity of the overall structure of the particles. The self-lubricating inorganic nano-particle shell forms a surface lubrication protective layer at the application interface. The three-layer structure relies on the integrated combination mode to perform different functions and cooperate with each other. The stable structure form is used as a lubrication function carrier to ensure the continuous and stable output of the lubrication effect.

Description

Technical Field

[0001] This invention relates to the field of inorganic nanomaterials technology, specifically to an energy-saving and environmentally friendly nano-graphite lubricant and its preparation method. Background Technology

[0002] Industrial lubrication is a core component in ensuring the stable operation of equipment in fields such as equipment manufacturing, transportation, and machining. As industrial production transforms towards heavy-duty, high-efficiency, and green production, the application scenarios for lubricating materials are becoming increasingly demanding. Currently, the whole society advocates low-carbon, environmentally friendly, and sustainable development, and industrial production has put forward clear requirements for the environmental compatibility of materials and the degree of greenness of production processes. Lubricating products under traditional industrial production models are no longer able to meet the needs of industrial development in the new era. Driven by both harsh working conditions and environmental protection policies, the lubricating materials field urgently needs to break through the dual bottlenecks of performance and environmental protection, and develop new lubricating materials that combine structural stability, long-lasting lubrication, and environmental friendliness. This has become an important direction for technological upgrading and green industrial development in the industry.

[0003] However, existing nano-lubricating materials generally suffer from problems such as unreasonable structural design, poor component compatibility, and lack of environmental performance. Single nano-lubricating particles cannot simultaneously achieve friction reduction, load bearing, and protection functions, and are prone to structural collapse and functional failure in practical applications. Physically blended lubricating systems have weak interparticle bonding forces, and are prone to stratification and agglomeration during friction, making it impossible to form a stable lubricating structure. Dispersants and anti-wear extreme pressure agents mostly use single components. Dispersants are difficult to achieve stable dispersion of particles in multiple media, and anti-wear extreme pressure agents cannot meet the lubrication and protection requirements of complex working conditions. At the same time, most lubricating products contain toxic components such as sulfur, phosphorus, and heavy metals. The preparation process relies on high temperature and high energy consumption, and the waste is prone to causing residual environmental pollution, failing to meet the dual standards of heavy-duty use and green production. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an energy-saving and environmentally friendly nano-graphite lubricant and its preparation method. This invention constructs a three-layer composite particle with nano-graphite as the core, transition metal oxide as the intermediate layer, and self-lubricating inorganic nanoparticles as the shell, allowing each layer to form a stable bond. The nano-graphite core provides basic lubrication support based on its own structure, the transition metal oxide intermediate layer builds a rigid support structure for the composite particle, maintaining the integrity of the overall particle structure, and the self-lubricating inorganic nanoparticle shell forms a surface lubrication and protective layer at the application interface. The three layers work together in an integrated manner, with each layer performing its own function and cooperating with the others. The stable structural form serves as the lubrication function carrier, ensuring a continuous and stable output of lubrication.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In one aspect, an energy-saving and environmentally friendly nano-graphite lubricant, comprising, by weight: Three-layer composite particles: 5-15 parts; Dispersant: 2-5 parts; Anti-wear extreme pressure agent: 1-3 parts; Base oil: 60-85 parts.

[0006] Furthermore, the three-layer composite particles are composed of nano-graphite, transition metal oxide, and self-lubricating inorganic nanoparticles. The mass ratio of nano-graphite, transition metal oxide, and self-lubricating inorganic nanoparticles is 1:0.2-0.6:0.1-0.4, with nano-graphite as the core, transition metal oxide as the middle layer, and self-lubricating inorganic nanoparticles as the outer shell. The particle size of the core is 20-100 nm, the thickness of the middle layer is 10-30 nm, and the thickness of the outer shell is 5-20 nm. The transition metal oxide is alumina or zirconium oxide, and the self-lubricating inorganic nanoparticles are molybdenum disulfide or tungsten disulfide.

[0007] Furthermore, the dispersant is a composition of polyisobutylene succinimide, polymethacrylate, and sorbitan oleate, wherein the mass ratio of polyisobutylene succinimide, polymethacrylate, and sorbitan oleate is 1-3:0.5-2:0.5-1.5.

[0008] Furthermore, the anti-wear extreme pressure agent is a composition of isobutylene sulfide, tricresyl phosphate, and borate ester, wherein the mass ratio of isobutylene sulfide, tricresyl phosphate, and borate ester is 0.5-2:0.3-1.5:0.2-1.

[0009] Furthermore, the base oil is a synthetic ester base oil or a mineral base oil.

[0010] On the other hand, a method for preparing an energy-saving and environmentally friendly nano-graphite lubricant, the specific steps of which are as follows: Nucleus preparation: Natural flake graphite is placed in an aqueous solvent and wet-milled or intercalated and exfoliated, and then post-processed to obtain nano-graphite material, which is then mixed with an aqueous solvent to obtain nano-graphite dispersion. Intermediate layer coating: The nano-graphite dispersion is mixed with the metal precursor solution, and the transition metal oxide is coated on the surface of the nano-graphite material by sol-gel method or co-precipitation method to obtain a composite particle precursor with an intermediate layer. Shell layer assembly: Self-lubricating inorganic nanoparticles are prepared into a dispersion, and then the composite particle precursor with the middle layer is mixed with the dispersion to obtain a three-layer composite particle material. Drying and compounding: The three-layer composite granular material is dried at low temperature to obtain dried composite granules, which are then mixed with base oil, dispersant, and anti-wear extreme pressure agent. After ultrasonic dispersion and homogenization, a lubricant is obtained.

[0011] Furthermore, in the core preparation process, the aqueous solvent is deionized water or an aqueous ethanol solution; the wet grinding speed is 3000-5000 r / min, and the grinding time is 2-4 h; the intercalation exfoliation uses sulfuric acid or nitric acid as the intercalating agent, with an intercalating agent concentration of 0.5-1 mol / L in an aqueous system, the exfoliation temperature is 25-40℃, and the exfoliation time is 1-3 h; the post-treatment steps are as follows: after standing, centrifugation, washing with deionized water, and sieving, nano-graphite material with a particle size of 20-100 nm is obtained; the nano-graphite material is mixed with an aqueous solvent at a solid-liquid mass ratio of 1:8-12, and ultrasonically dispersed to prepare a nano-graphite dispersion.

[0012] Furthermore, in the intermediate layer coating, the nano-graphite dispersion and the metal precursor solution are mixed at a mass ratio of 1:4-6. When the transition metal oxide is alumina, the metal precursor solution is a 0.1-0.3 mol / L aluminum nitrate solution or an aluminum isopropoxide solution; when the transition metal oxide is zirconium oxide, the metal precursor solution is a 0.2-0.4 mol / L zirconium oxychloride solution or a zirconium n-propoxide solution. When using the sol-gel method, the pH value of the reaction is adjusted to 3-5 by an acid-base regulator, and the reaction temperature is controlled at 40°C by a water bath. At 60℃, the concentration of the metal precursor is 0.1-0.3 mol / L, and the reaction time is 1-2 h. When using the co-precipitation method, the pH value of the reaction is adjusted to 8-10 by acid-base regulator, the reaction temperature is controlled at 60-80℃ by water bath, the concentration of the metal precursor is 0.2-0.4 mol / L, and the reaction time is 0.5-1 h. By controlling the mass ratio of feed, the pH value of acid-base regulator, the reaction temperature of water bath, the concentration of metal precursor, and the reaction time, a composite particle precursor with an intermediate layer of 10-30 nm is finally obtained.

[0013] Furthermore, in the outer shell assembly, self-lubricating inorganic nanoparticles are mixed with an aqueous solvent at a solid-liquid mass ratio of 1:60-100, ultrasonically dispersed for 20-30 minutes to prepare a dispersion with a mass concentration of 5-15 g / L. The composite particle precursor with an intermediate layer is added to the dispersion at a mass ratio of 1:5-15, ultrasonically dispersed for 10-20 minutes, stirred at a constant temperature of 25-35℃ for 0.5-1.5 hours, and allowed to stand for 10-20 minutes. Self-lubricating inorganic nanoparticles with a thickness of 5-20 nm are loaded onto the surface of the composite particle precursor with an intermediate layer to form an outer shell. Then, the mixture is centrifuged and washed 2-3 times with deionized water to obtain a three-layer composite particle material.

[0014] Furthermore, in the drying and compounding process, the low-temperature drying temperature is 40-80℃ and the drying time is 1-2 hours; the base oil is heated to 30-40℃, a dispersant is added and stirred until completely dissolved, then an anti-wear extreme pressure agent is added and mixed evenly, and finally the dried composite particles are added. The mixture is ultrasonically dispersed at 200-400W power for 10-20 minutes and stirred for 5-10 minutes. The mixture is then homogenized under a pressure of 10-20MPa to obtain the lubricant.

[0015] Compared with existing technologies, this energy-saving and environmentally friendly nano-graphite lubricant and its preparation method have the following beneficial effects: I. This invention constructs a three-layer composite particle with nano-graphite as the core, transition metal oxide as the intermediate layer, and self-lubricating inorganic nanoparticles as the outer shell. This allows each component to form a stable bond. The nano-graphite core provides basic lubrication support based on its own structure. The transition metal oxide intermediate layer builds a rigid support structure for the composite particle, maintaining the integrity of the overall particle structure. The self-lubricating inorganic nanoparticle shell forms a surface lubrication and protective layer at the application interface. The three layers work together in an integrated manner, each performing its own function. The stable structural form serves as the lubrication carrier, ensuring a continuous and stable output of lubrication.

[0016] II. This invention utilizes a ternary compound dispersant and a ternary compound anti-wear extreme pressure agent to form a compound additive system. Combined with an aqueous solvent and a low-temperature drying green preparation process, it achieves functional adaptation and environmental protection of the lubricant. The ternary compound dispersant components work synergistically to ensure stable dispersion of the composite particles into the oil phase system throughout the aqueous preparation stage, avoiding particle agglomeration and phase separation. The ternary compound anti-wear extreme pressure agent and the composite particles complement each other, meeting the protection requirements of lubrication scenarios. The entire preparation process uses an aqueous reaction medium and a low-temperature treatment method, eliminating high-pollution and high-energy-consumption stages. Both the raw materials and the finished product contain no toxic components, meeting the requirements of green and environmentally friendly applications.

[0017] Other advantages, objectives and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination or study, or may be learned from the practice of the invention. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0019] Figure 1A flowchart illustrating a method for preparing an energy-saving and environmentally friendly nano-graphite lubricant; Figure 2 A framework diagram of a method for preparing an energy-saving and environmentally friendly nano-graphite lubricant; Figure 3 This is a framework diagram of the outer shell assembly in a method for preparing an energy-saving and environmentally friendly nano-graphite lubricant. Detailed Implementation

[0020] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0021] Example 1: Raw material ratio (by weight): Ten portions of three-layer composite particles; 3 parts dispersant; 2 parts of anti-wear extreme pressure agent; 85 parts base oil.

[0022] The three-layer composite particles are composed of nano-graphite, alumina, and molybdenum disulfide in a mass ratio of 1:0.4:0.2. The dispersant is a compound of polyisobutylene succinimide, polymethyl methacrylate, and sorbitan oleate in a mass ratio of 2:1:1. The anti-wear extreme pressure agent is a compound of isobutylene sulfide, tricresyl phosphate, and borate in a mass ratio of 1:1:0.5. The base oil is a synthetic ester base oil.

[0023] Preparation method: Nuclear preparation: Natural flake graphite was added to deionized water and stirred thoroughly to form a graphite suspension. A wet mill was used for grinding at 3000 rpm for 3 hours. After grinding, the suspension was allowed to stand for 30 minutes. The upper layer of fine particles was collected and centrifuged at 8000 rpm for 15 minutes. The supernatant was discarded. The centrifuged precipitate was washed three times with deionized water. After washing, the precipitate was sieved through a 10000-mesh sieve to remove large particles larger than 100 nm, resulting in particles in the 20-100 nm range, i.e., nano-graphite material. The nano-graphite material was then mixed with deionized water at a solid-liquid mass ratio of 1:10 and ultrasonically dispersed for 30 minutes to prepare a uniform nano-graphite dispersion. Figure 1 As shown, the final nano-graphite dispersion obtained in this step is free of agglomeration and large particle impurities, with a particle size concentrated in the range of 20-100 nm, providing a regular substrate for subsequent three-layer structure coating.

[0024] Intermediate layer coating: The prepared nano-graphite dispersion was mixed with aluminum nitrate solution at a mass ratio of 1:5, with an aluminum nitrate solution concentration of 0.2 mol / L. Coating was performed using the sol-gel method. The pH of the reaction system was adjusted to 4 using an acid-base regulator. The reaction temperature was controlled at 50℃ using a water bath heating method, and the reaction was continuously stirred at a constant temperature for 1.5 hours. By synergistically controlling the mass ratio of materials, pH value, reaction temperature, metal precursor concentration, and reaction time, uniform alumina was coated onto the surface of the nano-graphite material, ultimately obtaining a composite particle precursor with an intermediate layer thickness of 10-30 nm. Figure 2 As shown, the alumina intermediate layer obtained in this step is completely and densely coated on the surface of nano-graphite, with tight interlayer bonding and no gaps, which can avoid structural damage during subsequent processing and use.

[0025] Shell layer assembly: Molybdenum disulfide and deionized water were mixed at a solid-liquid mass ratio of 1:80 and ultrasonically dispersed for 25 min to prepare a dispersion with a mass concentration of 10 g / L. The composite particle precursor with an intermediate layer was added to the dispersion, maintaining a mass ratio of 1:10 with the dispersion. The mixture was ultrasonically dispersed for 15 min to ensure thorough mixing. The mixture was then stirred at a constant temperature of 25-35℃ for 1 h, followed by standing for 15 min to allow the molybdenum disulfide to firmly adhere to the surface of the composite particle precursor. The reacted system was centrifuged, and the precipitate was washed twice with deionized water. A molybdenum disulfide shell with a thickness of 5-20 nm was loaded onto the surface of the composite particle precursor to obtain a three-layer composite particle material. Figure 3 As shown, this step produces a molybdenum disulfide shell and intermediate layer that are firmly bonded together without peeling or delamination, forming a three-layer structure that is integrally molded and possesses stable lubrication support and surface protection synergistic characteristics.

[0026] Drying and compounding: The three-layer composite granular material was placed in a constant temperature drying oven and dried at 60℃ for 1.5h to remove residual moisture on the surface, resulting in dried composite granules. The synthetic ester base oil was heated to 35℃, and a dispersant was added. The mixture was stirred at 300r / min until the dispersant was completely dissolved. Then, an anti-wear extreme pressure agent was added and stirred for another 5min until the mixture was homogeneous. Finally, the dried composite granules were added and ultrasonically dispersed at 300W for 15min to assist in particle dispersion. The mixture was then stirred for another 8min to eliminate air bubbles. Subsequently, the mixture was homogenized under 15MPa pressure to obtain an energy-saving and environmentally friendly nano-graphite lubricant.

[0027] Performance test results: Friction coefficient test: The average friction coefficient was 0.062, which was tested using a four-ball friction tester. The interfacial friction resistance was small, the lubrication was stable and continuous, and there were no scratches or local wear on the surface of the friction pair. Extreme pressure load test: The maximum non-seize load PB value is 890N, which can be adapted to conventional light and medium load conditions. There is no seize or sintering damage to the friction pair. Dispersion stability test: The room temperature static sedimentation method was used for testing. After 7 days of static sedimentation, the particle sedimentation rate was 1.2%, the system homogeneity remained intact, and there was no obvious particle sedimentation. Environmental performance testing: The biodegradation rate was tested using the CO2 release method. The biodegradation rate was 78% after 28 days. Furthermore, the use of water-based solvents and low-temperature drying processes resulted in low energy consumption and no toxic or harmful additives or pollutant emissions.

[0028] Example 2: Raw material ratio (by weight): 12 portions of three-layer composite particles; 4 parts dispersant; 2 parts of anti-wear extreme pressure agent; 82 parts base oil.

[0029] The three-layer composite particles are composed of nano-graphite, alumina, and molybdenum disulfide in a mass ratio of 1:0.4:0.2. The dispersant is a compound of polyisobutylene succinimide, polymethyl methacrylate, and sorbitan oleate in a mass ratio of 2:1:1. The anti-wear extreme pressure agent is a compound of isobutylene sulfide, tricresyl phosphate, and borate in a mass ratio of 1:1:0.5. The base oil is a synthetic ester base oil.

[0030] Preparation method: Core preparation: Natural flake graphite was added to deionized water and stirred thoroughly until the graphite was completely saturated to form a uniform graphite suspension. The suspension was then ground using a wet mill at a speed of 3000 r / min for 3 hours. After grinding, the graphite suspension was allowed to stand for 30 minutes. The upper fine particle suspension was then taken and centrifuged at 8000 r / min for 15 minutes. The supernatant was discarded, and the centrifuged precipitate was washed three times with deionized water. After washing, the precipitate was sieved to obtain nano-graphite material with a particle size of 20-100 nm. The nano-graphite material was mixed with deionized water at a solid-liquid mass ratio of 1:10 and ultrasonically dispersed for 30 minutes to prepare a uniform nano-graphite dispersion.

[0031] Intermediate layer coating: Nano-graphite dispersion and aluminum nitrate solution were mixed at a mass ratio of 1:5, with the aluminum nitrate solution concentration being 0.2 mol / L. The coating process was carried out using the sol-gel method. The pH value of the reaction system was adjusted to 4 using an acid-base regulator. The reaction temperature was controlled at 50℃ using a water bath heating method, and the reaction was carried out with constant temperature and continuous stirring for 1.5 h. By synergistically controlling the mass ratio of the feed materials, pH value, reaction temperature, metal precursor concentration, and reaction time, a uniform transition metal oxide was coated on the surface of the nano-graphite material, finally obtaining a composite particle precursor with an intermediate layer thickness of 10-30 nm.

[0032] Shell layer assembly: Molybdenum disulfide and deionized water were mixed at a solid-liquid mass ratio of 1:80 and ultrasonically dispersed for 25 min to prepare a dispersion with a mass concentration of 10 g / L. The composite particle precursor with an intermediate layer was added to the dispersion, and the mass ratio of the composite particle precursor to the dispersion was controlled at 1:10. The mixture was ultrasonically dispersed for 15 min to ensure thorough mixing. The mixture was stirred at a constant temperature of 25-35℃ for 1 h, and then allowed to stand for 15 min to allow the molybdenum disulfide to firmly adhere to the surface of the composite particle precursor. The reaction system was then centrifuged and the precipitate was washed twice with deionized water. A self-lubricating inorganic nanoparticle shell with a thickness of 5-20 nm was loaded onto the surface of the composite particle precursor to obtain a three-layer composite particle material.

[0033] Drying and compounding: The three-layer composite granular material was placed in a constant temperature drying oven and dried at 60℃ for 1.5h to remove residual moisture from the particle surface, resulting in dried composite granules. The synthetic ester base oil was heated to 35℃, and a dispersant was added. The mixture was stirred at 300r / min until the dispersant was completely dissolved. Then, an anti-wear extreme pressure agent was added and stirred for another 5min until the mixture was homogeneous. Finally, the dried composite granules were added and ultrasonically dispersed at 300W for 15min to assist particle dispersion. The mixture was then stirred for another 8min to eliminate air bubbles. Subsequently, the mixture was homogenized under 15MPa pressure to obtain an energy-saving and environmentally friendly nano-graphite lubricant.

[0034] Performance test results: Friction coefficient test: The average friction coefficient was 0.058, which is more prominent under heavy load conditions. Extreme pressure load test: The maximum non-jamming load PB value is 980N through the four-ball extreme pressure test, which greatly improves the extreme pressure load capacity and can withstand the continuous operation of high-load equipment. Dispersion stability test: The room temperature static sedimentation method was used for testing. After 7 days of static sedimentation, the particle sedimentation rate was 0.8%, which showed excellent long-term stability with almost no particle sedimentation. Environmental performance testing: The biodegradation rate was tested using the CO2 release method. The biodegradation rate was 76% after 28 days. The water-based low-temperature green preparation process has significant energy-saving and carbon-reduction effects and meets environmental protection standards.

[0035] Comparative example: Raw material ratio (by weight): 10 parts of single nano-graphite particles; 3 parts dispersant; Anti-wear extreme pressure agent: 2 parts; Base oil: 85 parts.

[0036] The dispersant is polyisobutylene succinimide, the anti-wear extreme pressure agent is a compound of sulfide isobutylene, tricresyl phosphate and borate ester in a mass ratio of 1:1:0.5, and the base oil is a synthetic ester base oil.

[0037] Preparation method: Natural flake graphite was directly dry-ground without post-processing such as centrifugation, washing, or sieving, resulting in single nano-graphite particles with uneven particle size distribution. The synthetic ester base oil was placed in a reaction vessel, heated to 35°C, and a single-component polyisobutylene succinimide dispersant was added. The mixture was stirred at 300 r / min until completely dissolved. Add the anti-wear extreme pressure agent and continue stirring for 5 minutes to ensure that all additives are mixed evenly. Then add the single nano-graphite particles. The conventional nano-lubricant was prepared by ultrasonic dispersion at 300W for 15 minutes, stirring for 8 minutes to eliminate air bubbles, and homogenization under 15MPa pressure.

[0038] This comparative example uses a traditional physical blending process, without a three-layer coating structure, without a ternary complex dispersion system, and does not employ an aqueous stepwise preparation process. Performance test results: Friction coefficient test: The average friction coefficient was 0.115, indicating poor interfacial lubrication and severe wear of the friction pair. Extreme pressure load test: The maximum non-seize load PB value was 520N through the four-ball extreme pressure test. The extreme pressure load capacity is weak and seize and sintering are prone to occur under high load. Dispersion stability test: The room temperature static sedimentation method was used for testing. After 7 days of static sedimentation, the particle sedimentation rate was 18.6%, indicating prominent problems of agglomeration and phase separation. Environmental performance testing: The biodegradation rate was tested using the CO2 release method. The biodegradation rate was 42% after 28 days. The preparation process lacked green and energy-saving control, resulting in poor environmental performance.

[0039] In summary, by constructing a three-layer integrated composite particle with nano-graphite as the core, transition metal oxide as the intermediate layer, and self-lubricating inorganic nanoparticles as the outer shell, and combining it with a ternary compound dispersant and a ternary compound anti-wear extreme pressure agent, and employing a green preparation process using water-based solvents and low-temperature drying, the technical challenges of existing nano-lubricating materials, such as easy structural failure, poor dispersion stability, insufficient extreme pressure performance, and weak environmental friendliness, have been solved. Example 1 is suitable for general light / medium load lubrication scenarios, while Example 2, by adjusting the dosage of the three-layer composite particles and dispersant, can meet the needs of heavy-load long-term lubrication. The formulation is flexible and adjustable, with strong scenario adaptability. While ensuring excellent lubrication and friction reduction, extreme pressure load-bearing capacity, and dispersion stability, it also has the environmental and energy-saving advantages of being water-based, low-energy consumption, free of toxic components, and having a high biodegradability rate. It fully meets the green, efficient, and long-term lubrication development needs of modern industry and has extremely high industrial application value.

[0040] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. An energy-saving and environmentally friendly nano-graphite lubricant, characterized in that, The lubricant, by weight, comprises: Three-layer composite particles: 5-15 parts; Dispersant: 2-5 parts; Anti-wear extreme pressure agent: 1-3 parts; Base oil: 60-85 parts.

2. The energy-saving and environmentally friendly nano-graphite lubricant according to claim 1, characterized in that, The three-layer composite particles are composed of nano-graphite, transition metal oxide, and self-lubricating inorganic nanoparticles. The mass ratio of nano-graphite, transition metal oxide, and self-lubricating inorganic nanoparticles is 1:0.2-0.6:0.1-0.

4. Nano-graphite forms the core, transition metal oxide forms the middle layer, and self-lubricating inorganic nanoparticles form the outer shell. The particle size of the core is 20-100 nm, the thickness of the middle layer is 10-30 nm, and the thickness of the outer shell is 5-20 nm. The transition metal oxide is alumina or zirconium oxide, and the self-lubricating inorganic nanoparticles are molybdenum disulfide or tungsten disulfide.

3. The energy-saving and environmentally friendly nano-graphite lubricant according to claim 1, characterized in that, The dispersant is a composition of polyisobutylene succinimide, polymethacrylate, and sorbitan oleate, wherein the mass ratio of polyisobutylene succinimide, polymethacrylate, and sorbitan oleate is 1-3:0.5-2:0.5-1.

5.

4. The energy-saving and environmentally friendly nano-graphite lubricant according to claim 1, characterized in that, The anti-wear extreme pressure agent is a composition of isobutylene sulfide, tricresyl phosphate, and borate ester, wherein the mass ratio of isobutylene sulfide, tricresyl phosphate, and borate ester is 0.5-2:0.3-1.5:0.2-1.

5. The energy-saving and environmentally friendly nano-graphite lubricant according to claim 1, characterized in that, The base oil is a synthetic ester base oil or a mineral base oil.

6. A method for preparing an energy-saving and environmentally friendly nano-graphite lubricant, the method being applicable to the energy-saving and environmentally friendly nano-graphite lubricant according to any one of claims 1-5, characterized in that, The specific steps of this method are as follows: Nucleus preparation: Natural flake graphite is placed in an aqueous solvent and wet-milled or intercalated and exfoliated, and then post-processed to obtain nano-graphite material, which is then mixed with an aqueous solvent to obtain nano-graphite dispersion. Intermediate layer coating: The nano-graphite dispersion is mixed with the metal precursor solution, and the transition metal oxide is coated on the surface of the nano-graphite material by sol-gel method or co-precipitation method to obtain a composite particle precursor with an intermediate layer. Shell layer assembly: Self-lubricating inorganic nanoparticles are prepared into a dispersion, and then the composite particle precursor with the middle layer is mixed with the dispersion to obtain a three-layer composite particle material. Drying and compounding: The three-layer composite granular material is dried at low temperature to obtain dried composite granules, which are then mixed with base oil, dispersant, and anti-wear extreme pressure agent. After ultrasonic dispersion and homogenization, a lubricant is obtained.

7. The preparation method of an energy-saving and environmentally friendly nano-graphite lubricant according to claim 6, characterized in that, In the core preparation process, the aqueous solvent is deionized water or an aqueous ethanol solution; the wet grinding speed is 3000-5000 r / min, and the grinding time is 2-4 h; the intercalation and exfoliation process uses sulfuric acid or nitric acid as the intercalating agent, with an intercalating agent concentration of 0.5-1 mol / L in an aqueous system, the exfoliation temperature is 25-40℃, and the exfoliation time is 1-3 h; the post-processing steps are: after standing, centrifugation, washing with deionized water, and sieving, nano-graphite material with a particle size of 20-100 nm is obtained; the nano-graphite material is mixed with an aqueous solvent at a solid-liquid mass ratio of 1:8-12, and ultrasonically dispersed to prepare a nano-graphite dispersion.

8. The preparation method of an energy-saving and environmentally friendly nano-graphite lubricant according to claim 6, characterized in that, In the intermediate layer coating, a nano-graphite dispersion and a metal precursor solution are mixed at a mass ratio of 1:4-6. When the transition metal oxide is alumina, the metal precursor solution is a 0.1-0.3 mol / L aluminum nitrate solution or an aluminum isopropoxide solution; when the transition metal oxide is zirconium oxide, the metal precursor solution is a 0.2-0.4 mol / L zirconium oxychloride solution or a zirconium n-propoxide solution. When using the sol-gel method, the reaction pH is adjusted by an acid-base regulator. The pH value is 3-5, the reaction temperature is controlled at 40-60℃ by water bath, the metal precursor concentration is 0.1-0.3mol / L, and the reaction time is 1-2h; when using the co-precipitation method, the pH value of the reaction is adjusted to 8-10 by acid-base regulator, the reaction temperature is controlled at 60-80℃ by water bath, the metal precursor concentration is 0.2-0.4mol / L, and the reaction time is 0.5-1h; finally, a composite particle precursor with an intermediate layer is obtained, and the intermediate layer is 10-30nm.

9. The method for preparing an energy-saving and environmentally friendly nano-graphite lubricant according to claim 6, characterized in that, In the outer shell assembly, self-lubricating inorganic nanoparticles are mixed with an aqueous solvent at a solid-liquid mass ratio of 1:60-100, ultrasonically dispersed for 20-30 minutes to prepare a dispersion with a mass concentration of 5-15 g / L. The composite particle precursor with an intermediate layer is added to the dispersion at a mass ratio of 1:5-15, ultrasonically dispersed for 10-20 minutes, stirred at a constant temperature of 25-35℃ for 0.5-1.5 hours, and allowed to stand for 10-20 minutes. Self-lubricating inorganic nanoparticles with a thickness of 5-20 nm are loaded onto the surface of the composite particle precursor with an intermediate layer to form an outer shell. The mixture is then centrifuged and washed 2-3 times with deionized water to obtain a three-layer composite particle material.

10. The method for preparing an energy-saving and environmentally friendly nano-graphite lubricant according to claim 6, characterized in that, In the drying and compounding process, the low-temperature drying temperature is 40-80℃ and the drying time is 1-2 hours. The base oil is heated to 30-40℃, a dispersant is added and stirred until completely dissolved, then an anti-wear extreme pressure agent is added and mixed evenly. Finally, the dried composite particles are added, ultrasonically dispersed at 200-400W power for 10-20 minutes, stirred for 5-10 minutes, and homogenized under 10-20MPa pressure to obtain the lubricant.

Images