Modified graphene oxide / chlorite / boron nitride composite lubricant additive, preparation method and application thereof

Abstract

The present invention discloses a modified graphene oxide / chlorite / boron nitride composite lubricant additive, its preparation method, and its application. The preparation steps include modifying graphene oxide with a silane coupling agent, modifying boron nitride with sodium hydroxide, and obtaining the modified graphene oxide / chlorite / boron nitride composite material by ball milling. When used as a lubricant additive, this composite material effectively reduces the coefficient of friction with only a small addition amount and forms a self-healing film on the worn surface, further enhancing the friction-reducing and anti-wear properties of the friction surface.

Description

Technical Field

[0001] The present invention belongs to the technical field of lubricating oils, and in particular relates to a modified graphene oxide / chlorite / boron nitride composite lubricating oil additive, a preparation method and applications thereof. Background Art

[0002] Friction and wear are the primary causes of component failure. To this end, researchers have made significant efforts to reduce friction and anti-wear in workpieces. Graphene, due to its unique structure, possesses strong mechanical properties. Its high strength, high tensile strength, and high elastic modulus can significantly improve the friction, wear, and mechanical properties of materials. Furthermore, due to its excellent mechanical properties and the shear force between its microplatelets, graphene has a lower coefficient of friction than graphite, demonstrating excellent anti-friction and lubricity. Cura et al. selected two different lubricants as matrices and found that the addition of graphene reduced the mean friction coefficient and the fluctuation range of the friction coefficient, demonstrating that graphene not only has a lubricating effect but also enhances the stability of the tribological system [CURàF, MURA A, ADAMO F. Experimental investigation about tribological performance of graphene-nanoplatelets as additive for lubricants [J]. Procedia Structural Integrity, 2018, 12:44-51.]. Graphene oxide has excellent lubrication properties similar to those of graphene due to the van der Waals force between its layers. At the same time, the surface is rich in oxygen-containing functional groups, which enable it to react and bond with other substances through functional groups, thereby exerting a synergistic effect and showing better friction reduction and anti-wear properties [Liu Ping, Tang Jian, et al. Modification of graphene oxide and its tribological properties in mineral oil [J]. Journal of Tribology, 2020, 40(1): 30-39.]. Hexagonal boron nitride has a lamellar structure similar to that of graphene and can also play a good lubricating role. Moreover, it is more effective as a lubricating additive than molybdenum disulfide and graphite [Guo Qiliang. Anti-friction effect of boron nitride as a lubricant additive [J]. China Mechanical Engineering, 1995(2): 57-58.]. Silicate minerals can be used as lubricating materials because the bonding force between their aluminum oxide layer and silicon oxide layer is weak and they are very easy to dissociate along the interlayer. For example, muscovite micropowder as a mineral oil additive can significantly improve the lubrication properties of oil samples [Yuan Ke, Wang Chengbiao, Yue Wen, et al. Tribological Properties of Muscovite Mineral Lubricant Additives [J]. Lubrication and Sealing, 2008, 08: 61-65.]. Chlorite is also a type of silicate mineral. It is a TOT-type layered silicate composed of tetrahedrons and octahedrons. The interlayer domains are filled with octahedral sheets with the same structure as brucite. The interlayer bonding force is mainly van der Waals forces and ionic bonds, and it also has a certain lubricating effect [Li Yujunwen. Preparation and Tribological Properties of Graphene-Silicate Composites [D]. Nanjing University of Science and Technology, 2021.]. Summary of the Invention

[0003] The present invention aims to provide a modified graphene oxide / chlorite / boron nitride composite lubricating oil additive, a preparation method and applications thereof.

[0004] In order to achieve the above-mentioned purpose, the technical solution adopted by the present invention is as follows: a modified graphene oxide / chlorite / boron nitride composite lubricating oil additive and a preparation method thereof, comprising the following steps:

[0005] (1) pre-hydrolyzing a silane coupling agent in deionized water for 15-60 min, adding a dispersion of graphene oxide, reacting at 40-90° C. for 0.5-4 h, separating, washing, and drying to obtain modified graphene oxide;

[0006] (2) adding 6 mol / L sodium hydroxide solution to the boron nitride aqueous dispersion, reacting at 100-200° C. for 6-24 hours, cooling, separating, washing, and drying to obtain modified boron nitride;

[0007] (3) taking the modified graphene oxide, chlorite and modified boron nitride in step (1), adding deionized water and ball milling at a certain speed for a certain time, separating and washing after the ball milling to obtain a modified graphene oxide / chlorite / boron nitride composite lubricating oil additive.

[0008] Preferably, in step (1), the amount of silane coupling agent added is 0.1-10 mL of silane coupling agent per gram of graphene oxide.

[0009] Preferably, in step (1), the dispersant in the graphene oxide dispersion is ethanol or deionized water.

[0010] Preferably, in step (2), the mass ratio of sodium hydroxide to boron nitride is 24:1.

[0011] Preferably, in step (3), the ball milling speed is 100-550 r / min, and the ball milling time is 2-12 h.

[0012] Preferably, in step (3), the mass ratio of modified graphene oxide: chlorite: modified boron nitride is 1: (0.1-6): (0.1-1), more preferably 1: (2-4): (0.2-0.5).

[0013] Use of the modified graphene oxide / chlorite / boron nitride composite lubricant additive in lubricating oil.

[0014] Preferably, the concentration of the additive in the lubricating oil is 0.1-3 mg / mL.

[0015] Preferably, the lubricant is any brand and any model of lubricant, such as Kunlun Scorpio F5000, SF15W-40 lubricant and Great Wall J600F lubricant, as well as any mineral base oil or synthetic base oil.

[0016] Compared with the prior art, the advantages of the present invention are:

[0017] The present invention uses ball milling to obtain a chemically bonded ternary composite material, in which the functional groups on the silane coupling agent-modified graphene oxide, chlorite, and modified boron nitride are all able to bond with each other, and the three layers can be intercalated and compounded under the action of ball milling to form a three-component composite product. Furthermore, the heat released by the direct ball milling reaction can accelerate the reaction, resulting in a modified graphene oxide / chlorite / boron nitride composite material with better bonding. The three components work together to not only reduce friction and resist wear, but also form a high-hardness self-healing film. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 1 and 2 are infrared images of the lubricating oil additive A1 and each single component material prepared in Example 1.

[0019] Figure 2 TEM images of the lubricating oil additive A1 prepared in Example 1 and the lubricating oil additive A2 prepared in Comparative Example 1 are shown.

[0020] Figure 3 Graph showing the tribological test results of the lubricating oil additive A1 prepared in Example 1 and the lubricating oil additive A2 prepared in Comparative Example 1 at an addition amount of 0.3 mg / mL.

[0021] Figure 4 Graph showing the tribological test results of the lubricating oil additive B1 prepared in Example 2 and the lubricating oil additive B2 prepared in Comparative Example 2 at an addition amount of 1 mg / mL. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below through specific embodiments, but the embodiments do not limit the present invention in any form.

[0023] The present invention uses a ternary inorganic nanocomposite material formed by compounding modified graphene oxide, chlorite and modified boron nitride through a ball milling method as a lubricating oil additive, which greatly improves the lubricating performance of the oil and plays an anti-wear and friction-reducing role.

[0024] Example 1:

[0025] (1) Using graphene oxide as a raw material, an aqueous dispersion of graphene oxide was prepared. 8.9 mL of a graphene oxide dispersion with a solid content of 11.26 mg / mL was taken and added to 91.1 mL of ethanol to disperse the mixture evenly. 1000 μL of a silane coupling agent (KH-550) was added dropwise to 10 mL of deionized water and stirred at room temperature for pre-hydrolysis for 60 min. The pre-hydrolyzed silane coupling agent aqueous solution was added dropwise to the graphene oxide dispersion, stirred at room temperature for 30 min, and then transferred to a flask and stirred in a water bath at 70°C for 3 h. The modified graphene oxide was obtained after separation, washing, and drying.

[0026] (2) 500 mg of nano-boron nitride was added to 50 mL of 6 mol / L sodium hydroxide aqueous solution and dispersed evenly. After stirring at room temperature for 30 min, the mixture was transferred to a reactor and hydrothermally reacted at 150°C for 10 h. The mixture was separated, washed, and dried to obtain modified boron nitride.

[0027] (3) Take all the modified graphene oxide (about 100 mg) obtained by drying in (1), 200 mg of chlorite and 100 mg of modified boron nitride, add 50 mL of deionized water and ball mill at a speed of 400 r / min for 8 hours. After the milling, separate and wash to obtain a modified graphene oxide / chlorite / boron nitride composite lubricant additive, named lubricant additive A1. The infrared image of lubricant additive A1 is as follows: Figure 1 As shown, it can be seen that chlorite and modified boron nitride are successfully composited with modified graphene oxide. The micromorphology TEM image of lubricating oil additive A1 is shown in Figure 2 As shown in (a), it can be seen from the figure that the modified graphene oxide, chlorite and modified boron nitride are connected by chemical bonds under the action of high-speed ball milling, and the sheets are intercalated to form a stable complex, which can better exert the anti-friction and anti-wear effects.

[0028] (4) Tribological performance evaluation

[0029] The prepared lubricating oil additive A1 was mixed with Kunlun Scorpio F5000 lubricating oil in different proportions. The friction and wear test was carried out using an MRS-10G four-ball friction and wear tester, and a GCr15 steel ball with a diameter of 12.7 mm was used for the test. Test conditions: load 197N, speed 600rpm, time 3600s. Table 1 shows the average friction coefficient and wear spot diameter of the lubricating oil additive A1 oil sample at different concentrations in this example, and for comparison, the test results of graphene oxide at a concentration of 0.3 mg / mL in Kunlun Scorpio F5000 lubricating oil are given. The friction test curve of the oil sample at an addition amount of 0.3 mg / mL of lubricating oil additive A1 is shown in Table 1. Figure 3This demonstrates that lubricant additive A1 exhibits excellent lubrication properties, reducing the coefficient of friction by approximately 53.9% and the wear spot diameter by approximately 20.2% compared to lubricant alone. Microhardness testing of the wear spot surface was also conducted, and the test results, shown in Table 2, show that lubricant additive A1, as a lubricant additive, increased the hardness of the wear spot surface by 48.5% compared to lubricant alone.

[0030] Table 2 Test results of average microhardness of wear spot surface in Example 1

[0031]

[0032] Comparative Example 1

[0033] For comparison, steps (1) and (2) of Example 1 were repeated, and modified graphene oxide (about 100 mg), 200 mg of chlorite, and 100 mg of modified boron nitride were added to 50 mL of deionized water and stirred at a speed of 400 r / min for 8 h. After separation and washing, a modified graphene oxide, chlorite, and boron nitride mixed material lubricant additive was obtained, which was named lubricant additive A2. The micromorphology TEM image of lubricant additive A2 is shown in FIG. Figure 2 As shown in (b) in Figure 2 From the comparison in (a), we can see that the modified graphene oxide, chlorite and modified boron nitride were not successfully compounded, and obvious agglomeration occurred, which made it difficult for the material to exert its friction reduction and anti-wear effects, indicating that ball milling is a key technology for preparing composite materials.

[0034] The lubricating oil additive A2 obtained by mixing the above components in the same proportion was added to Kunlun Scorpio F5000 lubricating oil at a concentration of 0.3 mg / mL. A friction test was carried out under the same conditions as in Example 1. The friction test curve obtained is shown in FIG. Figure 3 By comparison, it can be seen that the friction coefficient of the oil sample containing lubricant additive A2 is extremely high. Compared with pure lubricant, the average friction coefficient increased by 24.2%, and the wear spot diameter increased by 2.6%. Compared with the oil sample containing lubricant additive A1 at a concentration of 0.3 mg / mL, the average friction coefficient of lubricant additive A2 increased by 169.5%, and the wear spot diameter increased by 28.6%. This shows that stirring cannot effectively compound the materials, and the material particle size is too large to exert the friction reduction and anti-wear effect. This shows that ball milling is a key technology for preparing composite materials.

[0035] Example 2:

[0036] (1) Using graphene oxide as a raw material, an aqueous dispersion of graphene oxide was prepared. 8.9 mL of a graphene oxide dispersion with a solid content of 11.26 mg / mL was taken and added to 91.1 mL of deionized water for uniform dispersion. 10 μL of a silane coupling agent (KH-560) was added dropwise to 10 mL of deionized water and stirred at room temperature for pre-hydrolysis for 15 min. The pre-hydrolyzed silane coupling agent aqueous solution was added dropwise to the graphene oxide dispersion, stirred at room temperature for 30 min, and then transferred to a flask and stirred in a water bath at 90°C for 0.5 h. The modified graphene oxide was obtained after separation, washing, and drying.

[0037] (2) 500 mg of boron nitride was added to 50 mL of a 6 mol / L sodium hydroxide aqueous solution and dispersed evenly. After stirring at room temperature for 30 min, the mixture was transferred to a reactor and hydrothermally reacted at 100°C for 24 h. The mixture was separated, washed, and dried to obtain modified boron nitride.

[0038] (3) All the modified graphene oxide (about 100 mg) dried in (1) was added with 600 mg of chlorite and 10 mg of modified boron nitride, and the mixture was ball-milled at a speed of 100 r / min for 12 h. After the milling, the mixture was separated and cleaned to obtain a modified graphene oxide / chlorite / boron nitride composite lubricant additive, which was named lubricant additive B1.

[0039] (4) Tribological performance evaluation

[0040] The prepared lubricant additive B1 was mixed with Kunlun Scorpio SF15W-40 lubricant in different proportions. The friction and wear test was carried out using an MRS-10G four-ball friction and wear tester, and a GCr15 steel ball with a diameter of 12.7 mm was used for the test. Test conditions: load 197N, speed 600rpm, time 3600s. Table 1 shows the average friction coefficient and wear spot diameter of the lubricant additive B1 at different concentrations in this example, and for comparison, the test results of chlorite at a concentration of 1 mg / mL in Kunlun Scorpio SF15W-40 lubricant are given. It can be seen that the lubricant additive B1 has excellent lubrication properties, and the friction coefficient can be reduced by about 34.2% compared to that of pure lubricant, and the wear spot diameter is reduced by about 18.8%.

[0041] Comparative Example 2

[0042] For comparison, steps (1) and (3) of Example 2 were repeated, except that in step (3), the modified boron nitride was replaced with ordinary boron nitride (unmodified boron nitride). A modified graphene oxide / chlorite / boron nitride composite lubricant additive was prepared by ball milling using ordinary boron nitride in the same proportion and under the same conditions. The lubricant additive was named lubricant additive B2 for subsequent testing.

[0043] The lubricating oil additive B2 prepared by ball milling unmodified boron nitride was added to Kunlun Scorpio SF15W-40 lubricating oil at a concentration of 1 mg / mL, and a friction test was carried out under the same conditions as in Example 2. The friction test curve obtained is shown in FIG. Figure 4 By comparison, the friction coefficient of the lubricant additive B2 sample was only reduced by 27.5% compared to the pure lubricant, and the wear spot diameter was only reduced by 10.7%. This indicates that the unmodified boron nitride cannot chemically bond with the other two components to form a stable ternary composite material, resulting in poor synergy and weak friction and anti-wear effects. This indicates that modifying boron nitride is a key technology in the preparation of modified graphene oxide / chlorite / boron nitride composites.

[0044] Example 3:

[0045] (1) Using graphene oxide as a raw material, an aqueous dispersion of graphene oxide was prepared. 8.9 mL of a graphene oxide dispersion with a solid content of 11.26 mg / mL was taken and added to 91.1 mL of deionized water for uniform dispersion. 800 μL of a silane coupling agent (KH-570) was added dropwise to 10 mL of deionized water and stirred at room temperature for pre-hydrolysis for 40 min. The pre-hydrolyzed silane coupling agent aqueous solution was added dropwise to the graphene oxide dispersion, stirred at room temperature for 30 min, and then transferred to a flask and stirred in a water bath at 40°C for 4 h. The modified graphene oxide was obtained after separation, washing, and drying.

[0046] (2) 500 mg of nano-boron nitride was added to 50 mL of 6 mol / L sodium hydroxide aqueous solution and dispersed evenly. After stirring at room temperature for 30 min, the mixture was transferred to a reactor and hydrothermally reacted at 130°C for 15 h. The mixture was separated, washed, and dried to obtain modified boron nitride.

[0047] (3) All the modified graphene oxide (about 100 mg) dried in (1) was added with 10 mg of chlorite and 100 mg of modified boron nitride, and the mixture was ball-milled at a speed of 550 r / min for 2 h. After the milling, the mixture was separated and cleaned to obtain a modified graphene oxide / chlorite / boron nitride composite lubricant additive, which was named lubricant additive C1.

[0048] (4) Tribological performance evaluation

[0049] The prepared lubricating oil additive C1 was mixed with Great Wall J600F lubricating oil. The friction and wear test was carried out using an MRS-10G four-ball friction and wear tester, and a GCr15 steel ball with a diameter of 12.7 mm was used for the test. Test conditions: load 197 N, speed 600 rpm, time 3600 s. Table 1 shows the average friction coefficient and wear spot diameter of the lubricating oil additive C1 oil sample in this example, and for comparison, the test results of the modified boron nitride in the Great Wall J600F lubricating oil at a concentration of 0.1 mg / mL are given. It can be seen that the lubricating oil additive C1 has excellent lubrication performance, and the friction coefficient can be reduced by about 44.3% compared with the pure lubricating oil, and the wear spot diameter is reduced by about 13.7%.

[0050] Example 4:

[0051] (1) Using graphene oxide as a raw material, an aqueous dispersion of graphene oxide was prepared. 8.9 mL of a graphene oxide dispersion with a solid content of 11.26 mg / mL was taken and added to 91.1 mL of ethanol to disperse the dispersion evenly. 400 μL of a silane coupling agent (KH-792) was added dropwise to 10 mL of deionized water and stirred at room temperature for pre-hydrolysis for 20 min. The pre-hydrolyzed silane coupling agent aqueous solution was added dropwise to the graphene oxide dispersion, stirred at room temperature for 30 min, and then transferred to a flask and stirred in a water bath at 70°C for 2 h. The modified graphene oxide was obtained after separation, washing, and drying.

[0052] (2) 500 mg of nano-boron nitride was added to 50 mL of 6 mol / L sodium hydroxide aqueous solution and dispersed evenly. After stirring at room temperature for 30 min, the mixture was transferred to a reactor and hydrothermally reacted at 200°C for 6 h. The mixture was separated, washed, and dried to obtain modified boron nitride.

[0053] (3) All the modified graphene oxide (about 100 mg) dried in (1) was added with 500 mg of chlorite and 70 mg of modified boron nitride, and the mixture was ball-milled at a speed of 200 r / min for 10 h. After the milling, the mixture was separated and washed to obtain a modified graphene oxide / chlorite / boron nitride composite lubricant additive, which was named lubricant additive D1.

[0054] (4) Tribological performance evaluation

[0055] The prepared lubricant additive D1 was mixed with Great Wall J600F lubricant. Friction and wear tests were conducted using an MRS-10G four-ball friction and wear tester, employing GCr15 steel balls with a diameter of 12.7 mm. Test conditions: load 197 N, rotation speed 600 rpm, and time 3600 s. Table 1 shows the average friction coefficient and wear spot diameter of the lubricant additive C1 sample used in this example. It can be seen that lubricant additive D1 exhibits excellent lubrication properties, reducing the friction coefficient by approximately 14.5% and the wear spot diameter by approximately 3.2% compared to lubricant alone.

[0056] Table 1 Friction coefficient and wear spot diameter of composite lubricant additives under different examples

[0057]

[0058]

[0059] The above descriptions are merely examples of several embodiments of the present invention and are not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, they are not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the present invention, make slight changes or modifications to the above-disclosed structures and technical contents to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the present invention are still within the scope of the present invention.

Claims

1. A method for preparing a modified graphene oxide / chlorite / boron nitride composite lubricating oil additive, characterized in that: The steps include: (1) Pre-hydrolyzing the silane coupling agent in deionized water for 15-60 min, adding the graphene oxide dispersion, reacting at 40-90 °C for 0.5-4 h, separating, washing, and drying to obtain modified graphene oxide; (2) Add 6 mol / L sodium hydroxide solution to the boron nitride aqueous dispersion, react at 100-200 °C for 6-24 hours, cool, separate, wash, and dry to obtain modified boron nitride; (3) The modified graphene oxide, chlorite and modified boron nitride in step (1) are added to deionized water and ball-milled at a certain speed for a certain time. After the ball milling is completed, the mixture is separated and washed to obtain a modified graphene oxide / chlorite / boron nitride composite lubricant additive, wherein the mass ratio of modified graphene oxide:chlorite:modified boron nitride is 1:(0.1-6):(0.1-1).

2. The method according to claim 1, wherein In step (1), the amount of silane coupling agent added is 0.1-10 mL of silane coupling agent per gram of graphene oxide.

3. The method according to claim 1, wherein In step (1), the dispersant in the graphene oxide dispersion is ethanol or deionized water.

4. The method according to claim 1, wherein In step (2), the mass ratio of sodium hydroxide to boron nitride is 24:

1.

5. The method according to claim 1, wherein In step (3), the ball milling speed is 100-550 r / min, and the ball milling time is 2-12 h.

6. The method according to claim 1, wherein In step (3), the mass ratio of modified graphene oxide: chlorite: modified boron nitride is 1: (2-4): (0.2-0.5).

7. A modified graphene oxide / chlorite / boron nitride composite lubricating oil additive prepared by the method according to any one of claims 1 to 6.

8. Use of the modified graphene oxide / chlorite / boron nitride composite lubricant additive prepared by the method according to any one of claims 1 to 6 in lubricating oil.

9. The use according to claim 8, wherein The concentration of this additive in lubricating oil is 0.1-3 mg / mL.

10. The use according to claim 8, characterized in that The lubricant is Kunlun Scorpio F5000, SF15W-40 lubricant or Great Wall J600F lubricant.

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