Preparation method of water-soluble nano-copper and its application as an additive for water-based lubricating fluids when compounded with proton-type ionic liquids.

Abstract

This invention discloses a method for preparing water-soluble copper nanoparticles and their application as an additive in water-based lubricants when compounded with a proton-type ionic liquid. The invention rapidly and on a large scale prepares anionicly anchored copper nanoparticles through in-situ surface modification. The anionic groups are then modified with a thiol-containing surfactant to obtain water-soluble organic compounds that modify the surface of metallic copper, forming stable organic monomolecule-modified copper nanoparticles. Simultaneously, the resulting water-soluble copper nanoparticles, when compounded with a proton-type ionic liquid, can be stably dispersed in an aqueous-alcoholic system for a long period without oxidation, and imparts extremely high extreme pressure anti-wear lubrication performance to the system, exhibiting a low coefficient of friction and a maximum non-seizure Pg. B The maximum value can reach 3090N.

Description

Technical Field

[0001] This invention relates to a water-based lubricant additive, specifically to a method for preparing water-soluble nano-copper with high extreme pressure lubrication performance and its application in combination with proton-type ionic liquid as a water-based lubricant additive. Background Technology

[0002] Copper nanoparticles exhibit excellent extreme pressure and anti-wear properties as lubricant additives. In previous studies, Professor Zhang Zhijun of Henan University prepared an oil-soluble copper nanoparticle (CN110744068A) with no waste generation, and it demonstrated excellent lubrication and anti-wear properties as an organic solvent additive. However, research reports on water-soluble copper nanoparticles are still limited. Professor Zhang's team also reported a water-soluble copper nanoparticle (CN102554217A), in which a stable organic monomolecule-modified copper nanosol is formed on the surface. However, the main problem with this work is that the modifiers used are small-molecule organic compounds such as mercaptoacetic acid and mercaptoacrylic acid, with carbon chain lengths less than 5. When the concentration of the prepared copper nanoparticles in the liquid is high, they are prone to aggregation and cannot be repeatedly separated and dispersed in water. Therefore, developing a method for preparing copper nanoparticles that are stably dispersed in water has significant practical application value.

[0003] Ionic liquids are salts composed entirely of cations and anions that are liquid at or near room temperature; they are also known as low-temperature molten salts. They possess advantages such as high heat capacity, strong solubility, high chemical stability, low viscosity, high density, and low vapor pressure, which makes them suitable as lubricant additives with excellent extreme pressure anti-wear properties. Cai Meirong of the Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, reported a proton-type ionic liquid (CN110105228A) that uses an alcoholamine as the organic cation and phosphate ester or sulfonic acid as the organic anion. Its anti-friction and anti-wear performance as a water-based additive was evaluated using an SRV-IV micro-vibration friction and wear tester. The results demonstrate that this type of proton-type ionic liquid exhibits excellent lubrication performance as a water-based additive. Summary of the Invention

[0004] This invention provides water-soluble copper nanoparticles with uniform and controllable particle size and morphology. The particle size is between 1 and 10 nm and the distribution is uniform. These nanoparticles can be stably dispersed in water for a long period and do not exhibit irreversible aggregation or decomposition even after repeated separation and dispersion in water. This invention utilizes the strong interaction between sulfur atoms in xanthate and copper nanoparticles from the perspectives of in-situ surface modification and molecular design. Furthermore, it leverages the stronger coordination between bidentate ligands and metals compared to monodentate ligands. Therefore, the particle size of the xanthate-modified copper nanoparticles is more easily controlled.

[0005] Meanwhile, this invention utilizes an in-situ surface modification method. Specifically, during the initial formation of copper nanoparticles, a surface modifier binds to the surface of the copper nanoparticles through coordination bonds or other strong chemical bonds. This alters the surface microstructure of the copper nanoparticles, ensuring that they are dispersed in the medium as individual particles. This prevents further growth and aggregation of the copper nanoparticles, and the coating effect of the surface modifier also prevents the oxidation of the metallic copper nanoparticles in air, thus improving their stability.

[0006] The purpose of this invention is to provide a method for preparing water-soluble nano-copper and its application in combination with proton-type ionic liquids as an additive in water-based lubricants. This objective is achieved through the following technical solutions:

[0007] A method for preparing water-soluble nano-copper involves in-situ surface modification using thiol-containing polyethylene glycol monomethyl ether copper xanthate, which is reduced by a reducing agent in a one-pot process.

[0008] Furthermore, in the method for preparing the water-soluble nano-copper sulfide, the copper xanthate is prepared by ion exchange between water-soluble xanthate anions and water-soluble copper salts.

[0009] Furthermore, in the preparation method of the water-soluble nano copper sulfide, the copper source in the preparation of the xanthate copper is any one of copper sulfide, copper chloride, copper sulfate, copper nitrate, and copper acetate, with copper nitrate being preferred.

[0010] Furthermore, in the preparation method of the water-soluble nano-copper, the xanthate group is water-soluble and has a carbon chain length of 10-35 (e.g., carbon chain lengths of 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34 or 35), preferably 33.

[0011] Furthermore, in the preparation method of the water-soluble nano-copper, in the preparation of copper xanthate, the molar ratio of copper ions to xanthate is 1:1 to 5 (for example, the molar ratio of copper ions to xanthate is 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5 or 1:5), preferably 1:1.

[0012] Furthermore, in the method for preparing the water-soluble nano-copper, the concentration of the copper xanthate solution is 0.001–1 mol / L, preferably 0.01 mol / L.

[0013] Furthermore, in the method for preparing the water-soluble nano-copper, the reducing agent used is any one of hydrazine hydrate, sodium borohydride, and formaldehyde, with sodium borohydride being preferred.

[0014] Furthermore, in the preparation method of the water-soluble nano-copper, the reaction temperature is 10-30℃, preferably 25℃.

[0015] Furthermore, in the method for preparing the water-soluble nano-copper, the reaction system used is deionized water or an aqueous ethanol solution, preferably deionized water.

[0016] Specifically, a method for preparing water-soluble nano-copper includes the following steps:

[0017] Polyethylene glycol monomethyl ether xanthate and deionized water were mixed to obtain solution A;

[0018] Copper nitrate and deionized water are mixed to obtain solution B.

[0019] The reducing agent and deionized water are mixed to obtain solution C.

[0020] Solution B was added to solution A and stirred. Then solution C was added dropwise to the system and stirred continuously. After extraction and drying, copper nanoparticles were obtained.

[0021] The application of water-soluble nano-copper prepared by any of the above preparation methods, combined with proton-type ionic liquids, as an additive for water-based lubricants.

[0022] Furthermore, the preparation method of the proton-type ionic liquid includes the following steps: mixing equal amounts of phosphate ester and alcoholamine evenly and then heat-treating the mixture; after the reaction is completed, removing the solvent by vacuum distillation to obtain a colorless or pale yellow viscous solid.

[0023] Further, water-soluble nano-copper, a proton-type ionic liquid, a polyol, and deionized water are mixed to obtain a water-based lubricant. Preferably, the polyol is at least one of glycerol, polyethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, ethanol, and ethylene glycol. Preferably, the mass ratio of the water-soluble nano-copper, the proton-type ionic liquid, the polyol, and the deionized water is 0.4:0.05-0.18:9.6-9.8:9.6-9.8. For example, the mass ratio of the water-soluble nano-copper, proton-type ionic liquid, polyol, and deionized water is 0.4:0.06:9.6~9.8:9.6~9.8, 0.4:0.07:9.6~9.8:9.6~9.8, 0.4:0.08:9.6~9.8:9.6~9.8, 0.4:0.09:9.6~9.8:9.6~9.8, 0.4:0.1:9.6~9.8:9.6~9.8, 0.4:0.11: 9.6~9.8: 9.6~9.8, 0.4:0.12: 9.6~9.8: 9.6~9.8, 0.4:0.13: 9.6~9.8: 9.6~9.8, 0.4:0.14: 9.6~9.8: 9.6~9.8, 0.4:0.15: 9.6~9.8: 9.6~9.8, 0.4:0.16: 9.6~9.8: 9.6~9.8 or 0.4:0.17: 9.6~9.8: 9.6~9.8. Preferably, the mass ratio of the water-soluble nano-copper, proton-type ionic liquid, polyol and deionized water is 0.4:0.06:9.77:9.77, 0.4:0.1:9.15:9.15, 0.4:0.14:9.73-9.73, 0.4:0.16:9.72-9.72 or 0.4:0.18:9.71,9.71.

[0024] Furthermore, the preparation method of the proton-type ionic liquid includes the following steps: equal amounts of phosphate ester and alkylamine are mixed uniformly, a solvent is added, and heat treatment is performed. After the reaction is complete, the solvent is removed by vacuum distillation to obtain a colorless or pale yellow viscous solid. The reaction route is as follows:

[0025]

[0026] Where n = 1, 2, or 3, and R2 is -CH 2- CHOH-CH3 or CH2CH2OH, R3 is methyl (Me), ethyl (Et) or propyl (Pr), and R4 is n-pentyl (n-pentyl) or ethyl (Et).

[0027] Furthermore, the preparation method of the proton-type ionic liquid includes the following steps: adding bis(2-ethylhexyl) phosphate and acetonitrile to a reaction vessel, stirring until homogeneous, adding triisopropanolamine in an amount equal to that of bis(2-ethylhexyl) phosphate, stirring at 70-80°C for 12-24 hours, and removing the solvent by vacuum distillation to obtain the proton-type ionic liquid.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] 1. This invention achieves stable dispersion of copper nanoparticles in water by modifying the polarity of the modifier and its contained functional groups, thereby enabling the self-assembly of a dense and ordered monolayer on the surface of copper nanoparticles. Simultaneously, the resulting copper nanoparticles can be reversibly separated and redispersed in water.

[0030] 2. The present invention uses a one-pot method to prepare water-soluble copper nanoparticles, which is simple to operate and has a short procedure.

[0031] 3. The water-soluble copper nanoparticles and proton-type ionic liquid of this invention can be uniformly dispersed in water-alcohol lubricating fluids without stratification. As an additive, they can improve the extreme pressure anti-wear lubrication performance of the water-alcohol system, exhibiting a maximum non-seize load value P. B The maximum value can reach 3090N, and the coefficient of friction is <0.1. Attached Figure Description

[0032] Figure 1 The image shows the ultraviolet spectrum of the polyethylene glycol monomethyl ether xanthate potassium in this invention. Xanthates absorb at specific wavelengths. As can be seen from the image, the absorption peaks of the prepared polyethylene glycol monomethyl ether xanthate are around 301 nm and 226 nm, and the peak intensities are close to 2:1. This proves that the prepared product is a single polyethylene glycol monomethyl ether xanthate potassium compound.

[0033] Figure 2 The infrared spectrum of potassium polyethylene glycol monomethyl ether xanthate in this invention shows that the wavelength range is 2850–2960 cm⁻¹. -1 The peak at 1112 cm⁻¹ represents the stretching vibration of CH in -CH₃. -1 With 1200cm -1 The absorption peak belongs to the stretching vibration absorption peak of the COC group, 1040 cm⁻¹. -1 The absorption peak at that point is the stretching vibration absorption peak of C=S, which can help prove that the prepared compound is polyethylene glycol monomethyl ether potassium xanthate.

[0034] Figure 3 These are optical photographs of the water-soluble copper nanoparticles obtained in this invention dispersed in water and after being left to stand for two weeks. It was found that the copper nanoparticles can be stably dispersed in water without significant precipitation.

[0035] Figure 4 The transmission electron microscope (TEM) image of the copper nanoparticles obtained in this invention shows that the copper nanoparticles have a particle size of 1-10 nm, a uniform particle size distribution, and no aggregation.

[0036] Figure 5 The optical photographs of Comparative Examples 1-3 in this invention show that water and alcohol have excellent miscibility. The ionic liquid can be uniformly dissolved in the water-alcohol system without stratification. Copper nanoparticles can also be uniformly dispersed in the water-alcohol system without agglomeration or stratification.

[0037] Figure 6 Optical photographs of copper nanoparticles and proton-type ionic liquids used as additives in this invention, with copper nanoparticle concentration of 2% and proton-type ionic liquid concentrations of 0.3% (Example 1), 0.5% (Example 2), 0.7% (Example 3), 0.8% (Example 4), and 0.9% (Example 8), respectively, show that the combination of the two can be uniformly dispersed in the water-alcohol system without agglomeration or stratification.

[0038] Figure 7 The maximum non-seize load P in Examples 1-4, Example 8, and Comparative Examples 1-3 of this invention is shown. B The value shows that the maximum non-seize load P in the embodiment is... B All values ​​are greater than the comparative, with the highest being P. B The value can reach 3090N, indicating that the combination of copper nanoparticles and ionic liquid has a better effect and has a very high lubrication and load-bearing capacity.

[0039] Figure 8 The friction coefficient curves (a) for Examples 1-4, Example 8, and Comparative Examples 2-3 of this invention are shown. It can be seen that the friction coefficients of all examples are below 0.1. Under the same test conditions, the friction coefficients of the examples are significantly lower than those of Comparative Example 2, and the friction coefficients of some examples are lower than those of Comparative Example 3, indicating that the combination of copper nanoparticles and ionic liquid has excellent lubrication performance.

[0040] Figure 9 The friction coefficient curve (a) and the corresponding wear scar diameter (b) of copper nanoparticles added to the water-alcohol system in Example 5 of this invention are shown.

[0041] It can be seen that when the load in the test conditions is increased from 196N to 294N, the lubrication performance of the system is still excellent, and the wear scar diameter is about 0.653mm. Although it increases with the increase of load, it is still relatively small and the surface is smooth and flat. It can be seen that the system is applicable to a relatively wide range of loads, and the combination of copper nanoparticles and ionic liquid can achieve excellent lubrication effect.

[0042] Figure 10The friction coefficient curve (a) and the corresponding wear scar diameter (b) of copper nanoparticles added to the water-alcohol system in Example 6 of this invention are shown.

[0043] It can be seen that when the load in the test conditions is increased from 196N to 392N, the lubrication performance of the system is still excellent, the wear scar diameter is small, about 0.602mm, and the surface is smooth and flat. This shows that the system is applicable to a wide range of loads, and the combination of copper nanoparticles and ionic liquid can still achieve excellent lubrication effect under relatively harsh conditions.

[0044] Figure 11 The friction coefficient curve (a) and the corresponding wear scar diameter (b) of copper nanoparticles added to the water-alcohol system in Example 7 of this invention are shown.

[0045] It can be seen that when the test conditions are reduced from a load of 392N and the rotation speed from 1450r to 1200r, the lubrication performance of the system is still excellent, the wear scar diameter is small, about 0.618mm, and the surface is smooth and flat. This shows that the combination of copper nanoparticles and ionic liquid has excellent lubrication effect at lower rotation speeds. Detailed Implementation

[0046] The technical solution of the present invention will be further described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto.

[0047] Example 1

[0048] Add 1.73g of polyethylene glycol monomethyl ether potassium xanthate-750 (Aladdin) and 100mL of deionized water to the reaction vessel, mix well and record as solution A.

[0049] Add 0.48g of copper nitrate and 50mL of deionized water to another reaction vessel, mix well and label it solution B.

[0050] Add 0.5g of sodium borohydride and 100mL of deionized water to a reaction vessel, mix well, and label the mixture as solution C.

[0051] Solution B was added dropwise to solution A, and mechanical stirring was carried out for 2 hours. Then, solution C was slowly added dropwise to the system. After the addition was completed, stirring was continued for 1 hour. After the reaction was completed, chloroform was added, and the mixture was extracted and dried to obtain the desired copper nanoparticles.

[0052] Add 20g of bis(2-ethylhexyl) phosphate and 60mL of acetonitrile to a reaction vessel, stir until homogeneous, then add triisopropanolamine in an equal amount to bis(2-ethylhexyl) phosphate. Stir at 80°C for 12 hours. Remove the solvent by vacuum distillation to obtain a colorless or pale yellow viscous solid, which is the proton-type ionic liquid. The NMR data of ionic liquid I are as follows: 1HNMR(400MHz, CDCl3)δ6.46(brs,3H),4.43–4.00(m,3H),3.83–3.64(m,4H),3.41–3.28 (m,2H),3.26–3.00(m,4H),1.56–1.46(m,2H),1.44–1.20(m,26H),0.94–0.84(m,12H).

[0053] 13 C NMR (100MHz, CDCl3) δ67.7,67.6,62.4,62.3,62.0,61.6,60.7,60.5,40.2,40.1,29.9,28.8,23.2,22.9,21.2,21.0,20.6,13.9,10.8.

[0054] Take 0.4g of copper nanoparticles, 0.06g of proton-type ionic liquid, 9.77g of deionized water, and 9.77g of polyethylene glycol, mix them evenly, and then test their tribological properties.

[0055] The tribological properties of the prepared water-based lubricant were tested using a four-ball friction testing machine (MS-10A). The steel balls used in the test were... The test was conducted on GCr15 bearing steel balls. The test conditions were: room temperature, load 196 N, rotation speed 1450 r / min, and coefficient of friction (COF) after 30 minutes of grinding. The wear scar diameter on the steel ball surface was measured using an XDS-0745D optical microscope and a MicroXAM 3D non-contact surface testing instrument. The test results are as follows: Figure 8 As shown in Table 1.

[0056] Figure 1 The image shows the ultraviolet spectrum of the polyethylene glycol monomethyl ether xanthate potassium in this invention. Xanthates absorb at specific wavelengths. As can be seen from the image, the absorption peaks of the prepared polyethylene glycol monomethyl ether xanthate are around 301 nm and 226 nm, and the peak intensities are close to 2:1. This proves that the prepared product is a single polyethylene glycol monomethyl ether xanthate potassium compound.

[0057] Figure 2 The infrared spectrum of potassium polyethylene glycol monomethyl ether xanthate in this invention shows that the wavelength range is 2850–2960 cm⁻¹. -1 The peak at 1112 cm⁻¹ represents the stretching vibration of CH in -CH₃. -1 With 1200cm -1 The absorption peak belongs to the stretching vibration absorption peak of the COC group, 1040 cm⁻¹. -1 The absorption peak at that point is the stretching vibration absorption peak of C=S, which can help prove that the prepared compound is polyethylene glycol monomethyl ether potassium xanthate.

[0058] Figure 3 These are optical photographs of the water-soluble copper nanoparticles obtained in this invention dispersed in water and after being left to stand for two weeks. It was found that the copper nanoparticles can be stably dispersed in water without significant precipitation.

[0059] Figure 4 The transmission electron microscope (TEM) image of the copper nanoparticles obtained in this invention shows that the copper nanoparticles have a particle size of 1-10 nm, a uniform particle size distribution, and no aggregation.

[0060] Example 2

[0061] 0.4 g of copper nanoparticles (same as in Example 1), 0.1 g of proton-type ionic liquid (same as in Example 1), 9.75 g of deionized water, and 9.75 g of polyethylene glycol were mixed evenly and their tribological properties were tested.

[0062] The test conditions are the same as in Example 1, and the test results are as follows: Figure 8 As shown in Table 1.

[0063] Example 3

[0064] 0.4 g of copper nanoparticles (same as in Example 1), 0.14 g of proton-type ionic liquid (same as in Example 1), 9.73 g of deionized water, and 9.73 g of polyethylene glycol were mixed evenly and then subjected to tribological property testing.

[0065] The test conditions are the same as in Example 1, and the test results are as follows: Figure 8 As shown in Table 1.

[0066] Example 4

[0067] 0.4 g of copper nanoparticles (same as in Example 1), 0.16 g of proton-type ionic liquid (same as in Example 1), 9.72 g of deionized water, and 9.72 g of polyethylene glycol were mixed evenly and then subjected to tribological property testing.

[0068] The test conditions are the same as in Example 1, and the test results are as follows: Figure 8 As shown in Table 1.

[0069] Example 5

[0070] A water-based lubricant, the preparation method of which is the same as in Example 4.

[0071] The tribological properties of the prepared water-based lubricant were tested using a four-ball friction testing machine (MS-10A). The steel balls used in the test were... The test was conducted on GCr15 bearing steel balls. The test conditions were: room temperature, load 294 N, rotation speed 1450 r / min, and coefficient of friction (COF) after 30 minutes of grinding. The wear scar diameter on the steel ball surface was measured using an XDS-0745D optical microscope and a MicroXAM 3D non-contact surface testing instrument. The test results are as follows: Figure 9 As shown.

[0072] Figure 9 The friction coefficient curve (a) and the corresponding wear scar diameter (b) of copper nanoparticles added to the water-alcohol system in Example 5 of this invention are shown.

[0073] It can be seen that when the load in the test conditions is increased from 196N to 294N, the lubrication performance of the system is still excellent, and the wear scar diameter is about 0.653mm. Although it increases with the increase of load, it is still relatively small and the surface is smooth and flat. It can be seen that the system is applicable to a relatively wide range of loads, and the combination of copper nanoparticles and ionic liquid can achieve excellent lubrication effect.

[0074] Example 6

[0075] A water-based lubricant, the preparation method of which is the same as in Example 4.

[0076] The tribological properties of the prepared water-based lubricant were tested using a four-ball friction testing machine (MS-10A). The steel balls used in the test were... The test was conducted on GCr15 bearing steel balls. The test conditions were: room temperature, load 392 N, rotation speed 1450 r / min, and coefficient of friction (COF) after 30 minutes of grinding. The wear scar diameter on the steel ball surface was measured using an XDS-0745D optical microscope and a MicroXAM 3D non-contact surface testing instrument. The test results are as follows: Figure 10 As shown.

[0077] Figure 10 The friction coefficient curve (a) and the corresponding wear scar diameter (b) of copper nanoparticles added to the water-alcohol system in Example 6 of this invention are shown.

[0078] It can be seen that when the load in the test conditions is increased from 196N to 392N, the lubrication performance of the system is still excellent, the wear scar diameter is small, about 0.602mm, and the surface is smooth and flat. This shows that the system is applicable to a wide range of loads, and the combination of copper nanoparticles and ionic liquid can still achieve excellent lubrication effect under relatively harsh conditions.

[0079] Example 7

[0080] A water-based lubricant, the preparation method of which is the same as in Example 4.

[0081] The tribological properties of the prepared water-based lubricant were tested using a four-ball friction testing machine (MS-10A). The steel balls used in the test were... The test was conducted on GCr15 bearing steel balls. The test conditions were: room temperature, load 392 N, rotation speed 1200 r / min, and coefficient of friction (COF) after 30 minutes of grinding. The wear scar diameter on the steel ball surface was measured using an XDS-0745D optical microscope and a MicroXAM 3D non-contact surface testing instrument. The test results are as follows: Figure 11 As shown. Figure 11 The figures (a) and (b) show the friction coefficient curve and corresponding wear scar diameter of the copper nanoparticles added to the water-alcohol system in Example 7 of this invention. It can be seen that even when the test conditions are reduced from a load of 392 N to a rotational speed of 1450 r to 1200 r, the lubrication performance of this system remains excellent, with a small wear scar diameter of approximately 0.618 mm and a smooth, flat surface. This demonstrates that the combination of copper nanoparticles and ionic liquids exhibits excellent lubrication effects even at lower rotational speeds.

[0082] Example 8

[0083] 0.4 g of copper nanoparticles (same as in Example 1), 0.18 g of proton-type ionic liquid (same as in Example 1), 9.71 g of deionized water, and 9.71 g of polyethylene glycol were mixed evenly and their tribological properties were tested.

[0084] The test conditions are the same as in Example 1, and the test results are as follows: Figure 8 As shown in Table 1.

[0085] Figure 6 Optical photographs of copper nanoparticles and proton-type ionic liquids used as additives in this invention, with copper nanoparticle concentration of 2% and proton-type ionic liquid concentrations of 0.3% (Example 1), 0.5% (Example 2), 0.7% (Example 3), 0.8% (Example 4), and 0.9% (Example 8), respectively, show that the combination of the two can be uniformly dispersed in the water-alcohol system without agglomeration or stratification.

[0086] Comparative Example 1

[0087] 10g of deionized water and 10g of polyethylene glycol were mixed evenly and then subjected to tribological property testing.

[0088] The test conditions are the same as in Example 1, and the test results are as follows: Figure 8 As shown in Table 1.

[0089] Comparative Example 2

[0090] 0.2 g of proton-type ionic liquid (same as in Example 1), 9.9 g of deionized water, and 9.9 g of polyethylene glycol were mixed evenly and their tribological properties were tested.

[0091] The test conditions are the same as in Example 1, and the test results are as follows: Figure 8 As shown in Table 1.

[0092] Comparative Example 3

[0093] 0.4 g of copper nanoparticles (same as in Example 1), 9.8 g of deionized water, and 9.8 g of polyethylene glycol were mixed evenly and their tribological properties were tested.

[0094] The test conditions are the same as in Example 1, and the test results are as follows: Figure 8 As shown in Table 1.

[0095] Table 1 shows the wear scar diameter diagrams (b) corresponding to Examples 1-4, Example 8, and Comparative Examples 2-3 of this invention.

[0096] It can be seen that the wear scar diameter of each embodiment is smaller. Under the same test conditions, the wear scar diameter of the embodiments is significantly lower than that of comparative examples 2-3, and the surface is smoother and flatter, indicating that the combination of copper nanoparticles and ionic liquid has excellent lubrication performance.

[0097] Table 1

[0098]

[0099] Figure 5 The optical photographs of Comparative Examples 1-3 in this invention show that water and alcohol have excellent miscibility. The ionic liquid can be uniformly dissolved in the water-alcohol system without stratification. Copper nanoparticles can also be uniformly dispersed in the water-alcohol system without agglomeration or stratification.

[0100] Figure 7 The maximum non-seize load P in Examples 1-4, Example 8, and Comparative Examples 1-3 of this invention is shown. B The value shows that the maximum non-seize load P in the embodiment is... B All values ​​are greater than the comparative, with the highest being P. B The value can reach 3090N, indicating that the combination of copper nanoparticles and ionic liquid has a better effect and has a very high lubrication and load-bearing capacity.

[0101] Figure 8 The friction coefficient curves (a) for Examples 1-4, Example 8, and Comparative Examples 2-3 of this invention are shown. It can be seen that the friction coefficients of all examples are below 0.1. Under the same test conditions, the friction coefficients of the examples are significantly lower than those of Comparative Example 2, and the friction coefficients of some examples are lower than those of Comparative Example 3, indicating that the combination of copper nanoparticles and ionic liquid has excellent lubrication performance.

[0102] The parts of this invention not described in detail are well-known to those skilled in the art. The embodiments described above are merely preferred embodiments of the invention, and do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Various modifications and improvements to the technical solutions of this invention made by those skilled in the art without departing from the spirit of the invention should fall within the protection scope defined by the claims of this invention.

Claims

1. The application of water-soluble nano-copper combined with proton-type ionic liquid as an additive for water-based lubricating fluids, characterized in that, The water-soluble nano-copper was prepared by the following method: using an in-situ surface modification method, copper xanthate containing thiol groups was obtained by reduction with a reducing agent in a one-pot process. The copper xanthate is prepared by ion exchange between water-soluble xanthate anions and water-soluble copper salts. In the preparation of copper xanthate, the source of copper is any one of copper sulfide, copper chloride, copper sulfate, copper nitrate and copper acetate; In the preparation of copper xanthate, the xanthate group is water-soluble and its carbon chain length is 10~34. In the preparation of the precursor copper xanthate, the molar ratio of copper ions to xanthate ions is 1:1~4.5; The concentration of the copper xanthate precursor solution was 0.001~1 mol / L; The reaction temperature is 10-30°C. o C; The reaction system used is pure water or an aqueous ethanol solution; the preparation method of the proton-type ionic liquid includes the following steps: equal amounts of phosphate ester and alcoholamine are mixed evenly and then subjected to heat treatment. After the reaction is completed, the solvent is removed by vacuum distillation to obtain a colorless or pale yellow viscous solid. The reaction route is as follows: Where n = 1, 2 or 3, R2 is -CH2-CHOH-CH3 or -CH2CH2OH, R3 is methyl, ethyl or propyl, and R4 is n-pentyl or ethyl; A water-based lubricant is obtained by mixing water-soluble nano-copper, a proton-type ionic liquid, a polyol, and deionized water; the polyol refers to at least one of glycerol, polyethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,4-butanediol, ethanol, and ethylene glycol; the mass ratio of the water-soluble nano-copper, the proton-type ionic liquid, the polyol, and the deionized water is 0.4:0.05~0.18:9.6~9.8:9.6~9.

8.

2. The application according to claim 1, characterized in that, The reducing agent used is any one of hydrazine hydrate, sodium borohydride, and formaldehyde.

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