Natural ternary eutectic solvent lubricant, and preparation method and application thereof

Abstract

The application relates to the technical field of friction lubrication, and provides a natural ternary eutectic solvent lubricant as well as a preparation method and application thereof. The natural ternary eutectic solvent lubricant provided by the application comprises the following components in mole fraction: 20-80% of quaternary ammonium salt, 10-60% of ethanolamine, and the balance of sorbitol. The application takes the quaternary ammonium salt as a hydrogen bond acceptor, takes the sorbitol and the ethanolamine as hydrogen bond donors, simultaneously controls the proportion between the hydrogen bond acceptor and the hydrogen bond donor, forms a hydrogen bond network through the hydrogen bond acceptor and the hydrogen bond donor, and obtains the natural ternary eutectic solvent lubricant. Compared with traditional lubricants, the natural ternary eutectic solvent lubricant provided by the application can obviously reduce the friction coefficient, and the anti-wear performance is more excellent. The natural ternary eutectic solvent lubricant can realize a 'near zero' wear behavior on a steel surface under high load and a complex application environment, and exhibits excellent tribological performance. Moreover, the raw materials adopted by the application are green, economical, pollution-free, the preparation process is fast, simple and easy to operate.

Description

Technical Field

[0001] This invention relates to the field of friction lubrication technology, and in particular to a natural ternary eutectic solvent lubricant, its preparation method, and its application. Background Technology

[0002] In the field of tribology, liquid lubricants are among the most commonly used lubricating media for solving tribological problems. They possess self-cleaning, cooling, flame-retardant, and friction and wear control properties, thus playing a vital role in modern industrial production. Traditional liquid lubricants include water, organic solvents, and ionic liquids. While these materials exhibit good lubrication performance, they also have certain drawbacks. Water suffers from low lubricity, low viscosity, high corrosivity, and poor temperature resistance; organic solvents have low conductivity, high volatility, and are prone to leakage leading to environmental pollution; and ionic liquids exhibit toxicity, biocompatibility, and high manufacturing costs. These issues pose certain risks during application. Furthermore, the biggest challenge for liquid lubricants lies in their weak load-bearing capacity, making it difficult to protect machine contact surfaces in harsh environments, resulting in severe friction and wear. Therefore, finding a green, economical, and high-performance liquid lubricant has become one of the most pressing issues in the fields of tribology and engineering.

[0003] Eutectic solvents (DES) are a novel type of ionic liquid analogue. In recent years, due to their low cost, simple preparation, and environmentally friendly nature, DES have gradually become a green alternative to ionic liquids and other traditional liquid lubricants. A DES is a room-temperature solvent formed by hydrogen bond networks between hydrogen bond acceptors and hydrogen bond donors. The decrease in melting point is mainly due to the complex hydrogen bond network structure formed between the hydrogen bond acceptors and donors. Furthermore, by using some primary metabolites (such as amino acids, organic acids, sugars, or choline derivatives) as hydrogen bond donors and acceptors, green and economical natural DES (NADES) can be obtained. By selecting suitable hydrogen bond donors and acceptors, DES with different physicochemical properties can be prepared, such as viscosity, density, low volatility, high thermal stability, non-toxicity, economic sustainability, and biocompatibility. With a deeper understanding of eutectic solvents, it has been discovered that by adding an organic or inorganic compound to a binary eutectic solvent, the physicochemical properties of the solvent can be further controlled, resulting in a high-performance ternary eutectic solvent (TDES). The prepared ternary eutectic solvent possesses even better physicochemical properties, thus meeting its application requirements in various fields.

[0004] Based on their excellent rheological properties, viscosity properties, thermal stability, and polarity, eutectic solvents exhibit superior tribological properties as a novel liquid lubricant. Studies have shown that the polarity of eutectic solvents, along with their good affinity and wettability to the substrate material, facilitates the formation of a lubricating film on the substrate surface, resulting in a lower coefficient of friction and wear rate. However, as a liquid lubricant, traditional eutectic solvents (such as choline chloride-based eutectic solvents) suffer from poor load-bearing capacity, leading to easy rupture of the formed lubricating film and making it difficult to achieve ultra-low wear performance on steel substrates. Therefore, the exploration and preparation of novel natural eutectic solvent lubricants and their application to achieve low friction and ultra-low wear on steel surfaces are of significant research importance. Summary of the Invention

[0005] In view of this, the present invention provides a natural ternary eutectic solvent lubricant, its preparation method, and its application. The present invention applies a natural ternary eutectic solvent to the field of tribology, expanding the application range of eutectic solvents. Furthermore, the natural ternary eutectic solvent lubricant provided by the present invention has strong load-bearing capacity, good friction-reducing and anti-wear properties, can achieve near-zero wear behavior on steel substrates, and also exhibits excellent corrosion resistance.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A natural ternary eutectic solvent lubricant comprising the following components in molar fractions: 20-80% quaternary ammonium salt, 10-60% ethanolamine, and the balance sorbitol.

[0008] Preferably, the natural ternary eutectic solvent lubricant comprises the following components in molar fractions: 20-60% quaternary ammonium salt, 10-50% ethanolamine, and the balance sorbitol.

[0009] Preferably, the quaternary ammonium salt includes one or more of choline chloride, tetraethylammonium chloride, and tetrabutylammonium chloride.

[0010] Preferably, the ethanolamine includes one or more of monoethanolamine, diethanolamine, and triethanolamine.

[0011] Preferably, the viscosity coefficient of the natural ternary eutectic solvent lubricant at room temperature is 2 to 12 Pa·s.

[0012] This invention also provides a method for preparing the natural ternary eutectic solvent lubricant described above, comprising the following steps:

[0013] The natural ternary eutectic solvent lubricant was obtained by heating and stirring quaternary ammonium salt, sorbitol and ethanolamine.

[0014] Preferably, the heating and stirring temperature is 70-90°C, and the time is 10-12 hours; the heating and stirring are carried out under water bath conditions.

[0015] Preferably, the heating and stirring speed is 500-700 rpm.

[0016] Preferably, after heating and stirring, the product is further subjected to drying-stabilization treatment; the drying-stabilization treatment is carried out at a temperature of 50-70°C for a time of 20-30 hours.

[0017] The present invention also provides the application of the natural ternary eutectic solvent lubricant described in the above-described scheme or the natural ternary eutectic solvent lubricant prepared by the preparation method described in the above-described scheme in the field of friction lubrication.

[0018] This invention provides a natural ternary eutectic solvent lubricant (denoted as TDESs lubricant), comprising the following components in molar fractions: 20-80% quaternary ammonium salt, 10-60% ethanolamine, and the balance sorbitol. This invention uses the quaternary ammonium salt as the hydrogen bond acceptor and sorbitol (a hydroxyl-rich sugar) and ethanolamine (possessing active elements and corrosion resistance) as hydrogen bond donors. The hydrogen bond acceptor and donors form a natural ternary eutectic solvent through a hydrogen bond network. The natural ternary eutectic solvent provided by this invention is green, environmentally friendly, economical, and biocompatible. It also possesses excellent rheological properties, thermal stability, wettability on metal substrates, and corrosion resistance. Compared to traditional polyethylene glycol (PEG400) lubricants, it exhibits superior tribological properties, achieving a low coefficient of friction while maintaining near-zero wear behavior on steel substrates under high loads and various experimental conditions. In addition, its excellent thermal stability and rheological properties enable it to maintain good tribological properties under different application environments, such as high load conditions, medium and high temperature, high frequency and high relative humidity conditions. The prepared natural ternary eutectic solvent lubricant can maintain a low coefficient of friction and ultra-low wear volume.

[0019] This invention also provides a method for preparing the natural ternary eutectic solvent lubricant described in the above-mentioned scheme. This invention uses commonly found natural quaternary ammonium salts, sorbitol, and ethanolamine as raw materials. Through simple heating and stirring, a natural ternary eutectic solvent lubricant with excellent tribological properties is prepared. During the heating and stirring process, a complex hydrogen bond network structure is formed between hydrogen bond acceptors and hydrogen bond donors, resulting in a eutectic solvent with a melting point lower than that of each component material, i.e., a natural ternary eutectic solvent. The raw materials used in this invention are green, economical, and pollution-free. The preparation process is rapid, simple, and easy to operate, and minimizes environmental pollution, making it a green, environmentally friendly, and economical preparation method.

[0020] This invention also provides the application of the natural ternary eutectic solvent lubricant described above in the field of friction lubrication. Examples and test results show that when the natural ternary eutectic solvent lubricant provided by this invention is applied to steel / steel friction pairs, under high load conditions (100N), the average coefficient of friction is 0.103–0.123, and there are no obvious wear marks on the surface of the friction pair. Furthermore, during a long-term (2h) friction test, the average coefficient of friction of the natural ternary eutectic solvent lubricant is 0.095–0.100, and the wear rate is 0.78–1.62 × 10⁻⁶. -12 mm 3 ·mm -1 ·N -1 Meanwhile, when the natural ternary eutectic solvent lubricant provided by this invention was applied to steel / steel friction pairs, it exhibited excellent friction-reducing properties under different temperature (25–80°C), frequency (25–45 Hz), and relative humidity (50% and 80% RH) conditions. Furthermore, copper foil corrosion tests demonstrated that the natural ternary eutectic solvent lubricant provided by this invention caused a corrosion degree of 1a on copper foil, indicating its excellent corrosion resistance. Based on the above results, it can be concluded that the natural ternary eutectic solvent lubricant provided by this invention, when applied to steel surfaces, can achieve a low coefficient of friction and near-zero wear performance, while also exhibiting strong load-bearing capacity and good corrosion resistance, thus possessing broad application prospects. Attached Figure Description

[0021] Figure 1 Friction coefficient curves obtained by applying TDESs lubricants prepared in Examples 1, 3, and 5 and PEG400 lubricant in the comparative example to steel / steel friction pairs under high load conditions;

[0022] Figure 2 Friction curves of CES-TDES lubricant (a) prepared in Example 1 and CES-TDES lubricant (b) with different ethanolamine contents on steel surfaces;

[0023] Figure 3 Friction curves of TESE-TDES lubricant (a) prepared in Example 3 and TESE-TDES lubricant (b) with different ethanolamine contents on steel surfaces;

[0024] Figure 4 Friction curves of TBSE-TDES lubricant (a) prepared in Example 5 and TBSE-TDES lubricant (b) with different ethanolamine contents on steel surfaces. Detailed Implementation

[0025] This invention provides a natural ternary eutectic solvent lubricant comprising the following components in molar fractions: 20-80% quaternary ammonium salt, 10-60% ethanolamine, and the balance sorbitol.

[0026] The natural ternary eutectic solvent lubricant provided by the present invention comprises 20-80% quaternary ammonium salt, preferably 20-60%, by mole fraction; the quaternary ammonium salt preferably includes one or more of choline chloride, tetraethylammonium chloride and tetrabutylammonium chloride.

[0027] The natural ternary eutectic solvent lubricant provided by the present invention, by mole fraction, comprises 10-60% ethanolamine, preferably 10-50%; the ethanolamine preferably includes one or more of monoethanolamine, diethanolamine and triethanolamine.

[0028] The natural ternary eutectic solvent lubricant provided by this invention, by mole fraction, comprises the balance sorbitol. In this invention, the quaternary ammonium salt acts as a hydrogen bond acceptor, and sorbitol and ethanolamine act as hydrogen bond donors. The hydrogen bond acceptor and hydrogen bond donor interact through a hydrogen bond network to form a natural ternary eutectic solvent.

[0029] In a specific embodiment of the present invention, the molar ratio of the quaternary ammonium salt, sorbitol and ethanolamine is preferably (1-2):1:(0.5-2), more preferably 1:1:1, 1:1:0.5, 1:1:1.5, 1:1:2, 2:1:1, 2:1:0.5, 2:1:1.5 or 2:1:2.

[0030] In this invention, the quaternary ammonium salt, sorbitol, and ethanolamine are common compounds with a certain degree of universality. Furthermore, the aforementioned raw materials are all natural primary metabolites, possessing characteristics of being green, economical, sustainable, and biocompatible. This invention uses the quaternary ammonium salt as the hydrogen bond acceptor and sorbitol (a hydroxyl-rich sugar alcohol) and ethanolamine (possessing active elements and corrosion resistance) as hydrogen bond donors. A heating and stirring method is employed to obtain a eutectic solvent, namely the natural ternary eutectic solvent lubricant, by forming a complex hydrogen bond network structure between the hydrogen bond acceptor and the hydrogen bond donor. In this invention, the natural ternary eutectic solvent lubricant is a homogeneous, transparent, viscous liquid that exhibits Newtonian fluid behavior at room temperature (25°C), with a preferred viscosity coefficient of 2–12 Pa·s. The natural ternary eutectic solvent lubricant exhibits excellent wettability and corrosion resistance on metal substrate surfaces, with a corrosion degree of 1a and a contact angle of 25–40°.

[0031] The natural ternary eutectic solvent lubricant provided by this invention has excellent friction-reducing and anti-wear properties, and is a liquid lubricant material with excellent tribological properties, green economy, and environmental protection.

[0032] This invention also provides a method for preparing the natural ternary eutectic solvent lubricant described above, comprising the following steps:

[0033] The natural ternary eutectic solvent lubricant was obtained by heating and stirring quaternary ammonium salt, sorbitol and ethanolamine under water bath conditions.

[0034] In this invention, the heating and stirring temperature is preferably 70-90°C, more preferably 80°C, and the heating and stirring time is preferably 10-12 hours, more preferably 12 hours; the heating and stirring speed is preferably 500-700 rpm, more preferably 600 rpm; the heating and stirring is preferably carried out under sealed conditions to avoid the influence of evaporated water vapor on the product.

[0035] In a specific embodiment of the present invention, the quaternary ammonium salt, sorbitol, and ethanolamine are preferably added to a reaction vessel in a certain proportion, and the reaction vessel is preferably a round-bottom flask. The reaction vessel is sealed, and then the reaction vessel containing the mixture is placed in a water bath. The required heating temperature is set within the required range, and stirring is started at the same time. The mixture of quaternary ammonium salt, sorbitol, and ethanolamine gradually forms a eutectic solvent under the set temperature and stirring speed. During the stirring process, a complex hydrogen bond network structure is formed between the hydrogen bond acceptor and the hydrogen bond donor.

[0036] In this invention, after heating and stirring, the resulting product is preferably subjected to a drying-stabilization treatment; the drying-stabilization treatment is preferably performed by vacuum drying; the temperature of the drying-stabilization treatment is preferably 50-70℃, more preferably 60℃, and the time is preferably 20-30h, more preferably 24h. This invention removes trace amounts of moisture from the product through drying (the moisture in the product mainly comes from the crystal water and adsorbed water of the raw materials, as well as the moisture absorbed during the preparation process), obtaining an anhydrous natural ternary eutectic solvent lubricant, making the natural ternary eutectic solvent lubricant more stable. This invention, by selecting suitable hydrogen bond acceptors (quaternary ammonium salts) and hydrogen bond donors (sorbitol and ethanolamine), and choosing a suitable heating temperature, can prepare the natural ternary eutectic solvent lubricant with the aid of stirring. The required raw materials are green and environmentally friendly, the preparation process is simple and easy to operate, the cost is low, and it minimizes environmental pollution, conforming to the development concept of green chemistry.

[0037] The present invention also provides the application of the natural ternary eutectic solvent lubricant described in the above-described scheme or the natural ternary eutectic solvent lubricant prepared by the preparation method described in the above-described scheme in the field of friction lubrication.

[0038] This invention does not impose any particular requirements on the application method; methods well-known to those skilled in the art can be used. The natural ternary eutectic solvent lubricant provided by this invention exhibits excellent tribological properties on metal substrates, specifically in the following aspects: First, it has strong load-bearing capacity, exhibiting excellent friction-reducing and anti-wear properties under a load of 100N; second, it maintains good lubrication performance during high-load and long-term friction tests; third, it possesses good lubrication performance at high test frequencies; fourth, it maintains excellent friction-reducing and anti-wear properties at high temperatures; fifth, it exhibits excellent friction-reducing and anti-wear properties under high ambient humidity conditions; and sixth, it has good corrosion resistance, with a corrosion degree of 1a on steel surfaces. In summary, the natural ternary eutectic solvent provided by this invention possesses excellent tribological properties, achieving near-zero wear behavior on metal substrates under complex environments, and exhibits strong load-bearing capacity and good corrosion resistance. This is of great significance for the research and application of liquid lubricants in the field of tribology, and also has broad application prospects in the field of friction lubrication.

[0039] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0040] Example 1

[0041] (1) Weigh 1.3962g of choline chloride, 1.8217g of sorbitol and 0.6108g of monoethanolamine (the molar ratio of the three is 1:1:1), mix the three and place them in a 100mL round bottom flask, and seal the mouth of the flask with sealing film.

[0042] (2) Place the flask containing the mixture of choline chloride, sorbitol and monoethanolamine from step (1) in a water bath and stir at 80°C for 12 hours at a stirring speed of 600 rpm to obtain a transparent and homogeneous viscous solvent.

[0043] (3) Transfer the transparent homogeneous solvent prepared in step (2) into a 10mL glass vial, and then place it in a vacuum drying oven at 60℃ for drying-stabilization treatment for 24h to remove moisture, and obtain an anhydrous natural ternary eutectic solvent lubricant, denoted as CSE-TDES lubricant, with an average viscosity coefficient of 7.38Pa·s at room temperature.

[0044] Example 2

[0045] The molar ratios of choline chloride, sorbitol, and monoethanolamine were adjusted to 1:1:0.5, 1:1:1.5, and 1:1:2, respectively, and the remaining steps were the same as in Example 1, to obtain CSE-TDES lubricants with different molar ratios.

[0046] Example 3

[0047] (1) Weigh 3.3140g tetraethylammonium chloride, 1.8217g sorbitol and 0.6108g monoethanolamine (the molar ratio of the three is 2:1:1), mix the three and place them in a 100mL round bottom flask, and seal the mouth of the flask with sealing film.

[0048] (2) Place the flask containing the mixture of tetraethylammonium chloride, sorbitol and monoethanolamine from step (1) in a water bath and stir at 80°C for 12 hours (stirring speed is 600 rpm) to obtain a transparent and homogeneous viscous solvent.

[0049] (3) Transfer the transparent homogeneous solvent prepared in step (2) into a 10ml glass vial, and then place it in a vacuum drying oven at 60℃ for drying-stabilization treatment for 24h to remove moisture, and obtain an anhydrous natural ternary eutectic solvent lubricant, denoted as TESE-TDES lubricant, with an average viscosity coefficient of 2.73Pa·s.

[0050] Example 4

[0051] The molar ratios of tetraethylammonium chloride, sorbitol, and monoethanolamine were adjusted to 2:1:0.5, 2:1:1.5, and 2:1:2, respectively, and the remaining steps were the same as in Example 3, to obtain TESE-TDES lubricants with different molar ratios.

[0052] Example 5

[0053] (1) Weigh 5.9186g tetrabutylammonium chloride (monohydrate), 1.8217g sorbitol and 0.6108g monoethanolamine (molar ratio of the three is 2:1:1), mix the three and place them in a 100ml round bottom flask, and seal the mouth of the flask with sealing film.

[0054] (2) Place the flask containing the mixture of tetrabutylammonium chloride (monohydrate), sorbitol and monoethanolamine from step (1) in a water bath and stir at 80°C for 12 hours (stirring speed is 600 rpm) to obtain a transparent and homogeneous viscous solvent.

[0055] (3) Transfer the transparent homogeneous solvent prepared in step (2) into a 10ml glass vial, and then place it in a vacuum drying oven at 60℃ for drying-stabilization treatment for 24h to remove moisture, and obtain an anhydrous natural ternary eutectic solvent lubricant, denoted as TBSE-TDES lubricant, with an average viscosity coefficient of 11.26Pa·s.

[0056] Example 6

[0057] The molar ratios of tetrabutylammonium chloride (monohydrate), sorbitol, and monoethanolamine were adjusted to 2:1:0.5, 2:1:1.5, and 2:1:2, respectively, and the remaining steps were the same as in Example 5, to obtain TBSE-TDES lubricants with different molar ratios.

[0058] The natural ternary eutectic solvent lubricants prepared in Examples 1-6 are all transparent viscous liquids.

[0059] Comparative Example 1

[0060] To more fully describe the tribological properties of the natural ternary eutectic solvent lubricant on steel surfaces, a conventional polar lubricant, polyethylene glycol (PEG400), was used as a reference sample for subsequent test experiments. This further illustrates the low friction and near-zero wear performance of the natural ternary eutectic solvent lubricant on steel surfaces.

[0061] To further illustrate the excellent tribological properties of the prepared natural ternary eutectic solvent lubricant (TDESs), the present invention used an SRV-V friction testing machine to test the tribological properties of the TDESs lubricants prepared in each embodiment during the experiment. The testing process adopted a reciprocating mode, and a non-contact three-dimensional surface profilometer was used to test the wear volume of the wear track surface. The specific tests are shown in Test Examples 1 to 9.

[0062] Test Example 1: Tribological Properties of TDESs Lubricant under High Load Conditions

[0063] The tribological properties of the TDESs lubricants prepared in Examples 1-6 were tested using an SRV-V friction testing machine. In the experiment, the upper friction pair used steel balls (9Cr18Mo, D=10mm, HRC=55±2), and the lower friction pair used cylindrical steel discs (9Cr18Mo, 24mm×7.9mm, HRC=55±2). Before and after the test, the steel balls and discs of the upper and lower friction pairs were cleaned with anhydrous ethanol and dried before being installed on the SRV-V friction testing machine. The TDES lubricants prepared in Examples 1-6 were applied to the steel disc of the lower friction pair using a dropper, and tribological tests were conducted. The test conditions were: load 100N, frequency 25Hz, temperature 25℃, relative humidity 50%RH, stroke 1mm, and time 30min. The friction coefficient curves were recorded, and the wear volume was obtained by photographing the wear marks on the steel disc using a non-contact three-dimensional surface profilometer.

[0064] The friction coefficient curves of the TDESs lubricant prepared in Examples 1, 3, and 5 and the PEG400 lubricant in the comparative example on the steel block surface are shown below. Figure 1As shown; the friction curve of the CES-TDES lubricant prepared in Example 1 on the steel surface is shown in Figure 1. Figure 2 As shown in (a) of Example 2, the friction curves of CSE-TDES lubricants with different ethanolamine contents on the steel surface are as follows. Figure 2 As shown in (b) of the figure; the friction curve of the TESE-TDES lubricant prepared in Example 3 on the steel surface is shown in Figure 3. Figure 3 As shown in (a) of Example 4, the friction curves of TESE-TDES lubricants with different ethanolamine contents on the steel surface are as follows. Figure 3 As shown in (b) of the figure; the friction curve of the TBSE-TDES lubricant prepared in Example 4 on the steel surface is shown in Figure 4. Figure 4 As shown in (a) of Example 5, the friction curves of TBSE-TDES lubricants with different ethanolamine contents on the steel surface are as follows. Figure 4 As shown in (b) of the diagram.

[0065] Table 1 shows the coefficient of friction and wear volume of traditional polyethylene glycol (PEG400) lubricant on steel surfaces in the comparative example.

[0066] Table 1. Tribological properties of different lubricating materials under a test time of 30 min.

[0067]

[0068] like Figure 1 As shown in Table 1, the CSE-TDES, TESE-TDES, and TBSE-TDES lubricants prepared in Examples 1, 3, and 5 had average friction coefficients of 0.109, 0.123, and 0.103, respectively, and average wear volumes of 4.64 × 10⁻⁶, respectively, in a 30-minute friction and wear test. 4 μm 3 3.04×10 4 μm 3 2.95×10 4 μm 3 Compared to the conventional polyethylene glycol (PEG400) lubricant used in the comparative example (with an average coefficient of friction of 0.135 and an average wear volume of 22.39 × 10⁻⁶), this indicates a significant improvement. 4 μm 3 The average coefficient of friction decreased by 19.3%, 8.9%, and 23.7%, respectively, and the average wear volume decreased by 79.3%, 86.4%, and 86.8%, respectively, further demonstrating that the TDES lubricants prepared in Examples 1, 3, and 5 possess excellent tribological properties. Figure 2 (a) Figure 3 (a) and Figure 4Analysis (a) shows that the TDESs lubricants prepared in Examples 1, 3 and 5 have excellent friction reduction and anti-wear properties when applied to steel surfaces. The friction pair surfaces have almost no obvious wear marks, indicating that they have excellent friction reduction performance and "near-zero" wear performance.

[0069] Depend on Figure 2 (b) Figure 3 (b) and Figure 4 Analysis (b) in Examples 2, 4, and 6 shows that by controlling the molar ratio of ethanolamine in the entire system, the hydrogen bond network structure of the resulting natural ternary eutectic solvent can be altered, thereby obtaining a high-performance TDESs lubricant. Figure 2 As shown in (b) of Example 2, the CSE-TDES lubricants with different ethanolamine contents prepared in Example 2 are all homogeneous transparent viscous liquid solvents, and their friction coefficients on the steel block surface are almost similar. In subsequent friction experiments, CSE-TDES lubricants with a molar ratio of quaternary ammonium salt, sorbitol and ethanolamine of 1:1:1 were selected for tribological performance testing under other test conditions. Figure 3 (b) and Figure 4 (b) shows the TESE-TDES lubricant and TBSE-TDES lubricant with different ethanolamine contents prepared in Examples 4 and 6. They are all homogeneous, transparent, viscous liquids. The TESE-TDES lubricant and TBSE-TDES lubricant with different ethanolamine contents showed similar coefficients of friction on the steel block surface. Therefore, in subsequent experiments, the TESE-TDES lubricant and TBSE-TDES lubricant with a molar ratio of quaternary ammonium salt, sorbitol and ethanolamine of 2:1:1 were selected for other performance tests.

[0070] Test Example 2: Wear resistance test of TDESs lubricant under high load and long-term conditions.

[0071] The tribological properties of the TDESS lubricants prepared in Examples 1, 3, and 5 were tested using an SRV-V friction testing machine. In the experiment, the upper friction pair used steel balls (9Cr18Mo, D = 10 mm, HRC = 55 ± 2), and the lower friction pair used a cylindrical steel disc (9Cr18Mo, 24 mm × 7.9 mm, HRC = 55 ± 2). Before and after the test, the steel balls and discs of the upper and lower friction pairs were cleaned with anhydrous ethanol and dried before being installed on the SRV-V friction testing machine. The TDESS lubricants prepared in Examples 1, 3, and 5 were applied to the steel disc of the lower friction pair using a dropper, and tribological tests were conducted. The test conditions were: load 100 N, frequency 25 Hz, temperature 25 °C, relative humidity 50% RH, stroke 1 mm, and time 120 min. The friction coefficient curves were recorded, and the wear volume was obtained by photographing the wear marks on the steel disc using a non-contact three-dimensional surface profilometer. The test results are shown in Table 2.

[0072] Table 2. Tribological properties of different lubricating materials under a test time of 120 min.

[0073]

[0074] As can be seen from the results in Table 2, the TDESs lubricants prepared in Examples 1, 3, and 5 exhibit very small wear volume after high load and long-term friction, and their wear resistance is significantly better than that of the traditional lubricant PEG400.

[0075] Test Example 3: Tribological Properties of TDESs Lubricant under High Load and Different Frequency Conditions

[0076] The tribological properties of the TDESs lubricants prepared in Examples 1, 3, and 5 were tested using an SRV-V friction testing machine. In the experiment, the upper friction pair used a steel ball (9Cr18Mo, D = 10 mm, HRC = 55 ± 2), and the lower friction pair used a cylindrical steel disc (9Cr18Mo, 24 mm × 7.9 mm, HRC = 55 ± 2). Before and after the test, the steel balls and discs of the upper and lower friction pairs were cleaned with anhydrous ethanol and dried before being installed on the SRV-V friction testing machine. The TDESs lubricants prepared in Examples 1, 3, and 5 were applied to the steel disc of the lower friction pair using a dropper, and tribological tests were conducted. The test conditions were: load 100 N, frequency 25, 35, 45 Hz, temperature 25 °C, relative humidity 50% RH, stroke 1 mm, and time 30 min. The friction coefficient curves were recorded, and the wear volume was obtained by photographing the wear marks on the steel disc using a non-contact three-dimensional surface profilometer.

[0077] The test results are shown in Table 3.

[0078] Table 3. Tribological properties of different TDESs lubricants under different frequency conditions.

[0079]

[0080] As can be seen from the results in Table 3, the TDESs lubricant prepared by this invention has good tribological properties, low coefficient of friction, and good wear resistance under different frequency conditions.

[0081] Test Example 4: Tribological Properties of TDESs Lubricant under High Load and Different Temperature Conditions

[0082] The tribological properties of the TDESs lubricants prepared in Examples 1, 3, and 5 were tested using an SRV-V friction testing machine. In the experiment, the upper friction pair used a steel ball (9Cr18Mo, D = 10 mm, HRC = 55 ± 2), and the lower friction pair used a cylindrical steel disc (9Cr18Mo, 24 mm × 7.9 mm, HRC = 55 ± 2). Before and after the test, the steel balls and discs of the upper and lower friction pairs were cleaned with anhydrous ethanol and dried before being installed on the SRV-V friction testing machine. The TDESs lubricants prepared in Examples 1, 3, and 5 were applied to the steel disc of the lower friction pair using a dropper, and tribological tests were conducted. The test conditions were: load 100 N, frequency 25 Hz, temperature 25℃, 50℃, 80℃, relative humidity 50% RH, stroke 1 mm, and time 30 min. The friction coefficient curves were recorded, and the wear volume was obtained by photographing the wear marks on the steel disc using a non-contact three-dimensional surface profilometer.

[0083] The test results are shown in Table 4.

[0084] Table 4. Tribological properties of different TDESs lubricants under different temperature conditions.

[0085]

[0086] As can be seen from the results in Table 4, the TDESs lubricant prepared by this invention has good tribological properties, low coefficient of friction, and good wear resistance under different temperature conditions.

[0087] Test Example 5: Tribological Properties of TDESs Lubricant under High Load and Different Ambient Humidity Conditions

[0088] The tribological properties of the TDESs lubricants prepared in Examples 1, 3, and 5 were tested using an SRV-V friction testing machine. In the experiment, the upper friction pair used a steel ball (9Cr18Mo, D = 10 mm, HRC = 55 ± 2), and the lower friction pair used a cylindrical steel disc (9Cr18Mo, 24 mm × 7.9 mm, HRC = 55 ± 2). Before and after the test, the steel balls and discs of the upper and lower friction pairs were cleaned with anhydrous ethanol and dried before being installed on the SRV-V friction testing machine. The TDESs lubricants prepared in Examples 1, 3, and 5 were applied to the steel disc of the lower friction pair using a dropper, and tribological tests were conducted. The test conditions were: load 100 N, frequency 25 Hz, temperature 25 °C, relative humidity 50%, 80% RH, stroke 1 mm, and time 30 min. The friction coefficient curves were recorded, and the wear volume was obtained by photographing the wear marks on the steel disc using a non-contact three-dimensional surface profilometer.

[0089] The test results are shown in Table 5.

[0090] Table 5. Tribological properties of different TDESs lubricants under different humidity conditions.

[0091]

[0092] As can be seen from the results in Table 5, the TDESs lubricant prepared by this invention has good tribological properties, a small coefficient of friction, and good wear resistance under different humidity conditions.

[0093] Test Example 6: Rheological Properties Test of TDESs Lubricant

[0094] The rheological properties of the TDESs lubricants prepared in Examples 1, 3, and 5 were characterized using an MCR302 rheometer. The test temperature was 25°C, and the frequency range was 1–100 s⁻¹. -1 The test was repeated three times and the average value was taken. The test results show that the viscosity coefficients of the three lubricants CSE-TDES, TESE-TDES, and TBSE-TDES prepared in Examples 1, 3, and 5 do not change with the shear rate, and are classified as Newtonian fluids. At the same time, the average viscosity coefficients of the three lubricants are 7.38 Pa·s, 2.73 Pa·s, and 11.26 Pa·s, respectively, indicating that the TDESs lubricant prepared in this invention has good rheological properties.

[0095] Test Example 7: Contact Angle Performance Test of TDESs Lubricant on Steel Substrate Surface

[0096] The contact angle performance of the TDESs lubricants prepared in Examples 1, 3, and 5 on the selected steel substrate surface was characterized using a contact angle measuring instrument. Three repeated tests were conducted, and the average value was taken. The experimental results show that the contact angles of the three lubricants prepared in Examples 1, 3, and 5 (CSE-TDES, TESE-TDES, and TBSE-TDES) on the steel substrate surface are 31.8°, 35.3°, and 29.6°, respectively. This indicates that the TDESs lubricants prepared in this invention have good wetting properties and affinity on the steel substrate surface, thus facilitating their application in the field of friction lubrication.

[0097] Test Example 8: Thermal Stability Test of TDESs Lubricant

[0098] The thermal stability of the TDESs lubricants prepared in Examples 1, 3, and 5 was characterized by thermogravimetric analysis (TGA). The temperature range during the test was 50–500 °C, and the heating rate was 10 °C / min. -1 The test environment was a nitrogen atmosphere. The experimental results showed that the thermal decomposition temperatures of the three lubricants CSE-TDES, TESE-TDES, and TBSE-TDES prepared in Examples 1, 3, and 5 were 302.4℃, 286.5℃, and 229.9℃, respectively, indicating that the TDESs lubricant prepared in this invention has high thermal stability.

[0099] Test Example 9: Corrosion Resistance Test of TDESs Lubricant

[0100] A copper foil corrosion test was conducted according to ASTM D130 standards. Polished copper foil was immersed in the prepared TDESS lubricant and stored at 100°C for 24 hours. Afterward, any remaining lubricant was rinsed off with anhydrous ethanol. The experimental results showed that the three lubricants prepared in Examples 1, 3, and 5 (CSE-TDES, TESE-TDES, and TBSE-TDES) exhibited a corrosion degree of 1a on the copper foil.

[0101] In addition, monoethanolamine in Example 1 was omitted, and other conditions were the same as in Example 1 to prepare a binary eutectic solvent lubricant; the corrosion resistance of the obtained binary eutectic solvent lubricant was tested in the same way, and the results showed that its corrosion degree on copper foil was 1b.

[0102] The above results show that the TDESs lubricant prepared by this invention has superior corrosion resistance, and the addition of ethanolamine is beneficial to improving the corrosion resistance of the lubricant.

[0103] As can be seen from the above embodiments and test examples, the natural ternary eutectic solvent lubricant provided by the present invention exhibits excellent friction-reducing and anti-wear properties, especially achieving near-zero wear performance on steel surfaces, under high loads, and in various environmental conditions, thereby enhancing the application of the natural ternary eutectic solvent lubricant in the field of friction lubrication. Furthermore, the natural ternary eutectic solvent lubricant provided by the present invention has low preparation cost, uses green and pollution-free raw materials, and has a simple and easy-to-operate preparation process. Combined with other excellent properties such as rheological properties, high thermal stability, wettability to metal substrates, and corrosion resistance, it becomes a preferred lubricating material for practical applications.

[0104] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. The application of natural ternary eutectic solvent lubricants in the field of friction lubrication, characterized in that, The natural ternary eutectic solvent lubricant comprises the following components in molar fractions: 20-80% quaternary ammonium salt, 10-60% ethanolamine, and the balance sorbitol; the ethanolamine is monoethanolamine; the viscosity coefficient of the natural ternary eutectic solvent lubricant at room temperature is 2-12 Pa·s; and the contact angle of the natural ternary eutectic solvent lubricant on the metal substrate surface is 25-40°.

2. The application according to claim 1, characterized in that, The natural ternary eutectic solvent lubricant comprises the following components in molar fractions: 20-60% quaternary ammonium salt, 10-50% ethanolamine, and the balance sorbitol.

3. The application according to claim 1 or 2, characterized in that, The quaternary ammonium salt includes one or more of choline chloride, tetraethylammonium chloride, and tetrabutylammonium chloride.

4. The application according to claim 1, characterized in that, The preparation method of the natural ternary eutectic solvent lubricant includes the following steps: The natural ternary eutectic solvent lubricant was obtained by heating and stirring quaternary ammonium salt, sorbitol and ethanolamine.

5. The application according to claim 4, characterized in that, The heating and stirring temperature is 70~90℃, and the time is 10~12h; the heating and stirring are carried out under water bath conditions.

6. The application according to claim 4, characterized in that, The stirring speed is 500~700 rpm.

7. The application according to claim 4, characterized in that, After heating and stirring, the product is further subjected to drying-stabilization treatment; the drying-stabilization treatment is carried out at a temperature of 50~70℃ for 20~30h.

Images