Low-viscosity hydrophobic eutectic solvent lubricant and preparation method thereof

Abstract

The invention provides a low-viscosity hydrophobic eutecticevaporate solvent lubricant and a preparation method thereof, and relates to the technical field of lubricants, the low-viscosity hydrophobic eutecticevaporate solvent lubricant comprises a hydrogen bond donor and a hydrogen bond acceptor; the hydrogen bond donor and the hydrogen bond receptor are combined through a hydrogen bond; the hydrogen bond donor is thymol or carvacrol; the hydrogen bond receptor is menthol; the molar ratio of the hydrogen bond donor to the hydrogen bond acceptor meets a preset molar ratio, and the preset molar ratio ranges from 1: 0.5 to 1: 2. A series of novel hydrophobic deep-eutectic solvent lubricants with low viscosity, no corrosion and high bearing performance are prepared by regulating and controlling the molar ratio of a hydrogen bond donor to a hydrogen bond acceptor and utilizing the steric hindrance effect of functional groups.

Description

Technical Field

[0001] This invention relates to the field of lubricant technology, and in particular to a low-viscosity hydrophobic eutectic solvent lubricant and its preparation method. Background Technology

[0002] As a core transmission component in precision machining equipment, the ball screw assembly directly determines the positioning accuracy and load-bearing capacity of the mechanical system. However, the frictional behavior between the contact interfaces within the ball screw not only causes severe damage to the rolling elements and raceway surfaces but also deteriorates its transmission efficiency, motion smoothness, and service life. Against this backdrop, lubricants play a crucial role in improving the tribological behavior of the contact interfaces. Lubricants with excellent lubrication properties can form a stable, load-bearing oil film in the contact area, effectively preventing direct contact between the contact surfaces, thereby significantly reducing the coefficient of friction and wear. This is of great significance for ensuring the high-speed, stable transmission and long-life, reliable operation of the ball screw assembly.

[0003] In recent years, hydrophobic deep eutectic solvents (HDES) have emerged as a novel type of green solvent, exhibiting a series of significant advantages, such as low saturated vapor pressure, wide liquid phase range, good thermal stability, and low flammability. These superior properties make HDES a promising candidate for applications in various fields, particularly in lubrication and high-performance materials.

[0004] Most mainstream hydrophobic eutectic solvents are based on quaternary ammonium salts and long-chain fatty acid systems. They are not only plagued by the high energy consumption caused by high viscosity, but also face the risk of acidic components corroding metals. Summary of the Invention

[0005] To address the technical challenges of existing hydrophobic eutectic solvents, which are not only plagued by high energy consumption due to their high viscosity but also face the risk of corrosion of metals by acidic components, this invention provides a low-viscosity hydrophobic eutectic solvent lubricant and its preparation method.

[0006] The technical solutions provided by the embodiments of the present invention are as follows: This invention provides a low-viscosity hydrophobic eutectic solvent lubricant, comprising: a hydrogen bond donor and a hydrogen bond acceptor; The hydrogen bond donor and the hydrogen bond acceptor bind via hydrogen bonds; The hydrogen bond donor is thymol or carvacrol; The hydrogen bond acceptor is menthol; The molar ratio of the hydrogen bond donor to the hydrogen bond acceptor satisfies a preset molar ratio.

[0007] Furthermore, the preset molar ratio is between 1:0.5 and 1:2.

[0008] Furthermore, the preset molar ratio is specifically 1:0.5, 1:1, or 1:2.

[0009] Furthermore, the low-viscosity hydrophobic eutectic solvent lubricant has a viscosity coefficient of 25~50 mPa·s at room temperature of 25°C and a viscosity coefficient of 1~2 mPa·s at 100°C.

[0010] This invention provides a method for preparing a low-viscosity hydrophobic eutectic solvent lubricant, comprising: Step 1: Place the hydrogen bond donor and hydrogen bond acceptor into a sealed container according to a preset molar ratio; the hydrogen bond donor is thymol or carvacrol, and the hydrogen bond acceptor is menthol; Step 2: The hydrogen bond donor and the hydrogen bond acceptor are mixed by oil bath heating and magnetic stirring until a transparent and homogeneous liquid is formed, resulting in a low-viscosity hydrophobic eutectic solvent lubricant.

[0011] Furthermore, the preset molar ratio is between 1:0.5 and 1:2.

[0012] Furthermore, the preset molar ratio is specifically 1:0.5, 1:1, or 1:2.

[0013] Further, step 1 specifically involves placing the hydrogen bond donor and the hydrogen bond acceptor into a sealed container of 50 to 100 ml according to a preset molar ratio; Step 2 specifically involves: under oil bath heating at 60 to 80°C, magnetic stirring is performed at a speed of 500 to 1000 rpm for 0.5 to 1 hour until a transparent and homogeneous liquid is formed, thereby obtaining a low-viscosity hydrophobic eutectic solvent lubricant.

[0014] Furthermore, the preparation method of the low-viscosity hydrophobic eutectic solvent lubricant also includes: Step 3: Place the low-viscosity hydrophobic eutectic solvent lubricant into the centrifuge tube, and seal the centrifuge tube with a sealing ring to prevent oxidation.

[0015] Furthermore, the low-viscosity hydrophobic eutectic solvent lubricant has a viscosity coefficient of 25~50 mPa·s at room temperature of 25°C and a viscosity coefficient of 1~2 mPa·s at 100°C.

[0016] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: In this embodiment of the invention, by adjusting the molar ratio of hydrogen bond donors to hydrogen bond acceptors and utilizing the steric hindrance effect of functional groups, a series of novel hydrophobic eutectic solvent lubricants with low viscosity, non-corrosiveness, and high load-bearing capacity are prepared. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic flowchart illustrating a method for preparing a low-viscosity hydrophobic eutectic solvent lubricant according to an embodiment of the present invention.

[0019] Figure 2 The friction coefficient curves of a low-viscosity hydrophobic eutectic solvent lubricant provided in this embodiment of the invention are obtained by testing it under three load conditions (50, 100, 200N) on a bearing steel / 45 steel friction pair.

[0020] Figure 3 The present invention provides a low-viscosity hydrophobic eutectic solvent lubricant applied to a bearing steel / 45 steel friction pair, and the average friction coefficient and wear volume were obtained by testing under three load conditions (50, 100, 200N).

[0021] Figure 4 The present invention provides a low-viscosity hydrophobic eutectic solvent lubricant applied to a bearing steel / 45 steel friction pair, and the two-dimensional image, three-dimensional morphology and cross-sectional dimensions of the wear surface were obtained by testing under a 50 N load condition.

[0022] Figure 5 The present invention provides a low-viscosity hydrophobic eutectic solvent lubricant applied to a ball screw assembly, which measures the average friction torque under different operating conditions (30 rpm to 700 rpm).

[0023] As shown in the figure, specific structures and devices are marked in the figure to clearly illustrate the structure of the embodiments of the present invention. However, this is only for illustrative purposes and is not intended to limit the present invention to this specific structure, device and environment. Those skilled in the art can adjust or modify these devices and environments according to specific needs. Detailed Implementation

[0024] The technical solutions of the present invention will now be described with reference to the accompanying drawings. It should also be noted that, to make the embodiments more detailed, the following embodiments are the best and preferred embodiments. For some well-known technologies, those skilled in the art can also use other alternative methods to implement the invention; moreover, the accompanying drawings are only for more specific description of the embodiments and are not intended to specifically limit the present invention.

[0025] It should be noted that the use of terms such as "an embodiment," "an embodiment," "an exemplary embodiment," and "some embodiments" in the specification indicates that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments (whether explicitly described or not) should be within the knowledge of those skilled in the art.

[0026] Generally, terms can be understood at least partly from their use in context. For example, depending at least partly on the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in a singular sense, or a combination of features, structures, or characteristics in a plural sense. Additionally, the term "based on" can be understood not necessarily to convey an exclusive set of factors, but rather, alternatively, depending at least partly on the context, to allow for the presence of other factors that are not necessarily explicitly described.

[0027] It is understood that the meanings of “on”, “above”, and “above” in this invention should be interpreted in the broadest manner, such that “on” means not only “directly on” something, but also includes the meaning of being “on” something with an intervening feature or layer, and that “above” or “above” means not only “on” something, but also includes the meaning of being “on” something without an intervening feature or layer.

[0028] Furthermore, spatially related terms such as “below,” “under,” “lower,” “above,” and “upper” are used herein for convenience to describe the relationship of one element or feature to one or more other elements or features, as illustrated in the accompanying drawings. Spatially related terms are intended to cover different orientations in the use or operation of the device other than those depicted in the accompanying drawings. The device may be oriented in other ways, and the spatially related descriptive terms used herein can be interpreted similarly.

[0029] like Figures 1 to 4 As shown, an embodiment of the present invention provides a low-viscosity hydrophobic eutectic solvent lubricant, comprising: a hydrogen bond donor and a hydrogen bond acceptor.

[0030] Hydrogen bond donors and hydrogen bond acceptors bind together via hydrogen bonds.

[0031] The hydrogen bond donors are thymol or carvacrol. Thymol and carvacrol are isomers, and their functional groups differ in steric hindrance.

[0032] The hydrogen bond acceptor is menthol.

[0033] The molar ratio of hydrogen bond donors to hydrogen bond acceptors satisfies the preset molar ratio.

[0034] Optionally, the preset molar ratio is between 1:0.5 and 1:2.

[0035] Optionally, the preset molar ratio is 1:0.5, 1:1, or 1:2.

[0036] Optionally, the low-viscosity hydrophobic eutectic solvent lubricant has a viscosity coefficient of 25~50 mPa·s at room temperature of 25°C and a viscosity coefficient of 1~2 mPa·s at 100°C.

[0037] An embodiment of the present invention provides a method for preparing a low-viscosity hydrophobic eutectic solvent lubricant, characterized in that it includes: Step 1: Place the hydrogen bond donor and hydrogen bond acceptor into a sealed container according to a predetermined molar ratio. The hydrogen bond donor is thymol or carvacrol, and the hydrogen bond acceptor is menthol.

[0038] Step 2: The hydrogen bond donor and the hydrogen bond acceptor are mixed by heating in an oil bath and stirring with magnetic force until a transparent and homogeneous liquid is formed, resulting in a low-viscosity hydrophobic eutectic solvent lubricant.

[0039] Optionally, the preset molar ratio is between 1:0.5 and 1:2.

[0040] Optionally, the preset molar ratio is 1:0.5, 1:1, or 1:2.

[0041] Optionally, step 1 specifically involves placing the hydrogen bond donor and the hydrogen bond acceptor into a sealed container of 50 to 100 ml according to a preset molar ratio.

[0042] Step 2 is as follows: Under the condition of oil bath heating at 60 to 80°C, magnetic stirring is performed at a speed of 500 to 1000 rpm for 0.5 to 1 hour until a transparent and homogeneous liquid is formed, thus obtaining a low-viscosity hydrophobic eutectic solvent lubricant.

[0043] Optionally, the preparation method of the low-viscosity hydrophobic eutectic solvent lubricant further includes: Step 3: Place the low-viscosity hydrophobic eutectic solvent lubricant into the centrifuge tube. To prevent oxidation, seal the centrifuge tube with a sealing ring.

[0044] Optionally, the low-viscosity hydrophobic eutectic solvent lubricant has a viscosity coefficient of 25~50 mPa·s at room temperature of 25°C and a viscosity coefficient of 1~2 mPa·s at 100°C.

[0045] In this embodiment of the invention, by adjusting the molar ratio of hydrogen bond donors to hydrogen bond acceptors and utilizing the steric hindrance effect of functional groups, a series of novel hydrophobic eutectic solvent lubricants with low viscosity, low energy consumption, non-corrosiveness and high load-bearing capacity are prepared.

[0046] For example, hydrophobic eutectic solvents prepared by mixing thymol and menthol in molar ratios of 1:0.5, 1:1, and 1:2 are designated as DES-LT1, DES-LT2, and DES-LT3, respectively. Hydrophobic eutectic solvents prepared by mixing carvacrol and menthol in molar ratios of 1:0.5, 1:1, and 1:2 are designated as DES-LC1, DES-LC2, and DES-LC3, respectively.

[0047] To test the lubrication performance of the hydrophobic eutectic solvent lubricant of this invention, the friction pair pair selection for friction pair testing was: bearing steel ball / 45 steel substrate.

[0048] This invention provides the application of hydrophobic eutectic solvent lubricants prepared by the above-mentioned technical solutions or preparation methods in the field of friction lubrication.

[0049] The lubrication performance of hydrophobic eutectic solvents was tested using a ball screw pair friction torque test bench.

[0050] This invention provides a series of hydrophobic eutectic solvent lubricants, comprising menthol, thymol, and carvacrol, with a molar ratio of hydrogen bond donor to hydrogen bond acceptor of 1:0.5 to 1:2. This invention uses menthol as the hydrogen bond acceptor (HBA) and thymol and carvacrol as hydrogen bond donors (HBD). By controlling the ratio of hydrogen bond donors to acceptors, the strength of the hydrogen bond network formed between them is altered, resulting in a solvent with a melting point lower than that of each component, i.e., a hydrophobic eutectic solvent lubricant. The hydrophobic eutectic solvent lubricant provided by this invention has a viscosity of less than 50 mPa·s at room temperature (25 °C). Notably, it exhibits a low viscosity of less than 2 mPa·s at 100 °C, thereby improving heat dissipation during friction. Furthermore, the complex hydrogen bond network formed between the hydrogen bond donors and acceptors gives this natural eutectic solvent lubricant high thermal stability. Furthermore, the thymol, carvacrol, and menthol used are green, environmentally friendly, and non-toxic compounds, thus giving the hydrophobic eutectic solvent lubricant of this invention the characteristics of being biodegradable and environmentally friendly.

[0051] This invention provides a method for preparing hydrophobic eutectic solvent lubricants according to the above technical solutions. This invention uses a simple heating and stirring method to prepare natural eutectic solvent lubricants with excellent friction-reducing and anti-wear properties. The process is fast, simple, and easy to operate, and the preparation process avoids environmental pollution to the greatest extent. It is a green and environmentally friendly preparation technology.

[0052] Table 1. Combinations of hydrogen bond donors and hydrogen bond acceptors in hydrophobic eutectic solvents In this invention, thymol, carvacrol, and menthol are all common nonionic compounds with a certain degree of universality, and are characterized by being green, environmentally friendly, economical, and sustainable. This invention uses menthol as a hydrogen bond acceptor (HBA) and thymol or carvacrol as a hydrogen bond donor (HBD), while simultaneously controlling the ratio of hydrogen bond donors to hydrogen bond acceptors to obtain a solvent with a melting point lower than that of each component, i.e., a hydrophobic eutectic solvent lubricant. In this invention, the viscosity coefficient of the hydrophobic eutectic solvent lubricant is 20–47 mPa·s. The hydrophobic eutectic solvent lubricant is a colorless, transparent liquid with good hydrophobicity, has no strict requirements on the water content during storage, and does not require drying before use, simplifying the process and saving costs.

[0053] Example 1 A hydrophobic eutectic solvent lubricant is prepared by the following steps: (1) Weigh 7.815 g of menthol and 15.024 g of thymol (molar ratio of 1:2) and mix them in a 50 mL round-bottom flask.

[0054] (2) Place the flask containing the mixture of thymol and menthol from step (1) in an oil bath and stir at 60°C for 20 minutes at a stirring speed of 600 rpm to obtain a transparent and homogeneous viscous solvent (DES-LT1).

[0055] Examples 2 and 3 The molar ratios of thymol and menthol were adjusted to 1:1 and 1:2, respectively, while the rest remained the same as in Example 1, resulting in hydrophobic eutectic solvent lubricants (DES-LT2 and DES-LT3).

[0056] Examples 4 to 6 The molar ratios of carvacrol and menthol were adjusted to 1:2, 1:1 and 1:0.5, respectively, while the rest remained the same as in Example 1, to obtain hydrophobic eutectic solvent lubricants (DES-LC1, DES-LC2 and DES-LC3).

[0057] To fully elucidate the excellent tribological properties of the prepared hydrophobic eutectic solvent lubricant as a lubricant, this invention employs a UMT tribological testing machine to test the tribological properties of the hydrophobic eutectic solvent lubricants prepared in each embodiment. The testing process utilizes a rotation mode. Specific tests are as follows: Before testing, the surface of the lower specimen was polished using a metallographic polishing machine (MP-2DT / MP-2B). The grits of sandpaper used were 100, 320, 600, 1000, 2000, and 7000. The surface roughness was measured using a white light interferometer to ensure that the surface roughness of the lower specimen was uniformly below 20 nm. Then, the upper and lower specimens were wiped clean with anhydrous ethanol and allowed to dry before subsequent experiments were conducted.

[0058] Test 1: Tribological properties under low load conditions The tribological properties of the natural eutectic solvent lubricants prepared in Examples 1 to 6 were tested using a tribological testing machine. The upper friction pair used bearing steel balls (GCR15, HRC = 60 ± 2, D = 4 mm), and the lower specimen used a cylindrical 45 steel disc (SC45, HRC = 23 ± 1, R = 25 mm, H = 10 mm). The cylindrical 45 steel disc was polished, cleaned with alcohol, and placed in a 50°C oven for 30 minutes to dry before being mounted on the tribological testing machine. 10 ml of the hydrophobic eutectic solvent lubricant prepared in Examples 1 to 6 was dropped onto the cylindrical 45 steel disc of the friction pair using a dropper for tribological testing. The test conditions were: load 50 N, rotation radius 4 mm, rotation speed 60 rpm, and time 30 min. The friction coefficient curve, two-dimensional characterization of the worn surface, and three-dimensional wear track size were recorded.

[0059] Test 2: Tribological property testing under medium load conditions The tribological properties of the hydrophobic eutectic solvent lubricants prepared in Examples 1 to 6 were tested using a tribological testing machine. The upper friction pair used bearing steel balls (GCR15, HRC = 60 ± 2, D = 4 mm), and the lower specimen used a cylindrical 45 steel disc (SC45, HRC = 23 ± 1, 25 mm × 10 mm). The polished, alcohol-cleaned, and dried 45 steel disc was mounted on the tribological testing machine. 10 ml of the hydrophobic eutectic solvent lubricant prepared in Examples 1 to 6 was dropped onto the cylindrical 45 steel disc of the friction pair using a dropper, and tribological testing was performed. The test conditions were: load 100 N, rotation radius 4 mm, rotation speed 60 rpm, and time 30 min. The friction coefficient curve, two-dimensional characterization of the worn surface, and three-dimensional wear track size were recorded.

[0060] Test 3: Tribological performance testing under high load conditions The tribological properties of the hydrophobic eutectic solvent lubricants prepared in Examples 1 to 6 were tested using a tribological testing machine. The upper friction pair used bearing steel balls (GCR15, HRC = 60 ± 2, D = 4 mm), and the lower specimen used a cylindrical 45 steel disc (SC45, HRC = 23 ± 1, 25 mm × 10 mm). The polished, alcohol-cleaned, and dried 45 steel disc was mounted on the tribological testing machine. 10 ml of the hydrophobic eutectic solvent lubricant prepared in Examples 1 to 6 was dropped onto the cylindrical 45 steel disc of the friction pair using a dropper, and tribological testing was performed. The test conditions were: load 200 N, rotation radius 4 mm, rotation speed 60 rpm, and time 30 min. The friction coefficient curve, two-dimensional characterization of the worn surface, and three-dimensional wear track size were recorded.

[0061] Friction coefficient test results are as follows Figure 2 As shown, Figure 2 (a) is a graph showing the friction coefficient curves obtained by DES-LT1, DES-LT2 and DES-LT3 under 50N operating conditions. Figure 2 (b) is a graph showing the friction coefficients of DES-LT1, DES-LT2, and DES-LT3 under a 100N operating condition. Figure 2 (c) is a graph showing the friction coefficients of DES-LT1, DES-LT2, and DES-LT3 under a 200N operating condition. Figure 2 (d) is a graph showing the friction coefficients of DES-LC1, DES-LC2, and DES-LC3 under a 50N operating condition. Figure 2 (e) is a graph showing the friction coefficients of DES-LC1, DES-LC2, and DES-LC3 under a 100N operating condition. Figure 2(f) is a graph of the friction coefficient obtained by DES-LC1, DES-LC2 and DES-LC3 under 200N working conditions.

[0062] Friction coefficient test results show that, compared with the commercial lubricant PEG 200, the hydrophobic eutectic solvent lubricant exhibits a lower friction coefficient and excellent operational stability. Under a load of 50 N, the friction coefficient of PEG 200 fluctuates drastically but remains above 0.11; DES-LC2 has the best performance with a COF of only 0.075, while the other hydrophobic eutectic solvent lubricant samples are stable between 0.095 and 0.10. As the load increases to 100 N and 200 N, the friction coefficient of PEG 200 further increases to above 0.12 and continues to fluctuate, while the hydrophobic eutectic solvent lubricant samples remain stable. Specifically, at 100 N, the friction coefficient of DES-LT3 is as low as 0.09, while the friction coefficients of the other hydrophobic eutectic solvent lubricants are stable at 0.10; while under a high load of 200 N, the friction coefficients of DES-LC1, DES-LC2, DES-LT2, and DES-LT3 are stable at 0.10, and the friction coefficients of DES-LC3 and DES-LT1 are stable at 0.11.

[0063] The test results of average friction coefficient and average wear volume are as follows: Figure 3 As shown, Figure 3 (a) is a bar chart showing the average friction coefficient and average wear volume of DES-LT1, DES-LT2, and DES-LT3 under 50N operating conditions. Figure 2 (b) is a bar chart showing the average friction coefficient and average wear volume of DES-LT1, DES-LT2, and DES-LT3 under 100N operating conditions. Figure 2 (c) is a bar chart showing the average friction coefficient and average wear volume of DES-LT1, DES-LT2, and DES-LT3 under 200N operating conditions. Figure 2 (d) is a bar chart showing the average friction coefficient and average wear volume of DES-LC1, DES-LC2, and DES-LC3 under 50N operating conditions. Figure 2 (e) is a bar chart showing the average friction coefficient and average wear volume of DES-LC1, DES-LC2, and DES-LC3 under a 100N operating condition. Figure 2 (f) is a bar chart of the average friction coefficient and average wear volume obtained by DES-LC1, DES-LC2 and DES-LC3 under 200N working conditions.

[0064] The average friction coefficient and average wear volume test results show that the low-viscosity hydrophobic eutectic solvent lubricant provided by this invention, when applied to bearing steel / steel friction pairs, exhibits superior tribological properties compared to the commercial lubricant PEG 200 under different load conditions (50N, 100N, 200N). Specifically: under a low load of 50N, the friction coefficients of the DES-LT and DES-LC series were significantly reduced by 20.2% and 30.1%, respectively, and the wear volume was reduced by 76.7% and 74.3%, respectively; when the load increased to 100N, the friction coefficients of the two decreased by 15.5% and 18.7%, respectively, and the wear volume was reduced by 47.7% and 41.7%, respectively; even under a high load condition of 200N, the lubricant of this invention still maintains excellent performance, with the friction coefficient and wear volume of the DES-LT series decreasing by 9.1% and 44.4%, respectively, while those of the DES-LC series decreased by 15.4% and 43.1%, respectively.

[0065] The test results of two-dimensional images, three-dimensional morphology, and cross-sectional dimensions of the worn surface are as follows: Figure 4 As shown, Figure 4 (a1), (a2), and (a3) ​​are respectively the two-dimensional image, three-dimensional morphology, and cross-sectional dimensions of the worn surface obtained by DES-LT1 under 50N conditions. Figure 4 (b1), (b2), and (b3) are respectively the two-dimensional image, three-dimensional morphology, and cross-sectional dimensions of the worn surface obtained by DES-LT2 under 50N conditions. Figure 4 (c1), (c2), and (c3) are respectively the two-dimensional image, three-dimensional morphology, and cross-sectional dimensions of the worn surface obtained by DES-LT3 under 50N conditions. Figure 4 (d1), (d2), and (d3) are respectively the two-dimensional image, three-dimensional morphology, and cross-sectional dimensions of the worn surface obtained by DES-LC1 under 50N conditions. Figure 4 (e1), (e2), and (e3) are respectively the two-dimensional image, three-dimensional morphology, and cross-sectional dimensions of the worn surface obtained by DES-LC2 under 50N conditions. Figure 4 (f1), (f2), and (f3) are respectively the two-dimensional image, three-dimensional morphology, and cross-sectional dimensions of the worn surface obtained by DES-LC3 under 50N conditions. Figure 4 (g1), (g2), and (g3) are respectively the two-dimensional image, three-dimensional morphology, and cross-sectional dimensions of the wear surface obtained by PEG200 under 50N conditions.

[0066] The results of two-dimensional images, three-dimensional morphology, and cross-sectional dimensions of the worn surfaces show that, compared with the commercial lubricant PEG200, the wear track width and depth are significantly reduced under hydrophobic eutectic solvent lubrication. Specifically, under a 50 N load, the wear track width of PEG200 is 397 μm and the wear track depth is 6 μm; the wear track widths of DES-LT1, DES-LT2, and DES-LT3 are 299 μm, 249 μm, and 211 μm, respectively, and the wear track depths are 3 μm, 2.5 μm, and 2 μm, respectively; the wear track widths of DES-LC1, DES-LC2, and DES-LC3 are 292 μm, 260 μm, and 305 μm, respectively, and the wear track depths are 3.8 μm, 2.3 μm, and 3.9 μm, respectively.

[0067] Furthermore, to verify the lubrication performance of the prepared hydrophobic eutectic solvent-lubricated ball screw, this invention uses a ball screw friction torque test bench to test the friction torque of the hydrophobic eutectic solvent lubricant prepared in each embodiment. The specific tests are as follows: The parameters of the ball screw used are: nominal diameter 16mm, lead 5mm, and effective stroke 100mm. Before each experiment, the hydrophobic eutectic solvent lubricant prepared in Examples 1 to 6 and the control group PEG200 were respectively filled into the inside of the ball screw nut pair. They were then installed on the experimental table for a 5-minute run-in period to ensure that the ball screw was fully lubricated.

[0068] Subsequently, the friction torque was tested in real time using a gradually increasing speed approach, with the speed nodes set sequentially at 30, 60, 90, 100, 120, 150, 300, 400, 500, 600, and 700 rpm. To ensure data reliability, the experiment was repeated three times at each speed condition, and the average value was taken.

[0069] The average friction torque of the ball screw pair at varying speeds (30-700 rpm) was tested using a ball screw friction torque test bench.

[0070] The ball screw friction torque test results are as follows Figure 5 As shown, Figure 5 (a) Average frictional torque obtained by testing DES-LT1, DES-LT2, DES-LT3, PEG200 and unlubricated ball screw pairs under variable speed conditions. Figure 5 (b) Average frictional torque obtained by testing DES-LC1, DES-LC2, DES-LC3, PEG 200 and unlubricated ball screw pairs under variable speed conditions.

[0071] The ball screw friction torque test results show that as the rotational speed increases from 30 rpm to 100 rpm, the enhanced hydrodynamic effect improves the oil film's load-carrying capacity, prompting a shift in lubrication from boundary lubrication to mixed lubrication, resulting in a significant decrease in friction torque. However, as the rotational speed further increases from 100 rpm to 700 rpm, the friction torque shows a slow upward trend, mainly due to the gradual increase in fluid viscous resistance under high shear conditions. Throughout the entire test speed range, the friction torque of the hydrophobic eutectic solvent is significantly lower than that of dry friction and PEG 200 lubrication conditions. Specifically, at 700 rpm, the friction torques of DES-LT3 and DES-LC2 are 0.01825 Nm and 0.01775 Nm, respectively, while the corresponding values ​​for PEG 200 and dry friction are 0.02150 Nm and 0.03425 Nm, respectively. Compared with PEG 200, the frictional torque of DES-LT3 and DES-LC2 was reduced by 15.1% and 17.4%, respectively.

[0072] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the preferred embodiments, while those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0073] 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. A low-viscosity, hydrophobic, eutectic solvent lubricant, characterized in that, include: Hydrogen bond donors and hydrogen bond acceptors; The hydrogen bond donor and the hydrogen bond acceptor bind via hydrogen bonds; The hydrogen bond donor is thymol or carvacrol; The hydrogen bond acceptor is menthol; The molar ratio of the hydrogen bond donor to the hydrogen bond acceptor satisfies a preset molar ratio.

2. The low-viscosity hydrophobic eutectic solvent lubricant according to claim 1, characterized in that, The preset molar ratio is between 1:0.5 and 1:

2.

3. The low-viscosity hydrophobic eutectic solvent lubricant according to claim 2, characterized in that, The preset molar ratio is specifically 1:0.5, 1:1, or 1:

2.

4. The low-viscosity hydrophobic eutectic solvent lubricant according to claim 1, characterized in that, The low-viscosity hydrophobic eutectic solvent lubricant has a viscosity coefficient of 25~50 mPa·s at room temperature of 25℃ and a viscosity coefficient of 1~2 mPa·s at 100℃.

5. A method for preparing a low-viscosity hydrophobic eutectic solvent lubricant, characterized in that, include: Step 1: Place the hydrogen bond donor and hydrogen bond acceptor into a sealed container according to a preset molar ratio; The hydrogen bond donor is thymol or carvacrol, and the hydrogen bond acceptor is menthol; Step 2: Mix the hydrogen bond donor and the hydrogen bond acceptor until a transparent and homogeneous liquid is formed to obtain a low-viscosity hydrophobic eutectic solvent lubricant.

6. The method for preparing the low-viscosity hydrophobic eutectic solvent lubricant according to claim 5, characterized in that, The preset molar ratio is between 1:0.5 and 1:

2.

7. The method for preparing the low-viscosity hydrophobic eutectic solvent lubricant according to claim 6, characterized in that, The preset molar ratio is specifically 1:0.5, 1:1, or 1:

2.

8. The method for preparing the low-viscosity hydrophobic eutectic solvent lubricant according to claim 5, characterized in that, Step 1 specifically involves placing the hydrogen bond donor and the hydrogen bond acceptor into a sealed container of 50 to 100 ml according to a preset molar ratio. Step 2 specifically involves: under oil bath heating at 60 to 80°C, magnetic stirring is performed at a speed of 500 to 1000 rpm for 0.5 to 1 hour until a transparent and homogeneous liquid is formed, thereby obtaining a low-viscosity hydrophobic eutectic solvent lubricant.

9. The method for preparing the low-viscosity hydrophobic eutectic solvent lubricant according to claim 5, characterized in that, Also includes: Step 3: Place the low-viscosity hydrophobic eutectic solvent lubricant into the centrifuge tube, and seal the centrifuge tube with a sealing ring to prevent oxidation.

10. The method for preparing the low-viscosity hydrophobic eutectic solvent lubricant according to claim 5, characterized in that, The low-viscosity hydrophobic eutectic solvent lubricant has a viscosity coefficient of 25~50 mPa·s at room temperature of 25℃ and a viscosity coefficient of 1~2 mPa·s at 100℃.

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