Application of alcohol amine type ionic liquid and method for realizing super lubrication

Abstract

The invention discloses application of alcohol amine type ionic liquid as a lubricant. In the alcohol amine type ionic liquid, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1: (2-10). The invention also provides a method for realizing super lubrication, which comprises the following steps: coating the alcohol amine type ionic liquid on the surface of a friction pair, and realizing super lubrication after running-in; the friction pair is a silicon nitride / silicon dioxide friction pair; the friction conditions are as follows: the load is 2-3N, the linear speed is 50-80mm / s, the temperature is 20-25 DEG C, and the friction time is greater than or equal to 160s. The alcohol amine type ionic liquid is used as the lubricant for friction reduction and wear resistance of the friction pair, the friction reduction and wear resistance effects are remarkable, and super lubrication can be achieved on the silicon nitride / silicon dioxide friction pair.

Description

Technical Field

[0001] The present invention belongs to the field of lubricants, and particularly relates to the application of alcoholamine-based ionic liquids and a method for achieving superlubrication. Background Art

[0002] Friction and wear accompany many aspects of production and life, from the microscopic to the macroscopic. For thousands of years, humans have been committed to reducing friction, saving energy and resources, protecting the environment, and increasing the service life of machinery. According to incomplete statistics, nearly one-third of the world's primary energy is wasted during the friction process. Approximately 80% of mechanical components fail due to friction and wear. More than 50% of the serious accidents of mechanical equipment are related to lubrication failures during friction. Therefore, it is necessary to study lubrication to reduce friction and wear, which has significant social, environmental, and economic benefits.

[0003] Superlubrication was proposed in the 1990s. It is used to describe a theoretical sliding state in which friction or sliding resistance almost disappears. When the coefficient of friction is less than 0.01, it is considered to reach the superlubrication state. Ionic liquid-like substances are obtained by mixing salts with the ability to form hydrogen bonds with metal salts or hydrogen bond donor species. The components of many ionic liquid-like substances are biodegradable and inexpensive, such as amino acids and sugars. In many industrial applications, traditional lubricating oils are prone to causing environmental damage, difficult to recycle, and the coefficient of friction is difficult to reduce below 0.01. Therefore, ionic liquid-like substances as biodegradable alternatives have promising prospects in lubrication. Summary of the Invention

[0004] Based on the above technical problems, the present invention provides the application of alcoholamine-based ionic liquids as lubricants. Using alcoholamine-based ionic liquids as lubricants can show excellent friction reduction and anti-wear effects, and can achieve superlubrication on a silicon nitride / silica friction pair.

[0005] The specific solution of the present invention is as follows:

[0006] One of the objects of the present invention is to provide the application of alcoholamine-based ionic liquids as lubricants; in the alcoholamine-based ionic liquids, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:2 - 10.

[0007] Preferably, the molar ratio of the hydrogen bond acceptor to the hydrogen bond donor is 1:2 - 5.

[0008] The alcoholamine-based ionic liquids of the present invention contain a large number of hydroxyl groups, and it is easy to form a large number of intermolecular hydrogen bonds inside the lubricant, making it easy to form a low-shear interface during the friction process. Moreover, changing the ratio of the hydrogen bond donor to the hydrogen bond acceptor can regulate the viscosity of the ionic liquid-like lubricant, promote the hydrodynamic pressure effect during the friction process, and improve the lubrication performance.

[0009] Preferably, the hydrogen bond acceptor is selected from alcohol amine compounds or organic choline; the hydrogen bond donor is selected from any one of alcohol amine compounds, carboxylic acids, and alcohols.

[0010] Preferably, the alcohol amine-based ionic liquid is selected from any one of organic choline-alcohol amine ionic liquids, alcohol amine-carboxylic acid ionic liquids, and alcohol amine-alcohol ionic liquids.

[0011] In the ionic liquid-like substances of the present invention, the alcohol amine compounds can act as both hydrogen bond donors and hydrogen bond acceptors; in the organic choline-alcohol amine ionic liquids, the alcohol amine compounds act as hydrogen bond donors; in the alcohol amine-carboxylic acid ionic liquids and alcohol amine-alcohol ionic liquids, the alcohol amine compounds act as hydrogen bond acceptors.

[0012] Preferably, the alcohol amine compounds are selected from any one of monoethanolamine, diethanolamine, and triethanolamine; the organic choline is selected from any one of choline fluoride, choline chloride, and choline bromide; the carboxylic acid is selected from any one of acetic acid, oxalic acid, and citric acid; the alcohol is selected from any one of ethylene glycol, glycerol, 1,3-propanediol, and polyethylene glycol.

[0013] The ionic liquid-like substances of the present invention refer to eutectic mixtures formed by mixing two or more substances, whose melting points are lower than those of any component and exist in a liquid state within a relatively wide temperature range. Compared with traditional ionic liquids, the preparation process of ionic liquid-like substances is simpler and more economical, without the need for auxiliary technologies or purification, and their raw materials are easily available and inexpensive.

[0014] The ionic liquid-like substances of the present invention are prepared by a one-step synthesis method. The raw materials required for preparing the ionic liquid-like substances are mixed in proportion, and then a homogeneous and stable liquid is formed by means such as stirring, heating, and ultrasonic treatment, thus obtaining the product.

[0015] Preferably, the alcohol amine-based ionic liquid is used for friction reduction and anti-wear of friction pairs; the friction pairs are selected from any one of silicon nitride / silica friction pairs, silicon nitride / sapphire friction pairs, and silicon nitride / steel friction pairs.

[0016] Preferably, when the alcohol amine-based ionic liquid is used for a silicon nitride / silica friction pair, superlubrication can be achieved.

[0017] The present invention uses alcoholamine-based ionic liquids as lubricants. Alcoholamine-based ionic liquids have a large number of hydroxyl groups, resulting in a large number of hydrogen bond interactions within them, making it easy to form a low-shear interface during friction. In addition, the hydroxyl groups inside the alcoholamine-based ionic liquids can combine with polar groups on the surface of some friction pairs (such as silica friction pairs) to form hydrogen bonds, enabling the alcoholamine-based ionic liquids to be firmly adsorbed on the surface of the friction pairs, forming a stable adsorption film. This is manifested by a very small surface contact angle of the alcoholamine-based ionic liquids on the friction pairs, showing strong affinity, which can improve the load-carrying capacity of the lubrication system and achieve macroscopic superlubrication.

[0018] The second object of the present invention is to provide a method for achieving superlubrication, including: coating the alcoholamine-based ionic liquid on the surface of the friction pair, and achieving superlubrication after running-in; the friction pair is a silicon nitride / silica friction pair; the friction conditions include: a load of 2 - 3 N, a linear velocity of 50 - 80 mm / s, a temperature of 20 - 25 °C, and a friction time ≥ 160 s.

[0019] The beneficial effects of the present invention are as follows:

[0020] The present invention uses alcoholamine-based ionic liquids as lubricants, which have remarkable effects in reducing friction and wear, and can achieve superlubrication (friction coefficient < 0.01) after running-in on the friction pair for a period of time.

[0021] Compared with conventional lubricants on the market, the lubricant of the present invention has low raw material costs, is convenient to obtain, has a simple preparation process, is environmentally friendly, and has good potential application value. Description of the Drawings

[0022] Figure 1 It is a curve showing the change of the friction coefficient with time during friction when the alcoholamine-based ionic liquid described in Example 1 is used as a lubricant;

[0023] Figure 2 It is the average friction coefficient of the alcoholamine-based ionic liquid described in Example 1 under different loads when used as a lubricant;

[0024] Figure 3 It is the average friction coefficient of the alcoholamine-based ionic liquid described in Example 1 under different linear velocities when used as a lubricant;

[0025] Figure 4 It is a comparison of the average friction coefficients when the lubricating fluids of the alcoholamine-based ionic liquids described in Examples 1, 2, and 3 are used for lubrication;

[0026] Figure 5 It is the surface contact angle of the alcoholamine-based ionic liquid described in Example 1 on sapphire, steel, and silica discs when used as a lubricant;

[0027] Figure 6Curves showing the variation of the friction coefficient with time obtained from the friction tests of the alcoholamine-based ionic liquid as described in Example 1 on sapphire, steel, and silica disks;

[0028] Figure 7 Curves showing the variation of the friction coefficient with time during the friction process of the alcoholamine-based ionic liquid lubricant with different mass fractions of water added in Comparative Example 1. Specific Embodiments

[0029] Next, the technical solutions of the present invention will be described in detail through specific embodiments. However, it should be clearly stated that these embodiments are for illustrative purposes only and are not to be construed as limiting the scope of the present invention.

[0030] The alcoholamine-based ionic liquids described in the following examples were all prepared by a one-step synthesis method. For example, choline chloride-triethanolamine ionic liquid was obtained by mixing choline chloride and triethanolamine in a certain ratio, heating to 80 °C, and stirring for 2 hours.

[0031] Example 1

[0032] Application of an alcoholamine-based ionic liquid as a lubricant, wherein the alcoholamine-based ionic liquid is choline chloride-triethanolamine ionic liquid; among them: the molar ratio of choline chloride to triethanolamine is 1:2.

[0033] A method for achieving superlubrication, coating the alcoholamine-based ionic liquid on the surface of the friction pair, and achieving superlubrication after running-in; the friction pair is a silicon nitride ball / silica disk friction pair with a diameter of 5 mm; the friction conditions include: load 2 - 3 N, linear velocity 50 - 80 mm / s, temperature 20 - 25 °C, and friction time 3600 s.

[0034] The friction performance of the alcoholamine-based ionic liquid lubricant described in this example was tested, and the results are as Figures 1-3 shown, where:

[0035] Figure 1 is the curve of the friction coefficient varying with time (load 2 N, linear velocity 80 mm / s). It can be seen from the figure that the initial value of the friction coefficient is about 0.02. After a short running-in stage, the friction coefficient gradually decreases and finally stabilizes below 0.01, entering the superlubrication stage. This indicates that the alcoholamine-based ionic liquid lubricant described in the present invention has the ability to achieve macroscopic superlubrication.

[0036] Figure 2 is the average friction coefficient under different loads (linear velocity 80 mm / s). It can be seen from the figure that within the load range of 2 N - 3 N, this lubricant has good superlubrication performance.

[0037] Figure 3The average friction coefficient of the alcoholamine-based ionic liquid lubricant at different linear velocities (load 2 N). As can be seen from the figure, within the linear velocity range of 50 mm / s - 80 mm / s, this lubricant has excellent superlubricity performance.

[0038] Example 2

[0039] Application of the alcoholamine-based ionic liquid as a lubricant, wherein the alcoholamine-based ionic liquid is choline chloride-triethanolamine ionic liquid; wherein: the molar ratio of choline chloride to triethanolamine is 1:5.

[0040] Example 3

[0041] Application of the alcoholamine-based ionic liquid as a lubricant, wherein the alcoholamine-based ionic liquid is choline chloride-triethanolamine ionic liquid; wherein: the molar ratio of choline chloride to triethanolamine is 1:10.

[0042] The tribological experiment was carried out using an MPX-3G ball-disk friction and wear tester. The experimental conditions were: load 2 N, linear velocity 80 mm / s, temperature 20 - 25 °C, the friction pair was a silicon nitride ball with a diameter of 5 mm and a silica disk, and the friction time was 3600 s. The average friction coefficients of the alcoholamine-based ionic liquids described in Examples 2 and 3 during friction are as Figure 4 shown.

[0043] Examples 4 - 10

[0044] The present invention studied the tribological properties of different alcoholamine-based ionic liquids as lubricants. The specific examples and friction coefficients are shown in Table 1 below:

[0045] Table 1 Lubricants of alcoholamine-based ionic liquids and stable friction coefficients in Examples 4 - 10

[0046]

[0047] Note: The stable friction coefficient after running-in refers to the value when the friction coefficient tends to be stable after the friction pair has run-in under the conditions of a load of 2 N and a linear velocity of 80 mm / s.

[0048] Example 11

[0049] Using the alcoholamine-based ionic liquid described in Example 1 as a lubricant, the application effects on different friction pairs were compared. Specifically:

[0050] The alcoholamine-based ionic liquid-like described in Example 1 was coated on the surface of the friction pair for a friction experiment. The friction conditions included: a load of 2 N, a linear velocity of 80 mm / s, a temperature of 20 - 25 °C, and a friction time of 3600 s. The friction pairs were a silicon nitride ball / silica disc friction pair with a diameter of 5 mm, a silicon nitride ball / sapphire disc friction pair, and a silicon nitride ball / steel disc friction pair.

[0051] The surface contact angles of the alcoholamine-based ionic liquid-like lubricant on sapphire, steel, and silica discs are as Figure 5 shown; the curves of the friction coefficients varying with time obtained from the friction tests of the alcoholamine-based ionic liquid-like lubricant on sapphire, steel, and silica discs are as Figure 6 shown.

[0052] It can be seen that the contact angle of the alcoholamine-based ionic liquid-like of the present invention on the silica surface is the smallest, and the friction coefficient of the silicon nitride / silica friction pair is much smaller than that of the silicon nitride / sapphire friction pair and the silicon nitride / steel friction pair, achieving superlubrication. Through the analysis of the mechanism, it is considered that this is because the alcoholamine-based ionic liquid-like has extremely strong adsorption on the silica disc surface and can form a stable adsorption film, and the synergistic effect of the two can provide an excellent load-carrying capacity for the lubrication system, which is beneficial to achieving superlubrication.

[0053] Comparative Example 1

[0054] Different mass fractions of water were added to the alcoholamine-based ionic liquid-like lubricant described in Example 1 to obtain three lubricants, and their friction properties during the friction process were tested.

[0055] A tribological experiment was carried out using an MPX-3G ball-disc friction and wear tester. The experimental conditions were: a load of 2 N, a linear velocity of 80 mm / s, a temperature of 20 - 25 °C, the friction pair was a silicon nitride ball with a diameter of 5 mm and a silica disc, and the friction time was 3600 s. The friction coefficients of the alcoholamine-based ionic liquid-like lubricant described in Example 1 with different mass fractions of added water during the friction process are as Figure 7 shown.

[0056] It can be seen that as the water content increases, the performance of the lubricant gradually deteriorates, and when the water content reaches 10%, superlubrication cannot be achieved. Compared with the lubricant composition formed by the choline-based ionic liquid (choline chloride - magnesium chloride hexahydrate) and water involved in Patent CN114806673A, the influence of the addition of water on the lubrication performance in the two systems is completely different.

[0057] The above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, making equivalent substitutions or changes, shall be covered by the protection scope of the present invention.

Claims

1. Application of alcoholamine-based ionic liquid-like as lubricant; in the alcoholamine-based ionic liquid-like, the molar ratio of hydrogen bond acceptor to hydrogen bond donor is 1:2 - 10.

2. The application according to claim 1, characterized in that, The molar ratio of hydrogen bond acceptor to hydrogen bond donor is 1:2 - 5.

3. The application according to claim 1 or 2, characterized in that, The hydrogen bond acceptor is selected from alcoholamine compounds or organic choline; the hydrogen bond donor is selected from any one of alcoholamine compounds, carboxylic acids, and alcohols; preferably, the alcoholamine compound is selected from any one of monoethanolamine, diethanolamine, and triethanolamine.

4. The application according to any one of claims 1 to 3, characterized in that, The alcoholamine-based ionic liquid-like is selected from any one of organic choline-alcoholamine ionic liquids, alcoholamine-carboxylic acid ionic liquids, and alcoholamine-alcohol ionic liquids.

5. The application according to claim 4, wherein The organic choline is selected from any one of choline fluoride, choline chloride, and choline bromide.

6. The application according to claim 4, wherein The carboxylic acid is selected from any one of acetic acid, oxalic acid, and citric acid.

7. The application according to claim 4, wherein The alcohol is selected from any one of ethylene glycol, glycerol, 1,3-propanediol, and polyethylene glycol.

8. The application according to any one of claims 1-7, characterized in that, The alcoholamine-based ionic liquid-like is used for friction reduction and wear resistance of friction pairs; the friction pairs are selected from any one of silicon nitride / silica friction pairs, silicon nitride / sapphire friction pairs, and silicon nitride / steel friction pairs.

9. The application according to any one of claims 1 to 8, characterized in that The alcoholamine-based ionic liquid-like can achieve superlubrication when used for silicon nitride / silica friction pairs.

10. A method for achieving superlubricity, comprising: Coat the alcoholamine-based ionic liquid-like on the surface of the friction pair, and superlubrication is achieved after running-in; The friction pair is a silicon nitride / silica friction pair; The friction conditions include: load 2 - 3 N, linear velocity 50 - 80 mm / s, temperature 20 - 25 °C, and friction time ≥ 160 s.

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