A lubricating oil containing element-doped carbon quantum dots, and a preparation method and application thereof

Abstract

The application relates to the technical field of lubricating additives, in particular to a lubricating oil containing element-doped carbon quantum dots, a preparation method and application thereof, which comprises the following steps: adding a heterocyclic aromatic hydrocarbon compound precursor into base oil to obtain a mixed solution through ultrasonic dispersion; and irradiating the mixed solution under a pulse laser beam under inert gas conditions to generate the lubricating oil containing element-doped carbon quantum dots in situ. The element-doped carbon quantum dots prepared by the application have good dispersion stability in base lubricating oil, the lubricating oil improves the friction-reducing and wear-resistant performance of mechanical parts, the preparation method is simple, and the application range is wide.

Description

Technical Field

[0001] This invention relates to the field of lubricant additives, specifically to a lubricating oil containing element-doped carbon quantum dots, its preparation method, and its application. Background Technology

[0002] Against the backdrop of rapid modern industrial development, the widespread use of mechanical equipment has brought immense convenience to human life and has become an indispensable part. However, in complex mechanical systems involving the mating of components, friction and wear often lead to energy loss and equipment failure. According to reliable statistics, nearly one-third of the world's primary energy waste comes from friction, and about half of the power of mechanical equipment is dissipated during friction. Furthermore, heat accumulates at the contact interface during friction, and the friction materials adhere, shear, and tear, causing damage to the workpiece surface and significant wear. Approximately four-fifths of equipment damage originates from abnormal wear caused by lubrication failure. Therefore, reducing friction and wear in mechanical equipment to extend its effective operating time and improve its service life is crucial. Developing new lubricating materials and novel lubrication technologies to reduce friction and wear during equipment operation is one of the most effective and direct ways to save energy and resources and build a resource-saving society. Lubricating additives can effectively enhance the friction-reducing and anti-wear properties of base lubricating oils, working in conjunction with them.

[0003] Traditional friction-reducing and anti-wear additives are typically composed of organic polar materials, often containing environmentally harmful elements such as metals, sulfur, and phosphorus. Furthermore, with the development of nanotechnology, nano-lubricant additives, including elemental metals, metal oxides, metal sulfides, metal borates, polymers, and carbon-based nanomaterials, exhibit unique and superior properties. However, they often suffer from insufficient embedding stability on the friction pair surface, uneven size distribution, and high surface chemical inertness, making it difficult to improve their dispersion stability in base lubricating oils through chemical modification. Carbon quantum dots (CQDs), as a novel zero-dimensional carbon-based nanomaterial, have attracted researchers' attention due to their advantages such as uniform size distribution, good physicochemical properties, high chemical stability, convenient preparation and functionalization, and low toxicity and environmental friendliness.

[0004] Carbon quantum dots (CQDs) are spherical or quasi-spherical nanoparticles with a diameter of less than 10 nm and significant fluorescence properties, composed of a carbon core and surface groups. The carbon core has an amorphous graphitized or non-graphitized structure, and the surface contains polar groups such as hydroxyl (-OH) and carboxyl (-COOH) groups, while also exhibiting many defects, making them highly designable. However, they face three main challenges: 1. Complex preparation process: Traditional CQD preparation methods include top-down methods (chemical ablation, laser ablation, arc discharge, etc.) and bottom-up methods (microwave, ultrasonic, chemical oxidation, template, hydrothermal, etc.); 2. Difficult separation and purification: Previous separation and purification methods mainly include filtration, centrifugation, column chromatography, and gel electrophoresis; 3. In the lubrication field, their high specific surface area makes them prone to agglomeration in base lubricating oils. Traditional physical methods, such as ultrasonic treatment, easily cause secondary agglomeration, while chemical methods, such as surface modification, are cumbersome, difficult to operate, and costly. Therefore, in order to solve the above problems, it is urgent to develop a simple preparation process for functionalized carbon quantum dots that also has excellent tribological properties. Summary of the Invention

[0005] To address the shortcomings of the prior art, the present invention aims to provide a lubricating oil containing element-doped carbon quantum dots, its preparation method, and its application. The functionalized carbon quantum dots obtained by the present invention exhibit good dispersion stability in base lubricating oils and significantly improve the friction reduction and anti-wear performance of mechanical parts. The preparation method is simple, requires no further separation and purification, and exhibits good stability in base lubricating oils with excellent tribological properties.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0007] A method for preparing an element-doped carbon quantum dot lubricating additive includes the following steps:

[0008] A heterocyclic aromatic hydrocarbon precursor was added to a base oil and ultrasonically dispersed to obtain a mixture.

[0009] Under inert atmosphere conditions, the mixture is irradiated under a pulsed laser beam to obtain a lubricating oil containing element-doped carbon quantum dots.

[0010] In a preferred embodiment of the present invention, the heterocyclic aromatic hydrocarbon precursor is one of pyridine, quinoline, benzopyrrole, benzothiophene, benzothiazole, benzodiazepine, and benzotriazole.

[0011] In a preferred embodiment of the present invention, the mass fraction of the heterocyclic aromatic hydrocarbon precursor in the mixture is 0.1% to 10%.

[0012] In a preferred embodiment of the present invention, the base oil is one of PAO, PEG, and 500SN.

[0013] In a preferred embodiment of the present invention, the pulsed laser beam is an unfocused pulsed laser beam.

[0014] In a preferred embodiment of the present invention, the irradiation parameters are: laser beam output wavelength of 355–1064 nm, pulse frequency of 10 Hz, and laser irradiation energy of 10–800 mJ pulse. -1 cm 2 .

[0015] In a preferred embodiment of the present invention, the laser irradiation time is 5 to 60 minutes.

[0016] In a preferred embodiment of the present invention, the ultrasonic dispersion time is 0.5 h.

[0017] A second objective of this invention is to provide a lubricating oil containing element-doped carbon quantum dots prepared by any of the above-described preparation methods.

[0018] A third objective of this invention is to provide an application of the aforementioned lubricating oil containing element-doped carbon quantum dots in mechanical components.

[0019] In the above applications, the mixture irradiated by the pulsed laser beam can be directly transformed into a lubricating oil containing element-doped carbon quantum dots, without the need for further separation and purification, and can be directly applied to mechanical parts.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. This invention allows a mixture containing heterocyclic aromatic hydrocarbon precursors to be directly converted into a lubricating oil containing element-doped carbon quantum dots after being irradiated with a pulsed laser beam. Through liquid-phase pulsed laser irradiation technology, the surface of the generated carbon quantum dots is effectively passivated under extreme conditions. Therefore, the prepared functionalized carbon quantum dots have good dispersion stability in the base lubricating oil and significantly improve the friction reduction and anti-wear performance of mechanical parts.

[0022] 2. This invention uses liquid phase pulsed laser irradiation technology to generate lubricating oil containing element-doped carbon quantum dots in situ in one step. Compared with traditional methods such as hydrothermal methods, which require a production cycle of several hours or days, this invention can achieve in-situ one-step preparation in just 5-60 minutes, which greatly overcomes the limitations of its application as a lubricating additive and avoids the cumbersome steps of traditional separation, purification and re-addition.

[0023] 3. The mixture containing heterocyclic aromatic hydrocarbon precursors of the present invention can be directly converted into a lubricating oil containing element-doped carbon quantum dots after being irradiated by a pulsed laser beam, without the need for further separation and purification, and can be directly applied to mechanical parts. Attached Figure Description

[0024] Figure 1 Example 1a of the present invention: Morphology of nitrogen-doped carbon quantum dots prepared; b: Friction coefficient curve of lubricating oil containing 1 wt% nitrogen-doped carbon quantum dots and base oil PAO 10;

[0025] Figure 2 Example 2a of the present invention: Morphology of sulfur-doped carbon quantum dots prepared; b: Friction coefficient curve of lubricating oil containing 1 wt% sulfur-doped carbon quantum dots and base oil PAO 10;

[0026] Figure 3 Example 3a of the present invention: Morphology of nitrogen / sulfur co-doped carbon quantum dots; b: Friction coefficient curve of lubricating oil containing 1 wt% nitrogen / sulfur co-doped carbon quantum dots and base oil PAO 10. Detailed Implementation

[0027] The technical solutions of the embodiments of the present invention will be further described clearly and completely below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.

[0028] This invention addresses the problems of complex preparation processes, difficult separation and purification, and the tendency of high specific surface area to agglomerate in base lubricating oils caused by carbon quantum dots. It proposes a lubricating oil containing element-doped carbon quantum dots, its preparation method, and its applications. The method includes the following steps: adding a heterocyclic aromatic hydrocarbon precursor to a base oil and ultrasonically dispersing it to obtain a mixture; irradiating the mixture under an inert atmosphere with a pulsed laser beam to obtain a lubricating oil containing element-doped carbon quantum dots. This invention utilizes liquid-phase pulsed laser irradiation technology to generate a lubricating oil containing element-doped carbon quantum dots in situ in one step. Compared to traditional methods such as hydrothermal methods, which require production cycles of several hours or days, this invention can achieve in-situ one-step preparation in just 5-60 minutes, greatly overcoming the limitations of its application as a lubricating additive and avoiding the cumbersome steps of traditional separation, purification, and re-addition. Furthermore, thanks to liquid-phase pulsed laser irradiation technology, the surface of the generated carbon quantum dots is effectively passivated under extreme conditions. Therefore, the prepared functionalized carbon quantum dots exhibit good dispersion stability in base lubricating oils and significantly improve the friction-reducing and anti-wear properties of mechanical parts.

[0029] Example 1

[0030] A method for preparing a lubricating oil containing nitrogen-doped carbon quantum dots includes the following steps:

[0031] (1) Preparation of the mixture: 100 mg of benzopyrrole was dissolved in base oil PAO 10 and ultrasonically dispersed for 0.5 h to obtain a mixture with a concentration of 1 wt%.

[0032] (2) Preparation of lubricating oil containing nitrogen-doped carbon quantum dots: The mixture described in step (1) is irradiated under a nitrogen atmosphere by ultrasonic assistance under a non-focused pulsed laser beam. The specific irradiation parameters are: output wavelength of 355nm, pulse frequency of 10Hz, and laser irradiation energy of 40mJ pulse. -1 cm 2 Irradiation time was 10 min, and in-situ lubricating oil containing nitrogen-doped carbon quantum dots was generated, denoted as N-CQDs.

[0033] Example 2

[0034] A method for preparing a lubricating oil containing sulfur-doped carbon quantum dots includes the following steps:

[0035] (1) Preparation of the mixture: 100 mg of benzothiophene was dissolved in base oil PAO 10 and ultrasonically dispersed for 0.5 h to obtain a mixture with a concentration of 1 wt%.

[0036] (2) Preparation of lubricating oil containing sulfur-doped carbon quantum dots: The mixture described in step (1) is irradiated under a nitrogen atmosphere by ultrasonic assistance under a non-focused pulsed light beam. The specific parameters are: output wavelength of 355nm, pulse frequency of 10Hz, and laser irradiation energy of 40mJ pulse. -1 cm 2 Irradiation time was 10 min, and lubricating oil containing sulfur-doped carbon quantum dots was generated in situ, denoted as S-CQDs.

[0037] Example 3

[0038] A method for preparing a lubricating oil containing nitrogen / sulfur co-doped carbon quantum dots includes the following steps:

[0039] (1) Preparation of the mixture: Dissolve 100 mg of benzothiazole in base oil PAO 10, and disperse it evenly by sonication for 0.5 h to obtain a mixture with a concentration of 1 wt%.

[0040] (2) Preparation of lubricating oil containing nitrogen / sulfur co-doped carbon quantum dots: The mixture described in step (1) is irradiated under a nitrogen atmosphere by ultrasonic assistance under a non-focused pulsed light beam. The specific parameters are: output wavelength of 355nm, pulse frequency of 10Hz, and laser irradiation energy of 40mJ pulse. -1 cm 2 Irradiation time was 10 min, and lubricating oil containing nitrogen / sulfur co-doped carbon quantum dots was generated in situ, denoted as N,S-CQDs.

[0041] Example 4

[0042] A method for preparing a lubricating oil containing nitrogen-doped carbon quantum dots includes the following steps:

[0043] (1) Preparation of the mixture: 100 mg of pyridine was dissolved in the base oil PEG and ultrasonically dispersed for 0.5 h to obtain a mixture with a concentration of 10 wt%.

[0044] (2) Preparation of lubricating oil containing nitrogen-doped carbon quantum dots: The mixture described in step (1) is irradiated under a nitrogen atmosphere by ultrasonic assistance under a non-focused pulsed laser beam. The specific irradiation parameters are: output wavelength of 355nm, pulse frequency of 10Hz, and laser irradiation energy of 40mJ pulse. -1 cm 2 Irradiation time is 10 min, and lubricating oil containing nitrogen-doped carbon quantum dots is generated in situ.

[0045] Example 5

[0046] A method for preparing a lubricating oil containing nitrogen-doped carbon quantum dots includes the following steps:

[0047] (1) Preparation of the mixture: Dissolve 100 mg of quinoline in base oil 500SN, and disperse it evenly by sonication for 0.5 h to obtain a mixture with a concentration of 0.1 wt%.

[0048] (2) Preparation of lubricating oil containing nitrogen-doped carbon quantum dots: The mixture described in step (1) is irradiated under a nitrogen atmosphere by ultrasonic assistance under a non-focused pulsed laser beam. The specific irradiation parameters are: output wavelength of 355nm, pulse frequency of 10Hz, and laser irradiation energy of 40mJ pulse. -1 cm 2 Irradiation time is 10 min, and lubricating oil containing nitrogen-doped carbon quantum dots is generated in situ.

[0049] Example 6

[0050] A method for preparing a lubricating oil containing nitrogen-doped carbon quantum dots includes the following steps:

[0051] (1) Preparation of the mixture: Dissolve 100 mg of quinoline in base oil PAO 10, and disperse it evenly by sonication for 0.5 h to obtain a mixture with a concentration of 5 wt%.

[0052] (2) Preparation of lubricating oil containing nitrogen-doped carbon quantum dots: The mixture described in step (1) is irradiated under a nitrogen atmosphere by ultrasonic assistance under a non-focused pulsed laser beam. The specific irradiation parameters are: output wavelength of 355nm, pulse frequency of 10Hz, and laser irradiation energy of 40mJ pulse. -1 cm 2 Irradiation time is 10 min, and lubricating oil containing nitrogen-doped carbon quantum dots is generated in situ.

[0053] Example 7

[0054] A method for preparing a lubricating oil containing nitrogen-doped carbon quantum dots includes the following steps:

[0055] (1) Preparation of the mixture: 100 mg of benzopyrrole was dissolved in the base oil PEG and ultrasonically dispersed for 0.5 h to obtain a mixture with a concentration of 1 wt%.

[0056] (2) Preparation of lubricating oil containing nitrogen-doped carbon quantum dots: The mixture described in step (1) is irradiated under a nitrogen atmosphere by ultrasonic assistance under a non-focused pulsed laser beam. The specific parameters are: output wavelength of 532 nm, pulse frequency of 10 Hz, and laser irradiation energy of 10 mJ pulse. -1 cm 2 Irradiation time is 5 minutes, and lubricating oil containing nitrogen-doped carbon quantum dots is generated in situ.

[0057] Example 8

[0058] A method for preparing a lubricating oil containing nitrogen-doped carbon quantum dots includes the following steps:

[0059] (1) Preparation of the mixture: 100 mg of benzopyrrole was dissolved in base oil 500SN and ultrasonically dispersed for 0.5 h to obtain a mixture with a concentration of 1 wt%.

[0060] (2) Preparation of lubricating oil containing nitrogen-doped carbon quantum dots: The mixture described in step (1) is irradiated under a nitrogen atmosphere by ultrasonic assistance under a non-focused pulsed laser beam. The specific parameters are: output wavelength of 1064 nm, pulse frequency of 10 Hz, and laser irradiation energy of 800 mJ pulse. -1 cm 2 Irradiation time is 60 min, and lubricating oil containing nitrogen-doped carbon quantum dots is generated in situ.

[0061] Results Analysis

[0062] To investigate the tribological properties of the prepared lubricating oil containing functionalized carbon quantum dots, the tribological properties of the lubricating oils with a series of concentration gradients obtained in Examples 1-3 were characterized. A micro-vibration tribometer (SRV-5) was used with the following parameters: load 150 N, temperature 50 °C, frequency 25 Hz, stroke 1 mm, and test time 30 min. The change in the friction coefficient during the test was obtained. Subsequently, the wear morphology was characterized and evaluated using a three-dimensional optical profilometer. The anti-wear performance of the element-doped carbon quantum dot lubricating oil was mainly evaluated by the wear volume.

[0063] In-situ generated carbon quantum dots exhibit good dispersion stability in base lubricating oils. Lubricating oils containing element-doped carbon quantum dots obtained using the preparation method of this invention have excellent friction-reducing and anti-wear effects. Compared with the base lubricating oil PAO 10, lubricating oil containing 1 wt% nitrogen-doped carbon quantum dots (N-CQDs) can reduce the average coefficient of friction from 0.201 to 0.138, and the wear volume from 8.55 × 10⁻⁶. 5 μm 3 It decreased to 1.34 × 10 5 μm 3 The wear volume was reduced by 84.3%; the average coefficient of friction of the lubricating oil containing 1 wt% sulfur-doped carbon quantum dots (S-CQDs) was 0.106, and the wear volume was 4.63 × 10⁻⁶. 5 μm 3The wear volume was reduced by 45.8%; the lubricating oil containing 1 wt% nitrogen / sulfur co-doped carbon quantum dots (N,S-CQDs) had an average friction coefficient of 0.093 and a wear volume of 0.68 × 10⁻⁶. 5 μm 3 The wear volume was reduced by 92.0%.

[0064] In summary, this invention utilizes liquid-phase pulsed laser irradiation technology to generate, in situ, one-step lubricating oil containing element-doped carbon quantum dots. Compared to traditional methods such as hydrothermal methods, which require production cycles of several hours or days, this invention achieves in situ one-step preparation in just 5-60 minutes. This significantly overcomes the limitations of using it as a lubricating additive, avoiding the cumbersome steps of traditional separation, purification, and re-addition. Furthermore, thanks to liquid-phase pulsed laser irradiation technology, the surface of the generated carbon quantum dots is effectively passivated under extreme environments. Therefore, the prepared functionalized carbon quantum dots exhibit good dispersion stability in base lubricating oils and significantly improve the friction-reducing and anti-wear properties of mechanical parts. The preparation method is simple, requires no further separation or purification, and demonstrates good stability and excellent tribological properties in base lubricating oils.

[0065] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0066] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a lubricating oil containing element-doped carbon quantum dots, characterized in that, Includes the following steps: A heterocyclic aromatic hydrocarbon precursor was added to a base oil and ultrasonically dispersed to obtain a mixture. Under inert atmosphere conditions, the mixture is irradiated under a pulsed laser beam to generate in situ a lubricating oil containing element-doped carbon quantum dots; The heterocyclic aromatic hydrocarbon precursor is one of pyridine, quinoline, benzopyrrole, benzothiophene, benzothiazole, benzodiazepine, and benzotriazole. The pulsed laser beam is a non-focused pulsed laser beam; The irradiation parameters are as follows: laser beam output wavelength of 355~1064 nm, pulse frequency of 10 Hz, and laser irradiation energy of 10~800 mJ pulse. -1 cm 2 ; The laser irradiation time is 5-60 minutes.

2. The method for preparing lubricating oil containing element-doped carbon quanta according to claim 1, characterized in that, In the mixture, the mass fraction of the heterocyclic aromatic hydrocarbon precursor is 0.1% to 10%.

3. The method for preparing lubricating oil containing element-doped carbon quantum dots according to claim 1, characterized in that, The base oil is one of PAO, PEG, or 500SN.

4. The in-situ preparation method of lubricating oil containing element-doped carbon quantum dots according to claim 1, characterized in that, The ultrasonic dispersion time is 0.5 h.

5. A lubricating oil containing element-doped carbon quantum dots prepared by the preparation method according to any one of claims 1-4.

6. The application of the lubricating oil containing element-doped carbon quantum dots as described in claim 5 in mechanical parts.

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