Carbon quantum dot intercalated fluorinated graphene intercalation structure lubricant additive and its preparation method

Abstract

This invention discloses a carbon quantum dot intercalated fluorinated graphene intercalation structure lubricant additive and its preparation method. The preparation method includes: mixing sodium hydroxide and acetaldehyde thoroughly and then sonicating until flocculent matter appears; drying the final product in a freeze dryer to obtain CQDs powder; and dissolving hexadecyltrimethylammonium bromide and fluorinated graphene in deionized water and ball milling to obtain exfoliated FG-CTA. + Dispersion; CQDs powder was dispersed in deionized water, and stripped FG-CTA was added. + In the dispersion, the mixed slurry is ultrasonically treated, and then the mixture is placed in a flask and heated at 80-120℃ for 6-10 hours. Then, 0.2-0.6 g of ascorbic acid is added and reduced at 80-100℃ for 6-10 hours. Finally, the solid is separated, cleaned, and freeze-dried to obtain a carbon quantum dot intercalated fluorinated graphene intercalated structure lubricating additive with excellent anti-friction and anti-wear effects, exhibiting durable and excellent lubrication performance.

Description

Technical Field

[0001] This invention belongs to the field of functional materials technology, and relates to nanocomposite lubricating materials and their preparation methods, specifically to a carbon quantum dot intercalated fluorinated graphene intercalation structure lubricating additive and its preparation method. Background Technology

[0002] With the continuous advancement of industrial technology, the performance requirements for lubricating materials are becoming increasingly stringent. Especially under long-term operating conditions, traditional graphene-based lubricating materials often face problems such as poor lubrication performance and severe wear, hindering their further application in the lubrication field. This can be attributed to poor dispersion stability and insufficient oxidation resistance. First, the layered structure of graphene tends to stack during repeated friction, reducing its effective contact area and thus decreasing its anti-wear and anti-friction effects. Second, in practical use, graphene additives in engine lubricating oils also exhibit significant adverse effects such as the formation of complex oxides and soot, limiting their potential to improve the oxidation resistance of lubricating oils. Therefore, they cannot meet the durability and reliability requirements of lubricating materials for continuously operating mechanical components. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a carbon quantum dot intercalated fluorinated graphene intercalation structure lubricating additive with excellent chemical stability, high anti-friction and anti-wear effects, and its preparation method. As a lubricating additive, it has durable and excellent lubrication performance, and the preparation process is simple.

[0004] To achieve the above objectives, the present invention employs the following technical solution:

[0005] A method for preparing a carbon quantum dot intercalated fluorinated graphene intercalation structure lubricant additive includes the following steps:

[0006] Step 1: Take sodium hydroxide and acetaldehyde at a mass-to-volume ratio of (4~8) g: (10~30) mL. First, add acetaldehyde to a beaker, then slowly add sodium hydroxide and stir continuously for 1~3 h. Then, use dilute hydrochloric acid for ultrasonic treatment until flocculent matter appears. Finally, dry the product in a freeze dryer to obtain CQDs powder.

[0007] Step 2: Dissolve 0.8g of cetyltrimethylammonium bromide and 0.1-0.3g of fluorinated graphite in 30-50mL of deionized water, and ball mill in a ball mill for 5-10 hours to obtain the exfoliated FG-CTA. + Dispersion;

[0008] Step 3: Take 0.8~2.4g of the CQDs powder prepared in Step 1 and disperse it in 20 mL of deionized water, then add the exfoliated FG-CTA. +In the dispersion, the mixed slurry is ultrasonically treated for 3-5 hours, and then 0.2-0.6g of ascorbic acid is added. The mixture is placed in a flask and heated at 80-120℃ for 6-10 hours. Finally, the solid is separated, washed, and freeze-dried to obtain a carbon quantum dot intercalated fluorinated graphene intercalated structure lubricant additive.

[0009] The present invention also has the following technical features:

[0010] Preferably, the dilute hydrochloric acid mentioned in step one is prepared by mixing hydrochloric acid with a purity of 37% and deionized water at a volume ratio of 1:1.

[0011] Preferably, the ultrasonic frequency of the ultrasonic treatment in steps one and three is 40 kHz to 60 kHz.

[0012] Preferably, the freeze-drying time in steps one and three is 36 to 60 hours.

[0013] Preferably, the ball mill in step two operates at a rotation speed of 400-600 rpm.

[0014] This invention also protects a carbon quantum dot intercalated fluorinated graphene intercalation structure lubricant additive prepared by the method described above.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] This invention successfully confines graphene / reduced carbon quantum dots (FG / rCQDs) within the interlayer of graphene nanosheets using an electrostatic self-assembly method, fabricating an intercalated structure and obtaining a novel graphene / reduced carbon quantum dot (FG / rCQDs) hybrid material with ultra-large interlayer spacing and excellent lubrication properties. Under the induction of friction and frictional heat, the FG / rCQDs prepared in this invention exhibit frictional effects at different frictional stages: rolling effect, filling effect, and friction film effect. These effects work synergistically to achieve excellent and long-lasting lubrication performance.

[0017] In the initial stage of friction, under the action of frictional shear force, the intercalated FG / rCQDs form a lubrication component similar to a "cart". Due to the presence of interlayer CQDs, sliding friction can be converted into rolling friction, significantly reducing the coefficient of friction. As friction progresses, fine wear tracks are generated on the friction interface. Under the action of shear force, the CQDs on the surface of FG / rCQDs will fall off, thus generating many free CQDs in the friction gap. Since the CQDs are negatively charged, under the dual action of thermal motion and charge attraction, the free CQDs will be attracted to the positively charged wear track, blocking the wear track. It fills the wear channels; as the friction process deepens, FG nanosheets undergo defluorination under shear force and frictional heat, generating a large number of free fluoride ions. At the same time, a large number of positive charges are generated between the friction pairs, and fluoride ions are attracted to the friction pairs to form an adsorption layer composed of iron fluoride. Fluorine has strong electronegativity and easily combines with iron metal ions to form iron fluoride. Compared with iron oxide, iron fluoride has the advantage of being more stable, thus playing a more durable protective film role between the friction pairs and playing a crucial role in anti-wear and anti-friction. Therefore, FG / rCQDs have good practicality as a lubricating additive.

[0018] The preparation process of this invention is simple and does not require large-scale equipment or harsh conditions. Attached Figure Description

[0019] Figure 1 These are TEM images of FG and FG / rCQDs before and after composite preparation in Example 1;

[0020] Figure 2 The XRD patterns of FG and FG / rCQDs before and after composite preparation in Example 1 are shown.

[0021] Figure 3 These are images showing the dispersion stability of the FG / rCQDs / PAO dispersion prepared in Example 1;

[0022] Figure 4 These are the friction coefficient curves of different components prepared in Example 1. Detailed Implementation

[0023] The present invention will now be described in detail with reference to the accompanying drawings and embodiments, but the embodiments of the present invention are not limited thereto. The reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in this technical field. Test methods in the following embodiments that do not specify specific experimental conditions are generally performed under conventional experimental conditions. Unless otherwise specified, the reagents and raw materials used in the present invention are all commercially available.

[0024] The dilute hydrochloric acid used in the following examples was prepared by mixing 37% pure hydrochloric acid and deionized water at a volume ratio of 1:1.

[0025] Example 1:

[0026] Step 1: First, add 20 mL of acetaldehyde to a beaker, then slowly add 6 g of sodium hydroxide and stir continuously for 2 h. Then, use dilute hydrochloric acid to sonicate at a frequency of 40 kHz until flocculent matter appears. Finally, freeze-dry the product in a freeze dryer for 36 h to obtain CQDs powder.

[0027] Step 2: Dissolve 0.8g of cetyltrimethylammonium bromide and 0.2g of fluorinated graphite in 30mL of deionized water, and ball mill the mixture at 400rpm for 10 hours to obtain the exfoliated FG-CTA. + Dispersion;

[0028] Step 3: Take 1.6g of the CQDs powder prepared in Step 1 and disperse it in 20 mL of deionized water, then add the exfoliated FG-CTA. + In the dispersion, the mixed slurry was ultrasonically treated for 3 hours at a frequency of 60 kHz. Then, 0.6 g of ascorbic acid was added, and the mixture was placed in a flask and heated at 100 °C for 6 h. Finally, the solid was separated, washed with distilled water, and freeze-dried for 36 h to obtain a carbon quantum dot intercalated fluorinated graphene intercalated structure lubricating additive.

[0029] Example 2:

[0030] Step 1: First, add 10 mL of acetaldehyde to a beaker, then slowly add 6 g of sodium hydroxide and stir continuously for 2 h. Then, use dilute hydrochloric acid to sonicate at a frequency of 50 kHz until flocculent matter appears. Finally, freeze-dry the product in a freeze dryer for 48 h to obtain CQDs powder.

[0031] Step 2: Dissolve 0.8g of cetyltrimethylammonium bromide and 0.3g of fluorinated graphite in 30mL of deionized water, and ball mill the mixture at 400rpm for 10 hours to obtain the exfoliated FG-CTA. + Dispersion;

[0032] Step 3: Take 1.6g of the CQDs powder prepared in Step 1 and disperse it in 20 mL of deionized water, then add the exfoliated FG-CTA. + In the dispersion, the mixed slurry was ultrasonically treated for 3 hours at a frequency of 60 kHz. Then, 0.2 g of ascorbic acid was added, and the mixture was placed in a flask and heated at 80 °C for 8 h. Finally, the solid was separated, washed with distilled water, and freeze-dried for 36 h to obtain a carbon quantum dot intercalated fluorinated graphene intercalated structure lubricating additive.

[0033] Example 3:

[0034] Step 1: First, add 20 mL of acetaldehyde to a beaker, then slowly add 6 g of sodium hydroxide and stir continuously for 3 h. Then, use dilute hydrochloric acid to sonicate at a frequency of 40 kHz until flocculent matter appears. Finally, freeze-dry the product in a freeze dryer for 36 h to obtain CQDs powder.

[0035] Step 2: Dissolve 0.8g of cetyltrimethylammonium bromide and 0.2g of fluorinated graphite in 30mL of deionized water, and ball mill the mixture at 400rpm for 10 hours to obtain the exfoliated FG-CTA. + Dispersion;

[0036] Step 3: Take 2.4 g of the CQDs powder prepared in Step 1 and disperse it in 20 mL of deionized water, then add the exfoliated FG-CTA. + In the dispersion, the mixed slurry was ultrasonically treated for 3 hours at a frequency of 60 kHz. Then, 0.4 g of ascorbic acid was added, and the mixture was placed in a flask and heated at 120 °C for 6 h. Finally, the solid was separated, washed with distilled water, and freeze-dried for 36 h to obtain a carbon quantum dot intercalated fluorinated graphene intercalated structure lubricating additive.

[0037] Example 4:

[0038] Step 1: First, add 20 mL of acetaldehyde to a beaker, then slowly add 6 g of sodium hydroxide and stir continuously for 2 h. Then, use dilute hydrochloric acid to sonicate at a frequency of 40 kHz until flocculent matter appears. Finally, freeze-dry the product in a freeze dryer for 48 h to obtain CQDs powder.

[0039] Step 2: Dissolve 0.8g of cetyltrimethylammonium bromide and 0.2g of fluorinated graphite in 30mL of deionized water, and ball mill the mixture at 400rpm for 10 hours to obtain the exfoliated FG-CTA. + Dispersion;

[0040] Step 3: Take 1.6g of the CQDs powder prepared in Step 1 and disperse it in 20 mL of deionized water, then add the exfoliated FG-CTA. + In the dispersion, the mixed slurry was ultrasonically treated for 3 hours at a frequency of 60 kHz. Then, 0.3 g of ascorbic acid was added, and the mixture was placed in a flask and heated at 120 °C for 6 h. Finally, the solid was separated, washed with distilled water, and freeze-dried for 36 h to obtain a carbon quantum dot intercalated fluorinated graphene intercalated structure lubricating additive.

[0041] Example 5:

[0042] Step 1: First, add 30 mL of acetaldehyde to a beaker, then slowly add 8 g of sodium hydroxide and stir continuously for 1 h. Then, use dilute hydrochloric acid to sonicate at a frequency of 60 kHz until flocculent matter appears. Finally, freeze-dry the product in a freeze dryer for 60 h to obtain CQDs powder.

[0043] Step 2: Dissolve 0.8g of cetyltrimethylammonium bromide and 0.1g of fluorinated graphite in 40mL of deionized water, and ball mill at 500rpm for 5 hours to obtain the exfoliated FG-CTA. + Dispersion;

[0044] Step 3: Take 0.8g of the CQDs powder prepared in Step 1 and disperse it in 20 mL of deionized water, then add the exfoliated FG-CTA. + In the dispersion, the mixed slurry was ultrasonically treated for 4 hours at a frequency of 50 kHz. Then, 0.5 g of ascorbic acid was added, and the mixture was placed in a flask and heated at 80 °C for 10 h. Finally, the solid was separated, washed with distilled water, and freeze-dried for 48 h to obtain a carbon quantum dot intercalated fluorinated graphene intercalated structure lubricating additive.

[0045] Example 6:

[0046] Step 1: First, add 20 mL of acetaldehyde to a beaker, then slowly add 4 g of sodium hydroxide and stir continuously for 2 h. Then, use dilute hydrochloric acid to sonicate at a frequency of 40 kHz until flocculent matter appears. Finally, freeze-dry the product in a freeze dryer for 36 h to obtain CQDs powder.

[0047] Step 2: Dissolve 0.8g of cetyltrimethylammonium bromide and 0.1g of fluorinated graphite in 30mL of deionized water, and ball mill the mixture at 600rpm for 8 hours to obtain the exfoliated FG-CTA. + Dispersion;

[0048] Step 3: Take 1.6g of the CQDs powder prepared in Step 1 and disperse it in 20 mL of deionized water, then add the exfoliated FG-CTA. + In the dispersion, the mixed slurry was ultrasonically treated for 5 hours at a frequency of 40 kHz. Then, 0.2 g of ascorbic acid was added, and the mixture was placed in a flask and heated at 100 °C for 8 h. Finally, the solid was separated, washed with distilled water, and freeze-dried for 60 h to obtain a carbon quantum dot intercalated fluorinated graphene intercalated structure lubricating additive.

[0049] SEM and TEM images of FG and FG / rCQDs before and after composite preparation in Example 1 are shown below. Figure 1As shown in the figure, the morphological characteristics of FGi and FG / rCQDs can be seen: before insertion, FGi exhibits a multilayer structure, which provides conditions for the insertion of CQDs. After the intercalation process, CQDs are uniformly distributed on the surface of FG nanosheets, forming corresponding CQDs lattice stripes. Therefore, CQDs are embedded between FG nanolayers.

[0050] The XRD patterns of FG and FG / rCQDs before and after composite preparation in Example 1 are as follows: Figure 2 As shown; by Figure 2 It can be seen that all characteristic signals of multilayer FGi show a significant rightward shift of the (002) peak at 21.4°, reflecting the increase in interlayer spacing. This indicates that CQDs were successfully inserted into the interlayer of FGi, and the interlayer spacing significantly expanded from 0.42 nm to 1.08 nm. There is ample literature evidence that the 1.08 nm interlayer spacing is the largest among all studies.

[0051] The dispersion stability of the FG / rCQDs / PAO dispersion prepared in Example 1 is as follows: Figure 3 As shown. By Figure 3 It can be seen that even after standing for one or two days, the FG / rCQDs / PAO dispersion still exhibits good dispersion stability.

[0052] The friction coefficient curves of different components obtained in Example 1 are shown below. Figure 4 As shown. By Figure 4 It can be seen that, in the 30-minute friction test, the friction coefficient of FG / rCQDs lubrication was significantly lower than that of other components. Compared with mechanical mixing, the friction coefficient decreased from 0.11 to 0.03.

[0053] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; any deductions or substitutions made by those skilled in the art without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A method for preparing a carbon quantum dot intercalated fluorinated graphene intercalation structure lubricant additive, characterized in that, Includes the following steps: Step 1: Take sodium hydroxide and acetaldehyde at a mass-to-volume ratio of (4~8) g: (10~30) mL. First, add acetaldehyde to a beaker, then slowly add sodium hydroxide and stir continuously for 1~3 h. Then, use dilute hydrochloric acid for ultrasonic treatment until flocculent matter appears. Finally, dry the product in a freeze dryer to obtain CQDs powder. Step 2: Dissolve 0.8g of cetyltrimethylammonium bromide and 0.1-0.3g of fluorinated graphite in 30-50mL of deionized water, and ball mill in a ball mill for 5-10 hours to obtain the exfoliated FG-CTA. + Dispersion; Step 3: Take 0.8~2.4g of the CQDs powder prepared in Step 1 and disperse it in 20 mL of deionized water, then add the exfoliated FG-CTA. + In the dispersion, the mixed slurry is ultrasonically treated for 3-5 hours, then 0.2-0.6g of ascorbic acid is added, and the mixture is placed in a flask and heated at 80-120℃ for 6-10 hours. Finally, the solid is separated, washed, and freeze-dried to obtain a carbon quantum dot intercalated fluorinated graphene intercalated structure lubricant additive.

2. The preparation method of the carbon quantum dot intercalated fluorinated graphene intercalation structure lubricant additive as described in claim 1, characterized in that, The dilute hydrochloric acid mentioned in step one is prepared by mixing 37% pure hydrochloric acid and deionized water at a volume ratio of 1:

1.

3. The preparation method of the carbon quantum dot intercalated fluorinated graphene intercalation structure lubricant additive as described in claim 1, characterized in that, The ultrasonic frequency for the ultrasonic treatment described in steps one and three is 40 kHz to 60 kHz.

4. The preparation method of the carbon quantum dot intercalated fluorinated graphene intercalation structure lubricant additive as described in claim 1, characterized in that, The freeze-drying time in steps one and three is 36-60 hours.

5. The preparation method of the carbon quantum dot intercalated fluorinated graphene intercalation structure lubricant additive as described in claim 1, characterized in that, The ball mill used in step two operates at a speed of 400-600 rpm.

6. A carbon quantum dot intercalated fluorinated graphene intercalation structure lubricant additive prepared by any one of claims 1 to 5.

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