阅读说明：本技术 一种无溶剂碳纳米管类流体的应用 (Application of solvent-free carbon nanotube fluid ) 是由 张嘎 郭月霞 赵福燕 张利刚 李贵涛 于 2019-09-10 设计创作，主要内容包括：本发明涉及一种无溶剂碳纳米管类流体的应用,该无溶剂碳纳米管类流体是指以碳纳米管作为纳米内核,经超声处理、硅烷偶联剂和端氨基嵌段共聚物接枝来获得的,其应用在润滑剂或作为添加剂的基础油中,且在所述基础油的添加量为0.01wt%~10wt%。本发明将碳纳米管类流体作为润滑剂和多种基础油的添加剂均表现出显著的润滑特性,能够促进吸附膜和高性能摩擦膜的形成,有效增强体系摩擦学性能。(The invention relates to an application of a solvent-free carbon nanotube fluid, wherein the solvent-free carbon nanotube fluid is obtained by taking carbon nanotubes as nano cores and performing ultrasonic treatment and silane coupling agent and amino-terminated block copolymer grafting, is applied to a lubricant or base oil used as an additive, and the addition amount of the base oil is 0.01wt% ~ 10 wt%.)

1. The application of the solvent-free carbon nanotube fluid is characterized in that the solvent-free carbon nanotube fluid is obtained by taking carbon nanotubes as nano inner cores and performing ultrasonic treatment and silane coupling agent and amino-terminated block copolymer grafting, the solvent-free carbon nanotube fluid is applied to a lubricant or base oil used as an additive, and the addition amount of the base oil is 0.01wt% ~ 10 wt%.

2. The use of a solventless carbon nanotube-based fluid according to claim 1, wherein: the preparation method of the solvent-free carbon nanotube fluid comprises the following steps:

the method comprises the steps of ultrasonically dispersing a carbon nano tube in mixed acid at room temperature, washing with deionized water after 2 hours, centrifuging, and drying in vacuum to obtain an oxygen-containing group functionalized oxidized carbon nano tube, wherein the mass-to-volume ratio of the carbon nano tube to the mixed acid is 1: 1 ~ 1: 20;

ultrasonically dispersing the oxidized carbon nano tube in deionized water at room temperature for 2 hours to obtain 0.05 ~ 1 g/mL carbon nano tube suspension;

thirdly, dropwise adding a silane coupling agent into the carbon nano tube suspension, stirring for 0.2 ~ 2h, adding a sodium hydroxide solution or a potassium hydroxide solution with the mass concentration of 0.1 ~ 5% to adjust the pH value to 7, reacting at 50 ~ 120 ℃ for 1 ~ 24h to obtain a product A, washing the product A, removing the solvent by rotary evaporation, and drying in vacuum to obtain the carbon nano tube grafted by the silane coupling agent, wherein the adding amount of the silane coupling agent is 10 ~ 80 times of the mass of the carbon nano tube;

fourthly, ultrasonically dissolving the carbon nano tube grafted by the silane coupling agent in deionized water at room temperature, and obtaining 0.05 ~ 1 g/mL of silane coupling agent-grafted carbon nano tube suspension after 2 hours;

fifthly, dropwise adding 70 wt% of amino-terminated block copolymer aqueous solution into the silane coupling agent grafted carbon nanotube suspension under mechanical stirring, reacting at 50 ~ 120 ℃ for 1 ~ 24h to obtain a product B, removing the solvent from the product B through rotary evaporation, washing, dialyzing, and drying in vacuum to obtain the solvent-free carbon nanotube fluid, wherein the mass ratio of the silane coupling agent grafted carbon nanotube to the amino-terminated block copolymer is 1: 1 ~ 1: 10.

3. The application of the solvent-free carbon nanotube-based fluid as claimed in claim 2, wherein the carbon nanotubes have an outer diameter of 5 ~ 100 nm and an inner diameter of 2 ~ 90 nm.

4. The application of the solvent-free carbon nanotube fluid as recited in claim 2, wherein the mixed acid in the step is a mixed solution obtained by uniformly mixing concentrated nitric acid and concentrated sulfuric acid according to a volume ratio of 1: 1 ~ 1: 9.

5. The use of a solventless carbon nanotube-based fluid according to claim 2, wherein: the step I, the step III and the vacuum drying condition in the step fifth mean that the temperature is 70 ℃ and the time is 24 hours.

6. The use of the solvent-free carbon nanotube-based fluid according to claim 2, wherein the silane coupling agent in the step three is an aqueous solution of 3- (trihydroxysilyl) propanesulfonic acid with a concentration of 5 ~ 65 wt%.

7. The use of a solventless carbon nanotube-based fluid according to claim 2, wherein: the 70 wt% aqueous solution of the terminal amino block copolymer in the step fifthly is a solution obtained by dissolving 70g of the terminal amino block copolymer in 100mL of deionized water; the general formula of the amino-terminated block copolymer is NH₂(CH₃CH₂O)_XCH₂(CH₂O)_YCH₃，X=5~50，Y=5~50。

8. The use of a solventless carbon nanotube-based fluid according to claim 2, wherein: and step three and the washing in the step fifthly are all washing by adopting deionized water and then adopting absolute ethyl alcohol or tetrahydrofuran.

9. The application of the solvent-free carbon nanotube fluid as claimed in claim 2, wherein the dialysis membrane used in the dialysis in the step of fifthly has a molecular weight of 3000 ~ 100000.

10. The use of a solventless carbon nanotube-based fluid according to claim 1, wherein: the base oil is one of polyethylene glycol, poly-alpha-olefin, liquid paraffin or silicone oil.

Technical Field

The invention relates to the technical field of lubricants, in particular to application of a solvent-free carbon nanotube fluid.

Background

The friction and wear is a ubiquitous phenomenon in the nature, the worldwide primary energy consumption caused by the friction and wear accounts for over 1/3 of the total energy each year in the world, and is a main cause of 80% of mechanical equipment failure, and the friction and wear becomes a main bottleneck restricting the industrial development. The lubricant is an effective measure for controlling friction and slowing down abrasion, can effectively reduce mutual abrasion, extrusion and impact of mechanical surfaces, prolongs the service life of equipment, and plays roles in reducing friction, resisting abrasion, cooling, preventing corrosion, sealing, insulating and cleaning. However, with the rapid development of high-end equipment fields such as rail transit, aviation and the like, related mechanical equipment is continuously developed towards high speed, heavy load, high precision, integration and long service life, the service working condition of a related motion mechanism is more severe, so that a friction pair is frequently in mixed lubrication and even in a boundary lubrication interval to operate, and higher requirements are provided for the service performance and reliability of a lubricant.

The lubricant is composed of base oil and additives, and the nano material serving as an extreme pressure antiwear additive has the characteristics of high hardness, easiness in sintering, high ductility, large specific surface area and the like, so that the heat resistance, the antifriction antiwear property and the bearing capacity of an oil product can be remarkably improved, and further the abrasion of mechanical parts and the like is reduced. The carbon nano tube is used as a typical nano carbon material, has a structure similar to that of graphite, has high toughness and excellent self-lubricating property, and can be used as an additive to remarkably enhance the tribological property of base oil. At present, although there are patent reports (201610773707.5; 200510031996; 2007103085783) about carbon nanotube additives, due to the non-oil solubility of the nanocarbon materials, agglomeration easily occurs under the van der waals force effect, and the nanocarbon materials are difficult to be stably and uniformly dispersed in lubricating oil for a long time, which greatly limits the application and popularization of the nanocarbon materials in the field of lubricants. In order to overcome this drawback, researchers have used physicochemical methods to modify the surface of carbon nanotubes to enhance their surface lipophilicity and reduce the tendency of carbon nanotubes to agglomerate and entangle, in order to improve their dispersion stability in organic solvents and lubricating oils. Although the surface modification can change the surface structure and state of the carbon nano tube to a certain extent and relieve the agglomeration of the carbon nano tube, the current research work shows that any modified nano material is in a solid state in the absence of a solvent, so that the agglomeration problem of the carbon nano tube in the base oil cannot be fundamentally solved.

The solvent-free nano fluid is a special ionic liquid modified nano material, can show liquidity similar to liquid at room temperature without any other solvent, and has a core-shell structure, and a flexible long-chain shell structure of the solvent-free nano fluid can promote the nano fluid to be stably suspended in base oil. By varying different combinations of nanoparticles and shell compounds, the nanofluids can theoretically be designed into systems with any nanomaterial specific property. Although nano-fluids such as silicon dioxide and graphene have antifriction and antiwear properties as lubricant and base oil additives (Journal of Materials chemistry A, 2018, 6, 2817-.

Disclosure of Invention

The invention aims to solve the technical problem of providing the application of the solvent-free carbon nanotube fluid.

In order to solve the problems, the invention discloses an application of a solvent-free carbon nanotube fluid, which is characterized in that the solvent-free carbon nanotube fluid is obtained by taking carbon nanotubes as nano cores, performing ultrasonic treatment and grafting a silane coupling agent and an amino-terminated block copolymer, is applied to a lubricant or base oil serving as an additive, and the addition amount of the base oil is 0.01wt% ~ 10 wt%.

The preparation method of the solvent-free carbon nanotube fluid comprises the following steps:

the method comprises the steps of ultrasonically dispersing a carbon nano tube in mixed acid at room temperature, washing with deionized water after 2 hours, centrifuging, and drying in vacuum to obtain an oxygen-containing group functionalized oxidized carbon nano tube, wherein the mass-to-volume ratio of the carbon nano tube to the mixed acid is 1: 1 ~ 1: 20;

ultrasonically dispersing the oxidized carbon nano tube in deionized water at room temperature for 2 hours to obtain 0.05 ~ 1 g/mL carbon nano tube suspension;

thirdly, dropwise adding a silane coupling agent into the carbon nano tube suspension, stirring for 0.2 ~ 2h, adding a sodium hydroxide solution or a potassium hydroxide solution with the mass concentration of 0.1 ~ 5% to adjust the pH value to 7, reacting at 50 ~ 120 ℃ for 1 ~ 24h to obtain a product A, washing the product A, removing the solvent by rotary evaporation, and drying in vacuum to obtain the carbon nano tube grafted by the silane coupling agent, wherein the adding amount of the silane coupling agent is 10 ~ 80 times of the mass of the carbon nano tube;

fourthly, ultrasonically dissolving the carbon nano tube grafted by the silane coupling agent in deionized water at room temperature, and obtaining 0.05 ~ 1 g/mL of silane coupling agent-grafted carbon nano tube suspension after 2 hours;

fifthly, dropwise adding 70 wt% of amino-terminated block copolymer aqueous solution into the silane coupling agent grafted carbon nanotube suspension under mechanical stirring, reacting at 50 ~ 120 ℃ for 1 ~ 24h to obtain a product B, removing the solvent from the product B through rotary evaporation, washing, dialyzing, and drying in vacuum to obtain the solvent-free carbon nanotube fluid, wherein the mass ratio of the silane coupling agent grafted carbon nanotube to the amino-terminated block copolymer is 1: 1 ~ 1: 10.

The outer diameter of the carbon nano tube is 5 ~ 100 nm, and the inner diameter of the carbon nano tube is 2 ~ 90 nm.

The mixed acid in the step refers to mixed liquid obtained by uniformly mixing concentrated nitric acid and concentrated sulfuric acid according to the volume ratio of 1: 1 ~ 1: 9.

The step I, the step III and the vacuum drying condition in the step fifth mean that the temperature is 70 ℃ and the time is 24 hours.

The silane coupling agent in the step three is a 3- (trihydroxy silicon base) propane sulfonic acid aqueous solution with the concentration of 5 ~ 65 wt%.

The 70 wt% aqueous solution of the terminal amino block copolymer in the step fifthly is a solution obtained by dissolving 70g of the terminal amino block copolymer in 100mL of deionized water; the general formula of the amino-terminated block copolymer is NH₂(CH₃CH₂O)_XCH₂(CH₂O)_YCH₃，X=5~50，Y=5~50。

And step three and the washing in the step fifthly are all washing by adopting deionized water and then adopting absolute ethyl alcohol or tetrahydrofuran.

The molecular weight of the dialysis membrane used for dialysis in the step fifthly is 3000 ~ 100000.

The base oil is one of polyethylene glycol, poly-alpha-olefin, liquid paraffin or silicone oil.

Compared with the prior art, the invention has the following advantages:

1. the invention takes carbon nano-tubes as nano-cores to prepare the fluid of the carbon nano-tubes, firstly, the carbon nano-tubes are dispersed in mixed acid, and the surface of the carbon nano-tubes is enriched with oxygen-containing functional groups such as hydroxyl, carboxyl and the like through ultrasonic treatment, so as to obtain the oxidized carbon nano-tubes. And then, grafting a silane coupling agent and an amino-terminated block copolymer on the surface of the carbon nanotube by utilizing a covalent bond and an ionic bond, and obtaining the carbon nanotube fluids with different structures and performances by changing the type and chain length of the copolymer.

2. The carbon nanotube fluid prepared by the method can show fluid-like fluidity at room temperature without any solvent, and can be stably dispersed in organic solvents and base oil.

3. The carbon nanotube fluid is used as a lubricant and additives of various base oils to show remarkable lubricating characteristics, can promote the formation of an adsorption film and a high-performance friction film, and effectively enhances the tribological performance of a system. The inner crown and the outer crown of the carbon nanotube fluid are connected through ionic bonds, on one hand, the fluid is enabled to be adsorbed on the surface of a friction pair through electrostatic action in the friction process, on the other hand, active elements in the fluid can generate friction chemical reaction with a metal matrix to form an organic-inorganic hybrid structure friction film, direct contact of the friction pair is inhibited, and the bearing capacity and the lubricating property of the carbon nanotube are enhanced.

A friction experiment is carried out by using pure polyethylene glycol (Mw ~ 200) as a comparative example 1, pure liquid paraffin as a comparative example 2 and an example 1 ~ 8 by using an SRV-IV fretting friction wear tester, wherein the friction pair is CGr15 bearing steel, the test conditions are that a ball-disc contact mode is adopted, the diameter of a test ball is 10 mm, the diameter of a dual disc is 24.0 mm, the thickness is 7.9 mm, the test load is 30N, the frequency is 25Hz, the amplitude is 1mm, the temperature is 25 ℃, the period is 30min, after the friction experiment is finished, the wear volume is tested by using MicroXAM-3D, and the measurement results of the average friction coefficient and the wear volume of the lubricants prepared by the examples and the comparative examples are shown in Table 1.

TABLE 1

Research results show that the solvent-free carbon nanotube fluid obtained by the invention has remarkable friction reducing and wear resisting performances as a lubricant (example 1 and example 4) and a base oil additive (example 2 ~ 3 and example 5 ~ 8) compared with base oil (comparative example 1 ~ 2), and can remarkably improve the tribological performances of polyethylene glycol and liquid paraffin as the additive.

4. The carbon nano tubes of the invention do not have serious agglomeration and winding, and the nano fluid with different structures and performances can be obtained by changing the types and chain lengths of the copolymers.

5. When the carbon nanotube fluid is used as a base oil additive, the strength and the bearing capacity of the friction film can be enhanced by the synergistic effect between the carbon nanotube and the flexible long-chain molecules of the shell, the direct contact of a friction pair is effectively inhibited, and the abrasion is reduced.

Drawings

The following describes embodiments of the present invention in further detail with reference to the accompanying drawings.

Fig. 1 shows the transmission electron microscope morphology of the solvent-free carbon nanotube fluid obtained in example 1 of the present invention.

FIG. 2 shows the flow state of the solvent-free carbon nanotube-based fluid obtained in example 1 of the present invention at room temperature.

Fig. 3 is a curve of the change of modulus with temperature of the solvent-free carbon nanotube-based fluid obtained in example 1 of the present invention.

FIG. 4 is a graph showing the change of friction coefficient with time of the solvent-free carbon nanotube-based fluid obtained in example 1 of the present invention as a pure lubricant and the pure polyethylene glycol obtained in comparative example 1.

Detailed Description