阅读说明：本技术 一种复合碳材料的润滑添加剂、超滑水润滑剂及其制备方法和应用 (Lubricating additive of composite carbon material, super-lubricating water lubricant, and preparation method and application thereof ) 是由 车清论 梁森 张建军 徐洋 吕滨江 崔宁 王进 于 2020-06-05 设计创作，主要内容包括：本发明涉及一种复合碳材料的润滑添加剂、超滑水润滑剂及其制备方法和应用。为一种球状结构,由内至外依次为纳米金刚石层、聚多巴胺层、氧化石墨烯层的复合层结构,或由内之外的纳米金刚石层、聚多巴胺层、石墨烯层、聚多巴胺层的复合层结构,复合层的层数为单层或多层,多层的结构由若干复合层重复叠合组成。制备过程为将盐酸多巴胺溶液、水、Tris溶液混合,然后加入HCl溶液混合得到聚多巴胺包裹纳米金刚石复合材料,然后与氧化石墨烯反应得到氧化石墨烯/聚多巴胺/纳米金刚石复合材料,与水混合即得到超滑水润滑剂,摩擦因数达到0.003。(The invention relates to a lubricating additive of a composite carbon material, a super-lubricating water lubricant, and a preparation method and application thereof. The spherical structure is a composite layer structure of a nano diamond layer, a polydopamine layer and a graphene oxide layer from inside to outside in sequence, or a composite layer structure of a nano diamond layer, a polydopamine layer, a graphene layer and a polydopamine layer from inside to outside, the number of layers of the composite layer is single-layer or multi-layer, and the multi-layer structure is formed by repeatedly superposing a plurality of composite layers. The preparation process comprises the steps of mixing a dopamine hydrochloride solution, water and a Tris solution, adding the HCl solution, mixing to obtain a polydopamine-coated nano-diamond composite material, reacting with graphene oxide to obtain a graphene oxide/polydopamine/nano-diamond composite material, and mixing with water to obtain the super-smooth water lubricant, wherein the friction factor reaches 0.003.)

1. A lubricating additive for a composite carbon material, characterized by: the nano-diamond layer is a spherical structure and sequentially comprises a nano-diamond layer, a polydopamine layer and a graphene oxide layer from inside to outside, wherein the polydopamine layer coats the nano-diamond layer, and the graphene oxide layer coats the polydopamine layer; or the nano diamond layer, the polydopamine layer, the graphene layer and the polydopamine layer are sequentially arranged from inside to outside, the polydopamine coats the nano diamond layer, the graphene layer coats the polydopamine layer, and the polydopamine coats the graphene layer.

2. The carbon composite material as claimed in claim 1, wherein: the grain size of the nano diamond is 5-50 nm.

3. The carbon composite material as claimed in claim 1, wherein: the number of graphene oxide or graphene layers with spherical structures is 1-10.

4. A method for producing a lubricating additive for composite carbon materials as claimed in any one of claims 1 to 3, wherein: the method comprises the following specific steps:

1) mixing a dopamine hydrochloride solution, water and a Tris solution, then adding an HCl solution to adjust the pH value, then adding a nano-diamond colloidal aqueous solution, and reacting to obtain a polydopamine coated nano-diamond composite material;

2) adding the obtained polydopamine-coated nano-diamond composite material into a graphene oxide solution, and reacting to obtain a graphene oxide/polydopamine/nano-diamond composite material;

or, 3) sequentially repeating the reaction of mixing the graphene oxide/polydopamine/nano-diamond composite material obtained in the step 2) with dopamine hydrochloride, water, a Tris solution and an HCl solution in the step 1) and the reaction in the step 2);

preferably, the mixture obtained by the reaction in the step 3) is subjected to centrifugal separation, and after supernatant liquid is removed, the mixture is subjected to freeze drying to obtain the lubricant additive;

preferably, the volume ratio and the addition amount of the dopamine hydrochloride, the water, the Tris solution and the HCl solution participating in the reaction in the step 3) are the same as those in the step 1), and the addition amount and the concentration of the graphene oxide solution participating in the reaction are the same as those in the step 2).

5. A method for producing a lubricating additive for composite carbon materials as claimed in any one of claims 1 to 3, wherein: the method comprises the following specific steps: the method comprises the following specific steps:

1) mixing a dopamine hydrochloride solution, water and a Tris solution, then adding an HCl solution to adjust the pH value, then adding a nano-diamond colloidal aqueous solution, and reacting to obtain a polydopamine coated nano-diamond composite material;

2) adding the obtained polydopamine-coated nano-diamond composite material into a graphene oxide solution, and reacting to obtain a graphene oxide/polydopamine/nano-diamond composite material;

3) mixing the oxidized graphene/polydopamine/nano-diamond composite material obtained in the step 2) with dopamine hydrochloride, water, a Tris solution and a HCl solution for reaction to obtain a polydopamine/graphene/polydopamine/nano-diamond composite material;

or, 4) the polydopamine/graphene/polydopamine/nano-diamond composite material obtained in the step 3) is subjected to the reaction of mixing with dopamine hydrochloride, water, a Tris solution and an HCl solution in the steps 2) and 1) in sequence.

6. The method for producing a lubricating additive for composite carbon materials as claimed in claim 4 or 5, wherein: in the step 1), the volume ratio of the dopamine hydrochloride, the water, the Tris solution, the nano-diamond colloid solution and the HCl solution is 1:18-22:18-22:8-12: 3-5; preferably 1:20:20:10: 4;

or, in the step 1), the concentration of the dopamine hydrochloride is 2-5mg/mL, the concentration of the Tris solution is 0.05-0.15mol/L, and the concentration of the HCl solution is 0.05-0.15 mol/L; preferably, the concentration of dopamine hydrochloride is 2mg/mL, the concentration of Tris solution is 0.1mol/L, and the concentration of HCl solution is 0.1 mol/L;

or the concentration of the nano diamond colloid solution is 0.05-0.15 mol/L; preferably 0.1 mol/L;

or, the reaction time after the nano-diamond is added in the step 1) is 10-15 h;

or, the preparation method of the graphene oxide is a Hummer method;

or, the concentration of the graphene oxide solution in the step 2) is 0.5-2.5 mg/mL.

7. The method for producing a lubricating additive for composite carbon materials according to claim 5, wherein: centrifuging the mixture obtained after the reaction in the step 3), removing supernatant, and freeze-drying to obtain a polydopamine/graphene/polydopamine/nano-diamond composite material;

or, centrifuging the mixture obtained by the reaction in the step 4), removing the supernatant, and freeze-drying to obtain the lubricant additive;

or, the volume ratio and the adding amount of the dopamine hydrochloride, the water, the Tris solution and the HCl solution participating in the reaction in the step 3) or the step 4) are the same as those in the step 1), and the adding amount and the concentration of the graphene oxide solution participating in the reaction in the step 4) are the same as those in the step 2).

8. An ultra-lubricious water lubricant, comprising: comprising water and a lubricity additive as claimed in any one of claims 1 to 3.

9. The method of preparing the ultra-lubricious water lubricant of claim 8, wherein: and mixing the lubricating additive and water to obtain the super-lubricating water lubricant.

10. Use of the ultra-lubricious water lubricant of claim 8 in a machine component for use in an atmospheric environment.

Technical Field

The invention belongs to the field of nano materials and the technical field of super-lubricating water lubricants, and particularly relates to a lubricating additive of a composite carbon material, a super-lubricating water lubricant, and a preparation method and application thereof.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

Lubrication of many key components of motor vehicles, micro-nano mechanical components and the like is beneficial to reducing abrasion, component failure and material loss are avoided, and the conventional various solid and liquid lubricants can rarely realize ultra-smooth behavior on a macroscopic or engineering scale.

With the increasing emphasis on environmental issues, water has received much attention as a lubricant in the field of tribology. However, in the boundary lubrication or mixed lubrication state, the pure water has poor lubrication performance, and the water film is easy to break, so that the metal surface is in direct contact, namely solid-solid contact, thereby greatly limiting the application of the pure water in the fields of moving parts and joint fluid lubrication. The existing method for using diamond as a lubricating additive can realize low friction and cannot realize ultra-smooth behavior in a macroscopic atmospheric environment.

Disclosure of Invention

In view of the problems in the prior art, the invention aims to provide a lubricating additive of a composite carbon material, a super-lubricating water lubricant, and a preparation method and application thereof.

In order to solve the technical problems, the technical scheme of the invention is as follows:

the lubricating additive is of a spherical structure, and is of a composite layer structure consisting of a nano diamond layer, a polydopamine layer and a graphene oxide layer from inside to outside in sequence, or of the nano diamond layer, the polydopamine layer, the graphene layer and the polydopamine layer from inside to outside, the number of layers of the composite layer is single-layer or multi-layer, and the multi-layer structure consists of a plurality of composite layers in repeated overlapping mode.

The lubricant comprises two lubricating additives, wherein the first lubricating additive is a composite layer structure of a single-layer nano diamond layer, a polydopamine layer and a graphene oxide layer, and the composite layer can be the nano diamond layer, the polydopamine layer, the graphene oxide layer, the polydopamine layer and the graphene oxide layer; the second type is a composite layer structure of a single-layer nano diamond layer, a polydopamine layer, a graphene layer and a polydopamine layer, and the composite layer can be a composite layer structure of a nano diamond layer, a polydopamine layer, a graphene layer, a polydopamine layer, graphene and polydopamine.

The polydopamine has reducibility, one surface of the polydopamine, which is wrapped by graphene oxide, can be reduced, and the graphene oxide on the outermost layer does not react with the polydopamine, so that the graphene oxide on the outermost layer in the first lubricating additive is reduced on the inner side and not reduced on the outer side, and the graphene oxide positioned between the two polydopamine layers is actually reduced graphene. The graphene in the second type is located between two poly dopamine layers, so that the graphene is reduced from graphene oxide.

According to the lubricating additive prepared by the invention, the nano-diamond is positioned in the spherical structure, and the principle of the super-lubricity is that the nano-diamond has better wear resistance and hardness, so that the lubricating agent has better wear resistance, polydopamine is easy to disperse in water, graphene oxide can roll on a friction surface, and the diamond is combined with the polydopamine, so that the dispersity of the diamond is improved, the whole dispersing agent is more stable, and the lubricating property is better.

The nano-scale diamond has a spheroidal structure, and the surface of the nano-scale diamond is grafted with polydopamine: the graphene oxide layer can be grafted to the surface of the graphene oxide layer; the nano diamond with high hardness drives the graphene oxide to roll in the friction process, so that the contact area is reduced, and the friction is reduced, so that the water has good friction performance.

In a second aspect, the preparation method of the lubricating additive of the composite carbon material comprises the following specific steps:

1) mixing a dopamine hydrochloride solution, water and a Tris solution, then adding an HCl solution to adjust the pH value, then adding a nano-diamond colloidal aqueous solution, and reacting to obtain a polydopamine coated nano-diamond composite material;

2) adding the obtained polydopamine-coated nano-diamond composite material into a graphene oxide solution, and reacting to obtain a graphene oxide/polydopamine/nano-diamond composite material;

or, 3) repeating the reaction of mixing the graphene oxide/polydopamine/nano-diamond composite material obtained in the step 2) with dopamine hydrochloride, water, a Tris solution and an HCl solution in the step 1) and the reaction in the step 2) in sequence.

The other preparation method comprises the following specific steps:

1) mixing a dopamine hydrochloride solution, water and a Tris solution, then adding an HCl solution to adjust the pH value, then adding a nano-diamond colloidal aqueous solution, and reacting to obtain a polydopamine coated nano-diamond composite material;

2) adding the obtained polydopamine-coated nano-diamond composite material into a graphene oxide solution, and reacting to obtain a graphene oxide/polydopamine/nano-diamond composite material;

3) mixing the oxidized graphene/polydopamine/nano-diamond composite material obtained in the step 2) with dopamine hydrochloride, water, a Tris solution and a HCl solution for reaction to obtain a polydopamine/graphene/polydopamine/nano-diamond composite material;

or, 4) the polydopamine/graphene/polydopamine/nano-diamond composite material obtained in the step 3) is subjected to the reaction of mixing with dopamine hydrochloride, water, a Tris solution and an HCl solution in the steps 2) and 1) in sequence.

Grafting polydopamine on the surface of the nano-diamond in the step 1), and forming a graphene oxide layer on the surface of the polydopamine in the step 2) to obtain a spherical structure.

In a third aspect, a super-lubricious water lubricant comprises water and the above-described lubricious additive.

In a fourth aspect, the super-lubricious water lubricant is prepared by mixing the lubricant additive with water to obtain the super-lubricious water lubricant.

In a fifth aspect, the use of the ultra-slippery water lubricant described above in a machine component for use in an atmospheric environment. The water lubricant of the invention enables mechanical parts to achieve ultra-smooth behavior in atmospheric environments.

The invention has the beneficial effects that:

1. according to the invention, the nano-diamond is placed in the central part of the spherical structure, and the graphene oxide or graphene coated diamond has two benefits: firstly, even if graphene oxide or graphene spheres crack in the friction process, the graphene oxide or graphene sheet layer can also protect the surface of a matching pair, and the nano diamond can roll on the graphene oxide or graphene sheet layer, so that the friction is reduced; secondly, the diamond is wrapped by the graphene oxide or the graphene ball, so that the hardness of the diamond can be reduced, the diamond does not scratch the surface when rolling, and the dispersibility in water can be enhanced.

2. According to the invention, deionized water is used as a lubricating liquid, and in-situ assembled spherical graphene oxide or graphene composite material is used as a lubricating additive, so that the spherical graphene oxide or graphene can roll on a friction surface, and friction and wear are reduced; the poly-dopamine contains a large amount of hydroxyl groups and amino groups, and is easy to adsorb the surfaces of friction pairs, and the poly-dopamine is easy to disperse in water, so that the ultra-smooth water lubricant with different additive mass concentrations is prepared, the preparation is simple, the operation is easy, the process is stable, the quality is reliable, the cost is low, the additive is renewable and pollution-free, and the additive is easy to adsorb on the dual surfaces to form a transfer film, so that the poly-dopamine super-smooth water lubricant serving as an advanced lubricant material meets the commercial engineering macroscopic use requirement.

3. The super-smooth water lubricant can be stored for 1 year without obvious precipitation phenomenon, and has long shelf life.

4. Tribology tests show that the water lubricant obtained by the invention has super-smooth lubricating behavior and wear resistance, so that the water lubricant can be used as a super-smooth lubricant material for mechanical moving parts in atmospheric environment.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description, serve to explain the invention and not to limit the invention.

FIG. 1 is a plot of the friction test of a comparative example 1 pure deionized water lubricant of the present invention on a ball-and-disk.

Fig. 2 is a friction test curve of comparative example 2 of the present invention with 0.3% by mass concentration of graphene oxide additive water lubricant on a ball-disk.

Fig. 3 is a graph of the friction test of comparative example 3 of the present invention on a ball-disk with a 0.3% by mass concentration nanodiamond additive aqueous lubricant.

Fig. 4 is a graph of the friction test of a polydopamine/graphene oxide additive water lubricant at mass concentration on a ball-and-disk of comparative example 4 of the present invention.

Fig. 5 is a graph of the friction test of a polydopamine/nanodiamond additive aqueous lubricant at a 0.3% concentration by mass on a ball-and-disk of comparative example 5 of the present invention.

Fig. 6 is a friction test curve of nanodiamond/polydopamine/graphene oxide composite additive water lubricant with a mass concentration of 0.3% on a ball-disk in example 10 of the present invention.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments according to the present application. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The lubricating additive is of a spherical structure, and is of a composite layer structure consisting of a nano diamond layer, a polydopamine layer and a graphene oxide layer from inside to outside in sequence, or of the nano diamond layer, the polydopamine layer, the graphene layer and the polydopamine layer from inside to outside, the number of layers of the composite layer is single-layer or multi-layer, and the multi-layer structure consists of a plurality of composite layers in repeated overlapping mode.

The invention prepares a lubricating additive, which has the principle of super-lubricity that graphene oxide balls roll on a friction surface, so that the contact area is reduced, the friction and wear are reduced, and the super-lubricity is realized. It should be explained that: the rolling is easy to realize the ultra-slip, even if the graphene oxide ball is broken in the process, the nano diamond can roll on the graphene oxide sheet, the friction and the wear can be reduced by the laminar sliding of the graphene oxide sheet, and the ultra-slip can be realized by the cooperation of the graphene oxide and the nano diamond.

In some embodiments of the invention, the nanodiamonds have a particle size of 5 to 50 nm.

In some embodiments of the invention, the graphene oxide or graphene layers of the spherical structure are 1-10 layers.

In a second aspect, the preparation method of the lubricating additive of the composite carbon material comprises the following specific steps:

1) mixing a dopamine hydrochloride solution, water and a Tris solution, then adding an HCl solution to adjust the pH value, then adding a nano-diamond colloidal aqueous solution, and reacting to obtain a polydopamine coated nano-diamond composite material;

2) adding the obtained polydopamine-coated nano-diamond composite material into a graphene oxide solution, and reacting to obtain a graphene oxide/polydopamine/nano-diamond composite material;

or, 3) repeating the reaction of mixing the graphene oxide/polydopamine/nano-diamond composite material obtained in the step 2) with dopamine hydrochloride, water, a Tris solution and an HCl solution in the step 1) and the reaction in the step 2) in sequence.

In some embodiments of the invention, the mixture resulting from the reaction of step 3) is centrifuged to remove the supernatant and then freeze-dried to provide the lubricant additive.

In some embodiments of the present invention, the volume ratio and the addition amount of the dopamine hydrochloride, the water, the Tris solution and the HCl solution participating in the reaction in step 3) are the same as those in step 1), and the addition amount and the concentration of the graphene oxide solution participating in the reaction are the same as those in step 2).

The other preparation method comprises the following specific steps:

1) mixing a dopamine hydrochloride solution, water and a Tris solution, then adding an HCl solution to adjust the pH value, then adding a nano-diamond colloidal aqueous solution, and reacting to obtain a polydopamine coated nano-diamond composite material;

2) adding the obtained polydopamine-coated nano-diamond composite material into a graphene oxide solution, and reacting to obtain a graphene oxide/polydopamine/nano-diamond composite material;

3) mixing the oxidized graphene/polydopamine/nano-diamond composite material obtained in the step 2) with dopamine hydrochloride, water, a Tris solution and a HCl solution for reaction to obtain a polydopamine/graphene/polydopamine/nano-diamond composite material;

or, 4) sequentially and repeatedly carrying out the reaction of mixing the polydopamine/graphene/polydopamine/nano-diamond composite material obtained in the step 3) with the dopamine hydrochloride, water, a Tris solution and an HCl solution in the step 2) and the step 1).

In some embodiments of the invention, the volume ratio of the dopamine hydrochloride, the water, the Tris solution, the nanodiamond colloid solution and the HCl solution in the step 1) is 1:18-22:18-22:8-12: 3-5; preferably 1:20:20:10: 4.

In some embodiments of the invention, the concentration of dopamine hydrochloride in step 1) is 2-5mg/mL, the concentration of Tris solution is 0.05-0.15mol/L, and the concentration of HCl solution is 0.05-0.15 mol/L; preferably, the concentration of dopamine hydrochloride is 2mg/mL, the concentration of Tris solution is 0.1mol/L, and the concentration of HCl solution is 0.1 mol/L.

In some embodiments of the present invention, the concentration of the nanodiamond colloid solution is 0.05-0.15 mol/L; preferably 0.1 mol/L.

In some embodiments of the present invention, the reaction time after the addition of the nanodiamond in step 1) is 10 to 15 hours.

In some embodiments of the present invention, the method for preparing graphene oxide is a Hummer method.

In some embodiments of the present invention, the mixture after the reaction in step 1) is subjected to centrifugal separation, supernatant is removed, and drying is performed to obtain the poly-dopamine coated nano-diamond composite material.

In some embodiments of the invention, the concentration of the graphene oxide solution in step 2) is 0.5-2.5 mg/mL. And 2) grafting graphene oxide on the surface of the polydopamine at normal temperature. The surface of the graphene oxide contains functional groups such as hydroxyl, carboxyl and oxygen-containing groups, and the polydopamine is in graft connection with the graphene oxide through hydroxyl or pi-pi bonds.

In some embodiments of the present invention, the mixture after the reaction in step 2) is subjected to centrifugal separation, and freeze-dried after removing the supernatant to obtain the graphene oxide/polydopamine/nano-diamond composite material.

In some embodiments of the present invention, the mixture after the reaction in step 3) is subjected to centrifugal separation, and after removing the supernatant, the mixture is freeze-dried to obtain the poly-dopamine/graphene/poly-dopamine/nano-diamond composite material.

In some embodiments of the invention, the mixture resulting from the reaction of step 4) is centrifuged to remove the supernatant and then freeze-dried to provide the lubricant additive.

In some embodiments of the present invention, the volume ratio and the addition amount of the dopamine hydrochloride, the water, the Tris solution and the HCl solution participating in the reaction in step 3) or step 4) are the same as those in step 1), and the addition amount and the concentration of the graphene oxide solution participating in the reaction in step 4) are the same as those in step 2).

In a third aspect, a super-lubricious water lubricant comprises water and the above-described lubricious additive.

In some embodiments of the invention, the mass concentration of the lubricant additive in the ultra-smooth water-based lubricant is 0.01% to 0.5%; preferably 0.2% to 0.5%.

In a fourth aspect, the super-lubricious water lubricant is prepared by mixing the lubricant additive with water to obtain the super-lubricious water lubricant.

In a fifth aspect, the use of the ultra-slippery water lubricant described above in a machine component for use in an atmospheric environment.

The invention will be further illustrated by the following examples