Conductive graphene lubricating grease and preparation method thereof

Abstract

The invention relates to the technical field of lubricating oil, and particularly discloses conductive graphene lubricating grease and a preparation method thereof. The conductive graphene lubricating grease provided by the invention comprises the following components in parts by weight: 60-80 parts of base oil, 0.5-5 parts of graphene, 5-15 parts of a conductive additive, 5-10 parts of a thickening agent, 2-5 parts of an anti-wear reagent at extreme pressure, 1-3 parts of an antioxidant and 1-2 parts of a dispersing agent, the specific surface area of the graphene is 100-500m < 2 > / g; further, the conductive additive is selected from one or more of silver powder, copper powder, black phosphorene and carbon nanotubes; the invention also provides a preparation method of the conductive graphene lubricating grease. On one hand, the conductive graphene lubricating grease provided by the invention has excellent adhesiveness and stability, and can maintain a lubricating effect for a long time under a dynamic working condition; and on the other hand, good conductivity is achieved, the contact resistance between the pantograph and the carbon plate can be effectively reduced, and the conductivity is remarkably improved.

Description

Technical Field

[0001] The present application relates to the technical field of lubricating oils, and particularly relates to a conductive graphene grease and a preparation method thereof. Background Art

[0002] In a rail transit system, the electrical connection performance between a pantograph and a carbon plate directly affects the operation efficiency and stability of a train. With the improvement of railway transportation speed and the increase of carrying capacity, ensuring good sliding contact characteristics becomes particularly important. Traditional lubrication methods not only need to ensure smooth operation between devices to reduce mechanical losses, but also need to take into account the quality of power transmission, which puts higher functional requirements on lubricating media.

[0003] Currently, the lubricating greases widely used in the industry mainly include metal powder-added lubricating greases or single-component modified oils; among them, the metal powder-added lubricating greases enhance the current conduction ability by mixing conductor particles such as aluminum powder into a base oil. However, the above lubricating greases have poor long-lasting and stable lubrication effects; while the single-component modified oils achieve good lubrication effects by chemically changing the molecular structure of the oils, but their electrical conductivity is poor. That is to say, the existing lubricating greases generally have difficulty in simultaneously achieving high electrical conductivity and long-lasting and stable lubricity at an ideal level, which seriously affects the reliability and service life of the entire system.

[0004] Therefore, it is urgently necessary to develop a grease with both high electrical conductivity and strong lubricity, which is of great significance for the rail transit system. Summary of the Invention

[0005] In order to overcome the defect that the existing lubricating greases are difficult to simultaneously meet the requirements of electrical conductivity and lubricity, the present application provides a conductive graphene grease and a preparation method thereof.

[0006] In the first aspect, the present application provides a conductive graphene grease, adopting the following technical solution: A conductive graphene grease, comprising the following components in parts by weight: 60-80 parts of a base oil, 0.5-5 parts of graphene, 5-15 parts of a conductive additive, 5-10 parts of a thickener, 2-5 parts of an extreme pressure and anti-wear agent, 1-3 parts of an antioxidant, and 1-2 parts of a dispersant; the specific surface area of the graphene is 100-500m 2 / g.

[0007] This application prepares conductive graphene grease using base oil, graphene, conductive additives, etc. By using graphene with a specific specific surface area and controlling the addition amounts of each component within the above ranges, on the one hand, the grease can have excellent adhesion and stability, and can maintain the lubrication effect durably under dynamic working conditions; on the other hand, it also has good electrical conductivity, can effectively reduce the contact resistance between the pantograph and the carbon plate, and significantly improve the electrical conductivity performance. Specifically: The graphene with the above specific specific surface area can endow the grease with excellent electrical conductivity and lubricity. The conductive additive can strengthen the overall conductive network structure of the grease, while ensuring efficient and stable current transmission, reducing energy loss and component damage caused by electric arcs. The thickener can improve the structural stability of the grease, enhance its load-bearing capacity and high and low temperature resistance characteristics. The extreme pressure and anti-wear additive can greatly improve the ability of the grease to resist extreme pressure and extend the service life of the equipment. The dispersant can make the distribution state of each component uniform, avoid agglomeration phenomena, and ensure the consistency of product performance. In summary, the conductive graphene grease provided by this application has multiple functions of conduction, lubrication and protection, and can provide a strong guarantee for the operation efficiency and reliability of the rail transit system.

[0008] In some embodiments, the specific surface area of the graphene can be 100 - 200 m 2 / g, 100 - 300 m 2 / g, 100 - 400 m 2 / g, 100 - 500 m 2 / g, 200 - 300 m 2 / g, 200 - 400 m 2 / g, 200 - 500 m 2 / g, 300 - 400 m 2 / g, 300 - 500 m 2 / g or 400 - 500 m 2 / g.

[0009] In a specific embodiment, the specific surface area of the graphene can also be 100 m 2 / g, 200 m 2 / g, 300 m 2 / g, 400 m 2 / g or 500 m 2 / g.

[0010] Optionally, the conductive additive is selected from one or more of silver powder, copper powder, black phosphorus and carbon nanotubes.

[0011] Optionally, the conductive additive is copper powder and black phosphorus with a weight ratio of 1:(0.1 - 0.2).

[0012] In this application, by using a mixture of copper powder and black phosphorus as a conductive additive, the electrical conductivity of the grease can be further optimized. Specifically, copper powder, as an efficient conductive material, can significantly reduce the overall resistance of the grease, thereby improving the current transmission efficiency; black phosphorus, due to its unique two-dimensional structural characteristics, can form a stable conductive network in the grease system and also has certain flexibility and durability. After compounding the two in a specific ratio, it not only enhances the electrical conductivity of the grease but also avoids the instability problems that may be brought about by a single material, enabling the grease to maintain long-term effective electrical conductivity under dynamic working conditions and reducing the energy loss and component damage caused by electric arcs.

[0013] In some embodiments, the weight ratio of the copper powder to the black phosphorus can be 1:(0.1 - 0.13), 1:(0.1 - 0.15), 1:(0.1 - 0.18), 1:(0.1 - 0.2), 1:(0.13 - 0.15), 1:(0.13 - 0.18), 1:(0.13 - 0.2), 1:(0.15 - 0.18), 1:(0.15 - 0.2), or 1:(0.18 - 0.2).

[0014] In a specific embodiment, the weight ratio of the copper powder to the black phosphorus can also be 1:0.1, 1:0.13, 1:0.15, 1:0.18, or 1:0.2.

[0015] Optionally, the weight ratio of the copper powder to the black phosphorus is 1:(0.13 - 0.18).

[0016] In this application, through experimental exploration, it is found that by controlling the weight ratio of copper powder to black phosphorus within the above range, the synergistic effect of copper powder and black phosphorus can be further exerted, and then a more stable conductive network structure can be formed inside the grease, thereby significantly improving the overall electrical conductivity of the grease. At the same time, this ratio combination can also effectively balance the cost and performance of the materials, ensuring more efficient and stable current transmission.

[0017] Optionally, the base oil is selected from one or more of mineral oil, synthetic oil, and bio-based oil; the thickener is selected from one or more of lithium soap, calcium soap, and polyurea; the extreme pressure and anti-wear agent is selected from one or more of boron-based extreme pressure and anti-wear agents, sulfide extreme pressure and anti-wear agents, phosphorus-based extreme pressure and anti-wear agents, and chloride extreme pressure and anti-wear agents; the antioxidant is amine antioxidant and / or phenolic antioxidant; the dispersant is lithium laurate.

[0018] In the second aspect, this application provides a preparation method of a conductive graphene grease.

[0019] A preparation method of a conductive graphene grease includes the following steps: Graphene and a dispersant are added to a part of the base oil, and they are uniformly dispersed by ultrasonic treatment or high-speed stirring to form a graphene dispersion; A thickener is added to the remaining base oil, stirred and heated to 80 - 120 °C to dissolve it, obtaining a thickener mixture; The graphene dispersion is added to the thickener mixture and stirred evenly; then the remaining components are added and stirred evenly; it is cooled to room temperature and ground to obtain a conductive graphene grease.

[0020] Optionally, the weight ratio of the part of the base oil to the remaining base oil is (0.5 - 1):1.

[0021] Optionally, the power of the ultrasonic treatment is 200 - 500 W, and the time is 30 - 60 min.

[0022] In this application, by adjusting the power and time of the ultrasonic treatment to the above range, the van der Waals force between the graphene sheets can be effectively destroyed, promoting its dissociation and uniform distribution, thereby avoiding the occurrence of agglomeration phenomena, enabling the graphene to be more uniformly dispersed in the base oil, and this uniformly dispersed state helps to enhance the overall conductive network structure of the grease, further improving the conductive performance and lubricating stability.

[0023] Optionally, the rotation speed of the stirring is 500 - 2000 rpm.

[0024] In summary, this application has the following beneficial effects: 1. By selecting graphene with a specific specific surface area and cooperating with a conductive additive, on the one hand, the grease has excellent conductive performance, significantly reducing the contact resistance between the pantograph and the carbon plate, improving the power transmission efficiency and reducing energy loss; on the other hand, the grease has excellent adhesion and stability, and can maintain an effective lubricating effect for a long time under dynamic working conditions, thereby reducing mechanical wear and extending the service life of the equipment; 2. This application uses a mixture of copper powder and black phosphorus as a conductive additive, which can further optimize the conductive performance of the grease, enabling the volume resistivity of the grease to be reduced to 2.5 Ω·cm×10 3 or less, and the grease can still maintain long-term effective conductive performance under dynamic working conditions, reducing energy loss and component damage caused by electric arcs.

[0025] 3. In the preparation method of the conductive graphene grease provided by the present application, by adjusting the ultrasonic dispersion power and time of graphene, the agglomeration of graphene can be avoided, and it can be more uniformly dispersed in the base oil, which helps to enhance the overall conductive network structure of the grease, and further improve the conductive performance and lubrication stability. By further controlling the power of graphene ultrasonic treatment between 200 - 500 W and the time between 30 - 60 min, the obtained conductive graphene grease has better conductivity and lubricity effects, and its friction coefficient can be as low as below 0.10, and the volume resistivity can be as low as 2.0 Ω·cm×10 3 below. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a flowchart of the preparation method of the conductive graphene grease provided by the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0027] The present application provides a conductive graphene grease, which includes the following components in parts by weight: 60 - 80 parts of base oil, 0.5 - 5 parts of graphene, 5 - 15 parts of conductive additive, 5 - 10 parts of thickener, 2 - 5 parts of extreme pressure and anti-wear agent, 1 - 3 parts of antioxidant, and 1 - 2 parts of dispersant; the specific surface area of the graphene is 100 - 500 m 2 / g. Among them, the conductive additive is selected from one or more of silver powder, copper powder, black phosphorus, and carbon nanotubes. Further, the conductive additive is copper powder and black phosphorus in a weight ratio of 1:(0.1 - 0.2); still further, the weight ratio of copper powder to black phosphorus is 1:(0.13 - 0.18).

[0028] The present application also provides a preparation method of the above conductive graphene grease, which includes the following steps: (1) Add graphene and dispersant to 1 / 2 of the base oil, and ultrasonically treat it at a power of 200 - 500 W for 30 - 60 min to make it uniformly dispersed, forming a graphene dispersion; (2) Add the thickener to the remaining 1 / 2 of the base oil, stir at a rotation speed of 500 - 2000 rpm and heat to 80 - 120 °C to dissolve it, obtaining a thickener mixture; (3) Add the graphene dispersion to the thickener mixture and stir evenly at a rotation speed of 500 - 2000 rpm; then add the conductive additive, antioxidant, and extreme pressure and anti-wear agent, and stir evenly at a rotation speed of 500 - 2000 rpm; cool to room temperature and grind to obtain the conductive graphene grease.

[0029] In the embodiments of the present application, the base oil is polyalphaolefin (PAO); the graphene is purchased from Beijing Graphene Technology Research Institute Co., Ltd.; the particle size of the copper powder is 20 nm; the black phosphorus is purchased from Shenzhen Liutan Technology Co., Ltd.; the carbon nanotubes are purchased from J&K Scientific; the thickener is calcium 12-hydroxystearate; the extreme pressure and anti-wear agent is sodium thiosulfate; the antioxidant is amine antioxidant 5057; the dispersant is lithium laurate, purchased from Hubei Xinghengye Technology Co., Ltd.; the raw materials, reagents, solvents, etc. used in the present application can all be obtained through commercial purchase.

[0030] The present application will be further described in detail below in conjunction with examples, performance detection tests and the description of the drawings.

[0031] Examples 1-5 Examples 1-5 respectively provide a conductive graphene grease.

[0032] The difference between the above examples lies in: the specific surface area of graphene used in the conductive graphene grease is shown in Table 1 below.

[0033] The preparation method of the conductive graphene grease provided in Examples 1-5 includes the following steps: (1) Add 3 g of graphene and 1.5 g of lithium laurate dispersant to 35 g of polyalphaolefin, and ultrasonically treat it at a power of 400 W for 40 min to make it uniformly dispersed to form a graphene dispersion; (2) Add 8 g of calcium 12-hydroxystearate thickener to 35 g of polyalphaolefin, stir at a speed of 1000 rpm and heat to 100 °C to dissolve it to obtain a thickener mixture; (3) Add the graphene dispersion to the thickener mixture and stir evenly at a speed of 1000 rpm; then add 10 g of nano copper powder, 2 g of amine antioxidant and 4 g of sodium thiosulfate, and stir evenly at a speed of 1000 rpm; cool to room temperature and grind to obtain the conductive graphene grease.

[0034] Table 1 Specific surface area of graphene used in the conductive graphene grease provided in Examples 1-5 Example <![CDATA[Specific surface area of graphene (m 2 / g)]]> 1 100 2 200 3 300 4 400 5 500 Examples 6-14 Examples 6-14 respectively provide a conductive graphene grease.

[0035] The difference between the above examples and Example 3 lies in: the type and ratio of the conductive additive, which are shown in Table 2 below.

[0036] Table 2 Type and ratio of conductive additives in the conductive graphene grease provided in Examples 6-14 Example Type and ratio of conductive additives 3 Copper powder 6 Black phosphorene 7 Carbon nanotubes 8 Copper powder and black phosphorene with a weight ratio of 1:0.1 9 Copper powder and black phosphorene with a weight ratio of 1:0.13 10 Copper powder and black phosphorene with a weight ratio of 1:0.15 11 Copper powder and black phosphorene with a weight ratio of 1:0.18 12 Copper powder and black phosphorene with a weight ratio of 1:0.2 13 Copper powder and carbon nanotubes with a weight ratio of 1:0.15 14 Carbon nanotubes and black phosphorene with a weight ratio of 1:0.15 Examples 15 - 20 Examples 15 - 20 respectively provide a conductive graphene grease.

[0037] The difference between the above examples and Example 10 lies in: the power and time of ultrasonic treatment in step (3), as shown in Table 3 below.

[0038] Table 3 Power and time of ultrasonic treatment in step (3) of Example 10, Examples 15 - 20 Comparative Example 1 Comparative Example 1 provides a conductive graphene grease.

[0039] The difference between the above examples lies in: the specific surface area of graphene used in the conductive graphene grease is 600 m 2 / g.

[0040] Performance detection test The service performance of the conductive graphene greases obtained in Examples 1 - 20 and Comparative Example 1 was detected, and the results are shown in Table 4 below.

[0041] (1) Coefficient of friction: The lubricity of the grease was tested according to the method in Standard SH / T 0202; (2) Volume resistivity: The conductivity of the grease was tested according to GB1410; Table 4 Detection results of the service performance of the conductive graphene greases obtained in Examples 1 - 20 and Comparative Example 1 According to the detection results in Table 4, the coefficient of friction of the conductive graphene greases obtained in Examples 1 - 20 is 0.08 - 0.13 (≤0.15), and the volume resistivity is 1.24 - 4.57 Ω·cm×10 3 (≤5.0 Ω·cm×10 3 ); while the coefficient of friction of the conductive graphene grease obtained in Comparative Example 1 is as high as 0.20. Therefore, it shows that the present application uses base oil, graphene, conductive additives, etc. to prepare a conductive graphene grease, and controls the specific surface area of graphene within the range of 100 - 500 m 2 / g, then a conductive graphene grease with good lubricity and conductivity can be obtained.

[0042] The test results of Examples 1-5 showed that as the specific surface area of graphene increased, the friction coefficient of the resulting conductive graphene grease gradually increased, and the volume resistivity gradually decreased; further comparison found that the friction coefficient of the conductive graphene grease obtained in Examples 2-4 was 0.08-0.10 (≤0.10), and the volume resistivity was 3.31-3.83 Ω·cm×10 3 (≤4.0 Ω·cm×10 3 ). It shows that in this application, the specific surface area of graphene is further controlled within the range of 200-400 m 2 / g, and the comprehensive performance of lubricity and conductivity of the obtained conductive graphene grease is better.

[0043] From the test results of Example 3 and Examples 6-14, it can be seen that in Example 3 and Examples 6-7, copper powder, black phosphorus or carbon nanotubes were used as conductive additives, and the friction coefficient of the resulting conductive graphene grease was 0.11-0.13, and the volume resistivity was 3.65-4.57 Ω·cm×10 3 ; in Examples 13-14, copper powder and carbon nanotubes with a weight ratio of 1:0.15 or carbon nanotubes and black phosphorus with a weight ratio of 1:0.15 were used as conductive additives, and the friction coefficient of the resulting conductive graphene grease was 0.10, and the volume resistivity was 2.47-2.83 Ω·cm×10 3 ; while in Examples 8-12, copper powder and black phosphorus with a weight ratio of 1:(0.1-0.2) were used as conductive additives, and the friction coefficient of the resulting conductive graphene grease was 0.08-0.09 (≤0.10), and the volume resistivity was 1.24-2.33 Ω·cm×10 3 (≤2.5 Ω·cm×10 3 ). It shows that in this application, copper powder and black phosphorus with a weight ratio of 1:(0.1-0.2) are further used as conductive additives, and a conductive graphene grease with more excellent conductivity can be obtained while ensuring lubricity.

[0044] From the test results of Example 10 and Examples 15-20, it can be seen that the friction coefficient of the conductive graphene grease obtained in Example 10 and Examples 15-18 was 0.08-0.09 (≤0.10), and the volume resistivity was 1.24-1.61 Ω·cm×10 3 (≤2.0 Ω·cm×10 3 ); while the friction coefficient of the conductive graphene grease obtained in Examples 19-20 was 0.10-0.11, and the volume resistivity was 2.63-2.98 Ω·cm×10 3Therefore, it shows that when the power of ultrasonic treatment in this application is controlled between 200 - 500W and the time is controlled between 30 - 60min, the conductivity and lubricity effects of the obtained conductive graphene grease are better.

[0045] Although the present invention has been described in detail with general descriptions and specific embodiments above, some modifications or improvements can be made based on the present invention, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of the present invention claimed.

Claims

1. A conductive graphene grease, characterized in that, Comprising the following components in parts by weight: 60 - 80 parts of base oil, 0.5 - 5 parts of graphene, 5 - 15 parts of conductive additive, 5 - 10 parts of thickener, 2 - 5 parts of extreme pressure and anti-wear agent, 1 - 3 parts of antioxidant, 1 - 2 parts of dispersant; the specific surface area of the graphene is 100 - 500m 2 / g.

2. The electrically conductive graphene grease according to claim 1, wherein The conductive additive is selected from one or more of silver powder, copper powder, black phosphorene, and carbon nanotubes.

3. The electrically conductive graphene grease according to claim 2, characterized in that, The conductive additive is copper powder and black phosphorene with a weight ratio of 1:(0.1-0.2).

4. The electrically conductive graphene grease according to claim 3, characterized in that, The weight ratio of the copper powder to the black phosphorene is 1:(0.13-0.18).

5. The electrically conductive graphene grease according to any one of claims 1-4, characterized in that, The base oil is selected from one or more of mineral oil, synthetic oil, and bio-based oil; the thickener is selected from one or more of lithium-based soap, calcium-based soap, and polyurea; the extreme pressure and anti-wear agent is selected from one or more of boron-based extreme pressure and anti-wear agents, sulfide extreme pressure and anti-wear agents, phosphorus-based extreme pressure and anti-wear agents, and chloride extreme pressure and anti-wear agents; the antioxidant is an amine antioxidant and / or a phenolic antioxidant; the dispersant is lithium laurate.

6. The preparation method of the conductive graphene grease according to any one of claims 1-5, characterized in that, It includes the following steps: Adding graphene and a dispersant to a part of the base oil, and uniformly dispersing them by ultrasonic treatment or high-speed stirring to form a graphene dispersion; Adding the thickener to the remaining base oil, stirring and heating to 80-120°C to dissolve it to obtain a thickener mixture; Adding the graphene dispersion to the thickener mixture, stirring evenly; then adding the remaining components, stirring evenly; cooling to room temperature, and grinding to obtain the conductive graphene grease.

7. The preparation method of the conductive graphene grease according to claim 6, characterized in that, The weight ratio of the part of the base oil to the remaining base oil is (0.5-1):

1.

8. The preparation method of the conductive graphene grease according to claim 6, characterized in that, The power of the ultrasonic treatment is 200-500W, and the time is 30-60min.

9. The preparation method of the electrically conductive graphene grease according to claim 6, characterized in that, The rotation speed of the stirring is 500-2000rpm.

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