Compound grease, preparation method thereof and electric contact element

Abstract

The invention discloses compound grease, a preparation method thereof and an electric contact element, and relates to the technical field of compound grease. The preparation method of the compound grease comprises the following steps: providing graphene slurry, wherein the graphene slurry comprises graphene powder; a mixed solution is provided, the mixed solution comprises base oil, and the mixed solution is calendered to form a sheet-shaped intermediate; graphene slurry is sprayed on the surface of the sheet-shaped intermediate, after the graphene slurry is dried, a composite layer is formed, and the composite layer comprises the sheet-shaped intermediate and a graphene layer on the sheet-shaped intermediate; a plurality of composite layers are stacked to form a composite grease prefabricated body, and in the composite grease prefabricated body, the flaky intermediates and the graphene layers are sequentially and alternately stacked; and carrying out first stirring on the complex grease preform to obtain the complex grease. According to the preparation method of the compound grease, full and uniform contact of the graphene powder and the base oil is facilitated, and the high temperature resistance, moisture resistance, oxidation resistance, mildew resistance and chemical corrosion resistance of the compound grease are improved.

Description

Technical Field

[0001] The present application relates to the technical field of composite grease, and particularly relates to a composite grease, a preparation method thereof, and an electrical contact element. Background Art

[0002] For the contact surfaces of electrical connection conductors and contact surfaces of contacts, no matter how smooth the processing is, from a microscopic structure perspective, they are uneven. The actual effective contact area only accounts for a small part of the entire contact surface. Various metals will also form an oxide layer in the air, making the effective contact area even smaller. Electric power composite grease is a neutral conductive dressing with good electrical contact performance, and is applicable to the contact surfaces at the lap joints of busbars of high and low voltage electrical appliances and various electrical joints. The conductive fine particles in the electric power composite grease are filled in the gaps of the contact surface, which is equivalent to increasing the conductive contact surface. Under the action of compressive force or bolt tightening force, the conductive fine particles reduce the contact resistance, and the corresponding temperature rise of the joint also decreases, prolonging the service life of the joint.

[0003] Electric power composite grease is widely used in the contact surfaces at the joints between busbars and between busbars and equipment terminal blocks in substations and distribution substations, and on the contact surfaces of switch contacts. It can be used for the connection between conductors of the same and different metal materials, such as copper and copper, copper and aluminum, or aluminum and aluminum. It replaces and is superior to the tinning and silver plating processes for fastening connection contact surfaces, can greatly reduce the contact resistance, thereby reducing the temperature rise and improving the conductivity of the busbar connection.

[0004] However, after long-term operation, the current electric power composite grease will experience an oil separation phenomenon caused by thermal aging, corona aging, etc. This is because the organic molecular chains in the electric power composite grease break at the molecular chain segments under thermal or corona conditions, resulting in a decrease in molecular weight, and thus causing the organic grease to precipitate, leading to failures in the electrical connection parts of power grid equipment.

[0005] Therefore, the aging resistance of the existing electric power composite grease needs to be further improved. Summary of the Invention

[0006] In view of this, the present application provides a composite grease, a preparation method thereof, and an electrical contact element to improve the aging resistance of the composite grease.

[0007] The embodiment of the present application is implemented as follows. A preparation method of a composite grease includes:

[0008] Providing a graphene slurry, wherein the graphene slurry includes graphene powder;

[0009] Providing a mixed liquid, wherein the mixed liquid includes a base oil, and rolling the mixed liquid to form a sheet-shaped intermediate;

[0010] Spray the graphene slurry on the surface of the sheet-shaped intermediate. After the graphene slurry dries, a composite layer is formed. The composite layer includes the sheet-shaped intermediate and the graphene layer on the sheet-shaped intermediate;

[0011] Stack a plurality of the composite layers to form a composite resin preform. In the composite resin preform, the sheet-shaped intermediate and the graphene layer are alternately stacked in sequence;

[0012] Perform a first stirring on the composite resin preform to obtain a composite resin.

[0013] Optionally, in some embodiments of the present application, the thickness of the graphene powder is 1 nm to 30 nm; and / or

[0014] The sheet diameter of the graphene powder is 0.2 μm to 5 μm; and / or

[0015] The carbon content of the graphene powder is greater than 99%;

[0016] Optionally, in some embodiments of the present application,

[0017] The thickness of the graphene layer is 100 nm to 300 nm; and / or

[0018] In the composite resin preform, the number of the composite layers is 2 to 10.

[0019] Optionally, in some embodiments of the present application, the graphene slurry further includes one or more of a dispersant and a solvent.

[0020] Optionally, in some embodiments of the present application, the dispersant includes a polymer dispersant; the polymer dispersant includes one or more of sodium polyacrylate and DP-218 hyperdispersant; and / or

[0021] The solvent includes an alcohol solvent; the alcohol solvent includes one or more of anhydrous ethanol, methanol, n-propanol, isopropanol, tert-butanol, pentanol, glycerol, methoxyethanol, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, and ethylene glycol; and / or

[0022] In the graphene slurry, the mass ratio of the graphene powder, the dispersant, and the solvent is (2 to 4):(1 to 2):(94 to 97).

[0023] Optionally, in some embodiments of the present application, the preparation method of the graphene slurry includes: providing graphene powder, a dispersant, and a solvent, mixing, performing a second stirring and a first grinding, and then obtaining the graphene slurry.

[0024] Optionally, in some embodiments of the present application, the rotation speed of the second stirring is 500 r / min to 1000 r / min; and / or

[0025] the time of the first grinding is 1 h to 2 h; and / or

[0026] In the graphene slurry, the fineness of the graphene powder is 0.2 μm to 10 μm.

[0027] Optionally, in some embodiments of the present application, the mixed liquid further includes one or more of a thickening agent and an antioxidant.

[0028] Optionally, in some embodiments of the present application, the base oil includes a silicone-based base oil, and the silicone-based base oil includes one or more of methyltrifluoropropyl silicone oil, methyl long-chain alkyl silicone oil, benzyl silicone oil, and dimethyl silicone oil; and / or

[0029] The thickening agent includes a silicon-based thickening agent, and the silicon-based thickening agent includes one or more of fumed silica, lithium magnesium silicate, and bentonite; and / or

[0030] The antioxidant includes an organic antioxidant, and the organic antioxidant includes one or more of tris(2,4-di-tert-butylphenyl) phosphite and 2,4-bis(n-octylthiomethylene)-6-methylphenol; and / or

[0031] In the mixed liquid, the mass ratio of the base oil, the thickening agent, and the antioxidant is 10:(1 to 1.5):(1 to 1.5).

[0032] Optionally, in some embodiments of the present application, the temperature of the calendering is room temperature to 80 °C; the pressure is 1 Mpa to 2 Mpa; the pressure holding time is 3 s to 10 s; and / or

[0033] Before calendering the mixed liquid, second grinding is further included; the time of the second grinding is 30 min to 60 min; and / or

[0034] The thickness of the sheet-shaped intermediate is 0.01 mm to 0.1 mm.

[0035] Optionally, in some embodiments of the present application, the time of the first stirring is 2 min to 10 min; the rotation speed is 80 r / min to 120 r / min; the temperature is 80 °C to 100 °C.

[0036] Correspondingly, an embodiment of the present application further provides a composite grease prepared by the above preparation method.

[0037] Optionally, in some embodiments of the present application, in the composite grease, the graphene powder is dispersed in the base oil; the graphene powder has a sheet-like network structure; and / or

[0038] in the composite grease, the fineness of the graphene powder is 0.2 μm to 10 μm; and / or

[0039] in the composite grease, the mass ratio of the graphene powder to the base oil is (15 - 35):(50 - 75).

[0040] Correspondingly, an embodiment of the present application further provides an electrical contact element, which includes the composite grease prepared by the above preparation method, or includes the above composite grease.

[0041] The preparation method of the composite grease provided by the present application is conducive to the full and uniform contact between the graphene powder and the base oil, and improves the high-temperature resistance, moisture resistance, oxidation resistance, mildew resistance and chemical corrosion resistance of the composite grease. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for the description of the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0043] Figure 1 is a flowchart of a preparation method of a composite grease provided by an embodiment of the present application;

[0044] Figure 2 is a schematic structural diagram of a composite grease preform provided by an embodiment of the present application.

[0045] Composite grease preform 100; Composite layer 10; Flaky intermediate 11; Graphene layer 12. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, rather than all embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present application. In addition, it should be understood that the specific embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0047] In this application, unless otherwise stated, the orientation terms such as "upper" and "lower" generally refer to the upper and lower in the actual use or working state of the device, specifically the drawing direction in the attached drawings; while "inner" and "outer" refer to the outline of the device. In addition, in the description of this application, the term "comprising" means "including but not limited to". The terms first, second, third, etc. are only used as labels and do not impose numerical requirements or establish an order.

[0048] In this application, "and / or" describes the association relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. Wherein A and B can be singular or plural.

[0049] In this application, "at least one" means one or more, and "a plurality" means two or more. "One or several", "at least one (item) below" or similar expressions refer to any combination of these items, including any combination of single item (item) or plural items (items). For example, "at least one (item) of a, b, or c", or, "at least one (item) of a, b, and c" can both represent: a, b, c, a - b (that is, a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0050] The various embodiments of this application can exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of this application; therefore, it should be considered that the description of the range has specifically disclosed all possible sub - ranges and the individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub - ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and the individual numbers within that range, such as 1, 2, 3, 4, 5, and 6, and this applies regardless of the range. In addition, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0051] The technical solution of this application is as follows:

[0052] In a first aspect, please refer to Figures 1 to 2 , an embodiment of this application provides a method for preparing a composite grease, including:

[0053] S11. Provide a graphene slurry, and the graphene slurry includes graphene powder;

[0054] S12. Provide a mixed liquid, the mixed liquid includes base oil, and roll the mixed liquid to form a sheet - like intermediate 11;

[0055] S13. Spray the graphene slurry onto the surface of the sheet-shaped intermediate 11. After the graphene slurry dries, a composite layer 10 is formed. The composite layer 10 includes the sheet-shaped intermediate 11 and the graphene layer 12 on the sheet-shaped intermediate 11.

[0056] S14. Stack multiple composite layers 10 to form a composite grease preform. In the composite grease preform, the sheet-shaped intermediate 11 and the graphene layer 12 are alternately stacked in sequence.

[0057] S15. Conduct a first stirring on the composite grease preform 100 to obtain a composite grease.

[0058] For the preparation method of the composite grease provided in this application, the mixed liquid containing base oil is hydro-rolled into a sheet-shaped intermediate 11. By setting the graphene slurry on the sheet-shaped intermediate 11, and finally forming the composite grease through stirring. The setting of the sheet-shaped intermediate 11 and the graphene slurry is conducive to the full and uniform contact between the graphene powder and the base oil. Through precise spraying, the thickness of the graphene layer after drying is controllable. Generally, the thinner the coating thickness, the smaller the coating resistivity. This kind of structural design is significantly better than directly mixing the graphene powder into the base oil. When directly mixing the graphene powder into the base oil, the graphene powder is prone to agglomeration, and the subsequent thickness is not easy to control, often resulting in a relatively large resistivity. The graphene powder has excellent electrical conductivity and thermal stability, which can avoid the precipitation of organic grease caused by the breakage of molecular chain segments of organic molecules under thermal or corona conditions. Moreover, the graphene powder can improve the high-temperature resistance, moisture resistance, oxidation resistance, mildew resistance and chemical corrosion resistance of the composite grease, making it have the characteristics of not flowing at high temperature, not cracking at low temperature, stable physical and chemical properties, and long service life. It greatly improves the safety performance of the place where the composite grease is used, provides a reliable guarantee for the safe operation of substations and distribution stations, enhances the safety of power grid operation, saves a large amount of power loss, and can also avoid electrochemical corrosion on the contact surface.

[0059] It should be noted that the order of S11 and S12 is not limited. The graphene slurry can be provided first and then the mixed liquid, or the mixed liquid can be provided first and then the graphene slurry, or the graphene slurry and the mixed liquid can be provided simultaneously.

[0060] In S11:

[0061] In some embodiments, the thickness of the graphene powder is 1 nm to 30 nm, and for example, it can be 2 nm, 5 nm, 8 nm, 10 nm, 12 nm, 15 nm, 18 nm, 20 nm, 22 nm, 25 nm, 28 nm, etc.

[0062] In some embodiments, the sheet diameter of the graphene powder is 0.2 μm to 5 μm, and for example, it can be 0.5 μm, 0.8 μm, 1 μm, 1.2 μm, 1.5 μm, 1.8 μm, 2 μm, 2.2 μm, 2.5 μm, 2.8 μm, 3 μm, 3.2 μm, 3.5 μm, 3.8 μm, 4 μm, 4.2 μm, 4.5 μm, 4.8 μm, etc.

[0063] In some embodiments, the carbon content of the graphene powder is greater than 99%.

[0064] In some embodiments, the graphene slurry further includes one or several of a dispersant and a solvent.

[0065] In some embodiments, the dispersant includes a polymer dispersant.

[0066] Further, the polymer dispersant includes one or several of sodium polyacrylate and DP-218 super dispersant.

[0067] In some embodiments, the solvent includes an alcohol solvent.

[0068] Further, the alcohol solvent includes one or several of anhydrous ethanol, methanol, n-propanol, isopropanol, tert-butanol, pentanol, glycerol, methoxyethanol, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, and ethylene glycol.

[0069] In some embodiments, in the graphene slurry, the mass ratio of the graphene powder, the dispersant, and the solvent is (2 to 4):(1 to 2):(94 to 97), and for example, it can be 4:2:94, 3:2:95, 2:2:96, 4:1:95, 2:1:97, etc. Within the range of the mass ratio, it is beneficial to the uniform dispersion of the dissolution of the graphene powder.

[0070] In some embodiments, the method for preparing the graphene slurry includes: providing graphene powder, a dispersant, and a solvent, mixing, and performing second stirring and first grinding to obtain the graphene slurry.

[0071] In some embodiments, the rotation speed of the second stirring is 500 r / min to 1000 r / min, and for example, it can be 600 r / min, 700 r / min, 800 r / min, 900 r / min, etc.

[0072] In some embodiments, the time of the first grinding is 1 h to 2 h, and for example, it can be 1.2 h, 1.4 h, 1.6 h, 1.8 h, etc.

[0073] Thus, under the above-mentioned second stirring and first grinding conditions, it is beneficial to the uniform dispersion of graphene powder in the graphene slurry.

[0074] In some embodiments, in the graphene slurry, the fineness of the graphene powder is 0.2 μm to 10 μm, and for example, it can be 0.5 μm, 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, etc.

[0075] In S12:

[0076] In some embodiments, the base oil includes a silicone-based base oil.

[0077] Furthermore, the silicone-based base oil includes one or more of methyltrifluoropropyl silicone oil, methyl long-chain alkyl silicone oil, benzyl silicone oil, and dimethyl silicone oil.

[0078] In some embodiments, the mixed liquid further includes one or more of a thickening agent and an antioxidant.

[0079] In some embodiments, the thickening agent includes a silicon-based thickening agent.

[0080] Furthermore, the silicon-based thickening agent includes one or more of fumed silica, lithium magnesium silicate, and bentonite.

[0081] In some embodiments, the antioxidant includes an organic antioxidant.

[0082] Furthermore, the organic antioxidant includes one or more of tris(2,4-di-tert-butylphenyl) phosphite and 2,4-bis(n-octylthiomethylene)-6-methylphenol.

[0083] In some embodiments, in the mixed liquid, the mass ratio of the base oil, the thickening agent, and the antioxidant is 10:1:1, and for example, it can be 10:1.2:1, 10:1.5:1, 10:1:1.2, 10:1:1.5, etc. Within the range of the mass ratio, the thickening agent can be dispersed in the base oil and form a structural framework, and the base oil can be adsorbed and fixed in the structural framework, thereby forming a plastic semi-solid grease; the antioxidant can further improve the aging resistance of the base oil.

[0084] In some embodiments, before rolling the mixed liquid, second grinding is further included.

[0085] Furthermore, the time of the second grinding is 30 min to 60 min, and for example, it can be 35 min, 40 min, 45 min, 50 min, 55 min, etc.

[0086] In some embodiments, the temperature of calendering is room temperature to 80 °C, for example, it can be 40 °C, 50 °C, 60 °C, 70 °C, etc.; the pressure is 1 Mpa to 2 Mpa, for example, it can be 1.2 Mpa, 1.4 Mpa, 1.6 Mpa, 1.8 Mpa, etc.; the pressure holding time is 3 s to 10 s, for example, it can be 4 s, 6 s, 8 s, etc.

[0087] It can be understood that all grinding in this application can be carried out using a three-roll grinder. The three-roll grinder can effectively grind high-viscosity materials and achieve the grinding effect through the mutual extrusion of the surfaces of the three horizontal rollers and friction at different speeds; calendering can be carried out using a precision calender.

[0088] In some embodiments, the thickness of the sheet intermediate 11 is 0.01 mm to 0.1 mm, for example, it can be 0.01 mm, 0.02 mm, 0.04 mm, 0.06 mm, 0.08 mm, etc.

[0089] In S13:

[0090] In some embodiments, the spraying can be carried out using an aerosol spray gun.

[0091] It can be understood that after the graphene slurry is sprayed on the sheet intermediate 11, the solvent will volatilize, and the graphene layer 12 includes graphene powder and a dispersant.

[0092] In some embodiments, the thickness of the graphene layer 12 is 100 nm to 300 nm, for example, it can be 120 nm, 150 nm, 180 nm, 200 nm, 120 nm, 150 nm, 180 nm, etc.

[0093] In S14:

[0094] In some embodiments, in the composite grease preform, the number of the composite layers 10 is 2 to 10, for example, it can be 3, 4, 5, 6, 7, 8, 9 composite layers 10.

[0095] In S15:

[0096] In some embodiments, the time of the first stirring is 2 min to 10 min, for example, it can be 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min, etc.

[0097] The rotation speed of the first stirring is 80 r / min to 120 r / min, for example, it can be 85 r / min, 90 r / min, 95 r / min, 100 r / min, 105 r / min, 110 r / min, 115 r / min, etc.

[0098] The temperature of the first stirring is 80°C to 100°C, and for example, it can be 82°C, 85°C, 88°C, 90°C, 92°C, 95°C, 98°C, etc.

[0099] Under the conditions of the first stirring, it is beneficial to uniformly mix the graphene powder and the base oil.

[0100] Secondly, the embodiment of the present application also provides a composite grease prepared by the above preparation method.

[0101] In some embodiments, the composite grease can be an electric power composite grease.

[0102] In some embodiments, in the composite grease, the graphene powder is dispersed in the base oil. It should be noted that the graphene powder has a sheet-like network structure.

[0103] In some embodiments, in the composite grease, the fineness of the graphene powder is 0.2μm to 10μm, and for example, it can be 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm, etc.

[0104] It can be understood that the fineness of the graphene powder characterizes the dispersion degree of the graphene powder in the base oil.

[0105] In some embodiments, in the composite grease, the mass ratio of the graphene powder to the base oil is (15 - 35):(50 - 75). The mass ratio of the graphene powder to the base oil can be 20:60, 25:60, 30:60, 20:55, 20:65, 20:70, etc.

[0106] Thirdly, the embodiment of the present application also provides an application of the above composite grease. Specifically, an electrical contact element is provided, and the electrical contact element includes the above composite grease.

[0107] Furthermore, the electrical contact element can be a point contact head.

[0108] The present application will be specifically described below through specific embodiments. The following embodiments are only partial embodiments of the present application and do not limit the present application.

[0109] Example 1

[0110] This embodiment provides a composite grease, and its preparation method is as follows:

[0111] Weigh 4 parts of graphene powder, 1 part of sodium polyacrylate, and 95 parts of absolute ethanol, mix them, stir at a speed of 800 r / min, and grind for 1.5 h to obtain a graphene slurry;

[0112] Weigh 10 parts of methyltrifluoropropyl silicone oil, 1 part of lithium magnesium silicate, and 1 part of tris(2,4-di-tert-butylphenyl) phosphite, mix them, grind them, and then calender them to obtain a sheet-shaped intermediate with a thickness of 0.01 mm;

[0113] Use an aerosol spray gun to spray the graphene slurry on the surface of the sheet-shaped intermediate. After the anhydrous ethanol on its surface volatilizes, a graphene layer is formed. The thickness of the graphene layer is 100 nm. Stack the composite layers and stir them with a double planetary mixer for 5 min to obtain a composite grease.

[0114] Example 2

[0115] This example provides a composite grease, and its preparation method is as follows:

[0116] Weigh 3 parts of graphene powder, 2 parts of sodium polyacrylate, and 95 parts of anhydrous ethanol, mix them, stir at a speed of 1000 r / min, and grind for 2 h to obtain a graphene slurry;

[0117] Weigh 10 parts of methyltrifluoropropyl silicone oil, 1 part of lithium magnesium silicate, and 1 part of tris(2,4-di-tert-butylphenyl) phosphite, mix them, grind them, and then calender them to obtain a sheet-shaped intermediate with a thickness of 0.01 mm;

[0118] Use an aerosol spray gun to spray the graphene slurry on the surface of the sheet-shaped intermediate. After the anhydrous ethanol on its surface volatilizes, a graphene layer is formed. The thickness of the graphene layer is 200 nm. Stack the composite layers and stir them with a double planetary mixer for 5 min to obtain a composite grease.

[0119] Example 3

[0120] This example provides a composite grease, and its preparation method is as follows:

[0121] Weigh 4 parts of graphene powder, 1 part of sodium polyacrylate, and 95 parts of anhydrous ethanol, mix them, stir at a speed of 800 r / min, and grind for 1.5 h to obtain a graphene slurry;

[0122] Weigh 10 parts of methyl long-chain alkyl silicone oil, 1 part of lithium magnesium silicate, and 1 part of 2,4-bis(n-octylthiomethylene)-6-methylphenol, mix them, grind them, and then calender them to obtain a sheet-shaped intermediate with a thickness of 0.01 mm;

[0123] Use an aerosol spray gun to spray the graphene slurry on the surface of the sheet-shaped intermediate. After the anhydrous ethanol on its surface volatilizes, a graphene layer is formed. The thickness of the graphene layer is 300 nm. Stack the composite layers and stir them with a double planetary mixer for 5 min to obtain a composite grease.

[0124] Example 4

[0125] This example provides a composite grease, and its preparation method is as follows:

[0126] Weigh 4 parts of graphene powder, 1 part of sodium polyacrylate, and 95 parts of absolute ethanol, mix them, stir at a speed of 900 r / min, and grind for 1.5 h to obtain graphene slurry;

[0127] Weigh 10 parts of benzyl silicone oil, 1 part of lithium magnesium silicate, and 1 part of tris(2,4-di-tert-butylphenyl) phosphite, mix them, grind and then calender to obtain a sheet intermediate with a thickness of 0.03 mm;

[0128] Use an airbrush to spray the graphene slurry on the surface of the sheet intermediate. After the absolute ethanol on its surface evaporates, a graphene layer is formed. The thickness of the graphene layer is 100 nm. Stack the composite layers and stir with a double planetary mixer for 5 min to obtain the composite grease.

[0129] Example 5

[0130] This example provides a composite grease, and its preparation method is as follows:

[0131] Weigh 4 parts of graphene powder, 1 part of sodium polyacrylate, and 95 parts of absolute ethanol, mix them, stir at a speed of 800 r / min, and grind for 1 h to obtain graphene slurry;

[0132] Weigh 10 parts of methyltrifluoropropyl silicone oil, 1 part of lithium magnesium silicate, and 1 part of tris(2,4-di-tert-butylphenyl) phosphite, mix them, grind and then calender to obtain a sheet intermediate with a thickness of 0.04 mm;

[0133] Use an airbrush to spray the graphene slurry on the surface of the sheet intermediate. After the absolute ethanol on its surface evaporates, a graphene layer is formed. The thickness of the graphene layer is 100 nm. Stack the composite layers and stir with a double planetary mixer for 8 min to obtain the composite grease.

[0134] Example 6

[0135] This example provides a composite grease, and its preparation method is as follows:

[0136] Weigh 4 parts of graphene powder, 2 parts of DP-218, and 94 parts of absolute ethanol, mix them, stir at a speed of 800 r / min, and grind for 1.5 h to obtain graphene slurry;

[0137] Weigh 10 parts of methyltrifluoropropyl silicone oil, 1 part of lithium magnesium silicate, and 1 part of tris(2,4-di-tert-butylphenyl) phosphite, mix them, grind and then calender to obtain a sheet intermediate with a thickness of 0.05 mm;

[0138] The surface of the flaky intermediate is sprayed with graphene slurry using an airless spray gun. After the anhydrous ethanol on its surface volatilizes, a graphene layer is formed. The thickness of the graphene layer is 100 nm. The composite layers are stacked and stirred for 5 min using a double planetary mixer to obtain the composite grease.

[0139] The main properties of the composite greases of Test Examples 1 to 6 and their applications between the switching contacts of aluminum and aluminum were tested, and the performances of Examples 1 to 6 are shown in Table 1. Among them, the test method mainly refers to DL / T 373-2019 Technical Conditions for Electric Power Composite Grease for determination.

[0140] Table 1

[0141]

[0142]

[0143] As can be seen from Table 1, the composite greases provided in Examples 1 to 6 have good heat resistance, cold resistance, moisture resistance, and salt spray corrosion resistance, indicating that they have high stability, are not easily aged, and the aging resistance performance has been significantly improved.

[0144] The above has introduced in detail the composite grease, its preparation method, and the electrical contact element provided in the embodiments of the present application. Specific examples are used in this article to elaborate on the principle and implementation manner of the present application. The description of the above embodiments is only used to help understand the method and its core idea of the present application; at the same time, for those skilled in the art, according to the idea of the present application, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present application.

Claims

1. A preparation method of a composite grease, characterized in that, comprising: providing a graphene slurry, wherein the graphene slurry comprises graphene powder; providing a mixed liquid, wherein the mixed liquid comprises a base oil, and rolling the mixed liquid to form a sheet-shaped intermediate; spraying the graphene slurry on the surface of the sheet-shaped intermediate, and after the graphene slurry dries, forming a composite layer, the composite layer comprising the sheet-shaped intermediate and a graphene layer on the sheet-shaped intermediate; stacking a plurality of the composite layers to form a composite grease preform, in the composite grease preform, the sheet-shaped intermediate and the graphene layer are alternately stacked in sequence; performing a first stirring on the composite grease preform to obtain a composite grease.

2. The preparation method according to claim 1, characterized in that, the thickness of the graphene powder is 1 nm to 30 nm; and / or the sheet diameter of the graphene powder is 0.2 μm to 5 μm; and / or the carbon content of the graphene powder is greater than 99%.

3. The preparation method according to claim 1, characterized in that, the thickness of the graphene layer is 100 nm to 300 nm; and / or in the composite grease preform, the number of the composite layers is 2 to 10.

4. The preparation method according to claim 1, characterized in that, the graphene slurry further comprises one or more of a dispersant and a solvent.

5. The preparation method according to claim 4, characterized in that, the dispersant comprises a polymer dispersant; the polymer dispersant comprises one or more of sodium polyacrylate and DP-218 super dispersant; and / or the solvent comprises an alcohol solvent; the alcohol solvent comprises one or more of absolute ethanol, methanol, n-propanol, isopropanol, tert-butanol, amyl alcohol, glycerol, methoxyethanol, diethylene glycol monobutyl ether, trimethoxybutanol, triethylene glycol monobutyl ether, diethylene glycol dimethyl ether, and ethylene glycol; and / or in the graphene slurry, the mass ratio of the graphene powder, the dispersant, and the solvent is (2 to 4):(1 to 2):(94 to 97).

6. The preparation method according to claim 4, characterized in that, the preparation method of the graphene slurry comprises: providing graphene powder, a dispersant, and a solvent, mixing, performing a second stirring and a first grinding, and then obtaining the graphene slurry.

7. The preparation method according to claim 6, characterized in that, the rotation speed of the second stirring is 500 r / min to 1000 r / min; and / or the time of the first grinding is 1 h to 2 h; and / or in the graphene slurry, the fineness of the graphene powder is 0.2 μm to 10 μm.

8. The preparation method according to claim 1, characterized in that, the mixed liquid further comprises one or more of a thickening agent and an antioxidant.

9. The preparation method according to claim 8, characterized in that, the base oil comprises a silicone oil-based base oil, and the silicone oil-based base oil comprises one or more of methyltrifluoropropyl silicone oil, methyl long-chain alkyl silicone oil, benzyl silicone oil, and dimethyl silicone oil; and / or The thickener includes silicon-based thickeners, and the silicon-based thickeners include one or more of fumed silica, lithium magnesium silicate, and bentonite; and / or The antioxidant includes organic antioxidants, and the organic antioxidants include one or more of tris(2,4-di-tert-butylphenyl) phosphite and 2,4-bis(n-octylthiomethylene)-6-methylphenol; and / or In the mixture, the mass ratio of the base oil, the thickener, and the antioxidant is 10:(1-1.5):(1-1.5).

10. The preparation method according to claim 1, characterized in that the temperature of the rolling is room temperature to 80 °C; the pressure is 1 Mpa to 2 Mpa; the pressure holding time is 3 s to 10 s; and / or before rolling the mixture, second grinding is further included; the time of the second grinding is 30 min to 60 min; and / or the thickness of the sheet intermediate is 0.01 mm to 0.1 mm.

11. The preparation method according to claim 1, characterized in that the time of the first stirring is 2 min to 10 min; the rotation speed is 80 r / min to 120 r / min; the temperature is 80 °C to 100 °C.

12. A composite grease, characterized in that it is prepared by the preparation method according to any one of claims 1 to 11.

13. The composite grease according to claim 12, characterized in that in the composite grease, the graphene powder is dispersed in the base oil; the graphene powder is in a sheet-like network structure; and / or in the composite grease, the fineness of the graphene powder is 0.2 μm to 10 μm; and / or in the composite grease, the mass ratio of the graphene powder to the base oil is (15-35):(50-75).

14. An electrical contact element, characterized in that the electrical contact element includes the composite grease prepared by the preparation method according to any one of claims 1 to 11 or includes the composite grease according to any one of claims 12 to 13.

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