Self-lubricating graphene metal composite material under aerobic high-temperature condition and preparation method thereof

Abstract

The invention relates to the technical field of novel self-lubricating metal materials, in particular to a self-lubricating graphene metal composite material under the aerobic high-temperature condition and a preparation method of the self-lubricating graphene metal composite material under the aerobic high-temperature condition. S2, grinding and mixing the metal powder coated with the graphene, a lubricating reinforcing material and an antioxidant reinforcing material to obtain mixed powder; and S3, the mixed powder is subjected to die casting and sintering, and the graphene metal composite material is obtained after cooling. The self-lubricating graphene metal composite material provided by the invention has relatively good comprehensive properties such as self-lubricating property, strength, wear resistance, electric conductivity and thermal conductivity in a high-temperature aerobic environment.

Description

Technical Field

[0001] The present application relates to the technical field of novel self-lubricating metal materials, and in particular to a self-lubricating graphene metal composite material under oxygen and high-temperature conditions and a preparation method thereof. Background Art

[0002] Mechanical components made of metal materials, such as friction pairs, inevitably experience friction during operation. Conventional technology typically mitigates this wear by adding lubricants. However, safety and hygiene requirements in industries such as aerospace, military, and food and pharmaceuticals necessitate the cautious addition of lubricants, ideally requiring no or minimal oil operation. Therefore, the use of self-lubricating materials in mechanical components is being considered. With the rapidly increasing speeds and loads of modern machinery and mechanisms, self-lubricating materials offer significant advantages.

[0003] Taking into account the mechanical properties, electrical conductivity, thermal conductivity and other aspects, some metal materials with good self-lubricating properties and plastic properties are the focus of research in this field, such as copper-based materials. At present, solid lubricating materials (such as lead, molybdenum disulfide, graphene, etc.) are often compounded with copper to make copper-based self-lubricating materials to further improve their self-lubricating properties. However, when lead is added to the copper matrix as a solid lubricating material alone, it is easy to produce highly toxic compounds, which has certain limitations on the field of use and the use environment; and molybdenum disulfide is easily oxidized and decomposed during high-temperature molding to react with the copper matrix to form a brittle phase Cu2MoS3, which reduces the strength and wear resistance of the lubricating material; graphene has a high Young's modulus, high corrosion resistance, extremely high thermal conductivity and good electrical conductivity, as well as high mechanical strength and low interlaminar shear strength, but graphene is very easy to agglomerate and unevenly dispersed in copper, which increases the difficulty of compounding copper and graphene and makes it difficult to further improve the material properties.

[0004] Therefore, how to make self-lubricating metal composite materials have good comprehensive properties such as self-lubricating properties, wear resistance, electrical and thermal conductivity in a high-temperature aerobic environment (such as above 300°C) remains a key research direction in this field. Summary of the Invention

[0005] The present application aims to provide a self-lubricating graphene metal composite material under aerobic high-temperature conditions and a preparation method thereof, so as to solve the problem of performance degradation of the self-lubricating metal composite material under high-temperature aerobic environment.

[0006] The embodiment of the present application is implemented as follows:

[0007] In a first aspect, an embodiment of the present application provides a method for preparing a self-lubricating graphene metal composite material under oxygen and high temperature conditions, comprising:

[0008] S1: providing metal powder coated with graphene;

[0009] S2: Grinding and mixing the graphene-coated metal powder with the lubrication reinforcement material and the antioxidant reinforcement material to obtain a mixed powder;

[0010] S3: Die-casting and sintering the mixed powder to obtain a graphene metal composite material.

[0011] In some embodiments of the present application, in S3 , the mixed powder is die-cast and sintered in a mixed gas of hydrogen and an inert gas.

[0012] In some embodiments of the present application, in S3 , the mixed gas maintains a flowing state.

[0013] In some embodiments of the present application, in S3, the sintering temperature is 800-1200°C, the temperature is kept for 60 minutes, and the heating rate is 15°C / minute.

[0014] In some embodiments of the present application, the lubrication enhancing material includes at least one of tungsten disulfide, molybdenum disulfide, and graphite.

[0015] In some embodiments of the present application, the mass content of the tungsten disulfide is 0.2-1.5%; and / or the mass content of the molybdenum disulfide is 0.5-1.5%; and / or the total mass content of the graphite and graphene is 0.5-6%.

[0016] In some embodiments of the present application, the antioxidant enhancement material includes graphite and / or rare earth materials.

[0017] In some embodiments of the present application, the total mass content of the graphite and graphene is 0.5-6%.

[0018] In some embodiments of the present application, the graphite is in the form of fish scale layers and / or spheres.

[0019] In some embodiments of the present application, the total mass content of the rare earth material is 0.01%-0.8%.

[0020] In some embodiments of the present application, the rare earth material includes light rare earth elements.

[0021] In some embodiments of the present application, the rare earth material includes lanthanum and / or cerium.

[0022] In some embodiments of the present application, tellurium is added to the rare earth material.

[0023] In some embodiments of the present application, the mass content of tellurium is 0.1%-1%.

[0024] In some embodiments of the present application, at least one of silicon dioxide, boron hexanitride, zirconium, and titanium is added to S2, and the mixture is ground and mixed together to obtain a mixed powder.

[0025] In some embodiments of the present application, the mass content of the silicon dioxide is 0.1%-2%.

[0026] In some embodiments of the present application, the mass content of zirconium is 0.5%-8%.

[0027] In some embodiments of the present application, the mass content of titanium is 0.5%-8%.

[0028] In some embodiments of the present application, in S2, the grinding and mixing method is ball milling for 3 hours.

[0029] In some embodiments of the present application, the S1 includes:

[0030] S11: Grinding the composite powder of copper sulfate and copper nitrate using a planetary ball mill, wherein the particle size of the metal salt after ball milling is 500 nm to 5 μm;

[0031] S12: In an oxygen-free and high-temperature environment of 950-1050°C, the composite powder of copper sulfate and copper nitrate decomposes into copper oxide powder;

[0032] S13: Copper oxide and methane gas undergo chemical vapor deposition at a temperature of 950-1050° C., and the temperature is lowered after the chemical vapor deposition process is completed to obtain copper powder coated with graphene.

[0033] In a second aspect, an embodiment of the present application provides a self-lubricating graphene metal composite material under aerobic high-temperature conditions, wherein the graphene metal composite material is prepared using the preparation method of the self-lubricating graphene metal composite material under aerobic high-temperature conditions described in any one of the first aspects.

[0034] Beneficial effects: The technical solution provided by the present application grinds the graphene-coated metal powder together with the lubrication reinforcement material and the antioxidant reinforcement material and then die-casts the graphene, the lubrication reinforcement material and the antioxidant reinforcement material so that the graphene, the lubrication reinforcement material and the antioxidant reinforcement material are evenly dispersed in the metal powder. During sintering, each material forms an integrated composite structure with the metal powder. The evenly dispersed graphene and antioxidant reinforcement material have a good antioxidant effect in the graphene metal composite material, and can also have good self-lubrication performance, wear resistance, electrical and thermal conductivity under high-temperature aerobic environment (such as above 300°C). BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 Flowchart of the preparation method provided in the examples of the present application. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this 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.

[0038] In this application, unless otherwise indicated, directional terms such as "upper" and "lower" generally refer to the upper and lower positions of a device in actual use or operation, specifically in the drawing directions of the accompanying drawings; whereas "inner" and "outer" refer to the outline of the device. Furthermore, in the description of this application, the term "including" means "including but not limited to." Terms such as first, second, and third are used merely as labels and do not impose numerical requirements or establish a sequence.

[0039] In this application, "and / or" describes the association relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural.

[0040] In this application, "at least one" means one or more, and "plurality" means two or more. "At least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single items or plural items. For example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple.

[0041] Various embodiments of the present application may be presented 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 understood as a hard limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numbers within the range. For example, the description of a range from 1 to 6 should be considered to have 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., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0042] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0043] The embodiments of the present application provide a self-lubricating graphene metal composite material under aerobic high-temperature conditions and a preparation method thereof, so as to solve the problem of performance degradation of the self-lubricating metal composite material under high-temperature aerobic environment.

[0044] A method for preparing a self-lubricating graphene metal composite material under oxygen and high temperature conditions comprises the following steps:

[0045] S1: providing metal powder coated with graphene;

[0046] S2: Grinding and mixing the graphene-coated metal powder with the lubrication reinforcement material and the antioxidant reinforcement material to obtain a mixed powder;

[0047] S3: Die-casting and sintering the mixed powder to obtain a graphene metal composite material.

[0048] By grinding the graphene-coated metal powder together with the lubrication reinforcement material and the antioxidant reinforcement material and then die-casting, the graphene, the lubrication reinforcement material and the antioxidant reinforcement material are uniformly dispersed in the metal powder. During sintering, each material forms an integrated composite structure with the metal powder. The uniformly dispersed graphene and antioxidant reinforcement material have a good antioxidant effect in the graphene-metal composite material, and can also have good self-lubrication performance, strength, wear resistance, electrical and thermal conductivity under high-temperature aerobic environment (such as above 300°C).

[0049] In S1, the graphene-coated metal powder product can be directly purchased or prepared. Taking the metal powder as copper powder as an example, S1 includes:

[0050] S11: Grinding the composite powder of copper sulfate and copper nitrate using a planetary ball mill, wherein the particle size of the metal salt after ball milling is 500 nm to 5 μm;

[0051] S12: In an oxygen-free and high-temperature environment of 950-1050°C, the composite powder of copper sulfate and copper nitrate decomposes into copper oxide powder;

[0052] S13: Copper oxide and methane gas undergo chemical vapor deposition at a temperature of 950-1050° C., and the temperature is lowered after the chemical vapor deposition process is completed to obtain copper powder coated with graphene.

[0053] In order to ensure that the metal powder coated with graphene is fully mixed and activated with the lubrication reinforcement material and the antioxidant reinforcement material, the grinding and mixing method in S2 is ball milling for 3 hours.

[0054] The lubrication enhancing material includes at least one of tungsten disulfide, molybdenum disulfide, and graphite, which can enhance friction and wear properties, improve lubrication properties, and reduce friction coefficient.

[0055] By coating graphene on the surface of metal powder, adding antioxidant reinforcement materials and ball milling together, and always performing die-casting and sintering in a mixed gas atmosphere of hydrogen and inert gas, a graphene metal composite material with good self-lubricating properties can be prepared with a small amount of lubricating reinforcement material added, thereby taking into account the material's self-lubricating properties, strength, wear resistance and electrical and thermal conductivity.

[0056] Optionally, when the lubricity enhancing material includes tungsten disulfide, the mass content of tungsten disulfide is 0.2-1.5%.

[0057] Optionally, when the lubricity enhancing material includes molybdenum disulfide, the mass content of molybdenum disulfide is 0.5-1.5%.

[0058] Optionally, when the lubricity enhancing material includes graphite, the total mass content of graphite and graphene is 0.5-6%.

[0059] In some embodiments, the oxidation resistance enhancing material includes graphite, and / or rare earth materials.

[0060] In other words, the lubricity-enhancing material and the antioxidant-enhancing material can both be graphite, utilizing the reducibility and self-lubricating properties of graphite to improve the antioxidant and self-lubricating properties of the graphene-metal composite material and protect other lubricity-enhancing materials that may be present. When the antioxidant-enhancing material includes graphite, the total mass content of the graphite and graphene is 0.5-6%. In other words, in the graphene-metal composite material provided in the embodiments of the present application, if graphite is added, the total mass content of the added graphite and graphene is in the range of 0.5-6%.

[0061] The added graphite is in the form of fish scale flakes and spheres to further improve the self-lubricating performance.

[0062] When the antioxidant reinforcement material includes a rare earth material, the rare earth material not only acts as an antioxidant, improving the adhesion of the oxide film formed on the material surface, thereby enhancing the high-temperature oxidation resistance and wear resistance of the graphene-metal composite material, but also refines the grain size, resulting in a more uniform distribution of graphene and the various reinforcement materials within the metal material. The total weight content of the rare earth material is 0.01%-0.8%. This mitigates the oxidation of the metal material and other reinforcement materials under high temperature conditions, consumes oxidizing impurities in the material during sintering in S3, and ensures good antioxidant properties. Furthermore, it avoids the degradation of the material's processing performance due to excessive rare earth material addition.

[0063] Optionally, the added rare earth material includes a light rare earth element, which has a relatively low density, can make the graphene metal composite material relatively light in weight, and can also improve workability, while also reducing material costs. Exemplarily, the rare earth material includes lanthanum and / or cerium to improve the mechanical properties of the graphene metal composite material, such as strength, hardness, and rigidity, and refine the grains, improve the interface bonding between graphene and metal, enhance the mechanical connection of the interface, improve the interface strength, durability, tensile strength, wear resistance, and electrical conductivity, and effectively inhibit the oxidation reaction of the graphene metal composite material in a high temperature, oxidizing environment, thereby improving the anti-oxidation stability of the graphene metal composite material.

[0064] In some embodiments, tellurium is added to the rare earth material. In other words, tellurium is added simultaneously with the rare earth material. The addition of tellurium improves the material's strength and resistance to galvanic corrosion. Furthermore, the combination of tellurium and rare earth elements further enhances the material's high-temperature stability, thereby raising the threshold for lubricity-enhancing materials (such as molybdenum disulfide and tungsten disulfide) to fail due to oxidation. Optionally, the tellurium content is 0.1% to 1% by weight, resulting in relatively enhanced strength, hardness, wear resistance, and high-temperature stability, while maintaining relatively low production costs.

[0065] In some embodiments, in S2, at least one of silicon dioxide, boron hexanitride, zirconium, and titanium is added and ground and mixed together to obtain a mixed powder to improve the surface properties of the material and enhance the wear resistance.

[0066] Optionally, the mass content of silicon dioxide is 0.1%-2%.

[0067] Optionally, the mass content of boron hexanitride is 0.1-5%.

[0068] Optionally, the mass content of zirconium is 0.5%-8%.

[0069] Optionally, the mass content of titanium is 0.5%-8%.

[0070] Furthermore, in the preparation method provided in the embodiments of the present application, during step S3, the mixed powder is die-cast and sintered in a mixture of hydrogen and an inert gas. During the sintering process, the inert gas isolates the outside world to reduce oxygen interference. The antioxidant reinforcement material and hydrogen play a reducing role during the sintering process, preventing oxidation of the metal and lubricating reinforcement material during the sintering process, thereby improving the performance of the graphene composite metal material under high-temperature oxygen conditions.

[0071] Furthermore, the mixed gas of hydrogen and inert gas is kept in a flowing state so that there is always sufficient hydrogen during the sintering process, thereby alleviating the problem of high-temperature oxidation of the material during the sintering process.

[0072] The sintering temperature is 800-1200°C, the holding time is 60 minutes, and the heating rate is 15°C / minute.

[0073] In a second aspect, an embodiment of the present application provides a self-lubricating graphene metal composite material under oxygen and high temperature conditions, and the graphene metal composite material is prepared using the preparation method provided in any of the aforementioned embodiments.

[0074] The present application will be described in detail below through specific examples. The following examples are only some examples of the present application and are not limitations of the present application.

[0075] Example 1

[0076] S1: Grinding the composite powder of copper sulfate and copper nitrate with a planetary ball mill to prepare a metal salt having a particle size of 500 nm to 5 μm.

[0077] S2: In an oxygen-free environment at a high temperature of 950 to 1050° C., the composite powder of copper sulfate and copper nitrate is decomposed into copper oxide powder.

[0078] S3: Copper oxide and methane gas are chemically vapor deposited at a temperature of 950-1050° C., and the temperature is lowered after the chemical vapor deposition process is completed to obtain a copper powder coated with graphene, wherein the graphene content is 3%.

[0079] S4: The graphene-coated copper powder and reinforcement material powder are ball-milled in an omnidirectional planetary ball mill for 3 hours to mix uniformly. The reinforcement material powder includes tungsten disulfide, graphite, RE (Rare Earth), tellurium, zirconium, and titanium. Based on the total mass of the graphene-coated copper powder and the reinforcement material powder, the specific content of each reinforcement material powder added is: 1% tungsten disulfide, 4% graphite, 0.1% cerium-rich mixed rare earth, 0.2% tellurium, 0.6% zirconium, and 0.6% titanium.

[0080] S5: Die-casting is performed using an isostatic press, and sintering is performed in a sintering furnace with a flow of a mixed gas of hydrogen and argon. After sintering, the furnace is cooled to room temperature to obtain a graphene copper-based composite material.

[0081] Example 2

[0082] S1: Grinding the composite powder of copper sulfate and copper nitrate with a planetary ball mill to prepare a metal salt having a particle size of 500 nm to 5 μm.

[0083] S2: In an oxygen-free and high-temperature environment of 950-1050°C, the composite powder of copper sulfate and copper nitrate decomposes into copper oxide powder.

[0084] S3: Copper oxide and methane gas are chemically vapor deposited at a temperature of 950-1050° C., and the temperature is lowered after the chemical vapor deposition process is completed to obtain a copper powder coated with graphene, wherein the graphene powder content is 3%.

[0085] S4: The graphene-coated copper powder and the reinforcement material powder are ball-milled in an omnidirectional planetary ball mill for 3 hours to achieve uniform mixing. The reinforcement material powder comprises molybdenum disulfide, graphite, RE, tellurium, zirconium, and titanium. Based on the total mass of the graphene-coated copper powder and the reinforcement material powder, the specific amounts of each reinforcement material powder added are: 1.5% molybdenum disulfide, 2% graphite, 0.1% cerium-rich misch metal, 0.2% tellurium, 0.6% zirconium, and 0.6% titanium.

[0086] S5: Die-casting is performed using an isostatic press, and sintering is performed in a sintering furnace with a flow of a mixed gas of hydrogen and argon. After sintering, the furnace is cooled to room temperature to obtain a graphene copper-based composite material.

[0087] Example 3

[0088] S1: Grinding the composite powder of copper sulfate and copper nitrate with a planetary ball mill to prepare a metal salt having a particle size of 500 nm to 5 μm.

[0089] S2: In an oxygen-free and high-temperature environment of 950-1050°C, the composite powder of copper sulfate and copper nitrate decomposes into copper oxide powder.

[0090] S3: Copper oxide and methane gas are chemically vapor deposited at a temperature of 950-1050° C., and the temperature is lowered after the chemical vapor deposition process is completed to obtain copper powder coated with graphene, wherein the graphene powder content is 2%.

[0091] S4: The graphene-coated copper powder and the reinforcement material powder are ball-milled in an omnidirectional planetary ball mill for 3 hours to achieve uniform mixing. The reinforcement material powder comprises graphite, RE, tellurium, titanium, and silica. Based on the total mass of the graphene-coated copper powder and the reinforcement material powder, the specific content of each reinforcement material powder added is: 1% silica, 3% graphite, 0.2% cerium-rich misch metal, 0.2% tellurium, and 0.5% titanium.

[0092] S5: Die-casting is performed using an isostatic press, and sintering is performed in a sintering furnace with a flow of a mixed gas of hydrogen and argon. After sintering, the furnace is cooled to room temperature to obtain a graphene copper-based composite material.

[0093] Example 4

[0094] S1: Grinding the composite powder of copper sulfate and copper nitrate with a planetary ball mill to prepare a metal salt having a particle size of 500 nm to 5 μm.

[0095] S2: In an oxygen-free and high-temperature environment of 950-1050°C, the composite powder of copper sulfate and copper nitrate decomposes into copper oxide powder.

[0096] S3: Copper oxide and methane gas are chemically vapor deposited at a temperature of 950-1050° C., and the temperature is lowered after the chemical vapor deposition process is completed to obtain copper powder coated with graphene, wherein the content of the graphene powder is 1%.

[0097] S4: The graphene-coated copper powder and the reinforcement material powder are ball-milled in an omnidirectional planetary ball mill for 3 hours to mix them uniformly. The reinforcement material powder includes tungsten disulfide, boron nitride, RE, and zirconium. Based on the total mass of the graphene-coated copper powder and the reinforcement material powder, the content of each reinforcement material powder added is as follows: the reinforcement material powder includes 1% tungsten disulfide, 0.5% boron nitride, 0.05% cerium-rich mixed rare earth, and 0.7% zirconium.

[0098] S5: Die-casting is performed using an isostatic press, and sintering is performed in a sintering furnace with a flow of a mixed gas of hydrogen and argon. After sintering, the furnace is cooled to room temperature to obtain a graphene copper-based composite material.

[0099] Example 5

[0100] S1: Grinding the composite powder of copper sulfate and copper nitrate with a planetary ball mill to prepare a metal salt having a particle size of 500 nm to 5 μm.

[0101] S2: In an oxygen-free environment at a high temperature of 950 to 1050° C., the composite powder of copper sulfate and copper nitrate is decomposed into copper oxide powder.

[0102] S3: Copper oxide and methane gas are chemically vapor deposited at a temperature of 950-1050° C., and the temperature is lowered after the chemical vapor deposition process is completed to obtain a copper powder coated with graphene, wherein the graphene content is 3%.

[0103] S4: The graphene-coated copper powder and reinforcement material powder are ball-milled in an omnidirectional planetary ball mill for 3 hours to mix uniformly. The reinforcement material powder includes tungsten disulfide, graphite, RE, tellurium, zirconium, and titanium. Based on the total mass of the graphene-coated copper powder and the reinforcement material powder, the specific content of each reinforcement material powder added is: 1% tungsten disulfide, 2% graphite, 0.1% cerium-rich rare earth, 0.2% tellurium, 0.6% zirconium, and 0.6% titanium.

[0104] S5: Die-casting is performed using an isostatic press, and sintering is performed in a sintering furnace in an argon atmosphere. After sintering, the furnace is cooled to room temperature to obtain a graphene copper-based composite material.

[0105] Comparative Example 1

[0106] Self-lubricating graphene-copper composite materials were prepared by adding 2% graphene and 1% molybdenum disulfide to the copper matrix:

[0107] S1: Grinding the composite powder of copper sulfate and copper nitrate with a planetary ball mill to prepare a metal salt having a particle size of 500 nm to 5 μm.

[0108] S2: In an oxygen-free environment at a high temperature of 950 to 1050° C., the composite powder of copper sulfate and copper nitrate is decomposed into copper oxide powder.

[0109] S3: Copper oxide and methane gas are chemically vapor deposited at a temperature of 950-1050° C., and the temperature is lowered after the chemical vapor deposition process is completed to obtain a copper powder coated with graphene, wherein the graphene content is 2%.

[0110] S4: Evenly mix the graphene-coated copper powder and 1% molybdenum disulfide powder.

[0111] S5: Die-casting is performed using an isostatic press, and sintering is performed in a sintering furnace with a mixture of hydrogen and argon flowing therein. After sintering, the furnace is cooled to room temperature to obtain a self-lubricating graphene copper composite material.

[0112] Comparative Example 2

[0113] A copper-graphene composite material is prepared by mixing graphene in a copper matrix, wherein the graphene content is about 2%:

[0114] S1: Grinding the composite powder of copper sulfate and copper nitrate with a planetary ball mill to prepare a metal salt having a particle size of 500 nm to 5 μm.

[0115] S2: In an oxygen-free environment at a high temperature of 950 to 1050° C., the composite powder of copper sulfate and copper nitrate is decomposed into copper oxide powder.

[0116] S3: Copper oxide and methane gas are chemically vapor deposited at a temperature of 950-1050° C., and the temperature is lowered after the chemical vapor deposition process is completed to obtain a copper powder coated with graphene, wherein the graphene content is 2%.

[0117] S4: Die-casting is performed using an isostatic press, and sintering is performed in a sintering furnace with a mixture of hydrogen and argon flowing therein. After sintering, the copper graphene composite material is obtained by cooling the furnace to room temperature.

[0118] The materials prepared in Examples 1-5 and Comparative Examples 1-2 were tested for their self-lubricating properties, wear resistance, and electrical conductivity in an aerobic environment at a high temperature (350°C). The friction coefficient and wear rate of the materials were measured using a Japanese OUT-U Okoshi wear tester. The grinding ring was made of GCr15 steel with a hardness of 50 HRC. The test conditions were 0.2 m / s, a load of 100 N, a friction time of 10 minutes, a temperature of 350°C, and atmospheric pressure. The resistivity of the materials was measured using an eddy current conductivity meter. The sample surfaces were polished flat during testing. The test results are shown in Table 1.

[0119]

[0120] As shown in Table 1, Examples 1-5 exhibit lower dynamic friction coefficients, lower wear rates, and good electrical conductivity compared to Comparative Examples 1-2, indicating that the graphene-copper composite materials provided by the embodiments of the present application, compared to conventional graphene-copper composite materials and conventional self-lubricating graphene-copper composite materials, can still maintain good friction reduction and electrical conductivity in a high-temperature oxygen environment, and have good wear resistance and can maintain high mechanical properties. The workpiece manufactured by the self-lubricating graphene metal composite material processed by the technical solution provided by the present application can be used in a conductive, high-temperature atmospheric environment above 300°C, and has the characteristics of wear resistance, friction reduction, oxidation resistance, high electrical conductivity, and high mechanical properties.

[0121] Comparing Example 1 with Example 2, it is shown that the selection and mass content of the lubrication enhancement material can be adjusted within a certain range when the antioxidant enhancement material is added. Comparing Example 1 with Example 3, it is shown that further adding tellurium and silicon dioxide to graphite and rare earth materials can further improve the antioxidant and wear resistance. Comparing Example 1 with Example 4, it is shown that adding boron hexanitride to the lubrication enhancement material and the antioxidant enhancement material can further enhance the self-lubrication and wear resistance. Comparing Example 1 with Example 5, it is shown that although the material prepared by sintering only in an inert atmosphere is not optimal, it can still maintain good self-lubrication, wear resistance and electrical conductivity compared to the prior art.

[0122] The above description is merely a preferred embodiment of the present application and is not intended to limit the present application. Various modifications and variations are possible for those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present application shall be included within the scope of protection of the present application.

Claims

1. A method for preparing a self-lubricating graphene metal composite material under oxygen and high temperature conditions, characterized in that: include: S1: providing metal powder coated with graphene; S2: Grinding and mixing the graphene-coated metal powder with the lubrication reinforcement material and the antioxidant reinforcement material to obtain a mixed powder; S3: Die-casting and sintering the mixed powder to obtain a graphene metal composite material.

2. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 1, characterized in that: In S3, the mixed powder is die-cast and sintered in a mixed gas of hydrogen and an inert gas.

3. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 2, characterized in that: In S3 , the mixed gas is kept in a flowing state.

4. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 1, characterized in that: In the step S3 , the sintering temperature is 800-1200° C., the temperature is kept for 60 minutes, and the heating rate is 15° C. / minute.

5. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 1, characterized in that: The lubrication enhancing material includes at least one of tungsten disulfide, molybdenum disulfide, and graphite.

6. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 5, characterized in that: The mass content of the tungsten disulfide is 0.2-1.5%; and / or the mass content of the molybdenum disulfide is 0.5-1.5%; and / or the total mass content of the graphite and graphene is 0.5-6%.

7. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 1, characterized in that: The anti-oxidation enhancing material includes graphite and / or rare earth materials.

8. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 7, characterized in that: The total mass content of the graphite and graphene is 0.5-6%.

9. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to any one of claims 5 to 8, characterized in that: The graphite is in the form of fish scale flakes and / or spheres.

10. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 7, characterized in that: The total mass content of the rare earth material is 0.01%-0.8%.

11. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 7, characterized in that: The rare earth material includes light rare earth elements.

12. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 11, characterized in that: The rare earth material includes lanthanum and / or cerium.

13. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to any one of claims 7 or 8 or 10-12, characterized in that: Tellurium is added into the rare earth material.

14. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 13, characterized in that: The mass content of the tellurium is 0.1%-1%.

15. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 1, characterized in that: In the step S2, at least one of silicon dioxide, boron hexanitride, zirconium and titanium is added and ground and mixed together to obtain a mixed powder.

16. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 15, characterized in that: The mass content of the silicon dioxide is 0.1%-2%.

17. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 15, characterized in that: The mass content of the boron hexanitride is 0.1-5%.

18. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 15, characterized in that: The mass content of zirconium is 0.5%-8%.

19. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 15, characterized in that: The mass content of titanium is 0.5%-8%.

20. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 1, characterized in that: In S2, the grinding and mixing method is ball milling for 3 hours.

21. The method for preparing a self-lubricating graphene metal composite material under aerobic high temperature conditions according to claim 1, characterized in that: Said S1 comprises: S11: Grinding the composite powder of copper sulfate and copper nitrate using a planetary ball mill, wherein the particle size of the metal salt after ball milling is 500 nm to 5 μm; S12: In an oxygen-free and high-temperature environment of 950-1050°C, the composite powder of copper sulfate and copper nitrate decomposes into copper oxide powder; S13: Copper oxide and methane gas undergo chemical vapor deposition at a temperature of 950-1050° C., and the temperature is lowered after the chemical vapor deposition process is completed to obtain copper powder coated with graphene.

22. A self-lubricating graphene metal composite material under oxygen and high temperature conditions, characterized in that: The graphene metal composite material is prepared by the method for preparing a self-lubricating graphene metal composite material under oxygen and high temperature conditions according to any one of claims 1 to 21.

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