In-situ synthesized graphene reinforced copper-based composite material and preparation method thereof

Abstract

The invention provides an in-situ synthesized graphene reinforced copper-based composite material and a preparation method thereof, and belongs to the technical field of metal-based composite material preparation. The preparation method of the graphene reinforced copper-based composite material comprises the steps that sucrose is dissolved in water to obtain a sucrose solution, I2 and KI are added after heating stirring and solvent dilution, then copper powder is added, precursor powder is obtained after stirring, filtering and drying are conducted, the precursor powder is sintered in the atmosphere of hydrogen and argon, then vacuum pressure sintering is conducted, and the graphene reinforced copper-based composite material is obtained. The graphene reinforced copper-based composite material is obtained. According to the method, the graphene serves as a reinforcing phase, the bonding problem between a copper interface and a graphene interface is solved through an in-situ synthesis method, and the grown graphene is evenly distributed on the surface of the copper powder, so that the surface bonding performance of the copper powder is greatly improved, and the hardness, strength, abrasion resistance and conductivity of the composite material are further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of metal-based composite material preparation, and in particular relates to an in-situ synthesized graphene-reinforced copper-based composite material and a preparation method thereof. Background Art

[0002] Metal matrix composites have excellent mechanical properties (such as strength, modulus and fracture toughness, etc.) and excellent thermophysical properties (such as thermal expansion coefficient, wear resistance and electrical conductivity, etc.), so metal matrix composites are widely used in aerospace, transportation and electronic communications. Graphene has been a hot topic in recent years. Compared with traditional reinforcement phases, graphene has better comprehensive mechanical, thermal and electrical properties. Compared with one-dimensional carbon nanotubes, two-dimensional graphene has a higher specific surface area and greater reinforcement efficiency. Copper materials are widely used in defense, rail transportation and electronic devices due to their high electrical conductivity, thermal conductivity, high ductility and low price. However, the low strength, low hardness and poor wear resistance of pure copper limit its further application. Although a variety of methods for preparing graphene-enhanced copper composites have been developed at home and abroad, most of the methods have high preparation costs, and most of them are to directly add graphene to the matrix. Although this can improve the mechanical and electrical properties of copper-based materials, due to the non-wetting properties of graphene and the copper matrix surface, the degree of bonding is low, and the performance of the material cannot be better improved.

[0003] The patent with application number CN201611169561.X proposes a preparation method of in-situ grown graphene reinforced metal-based composite materials, which comprises dissolving and mixing carbon-containing organic matter (including sucrose) and metal or metal alloy powder in a solvent, then mechanically stirring and heating to 50-150°C to mix and evaporate the solvent, and obtaining a prefabricated powder through a 50-100°C vacuum drying and grinding process; using a powder metallurgy process of hot pressing, cold pressing-sintering or SPS sintering to press the prefabricated powder into a shape, converting the carbon-containing organic matter into graphene, and obtaining a three-dimensional graphene / metal-based composite material. However, since this method uses copper nitrate as the copper source, during the heat treatment process, the generated nitrogen dioxide is easily oxidized and decomposed by the added carbon source due to its strong oxidizing property, and graphene with stable yield cannot be produced.

[0004] Therefore, the present invention proposes an in-situ synthesized graphene-reinforced copper-based composite material and a preparation method thereof. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes an in-situ synthesized graphene-reinforced copper-based composite material and a preparation method thereof. Through the in-situ synthesis method, the catalytic effect of copper powder is utilized to make graphene grow directly on the surface of copper powder, thereby greatly improving its surface bonding performance, thereby further improving the hardness, strength, wear resistance and conductivity of the composite material.

[0006] To achieve the above object, the present invention provides a method for preparing an in-situ synthesized graphene-reinforced copper-based composite material, comprising the following steps:

[0007] (1) dissolving sucrose in water to obtain a sucrose solution, and heating and stirring to obtain a caramelized sucrose solution;

[0008] (2) diluting the caramelized sucrose solution with a solvent, adding I2 and KI, and stirring to obtain a mixed solution of graphene and sucrose;

[0009] (3) adding copper powder to the mixed solution of graphene and sucrose, stirring, filtering, and drying to obtain a precursor powder;

[0010] (4) The precursor powder is sintered in a hydrogen and argon atmosphere and then subjected to vacuum pressure sintering to obtain the graphene-reinforced copper-based composite material.

[0011] The amount of sucrose added in step (1) is 2.624g-10.49g, and the carbon quantum dots formed by the caramelized sucrose on the copper powder in step (3) are loaded in an amount of 1wt%-4wt% of the total mass of the copper powder. The above relationship is measured by a carbon-sulfur analyzer.

[0012] The addition of I2 can make use of iodine to react with copper powder, so that the generated iodine ions and copper ions can play a catalytic role, promoting the formation of carbon quantum dots of sucrose on the surface of copper powder. The introduction of KI is to ensure that the content of iodine ions in the solution is sufficient. Sometimes iodine and copper will form a white precipitate, so iodine ions must be introduced. At the same time, since I2 and KI are introduced in small amounts and will go through the filtering and washing stages, they will not affect the prepared bulk material.

[0013] Furthermore, the heating and stirring in step (1) also includes the step of adding a small amount of copper powder. In step (2), the mass ratio of the total mass of I2 and KI to the copper powder added in step (1) is 1:(1-5), and the heating and stirring temperature is 200°C and the time is 2h.

[0014] The purpose of adding a small amount of copper powder during hot stirring is to utilize the catalytic effect of the copper powder itself to promote the conversion of a small amount of sucrose into carbon quantum dots. It is worth noting that I2 and KI mentioned above also have catalytic effects, which do not conflict with this, and they are mutually reinforcing.

[0015] Furthermore, in step (2), the ratio of the mass of caramelized sucrose in the caramelized sucrose solution to the total mass of I2 and KI is (2-8):1.

[0016] Furthermore, the mass ratio of the total mass of I2 and KI in step (2) to the mass ratio of the copper powder in step (3) is (1-4):30.

[0017] Furthermore, the copper powder is electrolytic copper powder with a particle size of 10-30 μm.

[0018] Furthermore, in step (2), the solvent is ethanol and water in a volume ratio of (1-4):1, and is diluted to a concentration of 50-200 mg / L of the caramelized sucrose solution.

[0019] Furthermore, in step (4), the precursor powder is sintered at a temperature of 700-900° C. in a hydrogen and argon atmosphere, and the holding time is 5-20 min.

[0020] Furthermore, in step (4), the precursor powder is sintered. At high temperature, the sucrose molecules begin to decompose, and graphene grows on the surface of the copper powder with the carbon quantum dots as nucleation sites, thereby obtaining graphene-coated copper powder.

[0021] Furthermore, in step (4), the sintering temperature of the vacuum pressure sintering is 700-900°C, the holding time is 0.5-2h, and the heating rate is 3-10°C / min.

[0022] Furthermore, in step (4), vacuum pressure sintering is to ensure that the copper powder can be alloyed to form a bulk material, so that the copper powder is bonded to the interface of copper-copper, copper-graphene, graphene-graphene, etc., thereby improving the mechanical and electrical properties of the bulk material.

[0023] The invention also provides a graphene-reinforced copper-based composite material prepared by the preparation method.

[0024] Compared with the prior art, the present invention has the following advantages and technical effects:

[0025] (1) The present invention uses graphene as a reinforcing phase and an in-situ synthesis method to improve the bonding problem between the copper interface and the graphene interface, so that the grown graphene is evenly distributed on the surface of the copper powder, thereby greatly improving its surface bonding performance and further improving the hardness, strength, wear resistance and conductivity of the composite material.

[0026] (2) The graphene-reinforced copper-based composite material prepared by the present invention has excellent electrical conductivity and mechanical properties, and is suitable for working conditions with high requirements on metal conductivity, ductility and strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0028] Figure 1 XRD patterns of the graphene-reinforced copper-based composite materials and pure copper copper-based composite materials prepared in Example 1-6(a) and Comparative Example 1-4(b);

[0029] Figure 2 The microscopic morphology images (a)-(j) of the precursor powders prepared in Examples 1-6 and Comparative Examples 1-4 at different positions and the energy spectrum images (k)-(l) of the precursor powders obtained in Examples 2 and 3;

[0030] Figure 3 Transmission electron microscope images of graphene quantum dots obtained after ultrasonic dispersion of the precursor powder prepared in Example 1 at different magnifications;

[0031] Figure 4 The electrical conductivity test results of the graphene-enhanced copper-based composite materials and pure copper prepared in Examples 1-6 and Comparative Examples 1-4 are shown;

[0032] Figure 5 The hardness test results of the graphene-reinforced copper-based composite materials and pure copper prepared in Examples 1-6 and Comparative Examples 1-4 are shown;

[0033] Figure 6 The compression properties of the graphene-reinforced copper-based composite materials and pure copper prepared in Example 1-6 (a) and Comparative Example 1-4 (b) are measured;

[0034] Figure 7 These are the friction coefficient measurement results of the graphene-reinforced copper-based composite materials and pure copper prepared in Examples 1-6 and Comparative Examples 1-4. DETAILED DESCRIPTION

[0035] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0036] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0037] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0038] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0039] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0040] The embodiment of the present invention provides a method for preparing an in-situ synthesized graphene-reinforced copper-based composite material, comprising the following steps:

[0041] (1) dissolving sucrose in water to obtain a sucrose solution, and heating and stirring to obtain a caramelized sucrose solution;

[0042] (2) diluting the caramelized sucrose solution with a solvent, adding I2 and KI, and stirring to obtain a mixed solution of graphene and sucrose;

[0043] (3) adding copper powder to the mixed solution of graphene and sucrose, stirring, filtering, and drying to obtain a precursor powder;

[0044] (4) The precursor powder is sintered in a hydrogen and argon atmosphere and then subjected to vacuum pressure sintering to obtain the graphene-reinforced copper-based composite material.

[0045] In a preferred embodiment of the present invention, the loading amount of the carbon quantum dots formed by the sucrose in step (1) in the copper powder in step (3) is 1wt%-4wt%, that is, when the added amount of sucrose in step (1) is 2.624g-10.49g, the loading amount of the carbon quantum dots formed by the caramelized sucrose on the copper powder in step (3) (30g) is 1wt%-4wt% of the total mass of the copper powder. The above relationship is measured by a carbon-sulfur analyzer.

[0046] In a preferred embodiment of the present invention, the heating and stirring in step (1) also includes the step of adding a small amount of copper powder, and in step (2), the mass ratio of the total mass of I2 and KI to the mass of the copper powder is 1:(1-5), the temperature of the heating and stirring is 200°C, and the time is ≥2h.

[0047] In a preferred embodiment of the present invention, in step (2), the ratio of the mass of caramelized sucrose in the caramelized sucrose solution to the total mass of I2 and KI is (2-8) : 1. More preferably, in step (2), the ratio of the mass of caramelized sucrose in the caramelized sucrose solution to the total mass of I2 and KI is (4-7) : 1.

[0048] In a preferred embodiment of the present invention, the mass ratio of the total mass of I2 and KI in step (2) to the mass ratio of the copper powder in step (3) is (1-4):30.

[0049] In a preferred embodiment of the present invention, the copper powder is electrolytic copper powder with a particle size of 10-30 μm, and the copper powder used is purchased from Shanghai Naio Nano Technology Co., Ltd.

[0050] In a preferred embodiment of the present invention, in step (2), the solvent is ethanol and water in a volume ratio of (1-4):1, and is diluted to a concentration of 50-200 mg / L of the caramelized sucrose solution.

[0051] In a preferred embodiment of the present invention, in step (4), the precursor powder is sintered at a temperature of 700-900° C. in a hydrogen and argon atmosphere, and the holding time is 5-20 min.

[0052] In a preferred embodiment of the present invention, in step (4), the volume proportion of hydrogen in the hydrogen and argon atmosphere is 10-30%.

[0053] In a preferred embodiment of the present invention, in step (4), the sintering temperature of the vacuum pressure sintering is 700-900°C, the holding time is 0.5-2h, and the heating rate is 3-10°C / min.

[0054] In a preferred embodiment of the present invention, in step (4), the vacuum degree of the vacuum pressure sintering is less than 10 -3 Pa.

[0055] The invention also provides a graphene-reinforced copper-based composite material prepared by the preparation method.

[0056] The raw materials used in the examples of the present invention are all commercially available, and the purity of sucrose, I2 and KI is analytically pure.

[0057] The room temperature in the embodiments of the present invention refers to "25±3°C".

[0058] The technical solution of the present invention is further illustrated by the following embodiments.

[0059] Example 1

[0060] A method for preparing an in-situ synthesized graphene-enhanced copper-based composite material (1% Gn@Cu, i.e., the loading amount of carbon quantum dots on copper is 1 wt%), comprising the following steps:

[0061] (1) Dissolve 2.624 g of sucrose in 20 mL of deionized water, place on a magnetic stirrer at room temperature, and stir evenly until the sucrose is completely dissolved to obtain a sucrose solution;

[0062] (2) placing the stirred sucrose solution on a heating magnetic stirrer and heating at 200° C. while stirring, during which 1 g of copper powder is added and mixed evenly. After 2 h of heating and stirring, the solution turns light yellow. After further stirring and heating, a caramelized brown-yellow viscous liquid with high viscosity is obtained, i.e., a caramelized sucrose solution;

[0063] (3) The obtained caramelized sucrose solution was diluted with a solvent obtained by mixing ethanol and deionized water in a volume ratio of 1:1 to obtain a caramelized sucrose solution with a concentration of 200 mg / mL, and then 1 g of I2 and KI (the mass ratio of the two was 1:1) were added to make the ratio of the mass of caramelized sucrose in the caramelized sucrose solution to the total mass of I2 and KI be 4:1. After stirring on a magnetic stirrer at room temperature for 0.5 h, it was observed that the solution changed from brown to light yellow, in which the iodide ions generated by the reaction of I2 and copper can catalyze the conversion of sucrose to graphene together with the copper ions. After stirring for 1 h, a mixed solution of graphene and sucrose was obtained;

[0064] (4) adding 30 g of copper powder to the obtained mixed solution of graphene and sucrose in portions at a uniform speed, stirring for 3 h, and filtering and drying to obtain a precursor powder;

[0065] (5) The obtained precursor powder was placed in a tubular furnace and sintered in a hydrogen and argon atmosphere (hydrogen volume ratio is 10%), the sintering temperature was 800°C, the holding time was 5 min, the heating rate was 10°C / min, and the graphene-coated copper powder was obtained. The graphite powder was then placed in a graphite mold with a particle size of 30 mm and vacuum pressure sintered. The sintering temperature of the vacuum pressure sintering was 800°C, the holding time was 1 h, the heating rate was 10°C / min, and the vacuum degree was <10 -3 Pa, and then cooled in the furnace to obtain a graphene reinforced copper-based composite material.

[0066] Example 2

[0067] A method for preparing an in-situ synthesized graphene-reinforced copper-based composite material (2% Gn@Cu) comprises the following steps:

[0068] (1) Dissolve 5.2 g of sucrose in 50 mL of deionized water, place on a magnetic stirrer at room temperature, and stir evenly until the sucrose is completely dissolved to obtain a sucrose solution;

[0069] (2) placing the stirred sucrose solution on a heating magnetic stirrer and heating at 200° C. while stirring, during which 0.6 g of copper powder is added and mixed evenly. After 2 h of heating and stirring, the solution turns light yellow. After further stirring and heating, a caramelized brown-yellow viscous liquid with high viscosity is obtained, i.e., a caramelized sucrose solution;

[0070] (3) The obtained caramelized sucrose solution was diluted with a solvent obtained by mixing ethanol and deionized water in a volume ratio of 2:1 to obtain a caramelized sucrose solution with a concentration of 300 mg / mL, and then 2 g of I2 and KI (the mass ratio of the two is 1:1) were added to make the ratio of the mass of caramelized sucrose in the caramelized sucrose solution to the total mass of I2 and KI be 5:1. After stirring on a magnetic stirrer at room temperature for 0.5 h, it was observed that the solution changed from brown to light yellow, in which the iodide ions generated by the reaction of I2 and copper can catalyze the conversion of sucrose to graphene together with the copper ions. After stirring for 2 h, a mixed solution of graphene and sucrose was obtained;

[0071] (4) adding 30 g of copper powder to the obtained mixed solution of graphene and sucrose in portions at a uniform speed, stirring for 3 h, and filtering and drying to obtain a precursor powder;

[0072] (5) The obtained precursor powder was placed in a tubular furnace and sintered in a hydrogen and argon atmosphere (hydrogen volume ratio is 10%), the sintering temperature was 800°C, the holding time was 10 min, the heating rate was 10°C / min, and the graphene-coated copper powder was obtained. The graphite powder was then placed in a graphite mold with a particle size of 30 mm and vacuum pressure sintered. The sintering temperature of the vacuum pressure sintering was 800°C, the holding time was 1 h, the heating rate was 10°C / min, and the vacuum degree was <10-3 Pa, and then cooled in the furnace to obtain a graphene reinforced copper-based composite material.

[0073] Example 3

[0074] A method for preparing an in-situ synthesized graphene-reinforced copper-based composite material (3% Gn@Cu) comprises the following steps:

[0075] (1) Dissolve 7.87 g of sucrose in 75 mL of deionized water, place on a magnetic stirrer at room temperature, and stir evenly until the sucrose is completely dissolved to obtain a sucrose solution;

[0076] (2) placing the stirred sucrose solution on a heating magnetic stirrer and heating at 200° C. while stirring, during which 0.7 g of copper powder is added and mixed evenly. After 2 h of heating and stirring, the solution turns light yellow. After further stirring and heating, a caramelized brown-yellow viscous liquid with high viscosity is obtained, i.e., a caramelized sucrose solution;

[0077] (3) The obtained caramelized sucrose solution was diluted with a solvent obtained by mixing ethanol and deionized water in a volume ratio of 3:1 to obtain a caramelized sucrose solution with a concentration of 400 mg / mL, and then 3 g of I2 and KI (the mass ratio of the two is 1:1) were added to make the ratio of the mass of caramelized sucrose in the caramelized sucrose solution to the total mass of I2 and KI be 6:1. After stirring on a magnetic stirrer at room temperature for 0.5 h, it was observed that the solution changed from brown to light yellow, in which the iodide ions generated by the reaction of I2 and copper can catalyze the conversion of sucrose to graphene together with the copper ions. After stirring for 3 h, a mixed solution of graphene and sucrose was obtained;

[0078] (4) adding 30 g of copper powder to the obtained mixed solution of graphene and sucrose in portions at a uniform speed, stirring for 3 h, and filtering and drying to obtain a precursor powder;

[0079] (5) The obtained precursor powder was placed in a tubular furnace and sintered in a hydrogen and argon atmosphere (hydrogen volume ratio is 10%), the sintering temperature was 800°C, the holding time was 15 min, the heating rate was 10°C / min, and the graphene-coated copper powder was obtained. The graphite powder was then placed in a graphite mold with a particle size of 30 mm and vacuum pressure sintered. The sintering temperature of the vacuum pressure sintering was 800°C, the holding time was 1 h, the heating rate was 10°C / min, and the vacuum degree was <10 -3 Pa, and then cooled in the furnace to obtain a graphene reinforced copper-based composite material.

[0080] Example 4

[0081] A method for preparing an in-situ synthesized graphene-reinforced copper-based composite material (4% Gn@Cu) comprises the following steps:

[0082] (1) Dissolve 10.5 g of sucrose in 100 mL of deionized water, place on a magnetic stirrer at room temperature, and stir evenly until the sucrose is completely dissolved to obtain a sucrose solution;

[0083] (2) placing the stirred sucrose solution on a heating magnetic stirrer and heating it at 200° C. while stirring, during which 0.8 g of copper powder is added and mixed evenly. After 2 h of heating and stirring, the solution turns light yellow. After further stirring and heating, a caramelized brown-yellow viscous liquid with high viscosity is obtained, i.e., a caramelized sucrose solution;

[0084] (3) The obtained caramelized sucrose solution was diluted with a solvent obtained by mixing ethanol and deionized water in a volume ratio of 4:1 to obtain a caramelized sucrose solution with a concentration of 500 mg / mL, and then 4 g of I2 and KI (the mass ratio of the two was 1:1) were added to make the ratio of the mass of caramelized sucrose in the caramelized sucrose solution to the total mass of I2 and KI be 7:1. After stirring on a magnetic stirrer at room temperature for 0.5 h, it was observed that the solution changed from brown to light yellow, in which the iodide ions generated by the reaction of I2 and copper can catalyze the conversion of sucrose to graphene together with the copper ions. After 4 h of stirring, a mixed solution of graphene and sucrose was obtained;

[0085] (4) adding 30 g of copper powder to the obtained mixed solution of graphene and sucrose in portions at a uniform speed, stirring for 3 h, and filtering and drying to obtain a precursor powder;

[0086] (5) The obtained precursor powder was placed in a tubular furnace and sintered in a hydrogen and argon atmosphere (hydrogen volume ratio is 10%), the sintering temperature was 800°C, the holding time was 20 min, the heating rate was 10°C / min, and the graphene-coated copper powder was obtained. The graphite powder was then placed in a graphite mold with a particle size of 30 mm and vacuum pressure sintered. The sintering temperature of the vacuum pressure sintering was 800°C, the holding time was 1 h, the heating rate was 10°C / min, and the vacuum degree was <10 -3 Pa, and then cooled in the furnace to obtain a graphene reinforced copper-based composite material.

[0087] Example 5

[0088] (1) Dissolve 7 g of sucrose in 75 mL of deionized water, place on a magnetic stirrer at room temperature, and stir evenly until the sucrose is completely dissolved to obtain a sucrose solution;

[0089] (2) placing the stirred sucrose solution on a heating magnetic stirrer and heating at 200° C. while stirring, during which 0.3 g of copper powder is added and mixed evenly. After 2 h of heating and stirring, the solution turns light yellow. After further stirring and heating, a caramelized brown-yellow viscous liquid with high viscosity is obtained, i.e., a caramelized sucrose solution;

[0090] (3) The obtained caramelized sucrose solution was diluted with a solvent obtained by mixing ethanol and deionized water in a volume ratio of 1:1 to obtain a caramelized sucrose solution with a concentration of 130 mg / mL, and then 3 g of I2 and KI (the mass ratio of the two is 1:1) were added to make the ratio of the mass of caramelized sucrose in the caramelized sucrose solution to the total mass of I2 and KI be 6:1. After stirring on a magnetic stirrer at room temperature for 0.5 h, it was observed that the solution changed from brown to light yellow, in which the iodide ions generated by the reaction of I2 and copper can catalyze the conversion of sucrose to graphene together with the copper ions. After stirring for 3 h, a mixed solution of graphene and sucrose was obtained;

[0091] (4) adding 30 g of copper powder to the obtained mixed solution of graphene and sucrose in portions at a uniform speed, stirring for 3 h, filtering and drying to obtain a precursor powder, at which the content of quantum dots on the surface of the copper powder is 0.83 wt%;

[0092] (5) The obtained precursor powder was placed in a tubular furnace and sintered in a hydrogen and argon atmosphere (hydrogen volume ratio is 30%) at a sintering temperature of 900°C and a holding time of 15 min to obtain graphene-coated copper powder, which was then placed in a graphite mold with a particle size of 30 mm and subjected to vacuum pressure sintering. The sintering temperature of the vacuum pressure sintering was 900°C, the holding time was 0.5 h, the heating rate was 10°C / min, and the vacuum degree was <10 -3 Pa, and obtain graphene reinforced copper-based composite materials.

[0093] Example 6

[0094] (1) Dissolve 9 g of sucrose in 90 mL of deionized water, place on a magnetic stirrer at room temperature, and stir evenly until the sucrose is completely dissolved to obtain a sucrose solution;

[0095] (2) placing the stirred sucrose solution on a heating magnetic stirrer and heating it at 200° C. while stirring, during which 0.5 g of copper powder is added and mixed evenly. After 2 h of heating and stirring, the solution turns light yellow. After further stirring and heating, a caramelized brown-yellow viscous liquid with high viscosity is obtained, i.e., a caramelized sucrose solution;

[0096] (3) The obtained caramelized sucrose solution was diluted with a solvent obtained by mixing ethanol and deionized water in a volume ratio of 1:1 to obtain a caramelized sucrose solution with a concentration of 170 mg / mL, and then 4 g of I2 and KI (the mass ratio of the two is 1:1) were added to make the ratio of the mass of caramelized sucrose in the caramelized sucrose solution to the total mass of I2 and KI be 7:1. After stirring on a magnetic stirrer at room temperature for 0.5 h, it was observed that the solution changed from brown to light yellow, in which the iodide ions generated by the reaction of I2 with copper can catalyze the conversion of sucrose into graphene together with the copper ions. After 4 h of stirring, a mixed solution of graphene and sucrose was obtained;

[0097] (4) adding 40 g of copper powder to the obtained mixed solution of graphene and sucrose in portions at a uniform speed, stirring for 3 h, filtering and drying to obtain a precursor powder, at which the content of quantum dots on the surface of the copper powder is 0.97 wt%;

[0098] (5) The obtained precursor powder was placed in a tubular furnace and sintered in a hydrogen and argon atmosphere (hydrogen volume ratio is 20%) at a temperature of 700°C and a holding time of 5 min to obtain graphene-coated copper powder, which was then placed in a graphite mold with a particle size of 30 mm and subjected to vacuum pressure sintering. The sintering temperature of the vacuum pressure sintering was 700°C, the holding time was 2 h, the heating rate was 3°C / min, and the vacuum degree was <10 -3 Pa, and obtain graphene reinforced copper-based composite materials.

[0099] Comparative Example 1

[0100] A method for preparing an in-situ synthesized graphene-reinforced copper-based composite material comprises the following steps:

[0101] (1) Dissolve 5.4 g of sucrose in 50 mL of deionized water, place on a magnetic stirrer at room temperature, and stir evenly until the sucrose is completely dissolved to obtain a sucrose solution;

[0102] (2) placing the stirred sucrose solution on a heating magnetic stirrer and heating it at 200° C. while stirring, during which 0.5 g of copper powder is added and mixed evenly. After 2 h of heating and stirring, the solution turns light yellow. After further stirring and heating, a caramelized brown-yellow viscous liquid with high viscosity is obtained, i.e., a caramelized sucrose solution;

[0103] (3) diluting the obtained caramelized sucrose solution with a solvent obtained by mixing ethanol and deionized water in a volume ratio of 1:1 to obtain a caramelized sucrose solution with a concentration of 200 mg / mL;

[0104] (4) adding 30 g of copper powder to the caramelized sucrose solution obtained in step (3) in portions at a uniform speed, stirring for 3 h, and filtering and drying to obtain a precursor powder;

[0105] (5) The obtained precursor powder was placed in a tubular furnace and sintered in a hydrogen and argon atmosphere (hydrogen volume ratio is 10%), the sintering temperature was 800°C, the holding time was 5 min, the heating rate was 10°C / min, and the graphene-coated copper powder was obtained. The graphite powder was then placed in a graphite mold with a particle size of 30 mm and vacuum pressure sintered. The sintering temperature of the vacuum pressure sintering was 800°C, the holding time was 1 h, the heating rate was 10°C / min, and the vacuum degree was <10 -3 Pa, and then cooled in the furnace to obtain a graphene reinforced copper-based composite material.

[0106] Comparative Example 2

[0107] The same as Example 1, except that the mass of sucrose added in step (1) is 7 g, and the mass of copper powder added in step (4) is 40 g (the loading amount of carbon quantum dots on copper is 2.68% as determined by a carbon-sulfur analyzer).

[0108] Comparative Example 3

[0109] The same as Example 1, except that in step (5), the obtained precursor powder is placed in a tubular furnace and sintered in a hydrogen and argon atmosphere (hydrogen volume ratio is 10%), the sintering temperature is 500° C., and the holding time is 20 min.

[0110] Comparative Example 4

[0111] The same as Example 1, except that in step (5), the sintering temperature of the vacuum pressure sintering is 1000° C. and the holding time is 2 h.

[0112] Performance Testing

[0113] The XRD patterns of the graphene-enhanced copper-based composite materials and the copper-based composite materials of pure copper (electrolytic copper powder used in the examples) prepared in Examples 1-6 are shown in Figure 1 (a), XRD patterns of the graphene-enhanced copper-based composite materials and the copper-based composite materials of pure copper (electrolytic copper powder used in the examples) prepared in Comparative Examples 1-4 are shown in Figure 1 (b) Figure 1 It can be seen that the graphene-enhanced copper-based composite material prepared by the embodiment corresponds one to one with the peak of the pure copper block, indicating that the alloying degree of the prepared material is high. Comparing the composite materials prepared by pure copper and embodiment 1-6, the peaks obtained by the materials of embodiment 1-6 are all offset to the left relative to the pure copper peak, indicating that the interplanar spacing of the composite materials prepared by embodiment 1-6 is large, and the reason is that the interface bonding in the original position, in addition to the copper-copper interface bonding, also has the interface bonding of copper-graphene and graphene-graphene, so the interplanar spacing is enlarged. The copper-based composite material prepared by comparative example 1-4 is the same as the embodiment, and the peaks of the copper-based composite material and pure copper correspond one to one, and the peak is also offset to the left.

[0114] The microscopic morphology of the precursor powders prepared in Examples 1-6 and Comparative Examples 1-4 are shown in FIG. Figure 2 (a)-(j), the energy spectra of the precursor powders obtained in Examples 2 and 3 are shown in FIG. Figure 2 (k)-(l), it can be seen that the surface of the copper powder of the embodiment has grown graphene in a relatively good crystalline state, and from the scanning electron microscope image, it can be seen that the graphene is relatively complete and has a good coating effect on the copper powder. However, no graphene has grown on the surface of the comparative example. It is worth noting that the amount of sucrose used in comparative example 2 is increased, and there is more unconverted sucrose on the surface of the copper powder. From the scanning electron microscope image, it can be seen that the graphene is relatively complete and has a good coating effect on the copper powder. Figure 2 (g)-(h) show that due to the unconverted sucrose on the surface of the copper powder, the interplanar spacing of the composite material is enlarged, causing the peak to shift to the left, and the degree of left shift is greater than that in the embodiment, indicating that the interplanar spacing is greater than that in the embodiment, and it can also be explained that the sucrose has not been converted into sucrose.

[0115] The transmission electron microscopy images of graphene quantum dots obtained after ultrasonic dispersion of the precursor powder prepared in Example 1 at different magnifications are shown in Figure 3 , it can be seen that graphene quantum dots were successfully generated on the surface of copper powder.

[0116] The conductivity test results of the graphene-enhanced copper-based composite materials and pure copper prepared in Examples 1-6 and Comparative Examples 1-4 are shown in Figure 4 (Material type 1 in the figure corresponds to Example 1 or Comparative Example 1, and so on, pure copper is tested once). It can be seen that compared with pure copper samples, the conductivity of the samples prepared in the examples is greater than that of pure copper samples. This is because the charge carriers in graphene can move freely along the two-dimensional plane to form a highly conductive π electron band, which leads to the good conductivity of graphene. Introducing it into copper-based materials will increase the conductivity of the material, so the conductivity of the prepared bulk material increases. The conductivity of the comparative examples is lower than that of pure copper. This is because the sucrose on the surface of the copper powder has not been converted, which increases the resistance to carriers at the grain boundaries on the surface of the copper grains, and from Figure 1 It can be seen from the XRD of the comparative example that the peak shifts to the left to a greater extent than that of the embodiment, indicating that the grain gap is larger, which is not conducive to the movement of carriers, and thus the conductivity decreases.

[0117] The hardness of the graphene-enhanced copper-based composite materials and pure copper prepared in Examples 1-6 and Comparative Examples 1-4 is shown in FIG. Figure 5 , it can be seen that compared with the pure copper sample, the hardness of the samples of Examples 2-4 is higher than that of the pure copper sample. This is because the graphene is distributed at the interface of the copper matrix grains, which can effectively hinder the migration of dislocations and increase the hardness of the material. Among them, the sample hardness of Example 4 is the highest. In Examples 1, 5, and 6, due to the low concentration of the caramel solution used, the carbon content on the surface of the copper powder is low, and the generated graphene has a low strengthening effect on the copper matrix, resulting in a decrease in hardness. The hardness of Example 6 is almost equivalent to that of pure copper. In the comparative examples, only Comparative Examples 1 and 3 have a hardness higher than that of the pure copper sample. This is because the incompletely converted sucrose accumulates at the grain boundaries, resulting in the obstruction of dislocation migration and an increase in hardness. The hardness of Comparative Example 2 is slightly lower than that of pure copper. This is because the sucrose content on the surface of the copper powder is relatively high, resulting in a decrease in the overall strength of the copper matrix. The hardness of Comparative Example 4 is equivalent to that of pure copper. This is because at the sintering temperature of 900°C, the grains grow and the dislocations have more spatial migration, resulting in a decrease in hardness. Due to the accumulation of sucrose at the grain boundaries, under the action of the double layer, the macroscopic performance is that the hardness is equivalent to that of pure copper.

[0118] The compression performance of the graphene-enhanced copper-based composite material and pure copper prepared in Example 1-6 (a) and Comparative Example 1-4 (b) is shown in FIG. Figure 6 It can be seen that compared with the pure copper sample, the strength of the samples prepared in the examples and the comparative examples is improved, indicating that the graphene grown by this method and the unconverted sucrose can both highly improve the interfacial bonding strength between the copper matrix, thereby improving the material strength, among which the sample with the carbon content of Example 3 has the highest strength.

[0119] The friction coefficients of the graphene-enhanced copper-based composite materials and pure copper prepared in Examples 1-6 and Comparative Examples 1-4 are shown in FIG. Figure 7 (Material type 1 in the figure corresponds to Example 1 or Comparative Example 1, and so on, pure copper is tested once). It can be seen that compared with the pure copper sample, as the concentration of the caramel solution increases, the friction coefficient of the material decreases successively. This is because graphene is a lamellar structure, which shows that graphene plays a good lubricating role in the copper-based material. In the comparative example, although the friction coefficient is also reduced compared with pure copper, the reason is that during friction, a friction film of sucrose and copper is formed, which leads to a decrease in the friction coefficient, but the degree of reduction is less than that of the embodiment, indicating that the improvement of the friction performance of the copper-based material by graphene is greater than that of unconverted sucrose.

[0120] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for preparing an in-situ synthesized graphene-reinforced copper-based composite material, characterized in that: The following steps are involved: (1) dissolving sucrose in water to obtain a sucrose solution, and heating and stirring to obtain a caramelized sucrose solution; (2) diluting the caramelized sucrose solution with a solvent, adding I2 and KI, and stirring to obtain a mixed solution of graphene and sucrose; (3) adding copper powder to the mixed solution of graphene and sucrose, stirring, filtering, and drying to obtain a precursor powder; (4) The precursor powder is sintered in a hydrogen and argon atmosphere and then subjected to vacuum pressure sintering to obtain the graphene-reinforced copper-based composite material.

2. The method for preparing the in-situ synthesized graphene-reinforced copper-based composite material according to claim 1, characterized in that: In step (2), the ratio of the mass of caramelized sucrose in the caramelized sucrose solution to the total mass of I2 and KI is (2-8):

1.

3. The method for preparing the in-situ synthesized graphene-reinforced copper-based composite material according to claim 1, characterized in that: The mass ratio of the total mass of I2 and KI in step (2) to the mass ratio of the copper powder in step (3) is (1-4):

30.

4. The method for preparing the in-situ synthesized graphene-reinforced copper-based composite material according to claim 1, characterized in that: The copper powder is electrolytic copper powder with a particle size of 10-30 μm.

5. The method for preparing the in-situ synthesized graphene-reinforced copper-based composite material according to claim 1, characterized in that: In step (2), the solvent is ethanol and water in a volume ratio of (1-4):

1.

6. The method for preparing the in-situ synthesized graphene-reinforced copper-based composite material according to claim 1, characterized in that: In step (2), the caramelized sucrose solution is diluted to a concentration of 50-200 mg / L.

7. The method for preparing the in-situ synthesized graphene-reinforced copper-based composite material according to claim 1, characterized in that: In step (4), the precursor powder is sintered at a temperature of 700-900° C. in a hydrogen and argon atmosphere, and the holding time is 5-20 min.

8. The method for preparing the in-situ synthesized graphene-reinforced copper-based composite material according to claim 1, characterized in that: In step (4), the sintering temperature of the vacuum pressure sintering is 700-900°C, the holding time is 0.5-2h, and the heating rate is 3-10°C / min.

9. A graphene-reinforced copper-based composite material prepared by the preparation method according to any one of claims 1 to 8.

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