High-strength high-conductivity graphene copper composite material and preparation method thereof

Abstract

The application relates to a high-strength and high-conductivity graphene copper composite material and a preparation method thereof, and the preparation method comprises the following steps: step one: graphene powder and electrolytic copper powder are premixed to obtain premixed powder; step two: the premixed powder is cold-pressed to prepare a cold-pressed blank, the cold-pressed blank is placed in an atmosphere furnace, and after heat preservation for a period of time, a graphene copper composite rod is prepared through hot extrusion; step three: the graphene copper composite rod is further processed through a cold rolling process; and step four: the composite material after cold rolling is annealed to obtain the high-strength and high-conductivity graphene copper composite material. Through the hot extrusion and cold rolling process, the mechanical properties of the composite material are effectively enhanced, the high conductivity of the material is maintained, the sintering is not needed in the preparation process, the technological process is shortened, and the preparation cost is reduced. The strength and plasticity of the composite material are adjusted through heat treatment, the prepared graphene copper composite material has high conductivity, high strength and high plasticity, and the application prospect of the graphene copper composite material is widened.

Description

Technical Field

[0001] This invention relates to the field of composite material preparation technology, specifically to a high-strength, high-conductivity graphene-copper composite material and its preparation method. Background Technology

[0002] Copper and copper-based composites possess advantages such as high electrical and thermal conductivity, and ease of processing, making them widely used in industries such as electronics, power, and transportation. For metallic materials, strength and conductivity typically exhibit an inverse relationship; that is, increasing strength may sacrifice conductivity to some extent, and vice versa. The preparation of high-strength, high-conductivity copper materials often employs alloying or composite material methods. Alloying enhances the properties of the copper matrix by adding trace amounts of metallic elements, but these elements can exacerbate electron scattering, leading to a decrease in conductivity. Composite material methods strengthen the matrix by adding reinforcing phases that hinder dislocation movement, resulting in significantly less electron scattering than alloying. Traditional methods for preparing high-strength, high-conductivity copper-based composites significantly improve material strength by adding ceramic particles as reinforcing phases, but this usually comes at the cost of conductivity. Graphene, as a novel carbon nanomaterial, possesses extremely high conductivity and excellent mechanical properties, and is considered an ideal reinforcing phase for preparing high-strength, high-conductivity copper-based composites. Therefore, research on the preparation of graphene-copper composites with high conductivity and high strength has received widespread attention.

[0003] Patent CN104711443A discloses a method for preparing graphene / copper composite materials. The method involves mixing flake graphite with copper-nickel alloy powder using mechanical ball milling, and then separating graphene from the graphite using mechanical force to initially obtain graphene / copper composite powder. Graphene / copper composite blocks, filaments, and strips are then prepared using powder metallurgy, hot extrusion, and rolling techniques. This invention has a simple process and is easy to scale up for production. However, the conductivity of the prepared composite material is only 63.84–71.84% IACS, and the tensile strength is 246–250 MPa, which does not meet the requirements for high-strength, conductive copper-based composite materials. Summary of the Invention

[0004] To address the problems existing in the prior art, the purpose of this invention is to provide a high-strength, high-conductivity graphene-copper composite material and its preparation method. This preparation method shortens the process flow and can produce a graphene-copper composite material with high electrical conductivity and comprehensive mechanical properties.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a high-strength, high-conductivity graphene-copper composite material includes the following steps:

[0007] Step 1: Premix graphene powder and electrolytic copper powder to obtain premixed powder;

[0008] Step 2: The premixed powder is cold-pressed into a blank. The cold-pressed blank is placed in an atmosphere furnace and kept at a certain temperature for a period of time. Then, graphene copper composite rods are prepared by hot extrusion.

[0009] Step 3: Further process the graphene-copper composite rod using a cold rolling process;

[0010] Step 4: Anneal the cold-rolled composite material to obtain a high-strength, high-conductivity graphene-copper composite material.

[0011] Furthermore, in step one, the electrolytic copper powder has a particle size of 20-40 μm, the number of graphene layers is 1-3, and the graphene content is 0-1 wt%.

[0012] Furthermore, in step one, the graphene powder and electrolytic copper powder are premixed using an ultrasonic vibration device for a premixing time of 30–60 min.

[0013] Furthermore, in step two, before cold pressing the blank, the premixed powder is placed in a V-type mixer for further mixing for 10-12 hours to obtain mixed powder.

[0014] Furthermore, in step two, the heat preservation temperature is 600-800℃, the heat preservation time is 30-60min, and the diameter of the extruded bar is 6-10mm.

[0015] Furthermore, in step two, the cold pressing pressure of the billet is 400-500 MPa, and the holding time is 1-3 min.

[0016] Furthermore, in step three, the graphene-copper composite rod cold billet is directly formed by hot extrusion without sintering. The billet temperature is 600-800℃, the holding time is 30-60 minutes, and the extrusion ratio is 14-25.

[0017] Furthermore, in step three, a large amount of deformation can easily lead to material cracking. The graphene copper composite rod is cold rolled twice along the extrusion direction. The first cold rolling is to a material thickness of 4-4.5 mm, and the second cold rolling is to a material thickness of 2-2.5 mm. The main machine speed is 2 mm / min.

[0018] Furthermore, in step four, the annealing temperature is 450–650℃, and the annealing time is 30–60 min.

[0019] A high-strength, high-conductivity graphene-copper composite material is prepared by the above-mentioned method for preparing a high-strength, high-conductivity graphene-copper composite material.

[0020] In summary, the present invention has the following advantages:

[0021] (1) The present invention effectively enhances the mechanical properties of composite materials through hot extrusion and cold rolling processes, while maintaining the high electrical conductivity of the materials. Moreover, the preparation process does not require sintering, shortens the process flow, and reduces the preparation cost.

[0022] (2) The present invention controls the strength and plasticity of the composite material through heat treatment, and the prepared graphene copper composite material has high conductivity, high strength and high plasticity, which further broadens the application prospects of graphene copper composite material. Attached Figure Description

[0023] Figure 1 This is a flowchart of the preparation process according to an embodiment of the present invention;

[0024] Figure 2 The image shows the microstructure of the graphene-copper composite material prepared in Example 1. Detailed Implementation

[0025] The present invention will now be described in further detail.

[0026] Example 1

[0027] This example discloses a method for preparing high-strength, high-conductivity graphene-copper composite materials based on powder metallurgy. The specific preparation process is detailed below. Figure 1 This includes the following steps:

[0028] (1) Powder mixing: Take graphene (0.375g) reinforcement and electrolytic copper powder (125.625g) and put them into an ultrasonic vibration device, premix for 30min, and then put the premixed powder into a V-type mixer and mix for 12h.

[0029] (2) Cold pressing: The mixed powder is loaded into a mold with an inner diameter of φ30mm and cold pressed under a hydraulic press. The cold pressing pressure is 500MPa and the holding time is 3min. The molded sample is obtained after cold pressing.

[0030] (3) Hot extrusion: The cold-pressed sample was kept at a temperature of 10℃ / min in an argon-protected atmosphere furnace until it reached 600℃, where it was held for 60 min. After the holding time, the sample was removed from the furnace and hot-extruded at an extrusion ratio of 14.06. The final extruded bar with a diameter of 8 mm was obtained and cooled by water cooling.

[0031] (4) Cold rolling and annealing: The material is cold rolled twice, first to a thickness of 4.5 mm and second to a thickness of 2.5 mm, with a rolling mill speed of 2 mm / min. The material is then annealed at a temperature of 450℃ for 1 hour.

[0032] Metallographic images of graphene-copper composite materials are as follows: Figure 2 As shown. Figure 2It can be seen that the graphene is evenly distributed in the copper matrix, with no obvious agglomeration.

[0033] The prepared graphene-copper composite material had no surface cracks. The mechanical properties of the material were tested, and the results are as follows: the maximum yield strength was 185 MPa, the maximum tensile strength was 341 MPa, the maximum elongation was 43.8%, and the maximum electrical conductivity was 93.9% IACS.

[0034] Example 2

[0035] (1) Powder mixing: Take graphene (0.375g) reinforcement and electrolytic copper powder (125.625g) and put them into an ultrasonic vibration device, premix for 30min, and then put the premixed powder into a V-type mixer and mix for 12h.

[0036] (2) Cold pressing: The mixed powder is loaded into a mold with an inner diameter of φ30mm and cold pressed under a hydraulic press. The cold pressing pressure is 500MPa and the holding time is 3min. The molded sample is obtained after cold pressing.

[0037] (3) Hot extrusion: The cold-pressed sample was kept at a temperature of 10℃ / min in an argon-protected atmosphere furnace until it reached 600℃, where it was held for 60 min. After the holding time, the sample was removed from the furnace and hot-extruded at an extrusion ratio of 14.06. The final extruded bar with a diameter of 8 mm was obtained and cooled by water cooling.

[0038] (4) Cold rolling and annealing: The material is cold rolled twice, first to a thickness of 4.5 mm and second to a thickness of 2.5 mm, with a machine speed of 2 mm / min. The material is then annealed at a temperature of 550℃ for 1 hour.

[0039] The prepared graphene-copper composite material had no surface cracks. The mechanical properties of the material were tested, and the results are as follows: the maximum yield strength was 190 MPa, the maximum tensile strength was 346 MPa, the maximum elongation was 40.7%, and the maximum electrical conductivity was 94.1% IACS.

[0040] Example 3

[0041] (1) Powder mixing: Take graphene (0.375g) reinforcement and electrolytic copper powder (125.625g) and put them into an ultrasonic vibration device, premix for 30min, and then put the premixed powder into a V-type mixer and mix for 12h.

[0042] (2) Cold pressing: The mixed powder is loaded into a mold with an inner diameter of φ30mm and cold pressed under a hydraulic press. The cold pressing pressure is 500MPa and the holding time is 3min. The molded sample is obtained after cold pressing.

[0043] (3) Hot extrusion: The cold-pressed sample was kept at a temperature of 10℃ / min in an argon-protected atmosphere furnace until it reached 600℃, where it was held for 60 min. After the holding time, the sample was removed from the furnace and hot-extruded at an extrusion ratio of 14.06. The final extruded bar with a diameter of 8 mm was obtained and cooled by water cooling.

[0044] (4) Cold rolling and annealing: The material is cold rolled twice, first to a thickness of 4.5 mm and second to a thickness of 2.5 mm, with a machine speed of 2 mm / min. The material is then annealed at a temperature of 650℃ for 1 hour.

[0045] The prepared graphene-copper composite material had no surface cracks. The mechanical properties of the material were tested, and the results are as follows: the maximum yield strength was 181 MPa, the maximum tensile strength was 328 MPa, the maximum elongation was 47.1%, and the maximum electrical conductivity was 93.1% IACS.

[0046] Table 1. Test table of alloy mechanical properties obtained in the embodiments of the present invention.

[0047]

[0048] As shown in Table 1, the graphene-copper composite material prepared in the embodiments of the present invention has high conductivity, high strength and high plasticity, which further broadens the application prospects of graphene-copper composite materials.

[0049] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength, high-conductivity graphene-copper composite material, characterized in that: Includes the following steps, Step 1: Premix graphene powder and electrolytic copper powder to obtain premixed powder; Step 2: The premixed powder is cold-pressed into a blank. The cold-pressed blank is placed in an atmosphere furnace and kept at a certain temperature for a period of time. Then, graphene copper composite rods are prepared by hot extrusion. Step 3: Further process the graphene-copper composite rod using a cold rolling process; Step 4: Anneal the cold-rolled composite material to obtain a high-strength, high-conductivity graphene-copper composite material. In step two, the heat preservation temperature is 600-800℃, the heat preservation time is 30-60min, and the diameter of the extruded bar is 6-10mm; In step three, the graphene copper composite rod cold billet is directly formed by hot extrusion without sintering. The billet temperature is 600~800℃, the holding time is 30~60min, and the extrusion ratio is 14~25. In step three, the graphene copper composite rod is cold-rolled twice along the extrusion direction. The first cold rolling is to a material thickness of 4~4.5mm, and the second cold rolling is to a material thickness of 2~2.5mm. The main machine speed is 2mm / min.

2. The method for preparing a high-strength, high-conductivity graphene-copper composite material according to claim 1, characterized in that: In step one, the electrolytic copper powder has a particle size of 20-40 μm, the number of graphene layers is 1-3, and the graphene component content is greater than 0 to 1 wt%.

3. The method for preparing a high-strength, high-conductivity graphene-copper composite material according to claim 1, characterized in that: In step one, graphene powder and electrolytic copper powder are premixed using an ultrasonic vibration device for 30-60 minutes.

4. The method for preparing a high-strength, high-conductivity graphene-copper composite material according to claim 1, characterized in that: In step two, before cold pressing the blank, the premixed powder is placed in a V-type mixer and mixed again for 10-12 hours to obtain mixed powder.

5. The method for preparing a high-strength, high-conductivity graphene-copper composite material according to claim 1, characterized in that: In step two, the cold pressing pressure of the billet is 400~500MPa, and the holding time is 1~3min.

6. The method for preparing a high-strength, high-conductivity graphene-copper composite material according to claim 1, characterized in that: In step four, the annealing temperature is 450~650℃ and the annealing time is 30~60min.

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