Graphene aluminum-based composite material and preparation method thereof

Abstract

The invention relates to the technical field of material processing, in particular to a graphene aluminum-based composite material and a preparation method thereof.The preparation method of the graphene aluminum-based composite material comprises the steps that surface modification is conducted on graphene oxide through a silane coupling agent, and modified graphene oxide is obtained; uniformly mixing the modified graphene oxide with aluminum powder and a dispersion medium to obtain graphene oxide slurry; the aluminum-based material coated with the graphene oxide slurry is placed in a magnetic field to be cured, and an intermediate composite material is obtained; carrying out primary hot pressed sintering on the intermediate composite material; and a zinc layer is plated on the surface of the intermediate composite material obtained after primary hot pressing sintering, then secondary hot pressing sintering, cold rolling and annealing are sequentially conducted, and the graphene aluminum-based composite material is obtained. The graphene aluminum-based composite material has the effect of simultaneously improving the mechanical property and the conductivity of the graphene aluminum-based composite material.

Description

Technical Field

[0001] The present invention relates to the technical field of material processing, and in particular to a graphene aluminum-based composite material and a preparation method thereof. Background Art

[0002] As a nanomaterial, graphene has the characteristics of high strength, high conductivity and high thermal conductivity, and can provide significant reinforcement effects for the aluminum matrix. Therefore, graphene aluminum-based composite materials can be used to manufacture structural parts and thermal conductive parts for aircraft, rockets, etc.

[0003] However, the development of graphene-aluminum composites faces a series of challenges. First, graphene has extremely high surface activity at the nanoscale, which easily leads to agglomeration in the aluminum matrix, thus affecting its uniform dispersion. Second, graphene is also prone to interfacial reactions with the aluminum matrix to form brittle interfacial products Al4C3, making it difficult to balance electrical conductivity and mechanical properties. Summary of the Invention

[0004] The present invention aims to simultaneously improve the mechanical properties and electrical conductivity of a graphene aluminum-based composite material.

[0005] As a first aspect, the present invention provides a method for preparing a graphene aluminum-based composite material, comprising: Silane coupling agent is used to modify the surface of graphene oxide to obtain modified graphene oxide; The modified graphene oxide is mixed evenly with aluminum powder and a dispersion medium to obtain a graphene oxide slurry; placing the aluminum-based material coated with the graphene oxide slurry in a magnetic field for curing to obtain an intermediate composite material; performing a hot pressing sintering on the intermediate composite material; A zinc layer is plated on the surface of the intermediate composite material after the primary hot pressing and sintering, and then secondary hot pressing and sintering, cold rolling and annealing are carried out in sequence to obtain the graphene aluminum-based composite material.

[0006] Optionally, before placing the aluminum-based material coated with the graphene oxide slurry in a magnetic field for curing, the method further comprises: The aluminum-based material is etched with an acid solution to form a porous etching layer on the surface of the aluminum-based material.

[0007] Optionally, the surface modification of graphene oxide using a silane coupling agent comprises: The graphene oxide is dispersed in a solvent, and then a silane coupling agent is added to perform surface modification.

[0008] Optionally, the graphene oxide is dispersed in a solvent, and then a silane coupling agent is added to perform a surface modification reaction, comprising: The amount of the silane coupling agent added is 1% to 5% of the mass of the graphene oxide, the temperature of the surface modification reaction is 120 to 180° C., and the reaction time is 6 to 12 hours.

[0009] Optionally, the step of placing the aluminum-based material coated with the graphene oxide slurry in a magnetic field for curing comprises: a magnetic field strength of 0.5 to 1.5 T, a curing temperature of 60 to 100° C., and a curing time of 12 to 48 h.

[0010] Optionally, the primary hot pressing sintering includes: The first stage: heating the intermediate composite material from room temperature to 250 to 300° C. and keeping the temperature for 30 to 45 minutes; The second stage: the intermediate composite material is further heated from 250 to 300° C. to 450 to 600° C., and kept at this temperature for 0.5 to 2 hours.

[0011] Optionally, the pressure of the primary hot pressing sintering is 20 to 80 MPa.

[0012] Optionally, the temperature of the secondary hot pressing sintering is 250 to 300° C., and the pressure is 10 to 15 MPa.

[0013] Optionally, in the graphene oxide slurry, based on 100 wt% of the mass of the aluminum powder, the added amount of the modified graphene oxide is 0.5 wt% to 3 wt%, and the added amount of the dispersion medium is 10 wt% to 15 wt%.

[0014] As a second aspect, the present invention further provides a graphene aluminum-based composite material, which is prepared using the preparation method of the graphene aluminum-based composite material as described in the first aspect.

[0015] The beneficial effects of the present invention compared to the prior art are: The present invention first uses a silane coupling agent to modify the surface of graphene oxide. The silane coupling agent reacts with the oxygen-containing groups on the surface of the graphene oxide through its hydrophilic group to form a covalent bond, so that the graphene surface is converted from hydrophilic to hydrophobic, alleviating the wettability difference with the aluminum melt. At the same time, its hydrophobic alkyl chain extends outward, producing a steric hindrance effect, effectively blocking the interlamellar agglomeration, thereby improving dispersibility and interface compatibility. After the modified graphene oxide is mixed with aluminum powder and ball-milled, the graphene is oriented by magnetic field induction to construct a continuous conductive network. This structure is conducive to significantly reducing the percolation threshold and can construct a low-resistance path through the material at a low addition amount, thereby improving the electrical conductivity of the composite material. In addition, by further introducing a zinc layer as an interfacial transition phase on the surface of the intermediate composite material, it is conducive to suppressing the generation of the brittle phase Al4C3. In summary, the high dispersion and directional arrangement of graphene are achieved through coupling agent modification, magnetic field induction and zinc layer transition, while the interface reaction is suppressed, and the electrical conductivity and mechanical properties of the graphene aluminum matrix composite are comprehensively improved, so that the resistivity of the graphene aluminum matrix composite can be reduced to 2.1×10 -6 Ω·m or less, tensile strength greater than 480 MPa, and elongation greater than 8%. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The figure is a flow chart for preparing a graphene aluminum-based composite material in an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below.

[0018] Unless otherwise defined, all technical and scientific terms used in this application have the same meanings as those commonly understood by those skilled in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "including" and its variations used in this document are open inclusions, that is, "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one other embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiments". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first" and "second" mentioned in the present invention are used to distinguish different objects, rather than to describe a specific order or a primary and secondary relationship. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "multiple" means two or more.

[0019] Graphene-aluminum composites have attracted considerable attention due to their potential for superior mechanical properties (such as high strength and modulus), electrical and thermal conductivity, and low density. However, the significant surface energy difference and poor wettability between graphene and aluminum-based materials result in poor dispersion of graphene in the aluminum matrix. This is primarily due to the following: Graphene's extremely high surface area and surface energy cause the graphene sheets to cluster tightly together through strong van der Waals forces, thereby reducing its high surface energy. Molten aluminum, on the other hand, has a high surface tension and is bound by metallic bonds. However, graphene, a carbon material, is primarily bound by non-metallic covalent bonds / van der Waals forces. Therefore, the high surface tension of molten aluminum tends to "shrink" into a spherical shape rather than spreading out to wet the graphene surface. This makes it difficult for the aluminum melt to effectively wrap around the graphene sheets, preventing them from being "pulled" apart and dispersed. Agglomerated graphene clumps are repelled by the aluminum melt or trapped at grain boundaries. Furthermore, when graphene is randomly dispersed, the probability of contact between the sheets is low, and they are easily isolated by the insulating aluminum matrix. Electrons need to frequently cross the high-resistance aluminum substrate interface, or conduct through the tunneling effect, which can easily lead to limited improvement in overall conductivity.

[0020] Furthermore, at high temperatures and prolonged processing times, aluminum and carbon react at the interface to form the brittle intermetallic compound Al4C3. This formation of Al4C3 can etch and destroy graphene's carbon structure, severely compromising its excellent mechanical and electrical properties. Furthermore, the brittle Al4C3 phase often poorly bonds with the matrix, becoming a source of crack initiation and propagation, thereby degrading the overall mechanical properties of the composite.

[0021] In order to improve the mechanical properties and electrical conductivity of graphene aluminum-based composite materials, the present invention provides a method for preparing graphene aluminum-based composite materials, such as Figure 1 As shown, the preparation method comprises the following steps: Step S1: surface-modifying graphene oxide using a silane coupling agent to obtain modified graphene oxide; Step S2: uniformly mixing the modified graphene oxide with aluminum powder and a dispersion medium to obtain a graphene oxide slurry; Step S3: placing the aluminum-based material coated with the graphene oxide slurry in a magnetic field for curing to obtain an intermediate composite material; Step S4: hot pressing and sintering the intermediate composite material; Step S5: applying a zinc layer to the surface of the intermediate composite material after the primary hot pressing and sintering, and then sequentially performing secondary hot pressing and sintering, cold rolling, and annealing to obtain a graphene aluminum-based composite material.

[0022] In an embodiment of the present invention, a silane coupling agent is first used to modify the surface of graphene oxide. The silane coupling agent reacts with the oxygen-containing groups on the surface of graphene oxide through its hydrophilic groups to form covalent bonds, thereby converting the graphene surface from hydrophilic to hydrophobic, alleviating the wettability difference with the aluminum melt. At the same time, its hydrophobic alkyl chains extend outward, producing a steric hindrance effect, effectively blocking interlamellar agglomeration, thereby improving dispersibility and interfacial compatibility. The modified graphene oxide is then mixed with aluminum powder and ball-milled, and the graphene is oriented along the surface of the aluminum-based material by magnetic field induction, thereby constructing a continuous conductive network. This structure is conducive to significantly reducing the percolation threshold, and a low-resistance path through the material can be constructed at a low addition amount, thereby improving the conductive properties of the composite material. In addition, by further introducing a zinc layer on the surface of the intermediate composite material as an interfacial transition phase, it is beneficial to suppress the formation of the brittle phase Al4C3. In summary, through coupling agent modification, magnetic field induction and zinc layer transition, high dispersion and directional arrangement of graphene are achieved, while interfacial reaction is suppressed, and the electrical conductivity and mechanical properties of graphene aluminum matrix composites are comprehensively improved, so that the resistivity of graphene aluminum matrix composites is reduced to 2.1×10 -6 Ω·m or less, tensile strength greater than 480MPa, and elongation greater than 8%.

[0023] In some optional embodiments, before applying the graphene oxide slurry to the surface of the aluminum-based material, the method further includes etching the aluminum-based material with an acid solution to form a porous etching layer on the surface of the aluminum-based material. Alternatively, the acid solution can be a mixture of hydrochloric acid and sulfuric acid, wherein the concentration of the mixture is 0.5 to 2 mol / L, the volume ratio of hydrochloric acid to sulfuric acid is 1:1 to 3:1, the etching time is 1 to 4 hours, and the pore size of each pore in the porous etching layer is 20 to 200 nm.

[0024] In this embodiment, the aluminum-based material is etched with an acid solution to form a porous structure on the surface of the aluminum-based alloy to enhance the mechanical interlocking between the graphene oxide and the aluminum-based alloy, thereby further improving the interface bonding strength between the graphene oxide and the aluminum-based material.

[0025] In some optional embodiments, in step S1, surface modification of graphene oxide using a silane coupling agent includes dispersing the graphene oxide in a solvent, then adding the silane coupling agent to carry out a surface modification reaction. The amount of the silane coupling agent added is 1% to 5% of the mass of the graphene oxide, the surface modification reaction temperature is 120 to 180°C, and the reaction time is 6 to 12 hours. The silane coupling agent may be KH550 or KH560, and the solvent may be water or an organic solvent.

[0026] In this optional embodiment, a hydrothermal reduction method is used to achieve surface modification of graphene oxide with a silane coupling agent, that is, the surface modification reaction is controlled to proceed under solvent conditions and higher temperature conditions, which is beneficial to further improve the dispersibility of graphene oxide and its interfacial compatibility with aluminum-based alloys.

[0027] In some optional embodiments, in the above step S2, when the surface-modified graphene oxide is mixed with aluminum powder and a dispersion medium, the dispersion medium is a binder such as epoxy resin. Based on the mass of the aluminum powder as 100wt%, the added amount of the modified graphene oxide is 0.5wt% to 3wt%, and the added amount of the dispersion medium is 10wt% to 15wt%.

[0028] In some optional embodiments, in the above step S3, when the aluminum-based material coated with graphene oxide slurry is placed in a parallel magnetic field for curing, the magnetic field strength is 0.5 to 1.5 T, the curing temperature is 60 to 100° C., and the curing time is 12 to 48 h.

[0029] Specifically, the magnetic field can be either parallel or alternating, preferably parallel. By precisely controlling the magnetic field intensity, the graphene is oriented on the aluminum-based surface. This is combined with wet dispersion to address initial agglomeration issues. The magnetic field is maintained until the solvent evaporates. During the slurry curing process, the magnetic field continuously acts to keep the modified graphene oxide sheets oriented. As the solvent evaporates, the sheets are "frozen" in position, forming a stable structure, resulting in an intermediate composite material.

[0030] In some optional embodiments, in the above step S4, the one-time hot pressing sintering specifically includes: The first stage: the intermediate composite material is heated from room temperature to 250 to 300 ° C and kept at this temperature for 30 to 45 minutes; The second stage: continue to heat the intermediate composite material from 250 to 300°C to 450 to 600°C and keep it warm for 0.5 to 2 hours.

[0031] Optionally, during the hot pressing sintering process, the pressure applied is 20 to 80 MPa.

[0032] It should be noted that the entire hot-pressing sintering process is performed in a vacuum environment. The present invention employs a gradient heating method for hot-pressing sintering. This method first gently removes oxygen-containing groups at a low temperature to avoid drastic outgassing, and then sinters at a higher temperature to enhance interfacial bonding. This allows for precise coordination of the contradictions between graphene oxide reduction kinetics, aluminum matrix densification, and interfacial reaction control. Furthermore, by controlling the sintering temperature below 600°C, the formation of Al4C3 at higher temperatures is reduced.

[0033] In some optional embodiments, in the above step S5, a zinc layer may be deposited on the surface of the intermediate composite material by magnetron sputtering or electroplating, and the thickness of the zinc layer is 50 to 300 nm.

[0034] In the embodiment of the present invention, a zinc layer is further deposited on the surface of the intermediate composite material as an interface transition phase to inhibit the generation of Al4C3, thereby improving the interface bonding strength.

[0035] In some optional embodiments, the temperature of the secondary hot pressing sintering is 250 to 300° C., and the pressure is 10 to 15 MPa.

[0036] In the embodiment of the present invention, the bonding tightness between the zinc layer and the intermediate composite material is further improved through the secondary hot pressing sintering process, thereby improving the interface transition effect of the zinc layer.

[0037] Furthermore, in some optional embodiments, in step S5, cold rolling is performed at room temperature, the cold rolling deformation may be 20% to 60%, and the annealing process parameters may be specifically 250 to 350°C for 1 to 3 hours. Cold rolling further densifies the material, while the annealing process further eliminates residual stress.

[0038] Yet another embodiment of the present invention further provides a graphene aluminum-based composite material, which is prepared using the above method for preparing the graphene aluminum-based composite material.

[0039] The present invention is described in detail below through specific examples and comparative examples: Example 1 The preparation method of the graphene aluminum-based composite material in this embodiment includes the following steps: Step (1): Disperse 1 g of graphene oxide in 200 mL of ethanol, add 3% KH550 coupling agent, react at 80°C for 4 h, and centrifuge to obtain modified graphene oxide.

[0040] Step (2): The Al-7Si-0.3Mg alloy was immersed in a 1 mol / L HCl solution and etched for 2 h to form a porous etched layer with a pore size of 50 to 100 nm.

[0041] Step (3): The modified graphene oxide and aluminum powder were ball-milled for 2 h, epoxy resin was added, and ultrasonic dispersion was performed for 30 min to obtain a graphene oxide slurry. Wherein, based on the mass of the aluminum powder as 100 wt%, the amount of modified graphene oxide added was 1.5 wt%, and the amount of epoxy resin added was 10 wt%.

[0042] Step (4): After coating the graphene oxide slurry on the Al-7Si-0.3Mg alloy, the alloy was placed in a 1T parallel magnetic field for curing for 24 h to obtain an intermediate composite material.

[0043] Step (5): Under vacuum conditions, the intermediate composite material is first heated from room temperature to 300°C, kept at this temperature for 30 minutes, then heated to 500°C, and subjected to a hot pressing sintering process at 50 MPa for 1 hour. A zinc layer is then plated on the surface of the intermediate composite material with a thickness of 100 nm. Finally, a second hot pressing sintering process is performed at 300°C and 10 MPa for 40 minutes.

[0044] Step (6): cold rolling the intermediate composite material after the secondary hot pressing sintering at room temperature until the deformation is 40%, and finally keeping it at 300°C for 1 hour to obtain a graphene aluminum-based composite material.

[0045] Example 2 The difference between this embodiment and embodiment 1 is that in step (3) of this embodiment, the amount of modified graphene oxide added is 2 wt% based on the mass of aluminum powder being 100 wt%; and in step (4), the graphene oxide slurry is coated on the Al-7Si-0.3Mg alloy and then placed in a parallel magnetic field of 1.1 T for curing for 24 h. The other steps are the same as those in embodiment 1.

[0046] Example 3 The difference between this embodiment and embodiment 1 is that in step (3) of this embodiment, the amount of modified graphene oxide added is 2.5 wt% based on the mass of aluminum powder being 100 wt%; and in step (4), the graphene oxide slurry is coated on the Al-7Si-0.3Mg alloy and then placed in a parallel magnetic field of 1.2 T for curing for 24 h. The other steps are the same as those in embodiment 1.

[0047] Comparative Example 1 The difference between this comparative example and Example 1 is that step (1) is not performed in this comparative example, that is, a silane coupling agent is not used to modify the surface of graphene oxide. The other steps are the same as those in Example 1.

[0048] Comparative Example 2 The difference between this comparative example and Example 1 is that step (4) in this comparative example includes: coating the graphene oxide slurry on the Al-7Si-0.3Mg alloy, and then curing it in air at room temperature and pressure for 24 hours to obtain an intermediate composite material. The other steps are the same as in Example 1.

[0049] Comparative Example 3 The difference between this comparative example and Example 1 is that step (5) in this comparative example includes: in a vacuum environment, heating the intermediate composite material from room temperature to 300°C, holding the temperature for 30 minutes, then heating it to 500°C, performing a primary hot pressing sintering at 50 MPa, holding the temperature for 1 hour, and then performing a secondary hot pressing sintering at 300°C and 10 MPa for 40 minutes. The other steps are the same as those in Example 1.

[0050] The resistivity, tensile strength and elongation of the graphene aluminum-based composite materials in Examples 1 to 3 and Comparative Examples 1 to 3 were tested, and the relevant performance data are shown in Table 1: Table 1 Resistivity, tensile strength and elongation of graphene aluminum-based composite materials in Examples 1 to 3 and Comparative Examples 1 to 3

[0051] Analysis of Table 1 shows that in Comparative Example 1, where the graphene oxide was not modified, the resulting graphene aluminum-based composite material exhibited significantly higher resistivity, but significantly lower tensile strength and elongation, than those in Examples 1 to 3. In Comparative Example 2, where no magnetic field was applied to induce alignment of the graphene oxide, the resulting graphene aluminum-based composite material exhibited significantly higher resistivity. In Comparative Example 3, where a zinc layer was introduced as an interfacial transition layer, the resulting graphene aluminum-based composite material exhibited poor mechanical properties such as tensile strength and elongation.

[0052] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will fall within the protection scope of the present invention.

Claims

1. A method for preparing a graphene aluminum-based composite material, characterized in that: include: Silane coupling agent is used to modify the surface of graphene oxide to obtain modified graphene oxide; The modified graphene oxide is mixed evenly with aluminum powder and a dispersion medium to obtain a graphene oxide slurry; placing the aluminum-based material coated with the graphene oxide slurry in a magnetic field for curing to obtain an intermediate composite material; performing a hot pressing sintering on the intermediate composite material; A zinc layer is plated on the surface of the intermediate composite material after the primary hot pressing and sintering, and then secondary hot pressing and sintering, cold rolling and annealing are carried out in sequence to obtain a graphene aluminum-based composite material.

2. The method for preparing the graphene aluminum-based composite material according to claim 1, wherein Before placing the aluminum-based material coated with the graphene oxide slurry in a magnetic field for curing, the method further comprises: The aluminum-based material is etched with an acid solution to form a porous etching layer on the surface of the aluminum-based material.

3. The method for preparing the graphene aluminum-based composite material according to claim 1, wherein The surface modification of graphene oxide using a silane coupling agent comprises: The graphene oxide is dispersed in a solvent, and then a silane coupling agent is added to perform surface modification.

4. The method for preparing the graphene aluminum-based composite material according to claim 3, wherein The graphene oxide is dispersed in a solvent, and then a silane coupling agent is added to perform a surface modification reaction, comprising: The amount of the silane coupling agent added is 1% to 5% of the mass of the graphene oxide, the temperature of the surface modification reaction is 120 to 180° C., and the reaction time is 6 to 12 h.

5. The method for preparing the graphene aluminum-based composite material according to claim 1, wherein The step of placing the aluminum-based material coated with the graphene oxide slurry in a magnetic field for curing includes: a magnetic field intensity of 0.5 to 1.5 T, a curing temperature of 60 to 100° C., and a curing time of 12 to 48 h.

6. The method for preparing the graphene aluminum-based composite material according to claim 1, wherein The primary hot pressing sintering comprises: The first stage: heating the intermediate composite material from room temperature to 250 to 300° C. and keeping the temperature for 30 to 45 minutes; The second stage: the intermediate composite material is further heated from 250 to 300° C. to 450 to 600° C. and kept at this temperature for 0.5 to 2 hours.

7. The method for preparing the graphene aluminum-based composite material according to claim 6, wherein: The pressure of the primary hot pressing sintering is 20 to 80 MPa.

8. The method for preparing the graphene aluminum-based composite material according to claim 1, wherein The temperature of the secondary hot pressing sintering is 250 to 300° C., and the pressure is 10 to 15 MPa.

9. The method for preparing the graphene aluminum-based composite material according to claim 1, wherein: In the graphene oxide slurry, based on 100 wt% of the mass of the aluminum powder, the added amount of the modified graphene oxide is 0.5 wt% to 3 wt%, and the added amount of the dispersion medium is 10 wt% to 15 wt%.

10. A graphene aluminum-based composite material, characterized in that: The graphene aluminum-based composite material is prepared by the preparation method of the graphene aluminum-based composite material according to any one of claims 1 to 9.

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