A graphene / aluminum alloy composite material and preparation method thereof

Abstract

The present invention discloses a graphene / aluminum alloy composite material, wherein the composite material has aluminum as a matrix and graphene as an additive; wherein the amount of graphene added is 0.1-5 wt.% of the composite material. The graphene / aluminum alloy composite material comprises the following process steps: (1) graphene powder and a chemical plating solution are subjected to chemical plating treatment on the graphene surface by a high-pressure homogenizer; (2) metal aluminum powder is placed in a fluidized bed device and is ready for use; (3) the graphene chemical plating treatment solution is introduced into the fluidized bed device and fully mixed with the metal aluminum powder; (4) the graphene is loaded into a graphite mold and subjected to constant temperature vacuum hot pressing sintering; (5) the graphene is naturally cooled to room temperature in the furnace; and (6) hot extrusion or hot rolling is performed to produce the graphene / aluminum alloy composite material. The material preparation process of the present invention is simple, the process is adjustable and controllable, the material preparation cost is low, the material is suitable for industrial mass production, and the market prospect is good.

Description

Technical Field

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

[0002] Over the past few decades, materials science research has focused on composite materials because they can be developed into lightweight, environmentally friendly, and high-performance devices. Aluminum and its alloys are widely used in such applications due to their excellent physical and mechanical properties, lightness, good electrical and thermal conductivity, corrosion resistance, suitability for surface treatment, and recyclability. However, aluminum surfaces are poor in certain other mechanical properties, such as low tensile strength, low wear resistance, susceptibility to corrosion, and softness. In this context, producing aluminum alloys and composites with reduced specific density and improved mechanical and metallurgical properties is one of the most important goals of contemporary materials science research. Carbon nanomaterials, particularly graphene, have been widely used as aluminum reinforcements to meet these increasingly demanding requirements.

[0003] Recent reports describe the synthesis of graphene-reinforced aluminum-based composites, including the use of liquid methods, ball milling and isostatic pressing, hot pressing or hot extrusion, ball milling and sintering, sintering or sintering and extrusion, spark plasma sintering, or ultrasonic treatment and friction stir processing. Although these methods have improved the composite materials to some extent, there are still three issues that need to be improved:

[0004] (1) How to maintain the integrity of the graphene structure, further improve its distribution uniformity in the aluminum matrix, and maximize the modification effect is a problem that requires in-depth research.

[0005] (2) Currently, graphene / aluminum composite materials are mainly prepared by powder metallurgy. Although graphene can be effectively dispersed into aluminum matrix powder through various powder mixing processes, the process is complicated and the production efficiency is low, which restricts the development of graphene / aluminum composite materials.

[0006] (3) The phenomenon of Al4C3 interface reaction products often occurring during the molding process.

[0007] When adopting powder metallurgy to prepare graphene / aluminum composite material, considering the distribution uniformity of graphene in aluminum matrix, it is necessary to modify the graphene surface so that graphene has better uniform distribution in aluminum-based material. Authorization announcement number is that the Chinese patent of CN103361637B discloses a kind of preparation method of chemical nickel-plated graphene, and this technical scheme adds coating to graphene with the process of chemical nickel plating, and the graphene coating thickness obtained is uniform, and surface is smooth and clean, without gap. However, each stage process involved in this technical scheme needs to carry out the step of ultrasonic vibration and deionized water washing, for example, graphene coarsening, graphene sensitization, graphene activation, graphene reduction and other processes, and each deionized water washing step can cause part of graphene to lose, thereby causing the significant reduction of modified graphene preparation efficiency.

[0008] Therefore, finding a preparation process for graphene-reinforced aluminum-based composite materials with simple process and good uniformity is a problem to be solved in the future. Summary of the Invention

[0009] In order to overcome the above-mentioned shortcomings of the prior art, the present invention provides a technical solution that combines the advantages of powder metallurgy and graphene surface modification methods, and prepares a graphene / aluminum alloy composite material of graphene-modified aluminum wire by combining powder metallurgy with graphene surface modification.

[0010] The purpose of the present invention is achieved by adopting the following technical solutions:

[0011] In a first aspect, the present invention provides a graphene / aluminum alloy composite material, wherein the composite material has aluminum as a matrix and graphene as an additive; wherein the addition amount of graphene is 0.1 to 5 wt.% of the composite material.

[0012] Preferably, the added amount of the graphene is 0.1 to 1 wt.% of the composite material.

[0013] Preferably, the added amount of the graphene is 0.5 wt.% of the composite material.

[0014] In a second aspect, the present invention provides a method for preparing a graphene / aluminum alloy composite material. The method is used to prepare the above-mentioned graphene / aluminum alloy composite material, comprising the following process steps:

[0015] (1) mixing graphene powder with a mixture of silver nitrate, nickel nitrate, gold nitrate, silver chloride, nickel chloride, and gold chloride with a concentration of 0.01 to 1 mol / L, and treating the mixture with a high-pressure homogenizer to obtain a graphene treatment solution;

[0016] (2) placing aluminum powder in a fluidized bed device for later use;

[0017] (3) introducing the graphene treatment solution into the fluidized bed apparatus of step (2) and mixing thoroughly to obtain a graphene / aluminum powder mixture;

[0018] (4) collecting the graphene / aluminum powder mixture and placing it into a graphite mold, and performing constant temperature vacuum hot pressing sintering;

[0019] (5) After cooling naturally to room temperature in the furnace, a sintered body of the graphene / metal aluminum composite material is obtained;

[0020] (6) The graphene / metal aluminum composite material sintered body is hot-extruded or hot-rolled to prepare a graphene / aluminum alloy composite material.

[0021] More preferably, the concentration of the mixed solution is 0.02 to 0.5 mol / L.

[0022] Preferably, in step (2), the particle size of the metal aluminum powder is 3 to 5 μm.

[0023] Preferably, in step (3), the mixing time of the graphene treatment solution and the metal aluminum powder is 1 to 2 hours.

[0024] Preferably, in step (4), the hot pressing sintering conditions are set to: temperature 550-650°C, vacuum degree 1.0×10 -2 Pa and pressure 50Mpa.

[0025] Preferably, in step (4), the hot pressing sintering time is 2 hours.

[0026] Preferably, in step (6), the temperature of hot extrusion or hot rolling is 250-300°C.

[0027] The beneficial effects of the present invention are:

[0028] 1. In the technical solution provided by the present invention, a surface-modified graphene with several atomic layers of metal deposited on the surface is prepared by adopting a low-temperature and high-pressure homogenization technology in combination with a graphene surface metal co-precipitation technology. The density of the graphene is adjusted to the same density as that of metallic aluminum by depending on the difference in the thickness of the surface metal layer. In this way, the graphene can be evenly distributed in the aluminum matrix by a simple mixing technology. In the subsequent thermal process (hot pressing, hot extrusion, hot rolling, hot forging, vacuum sintering), the metal layer on the graphene surface not only provides a good interface for fusion with metallic aluminum, but also avoids the generation of the brittle intermediate phase of Al4C3. Under the same sintering density, the electrical conductivity and mechanical strength are improved simultaneously. Thus, the industrial production of graphite-modified aluminum wire is made possible.

[0029] 2. This invention utilizes low-temperature, high-pressure homogenization combined with graphene surface metal coprecipitation and fluidized bed technology to produce a "graphene / aluminum alloy" composite material that is uniformly distributed within an aluminum alloy matrix and exhibits excellent interface bonding. This maximizes the uniformity of graphene dispersion in the aluminum alloy liquid, avoids the formation of the brittle interphase Al4C3, and simultaneously enhances electrical conductivity and mechanical strength, thereby enabling the industrial production of graphite-modified aluminum alloy wires.

[0030] 3. The material preparation process of the present invention is simple, the process is adjustable and controllable, the material preparation cost is low, it is suitable for industrial mass production, and has a good market prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present invention is further described with reference to the accompanying drawings. However, the embodiments in the accompanying drawings do not constitute any limitation to the present invention. A person skilled in the art can obtain other drawings based on the following drawings without creative effort.

[0032] Figure 1 This is a line graph comparing the resistance of different graphene addition amounts under the same sintering conditions of the present invention;

[0033] Figure 2 The present invention is directed to different pressurization directions of sintered materials;

[0034] Figure 3 is a line graph showing the effect of sintering in different pressurization directions on resistance according to the present invention;

[0035] Figure 4 yes Figure 3 The line enlargement diagram at M in the middle;

[0036] Figure 5 It is a line graph showing the effect of replacing graphene with carbon nanotubes on resistance. DETAILED DESCRIPTION

[0037] Over the past few decades, materials science research has focused on composite materials because they can be developed into lightweight, environmentally friendly, and high-performance devices. Aluminum and its alloys are widely used in such applications due to their excellent physical and mechanical properties, lightness, good electrical and thermal conductivity, corrosion resistance, suitability for surface treatment, and recyclability. However, aluminum surfaces are poor in certain other mechanical properties, such as low tensile strength, low wear resistance, susceptibility to corrosion, and softness. In this context, producing aluminum alloys and composites with reduced specific density and improved mechanical and metallurgical properties is one of the most important goals of contemporary materials science research. Carbon nanomaterials, particularly graphene, have been widely used as aluminum reinforcements to meet these increasingly demanding requirements.

[0038] Carbon is arguably nature's most versatile chemical element. Its two 3D allotropes encompass this distinction: diamond and graphite. Diamond is an extremely hard, transparent insulator, while graphite is a soft, opaque conductor. Furthermore, carbon is a prolific atomic linker, capable of forming more compounds than any other element in nature and capable of shaping unique and complex structures. Carbon is the material surface of life and the foundation of all organic chemistry. Due to its flexible bonding, carbon-based systems exhibit an unlimited number of different structures and possess an equally diverse range of physical properties. These physical properties are largely a function of the size of these structures.

[0039] The fracture strength of graphene is 42N / m. The fracture strength of steel ranges from 250 to 1200 MPa = 0.25 to 1.2×10 9 N / m 2 For the hypothetical steel film with the same thickness as graphene (which can be considered as = (i.e., the layer thickness in graphite), the two-dimensional fracture strength is 0.084-0.40 N / m. Therefore, graphene is more than 100 times stronger than the strongest steel. The thin-layer conductivity of two-dimensional materials is given by phonons. Theoretically, at a carrier density of n = 10 12 cm -2 When the mobility is limited to μ = 200,000 cm 2 V -1 s -1 Thus, the 2D sheet resistivity (also called resistance per square) is 31Ω. Therefore, the area of ​​our imaginary hammock is 1m 2 , the resistance is 31Ω. σ=enμ. Using the layer thickness, we get the bulk conductivity of graphene to be 0.96x10 6 Ω -1 cm -1 , which is slightly higher than the conductivity of copper, which is 0.60x10 6 Ω -1 cm -1 .

[0040] Metal matrix composites (MMCs) are lightweight structural materials with widespread applications in aerospace, automotive, and electronics. Boron, carbon, and silicon carbide (SiC) are commonly used as continuous fiber reinforcements, while silicon carbide (SiCp), aluminum oxide (Al2O3), and boron carbide (B4C) are conventional particulate reinforcements. Aluminum-based MMCs have attracted significant interest due to the reinforcing effects of various reinforcements, such as Al2O3 and SiC. Graphene is an alternative reinforcement material. The 2D geometry of graphene nanosheets maximizes their surface-to-volume ratio, making it an ideal candidate for incorporation into an aluminum matrix to achieve high strength and electrical conductivity. Graphene nanoplatelets (GNPs), composed of multiple layers of graphene, are significantly cheaper and easier to produce than single-layer graphene. However, the high van der Waals forces between the graphene layers tend to limit the uniform dispersion of GNPs in the metal matrix. Traditional manufacturing routes for MMCs can be categorized into liquid-state (liquid metal infiltration and casting techniques) and solid-state (powder metallurgy) methods. Liquid metal infiltration and casting involves incorporating dispersed particles into a molten matrix metal, followed by solidification. However, due to the large density difference between graphene and the metal matrix, it is difficult to evenly disperse graphene in the matrix, and liquid processing methods often produce agglomerated particles in the ductile matrix, which leads to undesirable brittleness. Furthermore, agglomeration is more severe when the particle size is below the submicron or nanometer range. This is the case when using graphene as a reinforcement material.

[0041] Several recent reports describe the synthesis of graphene-reinforced aluminum matrix composites using liquid methods, ball milling and heated isostatic pressing, hot pressing or hot extrusion, ball milling and sintering, sintering or sintering and extrusion, spark plasma sintering, or ultrasonic processing and friction stir processing, as detailed below:

[0042] 1. Liquid method for preparing graphene-reinforced aluminum-based composites

[0043] Liquid-state graphene / aluminum composites are prepared by adding graphene to a molten aluminum matrix and then cooling and solidifying the resulting composite using conventional casting equipment. This method offers broad application prospects due to its simple equipment, high production efficiency, low cost, unlimited shape and size, and the ability to achieve large-scale production.

[0044] However, the graphene / aluminum composites prepared by this method have a high number of pores. Due to the poor wettability and large difference in specific gravity between graphene and aluminum, it is difficult to evenly disperse the graphene in the molten aluminum. Furthermore, carbon and aluminum are thermodynamically unstable. In particular, when aluminum is in a molten state, the two elements form a needle-shaped Al4C3 phase, a brittle phase that is sensitive to moisture and easily pulverizes in atmospheric conditions, resulting in reduced composite material performance. To prevent reactions between the graphene and the liquid aluminum matrix and to improve wettability, the graphene often requires certain treatments.

[0045] 1.1 Preparation of graphene reinforced aluminum matrix composites by stirring melt casting method

[0046] Stir casting is a liquid preparation method that mechanically stirs the molten metal under a gas shield to create vortexes, thereby introducing reinforcements and evenly distributing them. While stir casting can achieve relatively uniform distribution of graphene within the aluminum matrix, poor wettability between the matrix and reinforcements still exists.

[0047] 1.2 Preparation of graphene reinforced aluminum matrix composites by friction stir method

[0048] The friction stir method, derived from friction stir welding, is used to prepare graphene-reinforced aluminum-based composites. The intense heat generated by friction between a rotating shoulder and the workpiece softens the material in the processing area, and friction stirring is used to uniformly mix the reinforcement and matrix. However, this method cannot accurately control the graphene content during the composite preparation process, making it difficult to stably control the composite's properties.

[0049] 2. Solid-state preparation of graphene-reinforced aluminum-based composites

[0050] The most commonly used solid-state method for preparing graphene / aluminum composites is powder metallurgy. Powder metallurgy uses mechanical mixing to create composite powders. This allows the reinforcement to be evenly mixed with the matrix powder, and the reinforcement content can be adjusted and precisely controlled. Because the preparation temperature is below the melting point of aluminum, the formation of harmful Al4C3 phases that could damage the material's properties by reacting with the aluminum can be effectively avoided. This low-temperature synthesis process also effectively controls the interface between the graphene and aluminum matrix and limits the size of the aluminum matrix grains. Powder metallurgy involves two main steps: powder mixing and forming. To further improve material density and structural uniformity, thermal deformation processes such as extrusion, hot forging, and hot rolling are often performed.

[0051] 2.1 Powder mixing method

[0052] Effective dispersion of graphene in an aluminum matrix is ​​the primary challenge in preparing graphene / aluminum composites. Simple mechanical mixing of graphene and aluminum powders does not achieve complete and uniform dispersion. To reduce graphene agglomeration, various mixing methods have been proposed in the literature, including ultrasonic dispersion, wet mechanical mixing, ball milling, planetary high-energy ball milling, surface modification, and electrostatic adsorption.

[0053] (1) Wet mechanical stirring and mixing

[0054] The simplest powder mixing method is to directly mix graphene with the matrix aluminum powder together, but the van der Waals force and electrostatic effect between the graphene sheets make it difficult to disperse the graphene, and the powder mixing effect is not good.

[0055] (2) Surface modification and charge attraction method

[0056] In order to improve the dispersibility of graphene, it is sometimes necessary to perform surface modification on graphene or aluminum powder. The dispersibility and stability of graphene and aluminum powder can be improved by adding surfactants. Surfactants can be divided into two major categories: ionic and non-ionic. Ionic surfactants include sodium dodecylbenzene sulfonate (SDBS, anionic), sodium lauryl sulfate (SDS, anionic), and hexadecyltrimethylammonium bromide (CTMAB, cationic), and non-ionic surfactants include polyethylene glycol octylphenyl ether (TritonX-100), etc., which can effectively maintain the stability of graphene nanosheets.

[0057] However, the composite powder prepared by this method needs to be vacuum dried and heat treated under argon protection to remove the surfactant film and reduce the oxidized graphene. Moreover, if the surfactant cannot be completely removed, an impurity phase will be formed, affecting the performance of the material.

[0058] (3) Ball milling

[0059] Ball milling is also an important method for mixing graphene / aluminum composite materials. However, during the dry ball milling process, the structure of graphene is often destroyed, thereby reducing the effect of graphene on improving the performance of the composite material.

[0060] 2.2 Molding process

[0061] After preparing evenly dispersed graphene / aluminum composite powder, a suitable molding process is crucial for obtaining a graphene / aluminum composite material with good performance. During the molding process, it is necessary to form a good interface between the composite powders and eliminate pores in the material to achieve a dense bond. Currently used molding methods are mainly divided into primary molding and secondary molding. Primary molding methods mainly include pressureless sintering, vacuum hot pressing sintering, high-pressure torsion, hot isostatic pressing, hot extrusion, and hot rolling. Secondary molding methods are a combination of primary molding processes.

[0062] Among them, the one-shot molding method includes:

[0063] (1) Pressureless sintering method

[0064] Pressureless sintering, in which a pre-pressed blank is heated and sintered in air or a protective atmosphere at atmospheric pressure, is the simplest method for preparing graphene / aluminum composites. During the sintering process, only two adjustable process parameters are the sintering temperature and the heating rate. Studies on sintering temperatures have shown that while sufficiently high sintering temperatures are necessary for composite densification, they also lead to grain coarsening and interfacial reactions, which degrade the composite's performance.

[0065] (2) Hot pressing sintering method

[0066] Hot pressing sintering is to place the composite powder into the mold cavity and apply unidirectional pressure while heating. This not only inhibits the growth of grains, but also facilitates densification through plastic flow of the composite powder under the action of pressure, which can reduce the sintering temperature, shorten the sintering time, and reduce the chance of grain coarsening.

[0067] (3) High-pressure torsion method

[0068] High-pressure torsion (HPT) is a commonly used processing method for producing bulk submicron and nanocrystalline materials. This method involves placing a sample in a high-pressure torsion device at pressures of several GPa. The high pressure, friction, and shear forces generated by the indenter cause the sample to deform axially and tangentially, ultimately yielding ultrafine-grained materials with significantly improved elongation and strength.

[0069] (4) Hot extrusion method

[0070] Hot extrusion is the process of placing the extruded billet into an extrusion cylinder with the same shape as the billet, and allowing it to flow out of the extrusion die hole under the action of pressure, causing the material to undergo plastic deformation, thereby improving the material properties.

[0071] (5) Hot rolling method

[0072] In recent years, in order to further improve the performance of graphene / aluminum composites, some researchers have proposed using hot rolling to prepare composite materials.

[0073] In reality, all of the aforementioned one-shot molding methods involve high-temperature processing steps, which can lead to oxidation of the metal matrix and / or reactions between the graphene and the matrix. Thermodynamic calculations indicate that Al and graphite may react at high temperatures to form Al₄C₃. Therefore, to overcome these technical challenges, the present invention employs the following preparation method.

[0074] The present invention will be further described below with reference to the following examples.

[0075] Example 1:

[0076] The present invention provides a graphene / aluminum alloy composite material. The composite material takes aluminum as a matrix and graphene as an additive. The additive amount of the graphene is 0.1% of the composite material.

[0077] The preparation method of the above-mentioned graphene / aluminum alloy composite material comprises the following process steps:

[0078] (1) mixing graphene powder with a mixture of silver nitrate, nickel nitrate, gold nitrate, silver chloride, nickel chloride, and gold chloride with a concentration of 0.01 to 1 mol / L, and treating the mixture with a high-pressure homogenizer to obtain a graphene treatment solution;

[0079] (2) placing aluminum powder in a fluidized bed device for later use;

[0080] (3) introducing the graphene treatment solution into the fluidized bed apparatus of step (2) and mixing thoroughly to obtain a graphene / aluminum powder mixture;

[0081] (4) collecting the graphene / aluminum powder mixture and placing it into a graphite mold, and performing constant temperature vacuum hot pressing sintering;

[0082] (5) After cooling naturally to room temperature in the furnace, a sintered body of the graphene / metal aluminum composite material is obtained;

[0083] (6) The graphene / metal aluminum composite material sintered body is hot-extruded or hot-rolled to prepare a graphene / aluminum alloy composite material.

[0084] In the step (2), the particle size of the metal aluminum powder is 3 to 5 μm.

[0085] In the step (3), the mixing time of the graphene treatment solution and the metal aluminum powder is 1 to 2 hours.

[0086] In step (4), the hot pressing sintering conditions are set as follows: temperature 550-650°C, vacuum degree 1.0×10 -2 Pa and pressure 50Mpa.

[0087] In the step (4), the hot pressing sintering time is 2 hours.

[0088] In the step (6), the temperature of hot extrusion or hot rolling is 250-300°C.

[0089] Example 2

[0090] The present invention provides a graphene / aluminum alloy composite material. The composite material takes aluminum as a matrix and graphene as an additive. The additive amount of the graphene is 0.5% of the composite material.

[0091] The preparation method of the above-mentioned graphene / aluminum alloy composite material comprises the following process steps:

[0092] (1) mixing graphene powder with a mixture of silver nitrate, nickel nitrate, gold nitrate, silver chloride, nickel chloride, and gold chloride with a concentration of 0.01 to 1 mol / L, and treating the mixture with a high-pressure homogenizer to obtain a graphene treatment solution;

[0093] (2) placing aluminum powder in a fluidized bed device for later use;

[0094] (3) introducing the graphene treatment solution into the fluidized bed apparatus of step (2) and mixing thoroughly to obtain a graphene / aluminum powder mixture;

[0095] (4) collecting the graphene / aluminum powder mixture and placing it into a graphite mold, and performing constant temperature vacuum hot pressing sintering;

[0096] (5) After cooling naturally to room temperature in the furnace, a sintered body of the graphene / metal aluminum composite material is obtained;

[0097] (6) The graphene / metal aluminum composite material sintered body is hot-extruded or hot-rolled to prepare a graphene / aluminum alloy composite material.

[0098] In the step (2), the particle size of the metal aluminum powder is 3 to 5 μm.

[0099] In the step (3), the mixing time of the graphene treatment solution and the metal aluminum powder is 1 to 2 hours.

[0100] In step (4), the hot pressing sintering conditions are set as follows: temperature 550-650°C, vacuum degree 1.0×10 -2 Pa and pressure 50Mpa.

[0101] In the step (4), the hot pressing sintering time is 2 hours.

[0102] In the step (6), the temperature of hot extrusion or hot rolling is 250-300°C.

[0103] Example 3

[0104] The present invention provides a graphene / aluminum alloy composite material. The composite material takes aluminum as a matrix and graphene as an additive. The additive amount of the graphene is 1% of the composite material.

[0105] The preparation method of the above-mentioned graphene / aluminum alloy composite material comprises the following process steps:

[0106] (1) mixing graphene powder with a mixture of silver nitrate, nickel nitrate, gold nitrate, silver chloride, nickel chloride, and gold chloride with a concentration of 0.01 to 1 mol / L, and treating the mixture with a high-pressure homogenizer to obtain a graphene treatment solution;

[0107] (2) placing aluminum powder in a fluidized bed device for later use;

[0108] (3) introducing the graphene treatment solution into the fluidized bed apparatus of step (2) and mixing thoroughly to obtain a graphene / aluminum powder mixture;

[0109] (4) collecting the graphene / aluminum powder mixture and placing it into a graphite mold, and performing constant temperature vacuum hot pressing sintering;

[0110] (5) After cooling naturally to room temperature in the furnace, a sintered body of the graphene / metal aluminum composite material is obtained;

[0111] (6) The graphene / metal aluminum composite material sintered body is hot-extruded or hot-rolled to prepare a graphene / aluminum alloy composite material.

[0112] In the step (2), the particle size of the metal aluminum powder is 3 to 5 μm.

[0113] In the step (3), the mixing time of the graphene treatment solution and the metal aluminum powder is 1 to 2 hours.

[0114] In step (4), the hot pressing sintering conditions are set as follows: temperature 550-650°C, vacuum degree 1.0×10 -2 Pa and pressure 50Mpa.

[0115] In the step (4), the hot pressing sintering time is 2 hours.

[0116] In the step (6), the temperature of hot extrusion or hot rolling is 250-300°C.

[0117] Example 4

[0118] The present invention provides a graphene / aluminum alloy composite material. The composite material takes aluminum as a matrix and graphene as an additive. The additive amount of the graphene is 2% of the composite material.

[0119] The preparation method of the above-mentioned graphene / aluminum alloy composite material comprises the following process steps:

[0120] (1) mixing graphene powder with a mixture of silver nitrate, nickel nitrate, gold nitrate, silver chloride, nickel chloride, and gold chloride with a concentration of 0.01 to 1 mol / L, and treating the mixture with a high-pressure homogenizer to obtain a graphene treatment solution;

[0121] (2) placing aluminum powder in a fluidized bed device for later use;

[0122] (3) introducing the graphene treatment solution into the fluidized bed apparatus of step (2) and mixing thoroughly to obtain a graphene / aluminum powder mixture;

[0123] (4) collecting the graphene / aluminum powder mixture and placing it into a graphite mold, and performing constant temperature vacuum hot pressing sintering;

[0124] (5) After cooling naturally to room temperature in the furnace, a sintered body of the graphene / metal aluminum composite material is obtained;

[0125] (6) The graphene / metal aluminum composite material sintered body is hot-extruded or hot-rolled to prepare a graphene / aluminum alloy composite material.

[0126] In the step (2), the particle size of the metal aluminum powder is 3 to 5 μm.

[0127] In the step (3), the mixing time of the graphene treatment solution and the metal aluminum powder is 1 to 2 hours.

[0128] In step (4), the hot pressing sintering conditions are set as follows: temperature 550-650°C, vacuum degree 1.0×10 -2 Pa and pressure 50Mpa.

[0129] In the step (4), the hot pressing sintering time is 2 hours.

[0130] In the step (6), the temperature of hot extrusion or hot rolling is 250-300°C.

[0131] Example 5

[0132] The present invention provides a graphene / aluminum alloy composite material. The composite material takes aluminum as a matrix and graphene as an additive. The additive amount of the graphene is 5% of the composite material.

[0133] The preparation method of the above-mentioned graphene / aluminum alloy composite material comprises the following process steps:

[0134] (1) mixing graphene powder with a mixture of silver nitrate, nickel nitrate, gold nitrate, silver chloride, nickel chloride, and gold chloride with a concentration of 0.01 to 1 mol / L, and treating the mixture with a high-pressure homogenizer to obtain a graphene treatment solution;

[0135] (2) placing aluminum powder in a fluidized bed device for later use;

[0136] (3) introducing the graphene treatment solution into the fluidized bed apparatus of step (2) and mixing thoroughly to obtain a graphene / aluminum powder mixture;

[0137] (4) collecting the graphene / aluminum powder mixture and placing it into a graphite mold, and performing constant temperature vacuum hot pressing sintering;

[0138] (5) After cooling naturally to room temperature in the furnace, a sintered body of the graphene / metal aluminum composite material is obtained;

[0139] (6) The graphene / metal aluminum composite material sintered body is hot-extruded or hot-rolled to prepare a graphene / aluminum alloy composite material.

[0140] In the step (2), the particle size of the metal aluminum powder is 3 to 5 μm.

[0141] In the step (3), the mixing time of the graphene treatment solution and the metal aluminum powder is 1 to 2 hours.

[0142] In step (4), the hot pressing sintering conditions are set as follows: temperature 550-650°C, vacuum degree 1.0×10 -2 Pa and pressure 50Mpa.

[0143] In the step (4), the hot pressing sintering time is 2 hours.

[0144] In the step (6), the temperature of hot extrusion or hot rolling is 250-300°C.

[0145] Comparative Example

[0146] The present invention provides a pure aluminum material, wherein the material takes aluminum as a matrix; wherein the addition amount of graphene is 0%.

[0147] The preparation method of the above-mentioned graphene / aluminum alloy composite material comprises the following process steps:

[0148] (1) Put the aluminum powder into the graphite mold and perform constant temperature vacuum hot pressing sintering;

[0149] (2) After the furnace is naturally cooled to room temperature, a pure aluminum sintered body is obtained;

[0150] (3) The pure aluminum sintered body is hot-extruded or hot-rolled to produce pure aluminum material.

[0151] In the step (1), the particle size of the metal aluminum powder is 3 to 5 μm.

[0152] In the step (1), the hot pressing sintering conditions are set as follows: temperature 550-650°C, vacuum degree 1.0×10 -2 Pa and pressure 50Mpa.

[0153] In the step (1), the hot pressing sintering time is 2 hours.

[0154] In the step (3), the temperature of hot extrusion or hot rolling is 250-300°C.

[0155] In order to more clearly illustrate the present invention, the performance of the graphene / aluminum alloy composite materials or pure aluminum materials prepared in Examples 1 to 5 of the present invention and the comparative examples were tested and compared.

[0156] 1. Resistance comparison of different graphene additions under the same sintering conditions

[0157] like Figure 1 The figure shows the comparison of the resistance axis curves of various materials prepared in Examples 1 to 5 of the present invention and the comparative example. Figure 1 It can be seen that after adding graphene using the method of the present invention, the resistance value of the sintered body can be effectively reduced, and when the graphene content is 0.5wt.%, the resistance value is the lowest, and compared with the resistance value without adding graphene, it is reduced by two orders of magnitude. After that, as the graphene content increases, the resistance value will continue to increase, but generally speaking, it is one order of magnitude lower than the resistance value of the material without adding graphene.

[0158] 2. Effect of sintering in different pressure directions on resistance

[0159] like Figures 2-3 As shown, various materials prepared in Examples 1 to 5 of the present invention and the comparative examples are subjected to different pressurization directions.

[0160] Among them, parallel is AA, which refers to the force direction of the parallel hot press; vertical is BB / CC, which refers to the force direction of the vertical hot press.

[0161] The results show that the resistance value in the AA direction parallel to the vacuum hot press is approximately 20% lower than the resistance value in the BB / CC direction perpendicular to the vacuum hot press. This indicates that during the vacuum hot press process, the graphene is affected by the pressure within the aluminum matrix, self-adjusting its orientation and creating anisotropic conductivity.

[0162] 3. Experiment of replacing graphene with CNT with equal amount of carbon

[0163] The present invention also makes CNT (carbon nanotube) replace graphene and dopes it into aluminum alloy composite material, wherein, keep the total carbon content unchanged, make CNT replace part (or all) of graphene, observe its performance in aluminum alloy composite material, the final result obtained is as follows Figure 5 shown.

[0164] The results show that in the process of carbon nanotubes replacing graphene, the resistance has been increasing, which is several to dozens of times higher than the resistance when pure graphene is added. The possible reason for this phenomenon is that CNT is more difficult to disperse than graphene and is more likely to agglomerate, which in turn produces many small voids in the matrix, increasing the resistance.

[0165] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a graphene / aluminum alloy composite material, characterized in that: The composite material is based on aluminum and graphene is added as an additive; wherein the amount of graphene added is 0.1-5wt.% of the composite material. The method comprises the following process steps: (1) mixing graphene powder with a mixture of silver nitrate, nickel nitrate, gold nitrate, silver chloride, nickel chloride, and gold chloride with a concentration of 0.01 to 1 mol / L, and treating the mixture with a high-pressure homogenizer to obtain a graphene treatment solution; (2) Place the aluminum powder in a fluidized bed device for later use; (3) introducing the graphene treatment liquid into the fluidized bed apparatus of step (2), and after being fully mixed with the metallic aluminum powder, obtaining a graphene / aluminum powder mixture; (4) Collecting the graphene / aluminum powder mixture and placing it into a graphite mold for constant temperature vacuum hot pressing sintering; (5) After cooling naturally to room temperature in the furnace, a sintered body of graphene / metal aluminum composite material is obtained; (6) The graphene / metal aluminum composite material sintered body is hot-extruded or hot-rolled to prepare a graphene / aluminum alloy composite material.

2. The method for preparing a graphene / aluminum alloy composite material according to claim 1, wherein: In the step (2), the particle size of the metal aluminum powder is 3-5 μm.

3. The method for preparing a graphene / aluminum alloy composite material according to claim 1, wherein: In the step (3), the mixing time of the graphene treatment solution and the metal aluminum powder is 1 to 2 hours.

4. The method for preparing a graphene / aluminum alloy composite material according to claim 1, wherein: In step (4), the hot pressing sintering conditions are set as follows: temperature 550-650°C, vacuum degree 1.0×10 -2 Pa and pressure 50Mpa.

5. The method for preparing a graphene / aluminum alloy composite material according to claim 1, wherein: In the step (4), the hot pressing sintering time is 2 hours.

6. The method for preparing a graphene / aluminum alloy composite material according to claim 1, wherein: In the step (6), the temperature of hot extrusion or hot rolling is 250-300°C.

7. The graphene / aluminum alloy composite material prepared according to any one of claims 1 to 6.

8. The graphene / aluminum alloy composite material according to claim 7, characterized in that The added amount of the graphene is 0.1-1 wt.% of the composite material.

9. The graphene / aluminum alloy composite material according to claim 8, characterized in that The added amount of the graphene is 0.5 wt.% of the composite material.

Images