Graphene aluminum-based composite material and preparation method thereof

Abstract

The invention belongs to the technical field of composite material preparation, and particularly relates to a graphene aluminum-based composite material and a preparation method thereof. In order to solve the problems that when a graphene aluminum-based composite material is prepared through an existing method, mixing is prone to being uneven, graphene is prone to being burnt to form an aluminum-carbon phase, and the comprehensive performance needs to be improved, the preparation method of the graphene aluminum-based composite material is provided and comprises the following steps that a, graphene sheets and aluminum powder are weighed, and the graphene sheets are added into an isopropanol solution to be pretreated; adding polydimethylsiloxane into the aluminum powder to obtain flaky aluminum powder; b, the pretreated graphene, aluminum powder and a dispersing agent are jointly added into a conical mixing machine to be mixed, exhaust and cold isostatic pressing are conducted, then sintering is conducted, extrusion molding is conducted, and a graphene aluminum base material is obtained; and c, adding the graphene aluminum base material into pure aluminum water according to a certain proportion, fully stirring, cooling, extruding, and performing stress relief annealing to obtain the graphene aluminum-based composite material. The method can protect graphene, reduce defects, save energy and time, and is suitable for industrial production.

Description

Technical Field

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

[0002] With the continuous development of my country's industry, the demand for aluminum and its alloys in rail transportation, intelligent manufacturing and aerospace is increasing, and the performance requirements for aluminum and its alloy products are also getting higher and higher. It is difficult for a single material to meet the use requirements of complex, harsh and high-precision cutting-edge environments, and composite materials have become a trend in material development. There are endless studies on adding a second phase with certain specific properties to the metal matrix to form a composite material with specific properties.

[0003] In recent years, carbon-enhanced phases such as graphene have become a research hotspot in the field of composite materials because of their excellent comprehensive performance. The two-dimensional structure of graphene and the interface of aluminum bonding become larger, which can induce geometric dislocations and forest dislocations, increase the strain hardening ability of composite materials and improve elongation. Therefore, adding graphene is expected to improve the strength and plasticity of composite materials at the same time, and solve the problems of low plasticity and poor deformation ability of carbon-enhanced aluminum-based composite materials. However, due to the high specific surface area of ​​graphene, it is difficult to disperse in the aluminum matrix, especially through traditional casting processes. It is difficult to achieve processing, and the cost of using powder metallurgy processes is high, and it is difficult to industrialize on a large scale. In the current method, since graphene and aluminum powder are difficult to disperse, the high temperature in the mixing process easily forms an aluminum-carbon phase, thereby affecting the electrical conductivity and mechanical properties of the material, etc., there is no graphene aluminum-based composite material that reduces graphene damage, reduces aluminum-carbon phase formation, and enhances the comprehensive performance of composite materials, which is urgently needed to be developed. Summary of the invention

[0004] The technical problem to be solved by the present invention is that the existing method for preparing graphene aluminum-based composite materials is prone to uneven mixing, and graphene is easily burned to form an aluminum-carbon phase, and the comprehensive performance needs to be improved.

[0005] The technical solution of the present invention to solve the above technical problem is: to provide a method for preparing a graphene aluminum-based composite material. The method comprises the following steps:

[0006] a. Weigh graphene sheets and aluminum powder, add the graphene sheets to an isopropanol solution, and perform ultrasonic treatment for 1 to 2 hours to obtain pretreated graphene; add polydimethylsiloxane to the aluminum powder, and perform ball milling for 1 to 2 hours to obtain flaky aluminum powder;

[0007] b. Adding the graphene pretreated in step a, aluminum powder and dispersant into a conical mixer for mixing, introducing inert gas for exhaust during mixing, sintering after cold isostatic pressing, and extruding to obtain a graphene aluminum matrix;

[0008] c. Add graphene aluminum matrix material into pure aluminum water in a certain proportion, fully stir, cool, extrude, and perform stress relief annealing to obtain graphene aluminum-based composite material.

[0009] Among them, in the preparation method of the above-mentioned graphene aluminum-based composite material, the graphene sheet described in step a has a diameter of 5 to 50 μm, a thickness of 5 to 15 nm, and a number of layers ≤10.

[0010] Wherein, in the preparation method of the above-mentioned graphene aluminum-based composite material, the average particle size of the aluminum powder described in step a is 20 to 50 μm.

[0011] Wherein, in the preparation method of the above-mentioned graphene aluminum-based composite material, the graphene sheets described in step a account for 0.5-3wt%, and the aluminum powder accounts for 97-99.5wt%.

[0012] Wherein, in the preparation method of the above-mentioned graphene aluminum-based composite material, the concentration of the isopropanol solution in step a is 1-5%, and the added amount is 2-3 times the weight of the graphene.

[0013] Wherein, in the preparation method of the above-mentioned graphene aluminum-based composite material, the ultrasonic treatment power described in step a is 200-500W, and the stirring speed is 100-200r / min.

[0014] Wherein, in the preparation method of the above-mentioned graphene aluminum-based composite material, the addition amount of the polydimethylsiloxane described in step a is 1 to 10% of the weight of the aluminum powder.

[0015] Among them, in the preparation method of the above-mentioned graphene aluminum-based composite material, the ball milling described in step a uses oxide ceramic balls with a diameter of 2 to 3 mm, the ball-to-material ratio is 5 to 10:1, and the ball milling speed is 400 to 500 rpm.

[0016] Wherein, in the preparation method of the above-mentioned graphene aluminum-based composite material, the dispersant described in step b is polyethylene glycol, and the amount of the dispersant added is 30 to 80% of the total amount of graphene and aluminum powder.

[0017] Wherein, in the preparation method of the above-mentioned graphene aluminum-based composite material, the conical mixer described in step b is a single-helix conical mixer or a double-helix conical mixer.

[0018] Wherein, in the preparation method of the above-mentioned graphene aluminum-based composite material, the inert gas described in step b is at least one of argon, nitrogen, helium or neon.

[0019] Wherein, in the preparation method of the above-mentioned graphene aluminum-based composite material, the temperature during the cold isostatic pressing described in step b is 100-150° C. and the pressure is 150-500 MPa.

[0020] Wherein, in the preparation method of the above-mentioned graphene aluminum-based composite material, the annealing temperature described in step c is 260-400° C., and the annealing time is 4-6 hours.

[0021] The present invention also provides a graphene aluminum-based composite material directly prepared by the above method.

[0022] The beneficial effects of the present invention are:

[0023] The present invention provides a method for preparing a graphene aluminum-based composite material. The graphene and aluminum powder are first pre-treated respectively. After the graphene and isopropyl alcohol are pre-dispersed, the dispersion uniformity of the graphene is improved, and the mixing effect is better. The present invention also uses a polydimethylsiloxane to pre-ball-mill the aluminum powder. The treated aluminum powder has a flaky structure, which increases the contact area with the graphene, makes the mixing more uniform, and avoids ball-milling with the graphene, thereby reducing the damage to the graphene during mixing. Furthermore, the present invention uses a spiral conical mixer during mixing, which can reduce the burning of graphene more than the traditional ball-milling method, greatly improves the mixing efficiency, and avoids the formation of aluminum-carbon phase at high temperature, thereby improving the mechanical properties and elongation of the graphene aluminum-based composite material. The preparation method of the present invention has a simple process, a reliable and efficient process, and is easy to realize industrial mass production. The prepared graphene aluminum-based composite material has excellent comprehensive performance and can be used in fine fields with higher requirements for aluminum alloy performance. DETAILED DESCRIPTION

[0024] The present invention provides a method for preparing a graphene aluminum-based composite material. The method comprises the following steps:

[0025] a. Weigh graphene sheets and aluminum powder, add the graphene sheets to an isopropanol solution, and perform ultrasonic treatment for 1 to 2 hours to obtain pretreated graphene; add polydimethylsiloxane to the aluminum powder, and perform ball milling for 1 to 2 hours to obtain flaky aluminum powder;

[0026] b. Adding the graphene pretreated in step a, aluminum powder and dispersant into a conical mixer for mixing, introducing inert gas for exhaust during mixing, sintering after cold isostatic pressing, and extruding to obtain a graphene aluminum matrix;

[0027] c. Add graphene aluminum matrix material into pure aluminum water in a certain proportion, stir thoroughly, cool, extrude, and then perform stress relief annealing at a temperature of 260 to 400°C for 4 to 6 hours to obtain a graphene aluminum-based composite material.

[0028] In order to improve the dispersion effect of graphene, the present invention pre-treats the graphene and aluminum powder before mixing them, and screens the most suitable pre-treatment method through a large number of experiments. For graphene, the present invention uses isopropyl alcohol to pre-disperse it, thereby improving the dispersion uniformity of graphene and achieving a better mixing effect.

[0029] The key point of the present invention is that the aluminum powder is pretreated with polydimethylsiloxane, which is a high molecular polymer with controllable viscosity. When polydimethylsiloxane is ball-milled with aluminum powder, the aluminum powder gradually deforms into a flaky structure as the ball-milling time increases. The present invention ball-mills the aluminum powder into a flaky structure, increases the contact range between the aluminum powder and graphene, and obtains flaky aluminum powder with a large flake diameter, which is conducive to the uniform dispersion of graphene in the aluminum powder, increases the graphene coating content on the surface of the aluminum powder, and avoids graphene agglomeration in the system. At the same time, the reduction in the graphene defect content also retains the structural strength of the graphene, while avoiding the formation of the interface brittle phase.

[0030] In the present invention, the addition amount of graphene is 0.5-3wt%. If the content of graphene is too low, the function of the reinforcing phase is weak, and the comprehensive performance of the obtained composite material is poor. If the content of graphene is too high, burning defects are easily generated, which will also affect the comprehensive performance of the composite material.

[0031] On the one hand, the graphene of the present invention is not ball-milled, but is stirred and mixed by a mixer, thereby avoiding mechanical damage. On the other hand, during the stirring process, since the present invention adopts polydimethylsiloxane, it can play a role of lubrication and buffering. Since it has a certain viscosity, it will be evenly coated on the surface of graphene and aluminum powder during stirring, which is conducive to reducing the defect damage of graphene. Through the combined effect of the above measures, the method of the present invention significantly improves the dispersibility of graphene and aluminum powder, reduces the defect damage of graphene, and in the prepared graphene aluminum-based composite material, the graphene is evenly dispersed, and the structural integrity is maintained well, and no brittle phase Al4C3 is generated.

[0032] The specific implementation contents of the present invention will be further explained below through examples, but it is not intended to limit the protection scope of the present invention to the scope described in the examples.

[0033] The graphene sheets used in the examples have a sheet diameter of 150-350 nm, a thickness of 5-10 nm, and a layer number of ≤ 10. The average particle size of the aluminum powder is 20-50 μm.

[0034] The remaining reagents and equipment are common commercial products.

[0035] Example 1 Preparation of graphene aluminum-based composite materials using the method of the present invention

[0036] The specific steps are as follows:

[0037] a. Weigh 5 g of graphene sheets and 995 g of aluminum powder, add the graphene sheets to 10 g of 5% isopropanol solution, and ultrasonically treat for 2 h at 100 r / min to obtain pretreated graphene; add 99.5 g of polydimethylsiloxane to the aluminum powder, and ball mill for 1 h. The ball mill uses a 3 mm diameter white oxide ceramic ball, a ball-to-material ratio of 5:1, and a ball milling speed of 400 rpm to obtain flaky aluminum powder;

[0038] b. Add the graphene pretreated in step a, aluminum powder and 300 g of polyethylene glycol into a conical mixer and mix them. During mixing, introduce argon gas for exhaust. Cold isostatic pressing and sintering are performed at 100° C. and 150 MPa, and extrusion molding is performed to obtain a graphene aluminum matrix.

[0039] c. Add graphene aluminum matrix material into pure aluminum water in a certain proportion, stir thoroughly, cool, extrude, and then perform stress relief annealing at a temperature of 260°C for 4 hours to obtain a graphene aluminum-based composite material.

[0040] Example 2 Preparation of graphene aluminum-based composite materials using the method of the present invention

[0041] The specific steps are as follows:

[0042] a. Weigh 30 g of graphene sheets and 970 g of aluminum powder, add the graphene sheets to 90 g of 5% isopropanol solution, and ultrasonically treat for 1 h at 200 r / min to obtain pretreated graphene; add 9.7 g of polydimethylsiloxane to the aluminum powder, and ball mill for 2 h. The ball mill uses a 3 mm diameter white oxide ceramic ball, a ball-to-material ratio of 5:1, and a ball milling speed of 400 rpm to obtain flaky aluminum powder;

[0043] b. Add the graphene pretreated in step a, aluminum powder and 800 g of polyethylene glycol into a conical mixer and mix them. During mixing, introduce argon gas for exhaust. Cold isostatic pressing and sintering are performed at 100° C. and 150 MPa, and extrusion molding is performed to obtain a graphene aluminum matrix.

[0044] c. Add graphene aluminum matrix material into pure aluminum water in a certain proportion, stir thoroughly, cool, extrude, and then perform stress relief annealing at a temperature of 400°C for 6 hours to obtain a graphene aluminum-based composite material.

[0045] Example 3 Preparation of graphene aluminum-based composite materials using the method of the present invention

[0046] The specific steps are as follows:

[0047] a. Weigh 2 kg of graphene sheets and 98 kg of aluminum powder, add the graphene sheets to 4 kg of 5% isopropanol solution, and ultrasonically treat for 2 h at 100 r / min to obtain pretreated graphene; add 4.9 kg of polydimethylsiloxane to the aluminum powder, and ball mill for 1 h. The ball mill uses a 3 mm diameter white oxide ceramic ball, a ball-to-material ratio of 5:1, and a ball milling speed of 400 rpm to obtain flaky aluminum powder;

[0048] b. Add the graphene pretreated in step a, aluminum powder and 50 kg of polyethylene glycol into a conical mixer and mix them. During mixing, introduce argon gas for exhaust. Cold isostatic pressing and sintering are performed at 100° C. and 150 MPa, and extrusion molding is performed to obtain a graphene aluminum matrix.

[0049] c. Add graphene aluminum matrix material into pure aluminum water in a certain proportion, stir thoroughly, cool, extrude, and then perform stress relief annealing at a temperature of 300°C for 5 hours to obtain a graphene aluminum-based composite material.

[0050] Comparative Example 1 Preparation of graphene aluminum-based composite materials without pretreatment of graphene

[0051] Except that the graphene is used directly in step a without pretreatment, the other parameters are the same as those in Example 1.

[0052] Comparative Example 2 Preparation of graphene aluminum-based composite materials without pretreatment of aluminum powder

[0053] Except that the aluminum powder in step a is used directly without pretreatment, other parameters are the same as those in Example 1.

[0054] Comparative Example 3: Preparation of graphene aluminum-based composite materials by ball milling

[0055] The specific steps are as follows:

[0056] a. Weigh 5 g of graphene sheets and 995 g of aluminum powder, add the graphene sheets to 10 g of 5% isopropanol solution, and ultrasonically treat for 2 h at 100 r / min to obtain pretreated graphene; add 99.5 g of polydimethylsiloxane to the aluminum powder, and ball mill for 1 h. The ball mill uses a 3 mm diameter white oxide ceramic ball, a ball-to-material ratio of 5:1, and a ball milling speed of 400 rpm to obtain flaky aluminum powder;

[0057] b. The graphene pretreated in step a, aluminum powder and 300 g of polyethylene glycol are ball-milled together for 2 h, and then hot isostatically pressed at 500° C. and 150 MPa, extruded to obtain a graphene aluminum rod, and stress-relief annealed at 210° C. for 4 h to obtain a graphene aluminum-based composite material.

[0058] Comparative Example 4: Preparation of graphene aluminum-based composite materials by changing some of the preparation parameters of the present invention

[0059] The specific steps are as follows:

[0060] a. Weigh 5 g of graphene sheets and 995 g of aluminum powder, add the graphene sheets to 5 g of 5% isopropanol solution, and ultrasonically treat for 2 h at 100 r / min to obtain pretreated graphene; add 200 g of polydimethylsiloxane to the aluminum powder, and ball mill for 1 h. The ball mill uses a 3 mm diameter white oxide ceramic ball, a ball-to-material ratio of 5:1, and a ball milling speed of 400 rpm to obtain flaky aluminum powder;

[0061] b. Add the graphene pretreated in step a, aluminum powder and 200 g of polyethylene glycol into a conical mixer and mix them. During mixing, introduce argon gas for exhaust. Cold isostatic pressing and sintering are performed at 100° C. and 150 MPa. Graphene aluminum rods are obtained by extrusion molding, and stress relief annealing is performed at 210° C. for 4 h to obtain graphene aluminum-based composite materials.

[0062] The graphene aluminum-based composite materials prepared in the examples and comparative examples were tested for their mechanical properties at room temperature, the testing method was carried out in accordance with GB / T228.1-2010, and the tensile rate was 0.2 mm / min. The results of the mechanical properties are shown in Table 1 below.

[0063] Table 1 Mechanical properties of different graphene aluminum matrix composites

[0064] Yield strength MPa Tensile strength MPa Elongation % Example 1 259 307 22.1 Example 2 296 361 13.7 Example 3 271 352 16.4 Comparative Example 1 232 285 19.5 Comparative Example 2 239 279 18.3 Comparative Example 3 221 266 16.9 Comparative Example 4 244 290 20.6

[0065] It can be seen from the results of the embodiments and comparative examples that the graphene aluminum-based composite materials prepared by the embodiments of the method of the present invention have improved yield strength, tensile strength and elongation to varying degrees, and have excellent strength and plasticity. This is attributed to the fact that the present invention reduces the burning of graphene and enhances the effect of the interface bonding between graphene and aluminum. The method of the present invention provides a new option for preparing high-performance graphene aluminum-based composite materials.

[0066] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for preparing a graphene aluminum-based composite material, characterized in that: The following steps are involved: a. Weigh graphene sheets and aluminum powder, add the graphene sheets to an isopropanol solution, and perform ultrasonic treatment for 1 to 2 hours to obtain pretreated graphene; add polydimethylsiloxane to the aluminum powder, and perform ball milling for 1 to 2 hours to obtain flaky aluminum powder; b. Adding the graphene pretreated in step a, aluminum powder and dispersant into a conical mixer for mixing, introducing inert gas for exhaust during mixing, sintering after cold isostatic pressing, and extruding to obtain a graphene aluminum matrix; c. Add graphene aluminum matrix material into pure aluminum water in a certain proportion, fully stir, cool, extrude, and perform stress relief annealing to obtain graphene aluminum-based composite material.

2. The method for preparing the graphene aluminum-based composite material according to claim 1, characterized in that: The graphene sheets described in step a have a diameter of 5 to 50 μm, a thickness of 5 to 15 nm, and a number of layers of ≤10; and the average particle size of the aluminum powder described in step a is 20 to 50 μm.

3. The method for preparing the graphene aluminum-based composite material according to claim 1, characterized in that: The graphene sheets described in step a account for 0.5-3wt%, and the aluminum powder accounts for 97-99.5wt%.

4. The method for preparing the graphene aluminum-based composite material according to claim 1, characterized in that: The ultrasonic treatment power in step a is 200-500W, and the stirring speed is 100-200r / min.

5. The method for preparing the graphene aluminum-based composite material according to claim 1, characterized in that: The amount of polydimethylsiloxane added in step a is 1 to 10% of the weight of the aluminum powder.

6. The method for preparing the graphene aluminum-based composite material according to claim 1, characterized in that: The ball mill described in step a uses oxidized ceramic balls with a diameter of 2 to 3 mm, a ball-to-material ratio of 5 to 10:1, and a ball mill speed of 400 to 500 rpm.

7. The method for preparing the graphene aluminum-based composite material according to claim 1, characterized in that: The dispersant described in step b is polyethylene glycol, and the amount of the dispersant added is 30 to 80% of the total amount of graphene and aluminum powder.

8. The method for preparing the graphene aluminum-based composite material according to claim 1, characterized in that: The conical mixer described in step b is a single-helix conical mixer or a double-helix conical mixer.

9. The method for preparing the graphene aluminum-based composite material according to claim 1, characterized in that: The inert gas described in step b is at least one of argon, nitrogen, helium or neon.

10. The graphene aluminum-based composite material prepared by the method for preparing the graphene aluminum-based composite material according to any one of claims 1 to 9.