A method for preparing an isotropic mesh graphene-aluminum composite material

Abstract

A method for preparing an isotropic mesh graphene-aluminum composite material relates to a method for preparing a graphene-aluminum composite material. In order to achieve isotropic distribution of graphene in aluminum-based composite materials, and solve the problems of carbon-aluminum interface reaction, low graphene-aluminum bonding strength, and discontinuous graphene layers. The present invention mechanically ball-milled graphene is closely attached to the surface of aluminum metal powder through the strong chemical bonding of the skeleton structure metal, which is conducive to the uniform dispersion of high-content graphene in the preform. The mesh-connected skeleton structure constructed during the sintering process provides a three-dimensional path for the conduction of graphene stress and heat flow, showing macroscopic isotropy; the graphene sheets are bridged by the skeleton structure metal and the infiltrated aluminum metal, which effectively ensures the full conduction of stress between the graphene sheets, relieves material stress concentration, and is conducive to achieving material strain homogenization. The skeleton structure metal effectively improves the interface bonding between the graphene-aluminum metal matrix.

Description

Technical Field

[0001] The invention relates to a method for preparing a graphene-aluminum composite material. Background Art

[0002] Graphene is a two-dimensional reinforcement with extremely high theoretical strength. Its use in aluminum-based composites is expected to achieve a breakthrough in the performance of existing materials. However, the two-dimensional structure of graphene is anisotropic, with extremely high strength within its plane, and the normal direction is combined by van der Waals forces, with low bonding strength. Composite materials prepared from oriented graphene also have strong anisotropy and have been widely studied.

[0003] However, in the process of engineering application, isotropic materials have a wider range of applications. How to overcome the two-dimensional anisotropic structural characteristics of graphene through material design and achieve the isotropy of the entire material is a difficult point in the research. How to evenly and effectively distribute two-dimensional graphene nanosheets in the aluminum matrix is ​​the key to the preparation of isotropic high-quality materials. At the same time, due to the reaction of graphene with the aluminum matrix, the brittle phase of aluminum carbide is generated, which causes the interface of the composite material to break prematurely. Therefore, it is necessary to suppress the carbon-aluminum interface reaction while dispersing the graphene to achieve high-quality preparation of the composite material. The diameter of graphene nanosheets is often around 50-100nm, and there is no continuous path formed between the independent and dispersed graphene, which significantly hinders its performance transmission. Therefore, through material structure design, while achieving the isotropic distribution of graphene, suppressing the carbon-aluminum interface reaction, improving the graphene-aluminum bonding strength, and ensuring the continuity of the graphene layer are the difficulties in the structural design of isotropic graphene / aluminum composite materials.

[0004] The pressure infiltration process prepares composite materials by infiltration of the preform skeleton. Through the design of the preform structure, it is expected to achieve the regulation of the distribution configuration of graphene. Active metals or compounds represented by titanium have strong reactivity with both aluminum and graphene. Through the titanium element, it is expected to achieve a close combination of graphene and aluminum, which is a highly feasible carbon-aluminum interface modification scheme. However, there is currently no feasible solution for how to use titanium to achieve uniform dispersion of graphene, thereby assisting in the preparation of highly connected isotropic materials. Therefore, a method for preparing an isotropic mesh graphene-aluminum composite material is urgently needed. Summary of the invention

[0005] The invention provides a method for preparing an isotropic mesh graphene-aluminum composite material in order to achieve isotropic distribution of graphene in an aluminum-based composite material and solve the problems of carbon-aluminum interface reaction, low graphene-aluminum bonding strength and discontinuous graphene layer.

[0006] The preparation method of the isotropic mesh graphene-aluminum composite material of the present invention is carried out according to the following steps:

[0007] 1. Weighing

[0008] Weigh 0.3% to 4% of graphene, 0.2% to 10% of skeleton structure metal powder and the remainder of aluminum metal powder as raw materials according to mass fraction; weigh an aluminum metal block, and the weight ratio of the aluminum metal block to the aluminum metal powder is (3 to 10): 1; the aluminum metal powder and the aluminum metal block are made of the same material;

[0009] Step 1: The skeleton structure metal powder is made of one or a combination of titanium, tin, zinc, and nickel elements; the skeleton structure metal powder has a mesh-connected skeleton structure that forms a relatively stable bond with aluminum and graphene, which is beneficial to ensure the close bonding of graphene and aluminum matrix and improve the strengthening efficiency of graphene;

[0010] 2. Preparation of graphene-skeleton metal-aluminum network structure precursor

[0011] The skeleton structure metal powder and aluminum metal powder weighed in step 1 are mixed and subjected to high-energy ball milling, and the skeleton structure metal powder is cold welded to the surface of the aluminum metal powder to obtain a composite powder of the skeleton structure metal powder coated with the aluminum metal powder; the graphene weighed in step 1 is mixed with the composite powder by low-speed ball milling to obtain a (graphene-skeleton structure metal)-aluminum composite powder; the (graphene-skeleton structure metal)-aluminum composite powder is loaded into a steel mold, and the mold is placed in a vacuum heating furnace for heating to sinter the shell layer composed of the graphene and the skeleton structure metal into a connected structure, so as to obtain a preform of a network-connected graphene-skeleton structure metal-aluminum;

[0012] The heating temperature in step 2 is 500-600°C and the time is 1-4h;

[0013] 3. Aluminum metal infiltration and preparation of mesh graphene-aluminum composite materials

[0014] The preform obtained in step 2 and the aluminum metal block weighed in step 1 are placed in a vacuum infiltration furnace, the aluminum metal block is placed in a graphite mold at the bottom of the furnace chamber of the vacuum infiltration furnace, the preform is placed in the upper part of the furnace chamber of the vacuum infiltration furnace and above the graphite mold, the vacuum infiltration furnace is sealed, and then the vacuum infiltration furnace is heated to preheat the preform; the aluminum metal block is heated to 760-850° C. and kept warm for 0.5-3 hours to obtain molten aluminum metal; the preheated preform is immersed in the molten aluminum metal and then the heating is stopped, and the molten aluminum metal liquid infiltrates into the preform under the mechanical pressure of 50-500 kN, and the skeleton structure metal and the graphene and the aluminum matrix form a carbon-skeleton structure metal phase and a skeleton structure metal-aluminum phase at high temperature, respectively, to form a dense interface bond; after cooling to room temperature, a composite material ingot is obtained;

[0015] 4. Three-way forging process

[0016] The composite material ingot obtained in step 3 is placed in a steel mold, and external forces are uniformly applied along the X, Y, and Z directions for three-way forging to obtain an isotropic composite material;

[0017] The pressure of the three-way forging in step 4 is 10 kN to 500 kN, and the temperature is 450° C. to 550° C.;

[0018] 5. Homogenization of ingredients

[0019] The isotropic composite material obtained in step 4 is subjected to a component homogenization treatment, and the process is completed; in step 5, the component homogenization treatment is carried out at a temperature of 510° C. to 560° C. and for a time of 1 to 5 hours.

[0020] Principle and beneficial effects of the invention:

[0021] 1. The present invention proposes a method for preparing an isotropic graphene-aluminum composite material. Through the mechanical ball milling process, graphene is closely attached to the surface of aluminum metal powder through the strong chemical bonding of the skeleton structure metal, forming a (graphene-skeleton structure metal)-aluminum composite powder. Because the aluminum metal powder is completely randomly distributed in the preform, the graphene attached to the surface is also randomly distributed, making the material macroscopically isotropic. It is conducive to the uniform dispersion of high-content graphene in the preform, solving the key problem of easy agglomeration of nano-reinforcements.

[0022] 2. In the preparation process of the present invention, the graphene-skeleton structure metal shell is first coated on the surface of the aluminum metal powder by mechanical ball milling, and then the continuity of the contact between the shells is used to construct a network-connected skeleton structure during the sintering process. The network connection provides a three-dimensional path for the conduction of graphene stress and heat flow, showing macroscopic isotropy; the graphene sheets are bridged by the skeleton structure metal and the infiltrated aluminum metal, which effectively ensures the full conduction of stress between the graphene sheets, relieves the material stress concentration, and is conducive to achieving material strain homogenization.

[0023] 3. The existing graphene-aluminum is weakly physically bonded when there is no interface reaction. When an interface reaction occurs, brittle interface reaction phase aluminum carbide is generated, which causes the material to fail prematurely during service and has a significant damage to the material performance. The skeleton structure metal in the present invention effectively improves the interface bonding between graphene and the aluminum metal matrix. The skeleton structure metal is a metal element that has a high reactivity with both graphene and aluminum metal. In the preparation process, the skeleton structure metal powder is selected to be ball-milled with aluminum metal powder by mechanical ball milling first, so that the skeleton structure metal is coated on the surface of the aluminum powder; then graphene is added so that the graphene is coated on the surface of the skeleton structure metal shell, and the in-situ construction of the graphene-skeleton structure metal-aluminum interface is achieved by a simple mechanical method. The skeleton structure metal generates compounds with graphene and aluminum respectively, so that the chemical bonding of graphene and the aluminum metal matrix is ​​achieved, and the interface bonding strength is greatly improved. It ensures that the stress of the matrix is ​​effectively transferred to the graphene reinforcement, improves the load-bearing and strengthening efficiency of graphene, and greatly helps to improve the strength and plasticity of the material; the skeleton structure metal generates compounds with graphene and aluminum respectively to avoid interface cracking during the service and deformation of the material and cause material failure. The stress of the matrix can be fully transferred to the graphene reinforcement through the interface, so that the strengthening efficiency of graphene can be fully exerted.

[0024] 4. The present invention selects three-dimensional forging during the preparation process, avoiding the single-dimensional deformation process (such as extrusion, rolling, etc.) that causes the material to produce orientation and texture, ensuring the isotropy of the material and the uniformity of the material performance. Three-dimensional forging effectively improves the material densification degree and refines the matrix grains, further improving the mechanical properties of the material.

[0025] 5. The present invention utilizes homogenization treatment to dissolve the alloy elements in the matrix back into the aluminum lattice to form solid solution strengthening, thereby further improving the performance of the composite material.

[0026] 6. The isotropic graphene-aluminum composite material prepared by the present invention has excellent comprehensive performance, with an elastic modulus exceeding 81 GPa, a yield strength exceeding 400 MPa, a tensile strength exceeding 515 MPa, and an elongation exceeding 10%.

[0027] 7. The overall process flow of the present invention is clear and simple. The isotropic network material structure control is achieved through mechanical ball milling. It does not involve chemical methods, has low environmental pollution, short preparation cycle, low cost, simple equipment, and strong versatility. It is expected to be promoted for the design of preparing isotropic composite materials from two-dimensional nanomaterials and is easy to carry out large-scale production.

[0028] 8. The present invention adopts a pressure infiltration process to make molten aluminum metal liquid infiltrate into a preform with a network of interconnected parts under external pressure, and the aluminum metal infiltrates into the network skeleton layer to form a dense composite structure, thereby preparing a qualified composite material; the external pressure ensures that the infiltration liquid can overcome resistance, effectively infiltrate into small gaps, and discharge the pores of the graphene-skeleton structure metal layer, thereby further improving the density of the composite material. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The microstructure of the network-connected graphene-reinforced aluminum-based composite material obtained in Example 1. DETAILED DESCRIPTION

[0030] The technical solution of the present invention is not limited to the specific implementation modes listed below, but also includes any reasonable combination of the specific implementation modes.

[0031] Specific implementation method 1: The preparation method of the isotropic mesh graphene-aluminum composite material in this implementation method is carried out according to the following steps:

[0032] 1. Weighing

[0033] Weigh 0.3% to 4% of graphene, 0.2% to 10% of skeleton structure metal powder and the remainder of aluminum metal powder as raw materials according to mass fraction; weigh an aluminum metal block, and the weight ratio of the aluminum metal block to the aluminum metal powder is (3 to 10): 1; the aluminum metal powder and the aluminum metal block are made of the same material;

[0034] The skeleton structure metal powder in step 1 is made of one or a combination of titanium, tin, zinc and nickel elements;

[0035] 2. Preparation of graphene-skeleton metal-aluminum network structure precursor

[0036] The skeleton structure metal powder and aluminum metal powder weighed in step 1 are mixed and subjected to high-energy ball milling, and the skeleton structure metal powder is cold welded to the surface of the aluminum metal powder to obtain a composite powder of the skeleton structure metal powder coated with the aluminum metal powder; the graphene weighed in step 1 is mixed with the composite powder by low-speed ball milling to obtain a (graphene-skeleton structure metal)-aluminum composite powder; the (graphene-skeleton structure metal)-aluminum composite powder is loaded into a steel mold, and the mold is placed in a vacuum heating furnace for heating to sinter the shell layer composed of the graphene and the skeleton structure metal into a connected structure, so as to obtain a preform of a network-connected graphene-skeleton structure metal-aluminum;

[0037] The heating temperature in step 2 is 500-600°C and the time is 1-4h;

[0038] 3. Aluminum metal infiltration and preparation of mesh graphene-aluminum composite materials

[0039] The preform obtained in step 2 and the aluminum metal block weighed in step 1 are placed in a vacuum infiltration furnace, the aluminum metal block is placed in a graphite mold at the bottom of the furnace chamber of the vacuum infiltration furnace, the preform is placed in the upper part of the furnace chamber of the vacuum infiltration furnace and above the graphite mold, the vacuum infiltration furnace is sealed, and then the vacuum infiltration furnace is heated to preheat the preform; the aluminum metal block is heated to 760-850° C. and kept warm for 0.5-3 hours to obtain molten aluminum metal; the preheated preform is immersed in the molten aluminum metal and then the heating is stopped, and the molten aluminum metal liquid infiltrates into the preform under the mechanical pressure of 50-500 kN, and the skeleton structure metal and the graphene and the aluminum matrix form a carbon-skeleton structure metal phase and a skeleton structure metal-aluminum phase at high temperature, respectively, to form a dense interface bond; after cooling to room temperature, a composite material ingot is obtained;

[0040] 4. Three-way forging process

[0041] The composite material ingot obtained in step 3 is placed in a steel mold, and external forces are uniformly applied along the X, Y, and Z directions for three-way forging to obtain an isotropic composite material;

[0042] The pressure of the three-way forging in step 4 is 10 kN to 500 kN, and the temperature is 450° C. to 550° C.;

[0043] 5. Homogenization of ingredients

[0044] The isotropic composite material obtained in step 4 is subjected to a component homogenization treatment, and the process is completed; in step 5, the component homogenization treatment is carried out at a temperature of 510° C. to 560° C. and for a time of 1 to 5 hours.

[0045] This embodiment has the following beneficial effects:

[0046] 1. This embodiment proposes a method for preparing an isotropic graphene-aluminum composite material. Through the mechanical ball milling process, graphene is closely attached to the surface of aluminum metal powder through the strong chemical bonding of the skeleton structure metal, forming a (graphene-skeleton structure metal)-aluminum composite powder. Because the aluminum metal powder is completely randomly distributed in the preform, the graphene attached to the surface is also randomly distributed, making the material macroscopically isotropic. It is conducive to the uniform dispersion of high-content graphene in the preform, solving the key problem of easy agglomeration of nano-reinforcements.

[0047] 2. In the preparation process of this embodiment, the graphene-skeleton structure metal shell is first coated on the surface of aluminum metal powder by mechanical ball milling, and then the continuity of the shell contact is used to construct a network-connected skeleton structure during the sintering process. The network connection provides a three-dimensional path for the conduction of graphene stress and heat flow, showing macroscopic isotropy; the graphene sheets are bridged by the skeleton structure metal and the infiltrated aluminum metal, which effectively ensures the full conduction of stress between the graphene sheets, relieves the material stress concentration, and is conducive to achieving material strain homogenization.

[0048] 3. The existing graphene-aluminum is weakly physically bonded when there is no interface reaction. When an interface reaction occurs, brittle interface reaction phase aluminum carbide is generated, which causes the material to fail prematurely during service and has a significant damage to the material performance. In this embodiment, the skeleton structure metal effectively improves the interface bonding between the graphene-aluminum metal matrix. The skeleton structure metal is a metal element that has a high reactivity with both graphene and aluminum metal. During the preparation process, the skeleton structure metal powder is selected to be ball-milled with aluminum metal powder by mechanical ball milling first, so that the skeleton structure metal is coated on the surface of the aluminum powder; then graphene is added so that the graphene is coated on the surface of the skeleton structure metal shell, and the in-situ construction of the graphene-skeleton structure metal-aluminum interface is achieved by a simple mechanical method. The skeleton structure metal generates compounds with graphene and aluminum respectively, so that the chemical bonding of graphene and the aluminum metal matrix is ​​achieved, and the interface bonding strength is greatly improved. It ensures that the stress of the matrix is ​​effectively transferred to the graphene reinforcement, improves the load-bearing and strengthening efficiency of graphene, and greatly helps to improve the strength and plasticity of the material; the skeleton structure metal generates compounds with graphene and aluminum respectively to avoid interface cracking during the service and deformation of the material and cause material failure. The stress of the matrix can be fully transferred to the graphene reinforcement through the interface, so that the strengthening efficiency of graphene can be fully exerted.

[0049] 4. This embodiment uses three-dimensional forging during the preparation process to avoid the single-dimensional deformation process (such as extrusion, rolling, etc.) that causes the material to produce orientation and texture, ensuring the isotropy of the material and the uniformity of the material properties. Three-dimensional forging effectively improves the material densification degree and refines the matrix grains, further improving the mechanical properties of the material.

[0050] 5. This embodiment utilizes homogenization treatment to dissolve the alloy elements in the matrix back into the aluminum lattice to form solid solution strengthening, thereby further improving the performance of the composite material.

[0051] 6. The isotropic graphene-aluminum composite material prepared in this embodiment has excellent comprehensive performance, with an elastic modulus exceeding 81 GPa, a yield strength exceeding 400 MPa, a tensile strength exceeding 515 MPa, and an elongation exceeding 10%.

[0052] 7. The overall process flow of this implementation method is clear and simple. The isotropic network material structure control is achieved through mechanical ball milling. It does not involve chemical methods, has low environmental pollution, short preparation cycle, low cost, simple equipment, and strong versatility. It is expected to be promoted for the design of preparing isotropic composite materials from two-dimensional nanomaterials and is easy to carry out large-scale production.

[0053] 8. This embodiment uses a pressure infiltration process to allow molten aluminum metal liquid to infiltrate the preform with a network of interconnected bodies under external pressure. The aluminum metal infiltrates the network skeleton layer to form a dense composite structure, and a qualified composite material is prepared. The external pressure ensures that the infiltration liquid can overcome resistance, effectively infiltrate into small gaps, and discharge the pores of the graphene-skeleton structure metal layer, thereby further improving the density of the composite material.

[0054] Specific implementation method 2: This implementation method is different from specific implementation method 1 in that: the graphene described in step 1 is few-layer graphene with an average sheet diameter of 200nm to 20μm and an average thickness of 0.3 to 30nm.

[0055] Specific implementation method three: This implementation method is different from specific implementation methods one or two in that: the aluminum metal powder in step one is spherical aluminum alloy powder with an average particle size of 0.5 to 15 μm.

[0056] Specific embodiment 4: This embodiment differs from any one of specific embodiments 1 to 3 in that: the aluminum metal block in step 1 is one of pure aluminum, Al-Si alloy, Al-Si-Cu alloy, Al-Mg-Si alloy, Al-Cu-Mg alloy, Al-Zn-Cu alloy, Al-Zn-Mg-Cu alloy, Al-Si-Cu-Mg alloy, or a combination of several thereof;

[0057] The mass fraction of Si in the Al-Si alloy is 2% to 25%;

[0058] The mass fraction of Si in Al-Mg-Si alloy is 0.5% to 25%, and the mass fraction of Mg is 0.5% to 50%;

[0059] The mass fraction of Si in Al-Si-Cu alloy is 0.5% to 25%, and the mass fraction of Cu is 0.5% to 53%;

[0060] The mass fraction of Cu in Al-Cu-Mg alloy is 0.5% to 53%, and the mass fraction of Mg is 0.5% to 38%;

[0061] The mass fraction of Zn in Al-Zn-Cu alloy is 0.5% to 55%, and the mass fraction of Cu is 0.5% to 53%;

[0062] The mass fraction of Zn in Al-Zn-Mg-Cu alloy is 0.5% to 55%, the mass fraction of Mg is 0.5% to 38%, and the mass fraction of Cu is 0.5% to 53%;

[0063] The mass fraction of Si in the Al-Si-Cu-Mg alloy is 0.5% to 25%, the mass fraction of Cu is 0.5% to 53%, and the mass fraction of Mg is 0.5% to 38%.

[0064] Specific implementation method five: This implementation method is different from any one of specific implementation methods one to four in that: the process of high-energy ball milling in step two is: the ball-to-material ratio is (10-20):1, and the ball milling is performed at a rotation speed of 250-400 rpm for 0.5-4h.

[0065] Specific implementation method six: This implementation method is different from any one of specific implementation methods one to five in that: the process of low-speed ball milling in step two is: the ball-to-material ratio is (5-10):1, and the ball milling is performed at a rotation speed of 100-200 rpm for 2-4 hours.

[0066] Specific embodiment 7: This embodiment differs from any one of specific embodiments 1 to 6 in that: in step 3, the preform is preheated at a heating rate of 5 to 10°C / min, heated to 600 to 650°C, and kept warm for 0.5 to 6h.

[0067] Specific implementation eight: This implementation differs from any one of specific implementations one to seven in that the vacuum infiltration furnace used in step three is an atmosphere infiltration furnace, and the atmosphere is nitrogen, helium or argon.

[0068] Specific embodiment nine: This embodiment differs from any one of specific embodiments one to eight in that: in step three, the aluminum metal block is heated to 810°C and kept warm for 2 hours to obtain molten aluminum metal; the preheated preform is immersed in the molten aluminum metal and the heating is stopped, and the molten aluminum metal liquid penetrates into the preform under the action of a mechanical pressure of 50 to 500 kN, and the skeleton structure metal forms a carbon-skeleton structure metal phase and a skeleton structure metal-aluminum phase with the graphene and the aluminum matrix at high temperature, respectively, forming a dense interface bond; after cooling to room temperature, a composite material ingot is obtained.

[0069] Specific embodiment ten: This embodiment differs from any one of specific embodiments one to nine in that: in step three, the aluminum metal block is heated to 810°C and kept warm for 2 hours to obtain molten aluminum metal; the preheated preform is immersed in the molten aluminum metal and the heating is stopped, and under the action of a mechanical pressure of 200 kN, the molten aluminum metal liquid penetrates into the preform, and at high temperature, the skeleton structure metal and the graphene and aluminum matrix form a carbon-skeleton structure metal phase and a skeleton structure metal-aluminum phase, respectively, forming a dense interface bond; after cooling to room temperature, a composite material ingot is obtained.

[0070] Embodiment 1:

[0071] The preparation method of the isotropic mesh graphene-aluminum composite material of this embodiment is carried out according to the following steps:

[0072] 1. Weighing

[0073] 1% of graphene, 3% of skeleton structure metal powder and the rest of aluminum metal powder are weighed as raw materials according to mass fraction; an aluminum metal block is weighed, and the weight ratio of the aluminum metal block to the aluminum metal powder is 3:1; the aluminum metal powder and the aluminum metal block are made of the same material;

[0074] The graphene in step 1 is a few-layer graphene with an average sheet diameter of 300 nm and an average thickness of 10 nm;

[0075] The skeleton structure metal powder in step 1 is made of titanium;

[0076] The aluminum metal powder in step 1 is spherical aluminum alloy powder with an average particle size of 10 μm;

[0077] The aluminum metal block in step 1 is pure aluminum;

[0078] 2. Preparation of graphene-skeleton metal-aluminum network structure precursor

[0079] The skeleton structure metal powder and aluminum metal powder weighed in step 1 are mixed and subjected to high-energy ball milling, and the skeleton structure metal powder is cold welded to the surface of the aluminum metal powder to obtain a composite powder of the skeleton structure metal powder coated with the aluminum metal powder; the graphene weighed in step 1 is mixed with the composite powder by low-speed ball milling to obtain a (graphene-skeleton structure metal)-aluminum composite powder; the (graphene-skeleton structure metal)-aluminum composite powder is loaded into a steel mold, and the mold is placed in a vacuum heating furnace for heating to sinter the shell layer composed of the graphene and the skeleton structure metal into a connected structure, so as to obtain a preform of a network-connected graphene-skeleton structure metal-aluminum;

[0080] The process of high-energy ball milling in step 2 is as follows: the ball-to-material ratio is 10:1, and the ball milling is performed at a speed of 300 rpm for 2 hours;

[0081] The process of low-speed ball milling in step 2 is as follows: the ball-to-material ratio is 5:1, and the ball milling is performed at a speed of 50 rpm for 2 hours;

[0082] The heating temperature in step 2 is 600°C and the time is 3h;

[0083] 3. Aluminum metal infiltration and preparation of mesh graphene-aluminum composite materials

[0084] The preform obtained in step 2 and the aluminum metal block weighed in step 1 are placed in a vacuum infiltration furnace, the aluminum metal block is placed in a graphite mold at the bottom of the furnace chamber of the vacuum infiltration furnace, the preform is placed in the upper part of the furnace chamber of the vacuum infiltration furnace and above the graphite mold, the vacuum infiltration furnace is sealed, and then the vacuum infiltration furnace is heated to preheat the preform; the aluminum metal block is heated to 810°C and kept warm for 2 hours to obtain molten aluminum metal; the preheated preform is immersed in the molten aluminum metal and then the heating is stopped, and the molten aluminum metal liquid infiltrates into the preform under the mechanical pressure of 200kN, and the skeleton structure metal and the graphene and the aluminum matrix form a carbon-skeleton structure metal phase and a skeleton structure metal-aluminum phase at high temperature, respectively, to form a dense interface bond; after cooling to room temperature, a composite material ingot is obtained;

[0085] Step 3: The preform is preheated at a heating rate of 5°C / min to 610°C and kept warm for 1h;

[0086] The vacuum infiltration furnace used in step 3 is an atmosphere infiltration furnace, and the atmosphere is nitrogen;

[0087] 4. Three-way forging process

[0088] The composite material ingot obtained in step 3 is placed in a steel mold, and external forces are uniformly applied along the X, Y, and Z directions for three-way forging to obtain an isotropic composite material;

[0089] The pressure of the three-way forging in step 4 is 300 kN and the temperature is 450° C.

[0090] 5. Homogenization of ingredients

[0091] The isotropic composite material obtained in step 4 is subjected to a component homogenization treatment, and the process is completed; the temperature of the component homogenization treatment in step 5 is 520° C. and the time is 2 h;

[0092] The isotropic mesh graphene-aluminum composite material prepared in this embodiment has an elastic modulus of 82.1 GPa, an in-plane yield strength of 475 MPa, an in-plane tensile strength of 603 MPa, and an in-plane elongation of 12.1%; a normal yield strength of 458 MPa, a normal tensile strength of 577 MPa, and a normal elongation of 12.5%; the difference between the in-plane and normal mechanical properties is less than 5%, and the composite material as a whole exhibits good isotropy.

[0093] Embodiment 2:

[0094] The preparation method of the isotropic mesh graphene-aluminum composite material of this embodiment is carried out according to the following steps:

[0095] 1. Weighing

[0096] 4% of graphene, 8% of skeleton structure metal powder and the rest of aluminum metal powder are weighed as raw materials according to mass fraction; an aluminum metal block is weighed, and the weight ratio of the aluminum metal block to the aluminum metal powder is 8:1; the aluminum metal powder and the aluminum metal block are made of the same material;

[0097] The graphene in step 1 is a few-layer graphene with an average sheet diameter of 1 μm and an average thickness of 20 nm;

[0098] The skeleton structure metal powder in step 1 is made of nickel;

[0099] The aluminum metal powder in step 1 is spherical aluminum alloy powder with an average particle size of 10 μm;

[0100] Step 1: The aluminum metal block is an Al-Cu-Mg alloy, wherein the mass fraction of Cu in the Al-Cu-Mg alloy is 3%, and the mass fraction of Mg is 1.5%.

[0101] 2. Preparation of graphene-skeleton metal-aluminum network structure precursor

[0102] The skeleton structure metal powder and aluminum metal powder weighed in step 1 are mixed and subjected to high-energy ball milling, and the skeleton structure metal powder is cold welded to the surface of the aluminum metal powder to obtain a composite powder of the skeleton structure metal powder coated with the aluminum metal powder; the graphene weighed in step 1 is mixed with the composite powder by low-speed ball milling to obtain a (graphene-skeleton structure metal)-aluminum composite powder; the (graphene-skeleton structure metal)-aluminum composite powder is loaded into a steel mold, and the mold is placed in a vacuum heating furnace for heating to sinter the shell layer composed of the graphene and the skeleton structure metal into a connected structure, so as to obtain a preform of a network-connected graphene-skeleton structure metal-aluminum;

[0103] The process of high-energy ball milling in step 2 is as follows: the ball-to-material ratio is 15:1, and the ball milling is performed at a speed of 400 rpm for 3 hours;

[0104] The process of low-speed ball milling in step 2 is as follows: the ball-to-material ratio is 5:1, and the ball milling is performed at a speed of 100 rpm for 2 hours;

[0105] The heating temperature in step 2 is 600°C and the time is 4h;

[0106] 3. Aluminum metal infiltration and preparation of mesh graphene-aluminum composite materials

[0107] The preform obtained in step 2 and the aluminum metal block weighed in step 1 are placed in a vacuum infiltration furnace, the aluminum metal block is placed in a graphite mold at the bottom of the furnace chamber of the vacuum infiltration furnace, the preform is placed in the upper part of the furnace chamber of the vacuum infiltration furnace and above the graphite mold, the vacuum infiltration furnace is sealed, and then the vacuum infiltration furnace is heated to preheat the preform; the aluminum metal block is heated to 850°C and kept warm for 3 hours to obtain molten aluminum metal; the preheated preform is immersed in the molten aluminum metal and then the heating is stopped, and the molten aluminum metal liquid infiltrates into the preform under the mechanical pressure of 500kN, and the skeleton structure metal and the graphene and the aluminum matrix form a carbon-skeleton structure metal phase and a skeleton structure metal-aluminum phase at high temperature, respectively, to form a dense interface bond; after cooling to room temperature, a composite material ingot is obtained;

[0108] Step 3: The preform is preheated at a heating rate of 10°C / min to 630°C and kept warm for 2h;

[0109] The vacuum infiltration furnace used in step 3 is an atmosphere infiltration furnace, and the atmosphere is nitrogen;

[0110] 4. Three-way forging process

[0111] The composite material ingot obtained in step 3 is placed in a steel mold, and external forces are uniformly applied along the X, Y, and Z directions for three-way forging to obtain an isotropic composite material;

[0112] The pressure of the three-way forging in step 4 is 500 kN and the temperature is 510° C.

[0113] 5. Homogenization of ingredients

[0114] The isotropic composite material obtained in step 4 is subjected to a component homogenization treatment, and the process is completed; in step 5, the component homogenization treatment is carried out at a temperature of 550° C. and for 5 hours.

[0115] The isotropic mesh graphene-aluminum composite material prepared in this embodiment has an elastic modulus of 85.3 GPa, an in-plane yield strength of 527 MPa, an in-plane tensile strength of 701 MPa, and an in-plane elongation of 10.2%; a normal yield strength of 511 MPa, a normal tensile strength of 682 MPa, and a normal elongation of 11.9%; there is no significant difference in the in-plane and normal directions, and the composite material as a whole exhibits good isotropy.

Claims

1. A method for preparing an isotropic mesh graphene-aluminum composite material, characterized in that: The preparation method of the isotropic mesh graphene-aluminum composite material is carried out according to the following steps:

1. Weighing Weigh 0.3% to 4% of graphene, 0.2% to 10% of skeleton structure metal powder and the remainder of aluminum metal powder as raw materials according to mass fraction; weigh an aluminum metal block, and the weight ratio of the aluminum metal block to the aluminum metal powder is (3 to 10): 1; the aluminum metal powder and the aluminum metal block are made of the same material; The skeleton structure metal powder in step 1 is made of one or a combination of titanium, tin, zinc and nickel elements; 2. Preparation of graphene-skeleton metal-aluminum network structure precursor The skeleton structure metal powder and aluminum metal powder weighed in step 1 are mixed and subjected to high-energy ball milling, and the skeleton structure metal powder is cold welded to the surface of the aluminum metal powder to obtain a composite powder of the skeleton structure metal powder coated with the aluminum metal powder; the graphene weighed in step 1 is mixed with the composite powder by low-speed ball milling to obtain a graphene-skeleton structure metal-aluminum composite powder; the graphene-skeleton structure metal-aluminum composite powder is loaded into a steel mold, and placed in a vacuum heating furnace for heating so that the shell layer composed of the graphene and the skeleton structure metal is sintered into a connected structure, thereby obtaining a preform of a network-connected graphene-skeleton structure metal-aluminum; The heating temperature in step 2 is 500-600°C and the time is 1-4h; 3. Aluminum metal infiltration and preparation of mesh graphene-aluminum composite materials The preform obtained in step 2 and the aluminum metal block weighed in step 1 are placed in a vacuum infiltration furnace, the aluminum metal block is placed in a graphite mold at the bottom of the furnace chamber of the vacuum infiltration furnace, the preform is placed in the upper part of the furnace chamber of the vacuum infiltration furnace and above the graphite mold, the vacuum infiltration furnace is sealed, and then the vacuum infiltration furnace is heated to preheat the preform; the aluminum metal block is heated to 760-850° C. and kept warm for 0.5-3 hours to obtain molten aluminum metal; the preheated preform is immersed in the molten aluminum metal and then the heating is stopped, and the molten aluminum metal liquid infiltrates into the preform under the mechanical pressure of 50-500 kN, and the skeleton structure metal and the graphene and the aluminum matrix form a carbon-skeleton structure metal phase and a skeleton structure metal-aluminum phase at high temperature, respectively, to form a dense interface bond; after cooling to room temperature, a composite material ingot is obtained; 4. Three-way forging process The composite material ingot obtained in step 3 is placed in a steel mold, and external forces are uniformly applied along the X, Y, and Z directions for three-way forging to obtain an isotropic composite material; The pressure of the three-way forging in step 4 is 10 kN to 500 kN, and the temperature is 450° C. to 550° C.; 5. Homogenization of ingredients The isotropic composite material obtained in step 4 is subjected to a component homogenization treatment, and the process is completed; in step 5, the component homogenization treatment is carried out at a temperature of 510° C. to 560° C. and for a time of 1 to 5 hours.

2. The method for preparing the isotropic mesh graphene-aluminum composite material according to claim 1, characterized in that: The graphene in step 1 is a few-layer graphene with an average sheet diameter of 200nm to 20μm and an average thickness of 0.3 to 30nm.

3. The method for preparing the isotropic mesh graphene-aluminum composite material according to claim 1, characterized in that: The aluminum metal powder in step 1 is spherical aluminum alloy powder with an average particle size of 0.5 to 15 μm.

4. The method for preparing the isotropic mesh graphene-aluminum composite material according to claim 1, characterized in that: The aluminum metal block in step 1 is one of pure aluminum, Al-Si alloy, Al-Si-Cu alloy, Al-Mg-Si alloy, Al-Cu-Mg alloy, Al-Zn-Cu alloy, Al-Zn-Mg-Cu alloy, Al-Si-Cu-Mg alloy, or a combination of several thereof; The mass fraction of Si in the Al-Si alloy is 2% to 25%; The mass fraction of Si in Al-Mg-Si alloy is 0.5% to 25%, and the mass fraction of Mg is 0.5% to 50%; The mass fraction of Si in Al-Si-Cu alloy is 0.5% to 25%, and the mass fraction of Cu is 0.5% to 53%; The mass fraction of Cu in Al-Cu-Mg alloy is 0.5% to 53%, and the mass fraction of Mg is 0.5% to 38%; The mass fraction of Zn in Al-Zn-Cu alloy is 0.5% to 55%, and the mass fraction of Cu is 0.5% to 53%; The mass fraction of Zn in Al-Zn-Mg-Cu alloy is 0.5% to 55%, the mass fraction of Mg is 0.5% to 38%, and the mass fraction of Cu is 0.5% to 53%; The mass fraction of Si in the Al-Si-Cu-Mg alloy is 0.5% to 25%, the mass fraction of Cu is 0.5% to 53%, and the mass fraction of Mg is 0.5% to 38%.

5. The method for preparing the isotropic mesh graphene-aluminum composite material according to claim 1, characterized in that: The process of high-energy ball milling in step 2 is as follows: the ball-to-material ratio is (10-20):1, and the ball milling is performed at a speed of 250-400 rpm for 0.5-4 hours.

6. The method for preparing the isotropic mesh graphene-aluminum composite material according to claim 1, characterized in that: The process of low-speed ball milling in step 2 is as follows: the ball-to-material ratio is (5-10):1, and the ball milling is performed at a speed of 100-200 rpm for 2-4 hours.

7. The method for preparing the isotropic mesh graphene-aluminum composite material according to claim 1, characterized in that: In step 3, the preform is preheated at a heating rate of 5 to 10°C / min, heated to 600 to 650°C, and kept warm for 0.5 to 6h.

8. The method for preparing the isotropic network graphene-aluminum composite material according to claim 1, characterized in that: The vacuum infiltration furnace used in step 3 is an atmosphere infiltration furnace, and the atmosphere is nitrogen, helium or argon.

9. The method for preparing the isotropic network graphene-aluminum composite material according to claim 1, characterized in that: Step three: heat the aluminum metal block to 810°C and keep it warm for 2 hours to obtain molten aluminum metal; immerse the preheated preform into the molten aluminum metal and stop heating. Under the action of a mechanical pressure of 50 to 500 kN, the molten aluminum metal liquid penetrates into the preform. At high temperature, the skeleton structure metal and the graphene and aluminum matrix form a carbon-skeleton structure metal phase and a skeleton structure metal-aluminum phase, respectively, forming a dense interface bond; after cooling to room temperature, a composite material ingot is obtained.

10. The method for preparing the isotropic network graphene-aluminum composite material according to claim 1, characterized in that: Step 3: Heat the aluminum metal block to 810°C and keep it warm for 2 hours to obtain molten aluminum metal; immerse the preheated preform in the molten After the aluminum metal is filled inside, the heating is stopped, and the molten aluminum metal liquid penetrates into the preform under the mechanical pressure of 200kN. At high temperature, the skeleton metal, graphene and aluminum matrix form carbon-skeleton metal phase and skeleton metal-aluminum phase respectively. A dense interface bond is formed; after cooling to room temperature, a composite material ingot is obtained.

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