A method for preparing a graphene-aluminum composite material that utilizes the percolation effect of pressure infiltration to control the diffusion of Mg elements and achieve strong interface bonding

Abstract

A method for preparing a graphene-aluminum composite material that utilizes the seepage effect of pressure infiltration to control the diffusion of Mg elements and achieve strong interface bonding, relates to a method for preparing a graphene-aluminum composite material. In order to solve the problem of Mg element segregation on the graphene surface, the present invention proposes a method for preparing a graphene-aluminum composite material that utilizes the seepage effect of pressure infiltration to control the diffusion of Mg elements and achieve strong interface bonding, which can inhibit the interface segregation of Mg elements and compensate for the Mg content in the matrix. The graphene-aluminum composite material prepared by the present invention has excellent mechanical properties, and the tensile strength of the composite material can reach 550-650MPa, the elastic modulus exceeds 90GPa, and the elongation exceeds 13.5%. The composite material preparation process is safe and efficient, simple, pollution-free and low-cost, and is suitable for large-scale production.

Description

Technical Field

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

[0002] Aluminum alloy is a lightweight, high-strength, and multifunctional material with excellent thermal and electrical conductivity, finding increasing application in industrial production and everyday life. Since its discovery, graphene, a newly discovered two-dimensional material reinforcement, has garnered widespread attention. Graphene boasts exceptionally high theoretical properties, with a theoretical tensile strength of 130 GPa and a hardness of 0.5-1 TPa, several times that of diamond, and holds great promise for application in composite materials. Since its discovery, graphene has been widely applied in composite materials. Graphene-pure aluminum composites have significantly improved the performance of pure aluminum composites, with yield and tensile strengths of aluminum alloys 2-3 times those of pure aluminum. Therefore, to meet the demand for high-strength and high-stiffness composites, research on graphene-pure aluminum matrix composites has been gradually replaced by graphene-aluminum alloy composites in recent years. Composites based on aluminum alloys offer the potential for even higher mechanical properties, and alloying elements in aluminum alloys may also be beneficial in controlling the reaction between graphene and the aluminum matrix.

[0003] Mg in aluminum alloys segregates toward the graphene surface. This segregated Mg inhibits the formation of the brittle phase Al4C3 at the graphene-aluminum interface, thereby improving the mechanical properties of the composite. However, this interfacial segregation of Mg causes the Mg, which should be evenly distributed and provide precipitation strengthening, to segregate toward the graphene-aluminum composite interface, reducing the uniformly distributed Mg content in the matrix and, consequently, the precipitation strengthening effect. Therefore, a method for preparing graphene-aluminum composites that controls Mg interfacial segregation and compensates for the Mg content in the matrix is ​​urgently needed. Summary of the Invention

[0004] In order to solve the problem of Mg element segregation on the graphene surface, the present invention proposes a preparation method of a graphene-aluminum composite material that utilizes the seepage effect of pressure infiltration to control the diffusion of Mg element to achieve strong interface bonding, which can inhibit the interface segregation of Mg element and compensate for the Mg content in the matrix.

[0005] The preparation method of the graphene-aluminum composite material of the present invention, which utilizes the seepage effect of pressure infiltration to control the diffusion of Mg element and realize strong interface bonding, is carried out in the following steps:

[0006] 1. Weighing

[0007] Weigh 1% to 3% of graphene and the balance of aluminum alloy powder according to mass fraction; then weigh Mg metal, the mass of which is 3% to 10% of the total mass of the graphene and aluminum alloy powder;

[0008] The Mg metal is a magnesium-aluminum alloy; pure Mg is prone to explosion and sputtering during the infiltration process, while pressure infiltration of magnesium elements into the preform by the magnesium-aluminum alloy is safer and less prone to explosion and sputtering;

[0009] 2. Graphene dispersion and preform molding

[0010] 60% of the aluminum alloy powder weighed in step 1 and all of the graphene are mixed and ball-milled, the ball-milled mixed powder is placed into a steel mold, and cold-pressed using a hydraulic press to obtain a composite material preform;

[0011] The ball-to-material ratio of the ball milling process is (8-20):1, the rotation speed is (150-250) r / min, and the ball milling time is 6 hours. The ball milling can make the graphene uniformly dispersed on the aluminum surface, and the ball milling can form a strong mechanical bond between the graphene and the aluminum powder, thereby improving the strength of the composite material. The use of a larger ball-to-material ratio can make the graphene more uniformly dispersed, while breaking up the graphene clusters, reducing the agglomeration of the graphene on the aluminum surface, and reducing the large-scale aggregation of the brittle phase Al4C3 during subsequent sintering and infiltration processes. The appropriate rotation speed can obtain a material with better graphene dispersion effect, without uneven dispersion or graphene breakage.

[0012] 3. High temperature sintering of composite material preforms

[0013] The composite material preform obtained in step 2 is placed together with the mold in an atmosphere furnace, the atmosphere furnace is first evacuated to a vacuum, and then a protective gas is introduced into the atmosphere furnace for high-temperature sintering to obtain a graphene-aluminum composite material ingot;

[0014] The high-temperature sintering process comprises heating to 300-350° C. at a heating rate of 3-10° C. / min and holding the temperature for 2-3 hours, then heating to 600-650° C. at a heating rate of 3-10° C. / min and holding the temperature for 3-6 hours, applying a pressure of 100-200 MPa to the composite material preform during the heating process, and cooling the preform in the furnace after sintering to obtain a graphene-aluminum composite material ingot; sintering under pressure can ensure that the composite material has fine and dense grains;

[0015] The protective gas is a mixture of N2 and NO;

[0016] Evacuating the atmosphere furnace to a vacuum can prevent the composite material preform from being oxidized during the heating process. The protective gas composed of N2 and NO introduces a small amount of oxygen, which can generate a mixed film of aluminum nitride and aluminum oxide at the interface at high temperature, thereby increasing the interface bonding strength; the aluminum nitride and aluminum oxide generated at the grain boundary reduce the direct contact between graphene and Al, forming a protective interlayer to reduce the reaction between C-Al and thus reduce Al4C3; nitrogen can prevent the oxygen that may enter the atmosphere furnace during the heating process from oxidizing the preform, and the thermal conductivity of nitrogen is higher than that in vacuum, making the heat transfer more uniform, thereby improving the crystal growth behavior and reducing the uneven grain growth phenomenon; after nitrogen forms aluminum nitride at the interface, the combination of oxygen and aluminum is reduced, thereby reducing the accumulation of aluminum oxide at the grain boundary.

[0017] 4. Preparation of graphene-aluminum composites with strong interfacial bonding by pressure infiltration

[0018] The remaining aluminum alloy powder and all the Mg metal weighed in step 1 are mixed and melted to obtain a melt, which is then infiltrated into a graphene-aluminum composite ingot using a short-time pressure infiltration process. After the melt solidifies, it is demolded at high temperature and then quenched. The mixed melting of the aluminum alloy powder and the Mg metal can improve safety on the one hand and prevent pure Mg from exploding and sputtering during the pressure infiltration process. On the other hand, Mg can form magnesium-aluminum spinel with Al during the pressure infiltration process. Magnesium-aluminum spinel has good chemical stability and thermal stability. When magnesium and aluminum combine to form magnesium-aluminum spinel, the position of magnesium atoms can be effectively fixed, thereby suppressing the tendency of magnesium segregation, reducing Mg segregation, and making the distribution in the matrix more uniform.

[0019] The short-time pressure infiltration process is as follows: the preheating temperature of the preform is 640°C, the temperature of the infiltrated melt is 880°C, the infiltration pressure is 40-60KN, and the time is 5-15 minutes;

[0020] 5. Solution aging treatment

[0021] The composite material after quenching in step 4 is subjected to solution aging treatment to complete the process;

[0022] The solution aging treatment process is as follows: holding at 530°C for 1 hour, followed by quenching, and then holding at 175°C for 6 hours. The solution aging treatment allows the Mg element to be evenly distributed in the composite matrix and controls the interface segregation of Mg.

[0023] Principles and beneficial effects of the present invention:

[0024] 1. In the present invention, nitrogen is introduced during the hot sintering process in an atmosphere furnace. On the one hand, this can prevent the composite material from being oxidized by oxygen in the air. On the other hand, nitrogen atoms will generate aluminum nitride at the interface at high temperature, reducing the aggregation of the Al4C3 brittle phase generated by the reaction between graphene and the aluminum matrix at the interface, thereby strengthening the interface of the graphene-aluminum composite material.

[0025] 2. The present invention applies pressure to the composite material preform while sintering in an atmosphere furnace, which can refine the grains of the composite material, make the structure dense, and increase the interface bonding strength.

[0026] 3. The present invention adopts a short-time pressure infiltration process, preheats the prepared preform in advance, and mixes and melts the weighed aluminum alloy ingot and magnesium block, pours the molten mixed metal liquid into the preform mold, and slowly infiltrates the mixed molten alloy liquid into the graphene-aluminum composite material ingot under the action of pressure. Under the action of seepage (the melt fills into the preform under the action of pressure, and the flowing melt has a driving force), the Mg in the mixed liquid is more evenly distributed to the greatest extent, thereby increasing the Mg content in the matrix; through a short-time high-temperature infiltration process and quenching, the infiltration is completed before Mg segregates to the graphene interface, and after the infiltration is completed, the quenching and cooling are performed to reduce Mg segregation, which can effectively control the interface segregation behavior of the Mg element, make the Mg element distribution more uniform, and have a significant strengthening effect. In addition, the generated magnesium-aluminum spinel improves the interface strength and also improves the strength of the matrix;

[0027] 4. The present invention further adds Mg to the aluminum alloy. The Mg inherent in the aluminum alloy plays a role in interface regulation. During the preform sintering process, it segregates at the interface, inhibiting the formation of the brittle phase Al4C3 and improving the interfacial bonding strength of the composite material. The Mg added during the pressure infiltration process acts as an alloying element compensation. A small amount of Mg segregates at the interface, but more Mg remains in the matrix, where its uniform distribution contributes to precipitation strengthening.

[0028] 5. The present invention adopts high-temperature demoulding after pressure infiltration and then quenches in a cold oil bath. This allows the graphene-aluminum composite material to cool rapidly, fully suppresses the occurrence of a large amount of interface segregation of the Mg element, and retains the Mg element in the matrix to the greatest extent to play a strengthening role.

[0029] 6. The preparation process of the present invention is simple and efficient, does not require a complicated deformation process, has a simple processing method, and has low production cost. It has great application prospects for large-scale preparation of graphene-aluminum composite materials with strong interface bonding;

[0030] 7. The graphene-aluminum composite material prepared by the present invention has excellent mechanical properties, with a tensile strength of 550-650 MPa, an elastic modulus exceeding 90 GPa, and an elongation exceeding 13.5%. The composite material preparation process is safe, efficient, simple, pollution-free, and low-cost, making it suitable for large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 SEM image of the composite material without Mg compensation and the distribution of Mg elements near graphene;

[0032] Figure 2 SEM image of the composite material with 5% Mg compensation added and the Mg element distribution content near graphene. DETAILED DESCRIPTION

[0033] The technical solution of the present invention is not limited to the specific implementation methods listed below, but also includes any reasonable combination of the specific implementation methods.

[0034] Specific embodiment 1: In this embodiment, the preparation method of the graphene-aluminum composite material with strong interface bonding by controlling the diffusion of Mg element by the percolation effect of pressure infiltration is carried out in the following steps:

[0035] 1. Weighing

[0036] Weigh 1% to 3% of graphene and the balance of aluminum alloy powder according to mass fraction; then weigh Mg metal, the mass of which is 3% to 10% of the total mass of the graphene and aluminum alloy powder;

[0037] The Mg metal is a magnesium-aluminum alloy;

[0038] 2. Graphene dispersion and preform molding

[0039] 60% of the aluminum alloy powder weighed in step 1 and all of the graphene are mixed and ball-milled, the ball-milled mixed powder is placed into a steel mold, and cold-pressed using a hydraulic press to obtain a composite material preform;

[0040] The ball-to-material ratio of the ball milling process is (8-20):1, the rotation speed is (150-250) r / min, and the ball milling time is 6 hours;

[0041] 3. High temperature sintering of composite material preforms

[0042] The composite material preform obtained in step 2 is placed together with the mold in an atmosphere furnace, the atmosphere furnace is first evacuated to a vacuum, and then a protective gas is introduced into the atmosphere furnace for high-temperature sintering to obtain a graphene-aluminum composite material ingot;

[0043] The high-temperature sintering process comprises heating to 300-350° C. at a heating rate of 3-10° C. / min and holding the temperature for 2-3 hours, then heating to 600-650° C. at a heating rate of 3-10° C. / min and holding the temperature for 3-6 hours, applying a pressure of 100-200 MPa to the composite material preform during the heating process, and cooling the preform in the furnace after sintering to obtain a graphene-aluminum composite material ingot;

[0044] The protective gas is a mixture of N2 and NO;

[0045] 4. Preparation of graphene-aluminum composites with strong interfacial bonding by pressure infiltration

[0046] The remaining aluminum alloy powder and all the Mg metal weighed in step 1 are mixed and melted to obtain a melt, and then the melt is infiltrated into the graphene-aluminum composite ingot using a short-time pressure infiltration process. After the melt solidifies, it is demolded at high temperature and then quenched;

[0047] The short-time pressure infiltration process is as follows: the preheating temperature of the preform is 640°C, the temperature of the infiltrated melt is 880°C, the infiltration pressure is 40-60KN, and the time is 5-15 minutes;

[0048] 5. Solution aging treatment

[0049] The composite material after quenching in step 4 is subjected to solution aging treatment to complete the process;

[0050] The process of the solution aging treatment is: keeping the temperature at 530° C. for 1 hour, then quenching, and keeping the temperature at 175° C. for 6 hours after quenching.

[0051] This embodiment has the following beneficial effects:

[0052] 1. In this embodiment, nitrogen is introduced during the sintering process in an atmosphere furnace. On the one hand, this can prevent the composite material from being oxidized by oxygen in the air. On the other hand, at high temperatures, nitrogen atoms will generate aluminum nitride at the interface, reducing the aggregation of the Al4C3 brittle phase produced by the reaction between graphene and the aluminum matrix at the interface, thereby strengthening the interface of the graphene-aluminum composite material.

[0053] 2. In this embodiment, pressure is applied to the composite material preform during sintering in an atmosphere furnace, which can refine the grains of the composite material, make the structure dense, and increase the interface bonding strength.

[0054] 3. This embodiment adopts a short-time pressure infiltration process, preheats the prepared preform in advance, and mixes and melts the weighed aluminum alloy ingot and magnesium block, pours the molten mixed metal liquid into the preform mold, and slowly infiltrates the mixed molten alloy liquid into the graphene-aluminum composite material ingot under the action of pressure. Under the action of seepage (the melt fills into the preform under the action of pressure, and the flowing melt has a driving force), the Mg in the mixed liquid is more evenly distributed to the greatest extent, thereby increasing the Mg content in the matrix; through a short-time high-temperature infiltration process and quenching, the infiltration is completed before Mg segregates to the graphene interface, and after the infiltration is completed, the quenching and cooling are performed to reduce Mg segregation, which can effectively control the interface segregation behavior of the Mg element, make the Mg element distribution more uniform, and have a significant strengthening effect. In addition, the generated Mg-aluminum spinel improves the interface strength and also improves the strength of the matrix;

[0055] 4. This embodiment further adds Mg to the aluminum alloy. The Mg inherent in the aluminum alloy plays a role in interface regulation. During the preform sintering process, it segregates at the interface, suppressing the formation of the brittle phase Al4C3 and improving the interfacial bonding strength of the composite material. The Mg added during the pressure infiltration process acts as an alloying element compensation. A small amount of Mg segregates at the interface, but a larger amount remains in the matrix, where its uniform distribution contributes to precipitation strengthening.

[0056] 5. This embodiment uses high-temperature demoulding after pressure infiltration, followed by quenching in a cold oil bath. This allows the graphene-aluminum composite material to cool rapidly, fully suppressing the occurrence of a large amount of interfacial segregation of the Mg element, and retaining the Mg element in the matrix to the greatest extent to play a strengthening role.

[0057] 6. The preparation process of this embodiment is simple and efficient, does not require a complex deformation process, has a simple processing method, and has low production cost. It has great application prospects for large-scale preparation of graphene-aluminum composite materials with strong interface bonding;

[0058] 7. The graphene-aluminum composite material prepared in this embodiment has excellent mechanical properties, with a tensile strength of 550-650 MPa, an elastic modulus exceeding 90 GPa, and an elongation exceeding 13.5%. The composite material preparation process is safe, efficient, simple, pollution-free, and low-cost, making it suitable for large-scale production.

[0059] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the graphene described in step 1 is few-layer graphene with an average sheet diameter of 100 nm to 25 μm and an average thickness of 0.5 to 30 nm.

[0060] Specific embodiment three: The difference between this embodiment and specific embodiment one or two is that the average particle size of the aluminum alloy powder in step one is 8 to 20 μm.

[0061] Specific embodiment four: This embodiment differs from any one of specific embodiments one to three in that the aluminum alloy powder described in step one is one of 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 of them.

[0062] Specific embodiment 5: This embodiment is different from the specific embodiment 4 in that the mass fraction of Si in the Al-Si alloy is 2% to 25%; the mass fraction of Si in the 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 the 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 the Al-Cu-Mg alloy is 0.5% to 53%, and the mass fraction of Mg is 0.5 %~38%; the mass fraction of Zn in Al-Zn-Cu alloy is 0.5%~55%, and the mass fraction of Cu is 0.5%~53%; the mass fraction of Zn in Al-Zn-Mg-Cu alloy is 0.5%~55%, the mass fraction of Mg is 0.5%~38%, and the mass fraction of Cu is 0.5%~53%; the mass fraction of Si in Al-Si-Cu-Mg alloy is 0.5%~25%, the mass fraction of Cu is 0.5%~53%, and the mass fraction of Mg is 0.5%~38%.

[0063] Specific embodiment 6: This embodiment differs from any one of specific embodiments 1 to 5 in that: in step 2, the ball-to-material ratio in the ball milling process is 10:1, the rotation speed is 150 r / min, and the ball milling time is 6 h.

[0064] Specific embodiment 7: This embodiment differs from specific embodiments 1 to 6 in that the pressure applied during the cold pressing process in step 2 is 50-70 kN and the holding time is 5-20 minutes. Cold pressing is beneficial for obtaining a composite material with better structure and performance.

[0065] Specific embodiment eight: This embodiment differs from any one of specific embodiments one to seven in that: in step three, the volume ratio of N2 to NO is (1-3):1.

[0066] Specific embodiment 9: This embodiment differs from any one of specific embodiments 1 to 8 in that the temperature during demoulding in step 4 is 450°C to 550°C.

[0067] Specific embodiment 10: This embodiment differs from specific embodiments 1 to 9 in that water-soluble quenching oil is used during quenching in step 4. The water-soluble quenching oil can cool the composite material faster and fully inhibit the diffusion and segregation of the Mg element.

[0068] Example 1

[0069] The preparation method of the graphene-aluminum composite material in this embodiment, which utilizes the percolation effect of pressure infiltration to control the diffusion of Mg element and realize strong interface bonding, is carried out in the following steps:

[0070] 1. Weighing

[0071] Weigh 1% of graphene and the balance of 6061 aluminum alloy powder according to mass fraction; then weigh Mg metal, the mass of which is 5% of the total mass of graphene and aluminum alloy powder;

[0072] The graphene is a few-layer graphene with an average sheet diameter of 5 μm and an average thickness of 3 nm;

[0073] The average particle size of the aluminum alloy powder is 8 μm;

[0074] The Mg metal is AM60 magnesium-aluminum alloy;

[0075] 2. Graphene dispersion and preform molding

[0076] 60% of the aluminum alloy powder weighed in step 1 and all of the graphene are mixed and ball-milled, the ball-milled mixed powder is placed into a steel mold, and cold-pressed using a hydraulic press to obtain a composite material preform;

[0077] The ball-to-material ratio of the ball milling process is 10:1, the rotation speed is 150 r / min, and the ball milling time is 6 hours. The ball milling can evenly disperse the graphene on the aluminum surface, and the ball milling can form a strong mechanical bond between the graphene and the aluminum powder, thereby improving the strength of the composite material. A larger ball-to-material ratio can make the graphene more evenly dispersed, while breaking up the graphene clusters, reducing the agglomeration of the graphene on the aluminum surface, and reducing the large-scale aggregation of the brittle phase Al4C3 during subsequent sintering and infiltration processes. A suitable rotation speed can obtain a material with better graphene dispersion effect, without uneven dispersion or graphene breakage.

[0078] The pressure applied during the cold pressing process is 60KN, and the holding time is 10 minutes. Cold pressing is beneficial for obtaining a composite material with better structure and better performance.

[0079] 3. High temperature sintering of composite material preforms

[0080] The composite material preform obtained in step 2 is placed together with the mold in an atmosphere furnace, the atmosphere furnace is first evacuated to a vacuum, and then a protective gas is introduced into the atmosphere furnace for high-temperature sintering to obtain a graphene-aluminum composite material ingot;

[0081] The high-temperature sintering process comprises heating to 300°C at a heating rate of 4°C / min and holding the temperature for 2 hours, then heating to 600°C at a heating rate of 4°C / min and holding the temperature for 4 hours, applying a pressure of 100 MPa to the composite material preform during the heating process, and cooling the preform in the furnace after sintering to obtain a graphene-aluminum composite ingot. Sintering under pressure can ensure that the composite material has fine and dense grains.

[0082] The protective gas is a mixture of N2 and NO, with a volume ratio of N2 to NO of 2:1;

[0083] Evacuating the atmosphere furnace to a vacuum can prevent the composite material preform from being oxidized during the heating process. The protective gas composed of N2 and NO introduces a small amount of oxygen, which can generate a mixed film of aluminum nitride and aluminum oxide at the interface at high temperature, thereby increasing the interface bonding strength. The aluminum nitride and aluminum oxide generated at the grain boundary reduce the direct contact between graphene and Al, forming a protective interlayer to reduce the reaction between C-Al and thus reduce Al4C3. Nitrogen can prevent the oxygen that may enter the atmosphere furnace during the heating process from oxidizing the preform, and the thermal conductivity of nitrogen is higher than that in vacuum, making the heat transfer more uniform, thereby improving the crystal growth behavior and reducing the uneven grain growth. After nitrogen forms aluminum nitride at the interface, the combination of oxygen and aluminum is reduced, thereby reducing the accumulation of aluminum oxide at the grain boundary. 4. Preparation of graphene-aluminum composite materials with strong interface bonding by pressure infiltration

[0084] The remaining aluminum alloy powder and all the Mg metal weighed in step 1 are mixed and melted to obtain a melt, and then the melt is infiltrated into the graphene-aluminum composite ingot using a short-time pressure infiltration process. After the melt solidifies, it is demolded at high temperature and then quenched;

[0085] The demolding temperature is 500° C. The mixed melting of aluminum alloy powder and Mg metal can improve safety by preventing explosion and sputtering of pure Mg during pressure infiltration. On the other hand, Mg can form magnesium-aluminum spinel with Al during pressure infiltration. Magnesium-aluminum spinel has good chemical stability and thermal stability. When magnesium and aluminum combine to form magnesium-aluminum spinel, the position of magnesium atoms can be effectively fixed, thereby inhibiting the tendency of magnesium segregation, reducing Mg segregation, and making the distribution of Mg in the matrix more uniform.

[0086] The use of water-soluble quenching oil during quenching can make the composite material cool faster and fully inhibit the diffusion and segregation of Mg elements;

[0087] The short-time pressure infiltration process is as follows: the preheating temperature of the preform is 640°C, the temperature of the infiltrated melt is 880°C, the infiltration pressure is 50KN, and the time is 10 minutes;

[0088] 5. Solution aging treatment

[0089] The composite material after quenching in step 4 is subjected to solution aging treatment to complete the process;

[0090] The solution aging treatment process is as follows: holding at 530°C for 1 hour, then quenching, and then holding at 175°C for 6 hours. The solution aging treatment allows the Mg element to be evenly distributed in the composite matrix and controls the interface segregation of Mg.

[0091] Figure 1 SEM image of the composite material without Mg compensation (Mg metal was not added in the preparation process, and other aspects were the same as in Example 1) and the distribution of Mg elements near graphene; Figure 2 Example 1: SEM image of the composite material with 5% Mg added as compensation and the distribution of Mg elements near graphene. According to the SEM images of the two composite materials, we can see that: Figure 1 There is indeed a large amount of Mg segregation at the graphene interface, but Figure 2 After Mg compensation, the number of graphene layers is reduced. The Mg content in both the matrix and at the interface is higher than in the composite without Mg compensation, demonstrating that the addition of Mg metal compensates for the Mg element in the matrix of the composite. The graphene-aluminum composite prepared in this example achieved a tensile strength of 609 MPa, an elastic modulus of 94 GPa, and an elongation of 14.5%, demonstrating excellent tensile and elongation properties.

[0092] Example 2

[0093] The preparation method of the graphene-aluminum composite material in this embodiment, which utilizes the percolation effect of pressure infiltration to control the diffusion of Mg element and realize strong interface bonding, is carried out in the following steps:

[0094] 1. Weighing

[0095] Weigh 3% of graphene and the balance of 6061 aluminum alloy powder according to mass fraction; then weigh Mg metal, the mass of which is 10% of the total mass of graphene and aluminum alloy powder;

[0096] The graphene is a few-layer graphene with an average sheet diameter of 5 μm and an average thickness of 5 nm;

[0097] The average particle size of the aluminum alloy powder is 10 μm;

[0098] The Mg metal is AM60 magnesium-aluminum alloy;

[0099] 2. Graphene dispersion and preform molding

[0100] 60% of the aluminum alloy powder weighed in step 1 and all of the graphene are mixed and ball-milled, the ball-milled mixed powder is placed into a steel mold, and cold-pressed using a hydraulic press to obtain a composite material preform;

[0101] The ball-to-material ratio of the ball milling process is 10:1, the rotation speed is 150 r / min, and the ball milling time is 6 h;

[0102] The pressure applied during the cold pressing process is 70KN and the holding time is 10min;

[0103] 3. High temperature sintering of composite material preforms

[0104] The composite material preform obtained in step 2 is placed together with the mold in an atmosphere furnace, the atmosphere furnace is first evacuated to a vacuum, and then a protective gas is introduced into the atmosphere furnace for high-temperature sintering to obtain a graphene-aluminum composite material ingot;

[0105] The high-temperature sintering process comprises heating to 350°C at a heating rate of 5°C / min and holding the temperature for 3 hours, then heating to 650°C at a heating rate of 5°C / min and holding the temperature for 3 hours, applying a pressure of 150 MPa to the composite material preform during the heating process, and cooling the furnace after sintering to obtain a graphene-aluminum composite ingot;

[0106] The protective gas is a mixture of N2 and NO, with a volume ratio of N2 to NO of 2:1;

[0107] 4. Preparation of graphene-aluminum composites with strong interfacial bonding by pressure infiltration

[0108] The remaining aluminum alloy powder and all the Mg metal weighed in step 1 are mixed and melted to obtain a melt, and then the melt is infiltrated into the graphene-aluminum composite ingot using a short-time pressure infiltration process. After the melt solidifies, it is demolded at high temperature and then quenched;

[0109] The demoulding temperature is 500°C;

[0110] Water-soluble quenching oil is used during quenching;

[0111] The short-time pressure infiltration process is as follows: the preheating temperature of the preform is 640°C, the temperature of the infiltrated melt is 880°C, the infiltration pressure is 50KN, and the time is 10 minutes;

[0112] 5. Solution aging treatment

[0113] The composite material after quenching in step 4 is subjected to solution aging treatment to complete the process;

[0114] The solution aging treatment process was as follows: holding at 530°C for 1 hour, followed by quenching, and then holding at 175°C for 6 hours. The graphene-aluminum composite material prepared in this example achieved a tensile strength of 630 MPa, an elastic modulus of 98 GPa, and an elongation of 13.9%, exhibiting excellent tensile and elongation properties.

Claims

1. A method for preparing a graphene-aluminum composite material that utilizes the percolation effect of pressure infiltration to control the diffusion of Mg elements and achieve strong interfacial bonding, characterized in that: The preparation method of the graphene-aluminum composite material with strong interface bonding by controlling the diffusion of Mg element by the percolation effect of pressure infiltration is carried out in the following steps:

1. Weighing Weigh 1% to 3% of graphene and the balance of aluminum alloy powder according to mass fraction; then weigh Mg metal, the mass of which is 3% to 10% of the total mass of the graphene and aluminum alloy powder; The Mg metal is a magnesium-aluminum alloy; 2. Graphene dispersion and preform molding 60% of the aluminum alloy powder weighed in step 1 and all of the graphene are mixed and ball-milled, the ball-milled mixed powder is placed into a steel mold, and cold-pressed using a hydraulic press to obtain a composite material preform; The ball-to-material ratio of the ball milling process is (8-20):1, the rotation speed is (150-250) r / min, and the ball milling time is 6 hours; 3. High temperature sintering of composite material preforms The composite material preform obtained in step 2 is placed together with the mold in an atmosphere furnace, the atmosphere furnace is first evacuated to a vacuum, and then a protective gas is introduced into the atmosphere furnace for high-temperature sintering to obtain a graphene-aluminum composite material ingot; The high-temperature sintering process comprises heating to 300-350° C. at a heating rate of 3-10° C. / min and holding the temperature for 2-3 hours, then heating to 600-650° C. at a heating rate of 3-10° C. / min and holding the temperature for 3-6 hours, applying a pressure of 100-200 MPa to the composite material preform during the heating process, and cooling the preform in the furnace after sintering to obtain a graphene-aluminum composite material ingot; The protective gas is a mixture of N2 and NO; 4. Preparation of graphene-aluminum composites with strong interfacial bonding by pressure infiltration The remaining aluminum alloy powder and all the Mg metal weighed in step 1 are mixed and melted to obtain a melt, and then the melt is infiltrated into the graphene-aluminum composite ingot using a short-time pressure infiltration process. After the melt solidifies, it is demolded at high temperature and then quenched; The short-time pressure infiltration process is as follows: the preheating temperature of the preform is 640°C, the temperature of the infiltrated melt is 880°C, the infiltration pressure is 40-60KN, and the time is 5-15 minutes; 5. Solution aging treatment The composite material after quenching in step 4 is subjected to solution aging treatment to complete the process; The process of the solution aging treatment is: keeping the temperature at 530° C. for 1 hour, then quenching, and keeping the temperature at 175° C. for 6 hours after quenching.

2. The method for preparing a graphene-aluminum composite material with strong interfacial bonding by controlling the diffusion of Mg element through the seepage effect of pressure infiltration according to claim 1, characterized in that: The graphene described in step 1 is few-layer graphene with an average sheet diameter of 100nm to 25μm and an average thickness of 0.5 to 30nm.

3. The method for preparing a graphene-aluminum composite material that utilizes the seepage effect of pressure infiltration to control the diffusion of Mg element and achieve strong interface bonding according to claim 1, characterized in that: The average particle size of the aluminum alloy powder in step 1 is 8 to 20 μm.

4. The method for preparing a graphene-aluminum composite material that utilizes the seepage effect of pressure infiltration to control the diffusion of Mg element and achieve strong interface bonding according to claim 1, characterized in that: The aluminum alloy powder described in step 1 is one of 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.

5. The method for preparing a graphene-aluminum composite material that utilizes the seepage effect of pressure infiltration to control the diffusion of Mg element and achieve strong interface bonding according to claim 4, characterized in that: The mass fraction of Si in the Al-Si alloy is 2% to 25%; the mass fraction of Si in the 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 the 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 the 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 the 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 the 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%.

6. The method for preparing a graphene-aluminum composite material that utilizes the seepage effect of pressure infiltration to control the diffusion of Mg element and achieve strong interface bonding according to claim 1, characterized in that: The ball-to-material ratio in the ball milling process of step 2 is 10:1, the rotation speed is 150 r / min, and the ball milling time is 6 h.

7. The method for preparing a graphene-aluminum composite material that utilizes the seepage effect of pressure infiltration to control the diffusion of Mg element and achieve strong interface bonding according to claim 1, characterized in that: The pressure applied during the cold pressing process in step 2 is 50 to 70 kN, and the holding time is 5 to 20 minutes.

8. The method for preparing a graphene-aluminum composite material that utilizes the seepage effect of pressure infiltration to control the diffusion of Mg element and achieve strong interface bonding according to claim 1, characterized in that: In step 3, the volume ratio of N2 and NO is (1-3):

1.

9. The method for preparing a graphene-aluminum composite material that utilizes the seepage effect of pressure infiltration to control the diffusion of Mg element and achieve strong interface bonding according to claim 1, characterized in that: The temperature during demoulding in step 4 is 450°C to 550°C.

10. The method for preparing a graphene-aluminum composite material that utilizes the seepage effect of pressure infiltration to control the diffusion of Mg element and achieve strong interface bonding according to claim 1, characterized in that: During the quenching in step 4, water-soluble quenching oil is used.

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