Preparation method of in-situ grown graphene reinforced foam metal skeleton-based composite material

Abstract

The present invention discloses a method for preparing an in-situ graphene-reinforced foam metal skeleton-based composite material. The method comprises using a foam metal skeleton as a matrix and in-situ growing graphene on the surface of the foam metal skeleton by a chemical method combined with calcination, thereby preparing the in-situ graphene-reinforced foam metal skeleton-based composite material. The steps include: 1) removing impurities from the surface of the foam metal skeleton; 2) preparing a mixed solution of carbon-containing organic matter and carbon quantum dots, and immersing the foam metal skeleton in the solution; and 3) heat treating the foam metal skeleton in a spark plasma sintering system. The present invention in-situ grows graphene on the surface of the foam metal skeleton, wherein the microscopic morphology and content of the graphene are controllable. The solution immersion method combined with the heat treatment process can achieve in-situ growth of graphene in the pores within the foam metal skeleton, thereby further improving the comprehensive service performance of the foam metal skeleton.

Description

Technical Field

[0001] The invention relates to a method for preparing in-situ grown graphene, and in particular to a method for preparing an in-situ grown graphene reinforced foam metal skeleton-based composite material. Background Art

[0002] Graphene possesses mechanical properties far exceeding those of traditional reinforced phase materials, and also possesses excellent electrical and thermal conductivity. At the same time, metal foam skeleton materials, due to their porous structure, can be widely used in lightweight heat dissipation components, catalytic carriers, and impact-resistant materials. Graphene-enhanced metal foam skeleton-based composites can comprehensively improve the mechanical, thermal, electrical, and magnetic properties of metal foam skeleton materials, facilitating the further expansion of metal foam skeleton applications. Due to the complex microstructure of the metal foam skeleton, it is difficult to composite graphene and metal foam skeleton materials using traditional preparation processes. Traditional graphene-enhanced metal-based composites are mainly prepared by external addition, but due to the poor surface activity and large specific surface area of graphene, graphene is prone to agglomeration in the metal matrix, resulting in its overall performance being significantly lower than expected. The high degree of microstructural complexity of the metal foam skeleton further exacerbates the difficulty of composite graphene onto the surface of the metal foam skeleton by external addition.

[0003] Graphene-reinforced metal-matrix composites can be prepared using either external addition or in-situ synthesis, depending on the method of graphene addition. External addition methods primarily include ball milling, solution mixing, flake powder metallurgy, electrodeposition, and molecular-level mixing, while in-situ synthesis primarily utilizes vapor deposition. However, these methods for preparing graphene-reinforced metal-matrix composites are difficult to apply to the preparation of graphene-reinforced metal foam skeleton-based composites.

[0004] To address this problem, some studies have provided solutions to some extent, such as:

[0005] CN110257795A discloses a method for preparing a three-dimensional graphene-reinforced copper-based composite material. The process involves in-situ growth of graphene-reinforced copper foam using vapor deposition. The overall process focuses on achieving in-situ growth of graphene within the complex structure of the copper foam. However, the high cost of producing graphene using vapor deposition has hindered its industrialization. Furthermore, limitations in vapor deposition equipment make it difficult to process large-scale graphene-reinforced copper foam composite materials.

[0006] CN114214602A discloses a continuous preparation method for a three-dimensional in-situ graphene-reinforced metal-based composite material. The preparation process combines chemical vapor deposition with a hot rolling process to achieve continuous production of the graphene-reinforced foam metal-based composite material. The overall process focuses on achieving continuous production of the composite material. However, the subsequent hot rolling process destroys the three-dimensional network structure of the metal foam, thereby affecting its application in fields such as heat dissipation and electromagnetic shielding.

[0007] CN110697695A discloses a method for preparing a graphene-reinforced metal-based foam skeleton structure composite material. The preparation process described herein uses a chemical deposition method to in-situ grow graphene on the surface of copper foam. The key point of the preparation process is to facilitate the oxidation method to grow nano-copper oxide on the surface of the copper foam to achieve regulation of the specific surface area of the copper foam. However, this application still uses the commonly used chemical vapor deposition method to achieve in-situ growth of graphene, resulting in unclear prospects for its industrial application.

[0008] CN108199018A discloses a foamed graphene / carbon nanotube / molybdenum disulfide composite material with a tertiary structure, its preparation method, and its application. The preparation process described combines chemical vapor deposition, carbon source pyrolysis, and atomic layer deposition to achieve the preparation of the foamed graphene / carbon nanotube / molybdenum disulfide composite material. However, due to the complex preparation process, high production costs, and low reproducibility, this application is not easily transferable to the preparation of graphene-reinforced foamed metal-based composite materials. Summary of the Invention

[0009] In order to overcome the problems existing in the prior art, the present invention provides a method for preparing an in-situ grown graphene-enhanced foam metal skeleton-based composite material, which is achieved by adopting a solution immersion method in combination with a heat treatment process to allow graphene to be in-situ grown in the internal pores of the foam metal skeleton, thereby avoiding the occurrence of graphene agglomeration to a certain extent, thereby achieving the purpose of graphene-enhanced foam metal skeleton. At the same time, since the solution immersion method has low requirements for equipment, operating conditions and equipment costs, it is beneficial for its process flow to achieve high repeatability and industrial preparation. The addition of carbon quantum dots can serve as nucleation sites for subsequent graphene growth, thereby reducing the difficulty of graphene in-situ growth, making the prepared graphene microstructure more likely to present a lamellar shape. Due to the use of a solution immersion method in combination with a heat treatment process, the microstructure and content of the graphene of the graphene-enhanced foam metal skeleton-based composite material prepared by the present invention are controllable, and the preparation process of the present invention is simple and has strong versatility, and is promoted by subsequent industrialization.

[0010] The preparation method of the present invention specifically comprises the following steps:

[0011] (1) Soaking the metal foam skeleton in an acidic solution (oxalic acid solution with a concentration of 5 ml / L to 150 ml / L) at 25°C to 70°C for 5 to 30 minutes, and then washing it with deionized water until it is neutral, thereby obtaining a metal foam skeleton after removing surface oxides; during the operation, the parameters of soaking time, temperature and oxalic acid concentration are adjusted to achieve the best oxide removal effect;

[0012] (2) A mixed solution of carbon-containing organic matter and carbon quantum dots is prepared, wherein the concentration of the carbon-containing organic matter solution is 5-30 g / L and the amount of carbon quantum dots added is 1-10 mg / ml. The two solutions are magnetically stirred and mixed for 2 hours, and the solution is heated to 50°C during the mixing process. The foam metal skeleton is then immersed in the mixed solution, and an appropriate amount of iodine solution (10-50 ml / L) is added during the immersion process to increase the nucleation sites and carbon source for the in situ growth of graphene on the surface of the foam metal skeleton;

[0013] (3) The pre-soaked foam metal skeleton is subjected to physical drying or freeze-drying technology to adsorb and fix carbon-containing organic matter and carbon quantum dots on the skeleton surface of the foam metal skeleton, thereby obtaining a precursor of an in-situ grown graphene-reinforced foam metal skeleton-based composite material;

[0014] (4) The precursor is placed in a spark plasma sintering (SPS) system for heat treatment, and after the reaction is completed, an in-situ grown graphene-reinforced foam metal skeleton-based composite material is obtained.

[0015] Further:

[0016] In step (1), the foam metal skeleton includes foam copper, foam nickel, foam aluminum, foam titanium and other alloy foam metal skeletons, the purity of the foam metal skeleton is above 99%, and the porosity is 50-90%.

[0017] In step (2), the soaking time is 24 hours.

[0018] In step (3), the parameters of the vacuum drying are a temperature of 70°C and a drying time of 12 to 24 hours; the parameters of the freeze drying are a temperature of -20°C, a time of 12 to 24 hours, and a vacuum degree of <30Pa.

[0019] In step (4), the heat treatment process is to place the precursor foam metal skeleton in a spark plasma sintering system for heat treatment at a temperature of 300-600°C, a treatment time of 5-30 minutes, and a vacuum degree of <10 -3 Pa, and finally the in-situ grown graphene reinforced foam metal skeleton-based composite material was prepared.

[0020] Compared with the existing technology, the present invention has the following advantages and positive effects:

[0021] (1) Compared with the chemical vapor deposition method, the solution immersion method adopted in this invention has simple process steps, short preparation cycle, easy operation, convenient equipment cost and maintenance, and is conducive to large-scale production;

[0022] (2) Compared with the traditional graphene external addition method, this invention can uniformly adsorb carbon sources and nucleation sites inside and on the surface of the complex microstructure of the foam metal through the solution immersion method, thereby catalyzing the formation of lamellar graphene in the discharge plasma system. This method can achieve in-situ growth of graphene inside and on the surface of the foam metal skeleton by regulating the concentration of the immersion solution and the reaction conditions, and the content and micromorphology of graphene can be controlled. In addition, the reaction process has little pollution to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The process flow chart of the preparation method of in-situ grown graphene reinforced foam metal skeleton-based composite material.

[0024] Figure 2 This is the SEM image of the in-situ grown graphene reinforced foam metal skeleton-based composite material in Example 1.

[0025] Figure 3 This is the SEM image of the in-situ grown graphene reinforced foam metal skeleton-based composite material in the comparative example. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to specific examples, but the protection scope of the present invention is not limited thereto.

[0027] Example 1

[0028] The method for preparing the in-situ grown graphene reinforced foam metal skeleton-based composite material of the present invention specifically comprises the following steps:

[0029] Step 1) Immerse a 5×5×1 cm copper foam in 50 ml / L oxalic acid solution for 20 minutes at 50°C to remove oxides from the surface of the copper foam.

[0030] Step 2) Prepare a mixed solution of sucrose and carbon quantum dots at a concentration of 10 g / L and 5 mg / mL of carbon quantum dots. Mix the two solutions under magnetic stirring for 2 hours, heating the solution to 50°C. Then, soak the copper foam in the mixed solution, adding 20 mL / L of iodine solution.

[0031] Step 3) vacuum drying the copper foam after pre-soaking for 24 hours to adsorb and fix sucrose and carbon quantum dots on the surface of the copper foam skeleton (vacuum drying parameters: drying temperature 70°C, drying time 24 hours), thereby obtaining a precursor of the in-situ grown graphene-reinforced copper foam-based composite material;

[0032] Step 4) The precursor was placed in a Spark Plasma Sintering (SPS) system for heat treatment at a temperature of 300°C, a reaction time of 10 minutes, and a vacuum degree of <10 -3 Pa, after the reaction is completed, an in-situ grown graphene reinforced foam copper-based composite material is obtained.

[0033] Comparative Example 1

[0034] Comparative Example 1 is different from Example 1 except that no carbon quanta are added during the operation of step (2). The other preparation processes and component ratios are the same as those of Example 1. The in-situ grown graphene reinforced foam copper-based composite materials of the embodiment and the comparative example were subjected to SEM analysis. Figure 2-3 It can be found that the graphene sheet structure grown in situ with the added carbon quantum dots as nucleation sites is more obvious, has a larger specific surface area and higher structural integrity.

[0035] Example 2

[0036] The method for preparing the in-situ grown graphene reinforced foam metal skeleton-based composite material of the present invention specifically comprises the following steps:

[0037] Step 1) Soak a 4×4×1 cm nickel foam in 70 ml / L oxalic acid solution for 10 minutes at 60°C to remove oxides on the surface of the nickel foam.

[0038] Step 2) Glucose and carbon quantum dots are prepared into a mixed solution with a glucose concentration of 20g / L and a carbon quantum dot concentration of 15mg / ml. The two solutions are magnetically stirred and mixed for 2 hours, while being heated to 50°C. The nickel foam is then immersed in the mixed solution, and 30ml / L of iodine solution is added during the immersion process.

[0039] Step 3) freeze-drying the nickel foam after pre-soaking for 24 hours to adsorb glucose and carbon quantum dots onto the surface of the nickel foam skeleton (freeze-drying parameters are temperature of -20°C, time of 24 hours, vacuum degree <20Pa), thereby obtaining a precursor of the in-situ grown graphene-reinforced nickel foam-based composite material;

[0040] Step 4) The precursor is placed in a Spark Plasma Sintering (SPS) system for heat treatment at a temperature of 400°C, a reaction time of 15 minutes, and a vacuum degree of <10 -3 Pa, after the reaction is completed, an in-situ grown graphene reinforced nickel foam based composite material is obtained.

[0041] Example 3

[0042] The method for preparing the in-situ grown graphene reinforced foam metal skeleton-based composite material of the present invention specifically comprises the following steps:

[0043] Step 1) Soak a 5×5×2 cm aluminum foam in 15 ml / L oxalic acid solution for 30 minutes at 40°C to remove oxides from the surface of the copper foam.

[0044] Step 2) A mixed solution of ketohexose and carbon quantum dots was prepared, wherein the ketohexose solution concentration was 30 g / L and the carbon quantum dots were added at a concentration of 15 mg / mL. The two solutions were magnetically stirred and mixed for 2 hours, while the solution was heated to 50°C. The aluminum foam was then immersed in the mixed solution, and 20 mL / L of iodine solution was added during the immersion process.

[0045] Step 3) freeze-drying the aluminum foam that has been pre-soaked for 24 hours to adsorb and fix the ketohexose and carbon quantum dots on the surface of the foam metal skeleton (freeze-drying parameters are temperature of -20°C, time of 24 hours, vacuum degree <20Pa), thereby obtaining a precursor of the in-situ grown graphene-reinforced aluminum foam matrix composite material;

[0046] Step 4) The precursor was placed in a Spark Plasma Sintering (SPS) system for heat treatment at a temperature of 350°C, a reaction time of 15 minutes, and a vacuum degree of <10 -3 Pa, after the reaction is completed, an in-situ grown graphene reinforced foam aluminum matrix composite material is obtained.

[0047] Example 4

[0048] The method for preparing the in-situ grown graphene reinforced foam metal skeleton-based composite material of the present invention specifically comprises the following steps:

[0049] Step 1) Soak a 3×3×3 cm titanium foam in 20 ml / L oxalic acid solution for 15 minutes at 70°C to remove oxides from the surface of the copper foam.

[0050] Step 2) A mixed solution of carbon-containing organic matter and carbon quantum dots was prepared, wherein the concentration of the carbon-containing organic matter solution was 10g / L and the amount of carbon quantum dots added was 20mg / ml. The two solutions were magnetically stirred and mixed for 2 hours, and the solution was heated to 50°C during the mixing process. The copper foam was then immersed in the mixed solution of carbon-containing organic matter and carbon quantum dots, and 30ml / L of iodine solution was added during the immersion process;

[0051] Step 3) vacuum drying the titanium foam after pre-soaking for 24 hours to adsorb and fix sucrose and carbon quantum dots on the surface of the foam metal skeleton (vacuum drying parameters: drying temperature 70°C, drying time 18 hours), thereby obtaining a precursor of the in-situ grown graphene-reinforced titanium foam-based composite material;

[0052] Step 4) The precursor is placed in a Spark Plasma Sintering (SPS) system for heat treatment at a temperature of 500°C, a reaction time of 20 minutes, and a vacuum degree of <10 -3 Pa, after the reaction is completed, an in-situ grown graphene reinforced foam titanium-based composite material is obtained.

[0053] The above-mentioned embodiments are only several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they cannot be understood as limiting the scope of protection of the present invention. It should be pointed out that for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention.

Claims

1. A method for preparing an in-situ grown graphene reinforced foam metal skeleton-based composite material, characterized in that: The following steps are involved: Step (1), soaking the foam metal skeleton in an acidic solution at 25°C to 70°C for a period of time, and then washing with deionized water until neutral, to obtain the foam metal skeleton after removing surface oxides; during the operation, the parameters of soaking time, temperature and oxalic acid concentration are adjusted to achieve the best effect of removing oxides; Step (2), adding carbon-containing organic matter and carbon quantum dots into a solvent to prepare a mixed solution, mixing the two solutions by magnetic stirring, and then immersing the foam metal skeleton in the mixed solution, adding an appropriate amount of iodine solution during the immersion process to increase nucleation sites and carbon sources for in situ growth of graphene on the surface of the foam metal skeleton; Step (3), vacuum drying or freeze drying the pre-soaked metal foam skeleton to adsorb and fix the carbon-containing organic matter and carbon quantum dots on the skeleton surface of the metal foam skeleton, thereby obtaining a precursor of an in-situ grown graphene-reinforced metal foam skeleton-based composite material; Step (4) is to place the precursor in a spark plasma sintering system for heat treatment, and after the reaction is completed, an in-situ grown graphene reinforced foam metal skeleton-based composite material is obtained.

2. The method for preparing the in-situ grown graphene reinforced foam metal skeleton-based composite material according to claim 1, characterized in that: In step (1), the soaking time is 5 to 30 minutes.

3. The method for preparing the in-situ grown graphene reinforced foam metal skeleton-based composite material according to claim 1, characterized in that: In step (1), the foam metal skeleton comprises any one of foam copper, foam nickel, foam aluminum and foam titanium; the purity of the foam metal skeleton is above 99%, and the porosity is 50-90%.

4. The method for preparing the in-situ grown graphene reinforced foam metal skeleton-based composite material according to claim 1, characterized in that: In step (2), the carbon-containing organic matter includes starch, sucrose, glucose and polymethyl methacrylate; the purity of the carbon quantum dots is greater than 99%, and the particle size is 2-5 nm.

5. The method for preparing the in-situ grown graphene reinforced foam metal skeleton-based composite material according to claim 1, characterized in that: In step (2), the solvent includes deionized water, anhydrous ethanol and methanol.

6. The method for preparing the in-situ grown graphene reinforced foam metal skeleton-based composite material according to claim 1, characterized in that: In step (2), the amount of carbon-containing organic matter added is 5-30 g / L, the amount of carbon quantum dots added is 1-20 mg / ml, and the immersion time of the foam metal skeleton is 24 h.

7. The method for preparing the in-situ grown graphene reinforced foam metal skeleton-based composite material according to claim 1, characterized in that: In step (2), the carbon-containing organic matter and the carbon quantum dots are prepared into a mixed solution, and the two solutions are mixed by magnetic stirring for 2 hours. During the mixing process, the solution is heated to 50°C.

8. The method for preparing the in-situ grown graphene reinforced foam metal skeleton-based composite material according to claim 1, characterized in that: In step (3), the vacuum drying parameters are a temperature of 70° C. and a drying time of 12 to 24 hours.

9. The method for preparing the in-situ grown graphene reinforced foam metal skeleton-based composite material according to claim 1, characterized in that: In step (3), the technical parameters of the freeze-drying method are temperature -20°C, time 12~24h, and vacuum degree <30Pa.

10. The method for preparing the in-situ grown graphene reinforced foam metal skeleton-based composite material according to any one of claims 1 to 9, characterized in that: In step (4), the heat treatment temperature is 300-600°C, the treatment time is 5-30 minutes, and the vacuum degree is <10 -3 Pa.

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