Method for preparing uniform and compact graphene / high-entropy alloy composite material through stacking hot-pressing method

Abstract

The invention discloses a preparation method of a graphene (alias black gold) / high-entropy alloy composite material, and belongs to the field of novel structural materials. The method comprises the following steps: mixing graphene and N-methyl pyrrolidone (NMP), adding the mixture into ammonia water, putting the mixed solution into a microwave oven for radiation, carrying out electro-deposition on a graphene dispersion solution heated by microwaves, connecting a positive electrode with a steel sheet, connecting a negative electrode with a high-entropy alloy, stacking high-entropy alloy sheets subjected to electro-deposition together, putting the stacked high-entropy alloy sheets into a mold, and carrying out heat treatment to obtain the graphene / NMP composite material. And putting the mold into an induction coil, and regulating and controlling the temperature and the time to obtain the composite material. And finally, carrying out vacuum annealing on the composite material. The graphene and the high-entropy alloy are uniformly mixed and tightly combined by adopting lamination compounding, so that the problem of non-uniform structure in a traditional smelting method is avoided. Meanwhile, the graphene dispersion liquid can be efficiently prepared within a short time through microwave radiation treatment and can be stably dispersed in a solvent. The material has the characteristics of high hardness, corrosion resistance and the like.

Description

Technical Field

[0001] The invention relates to a composite process of graphene and high entropy alloy, and belongs to the field of new structural materials. Background Art

[0002] Nowadays, with the development of society, various industries are also developing rapidly, especially in the fields of machinery and industry, which makes the working environment of materials more severe. Among them, metal materials, as an indispensable part of human industrialization, are used in all aspects of human society, such as aviation, national defense, transportation and civil fields. High-strength and high-plasticity materials have always been the eternal pursuit of metal materials, but traditional materials can no longer meet the increasingly developing performance requirements, and the preparation and application prospects of single-principal alloy materials are becoming increasingly narrow. Therefore, new materials with superior performance are urgently needed to meet today's performance requirements. With the discovery of HEA by Ye Junwei and others, HEA was defined as an alloy composed of 5 or more principal elements, each of which has an atomic percentage of 5 to 35%, and has a high configuration entropy. Traditional alloys are alloys that add trace alloying elements to a single principal element, but they will form a brittle phase in the alloy, resulting in low overall performance of the alloy. However, the use of the design concept of HEA can obtain alloy materials with superior comprehensive performance. By designing different principal elements in different proportions, it is currently known that HEA has four major effects, as well as some simple structures such as face-centered cubic (FCC), body-centered cubic (BCC) and hexagonal close-packed (HCP). Materials with different superior properties can be obtained.

[0003] High entropy alloys have become a new research hotspot in the field of materials science and condensed matter physics after bulk amorphous materials due to their superior comprehensive properties that are unmatched by traditional alloys, such as high strength, high hardness, high toughness, high fatigue resistance, excellent wear and corrosion resistance, high thermal resistance, high electrical resistance and electromagnetic properties. It is known as one of the three most promising research hotspots in the field of materials in the next few decades: bulk amorphous materials, composite materials and high entropy alloys. At present, the low comprehensive properties of high entropy alloys limit their application in the engineering field. In order to further improve the performance of high entropy alloys, introducing appropriate reinforcement phases into their matrix to form high entropy alloy-based composites (HEAMCs) has become an important way to improve and enhance the comprehensive properties of high entropy alloys.

[0004] Graphene is one of the strongest materials known, with excellent mechanical and electrical properties, good toughness and flexibility. Compared with traditional reinforcement phases, graphene's high specific surface area gives it a significant advantage in reinforcement efficiency, making it the most promising reinforcement material for improving the performance of composite materials. However, its serious agglomeration problem and poor wettability with the matrix affect its reinforcement effect. Summary of the invention

[0005] In order to solve the problems of uneven dispersion of reinforcing phase and loose structure in the preparation process of composite materials, the present invention aims to provide a high-strength interface bonding material of graphene-high entropy metal. The method utilizes lamination composite technology to stack and heat high entropy alloy sheets and graphene dispersion to prepare graphene-high entropy alloy composite materials with excellent electrical and thermal conductivity. The specific steps include:

[0006] (1) First, the high entropy alloy sheet is polished to remove surface pollutants and oxides;

[0007] (2) adding graphene oxide to N-methylpyrrolidone (NMP), stirring thoroughly, and then adding an appropriate amount of ammonia water to mix;

[0008] (3) subjecting the obtained mixed solution to microwave radiation. After the microwave radiation is completed, the mixed solution is taken out and allowed to stand for a period of time;

[0009] (4) pouring the supernatant of the graphene dispersion into an electrodeposition device, connecting the positive electrode to the steel sheet, and connecting the negative electrode to the high entropy alloy;

[0010] (5) stacking the electro-deposited high entropy alloy sheets in multiple layers and cold pressing and exhausting them to avoid the introduction of oxidized inclusions;

[0011] (6) hot pressing the cold pressed sample;

[0012] (7) The hot pressed sample is subjected to vacuum annealing.

[0013] The invention is characterized in that the composite material is prepared by microwave radiation, lamination and vacuum annealing. Microwave radiation can avoid damaging the surface structure of graphene and affecting its performance. The lamination method can make graphene and high entropy alloy closely combined. This production method not only ensures high efficiency of preparation, but also meets the high performance requirements of the composite material. The vacuum annealing adopted by the invention avoids oxidation of the surface graphene.

[0014] Beneficial effects of the present invention:

[0015] The present invention uses microwave radiation to process graphene. Compared with the traditional ultrasonic dispersion method, it avoids destroying the surface structure of graphene during ultrasonic dispersion and affecting its performance. At the same time, it can efficiently prepare a graphene dispersion in a short time, and the prepared graphene can be stably dispersed in a solvent. On the other hand, by using a lamination composite method, by accurately controlling parameters such as temperature, pressure and time during the lamination process, the uniform mixing and close combination of graphene and high entropy alloy are achieved, which not only avoids the structural unevenness problem in the traditional smelting method, but also can maintain the excellent performance of graphene and high entropy alloy. In addition, during the lamination process, fine grain strengthening and second phase strengthening are used to further improve the performance of the composite material.

[0016] In the present invention, since the composite material is finally subjected to vacuum annealing, oxidation of the surface graphene is avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Metallographic diagram of case 1 Figure 2 Metallographic diagram of case 2 Figure 3 Metallographic diagram of case 3 DETAILED DESCRIPTION

[0018] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0019] Implementation Case 1

[0020] Take 20mg of graphene oxide and 200ml of N-methylpyrrolidone (NMP), stir them thoroughly, and then add 75ml of ammonia water. Put the resulting mixture into a microwave oven with a power of 200W and heat it for 3 minutes. The resulting dispersion is deposited on the surface of the high entropy alloy by electrodeposition for 1 minute. Stack them together and put them into a hot pressing device. First, cold pressing and exhaust treatment is performed for 30 minutes, followed by hot pressing treatment, setting the temperature to 500 degrees, the hot pressing time to 2h, and the reduction rate to 50%. Finally, vacuum annealing treatment is performed at a temperature of 800 degrees and kept warm for 1h.

[0021] The test performance of the graphene-high entropy alloy composite material prepared in this embodiment is as follows: the measured tensile strength is 780 MPa, the hardness is 410 HV, and the elongation is 20.1%.

[0022] Implementation Case 2

[0023] Take 20mg of graphene oxide and 200ml of N-methylpyrrolidone (NMP), stir them thoroughly, and then add 75ml of ammonia water. Put the resulting mixture into a microwave oven with a power of 200W and heat for 3 minutes. The resulting dispersion is deposited on the surface of the high entropy alloy by electrodeposition for 1 minute. Stack them together and put them into a hot pressing device. First, cold pressing and exhaust treatment are performed for 30 minutes, followed by hot pressing treatment, setting the temperature to 600 degrees, hot pressing time to 2h, and pressing rate to 50%. Finally, vacuum annealing temperature is 800 degrees and kept warm for 1h.

[0024] The test performance of the graphene-high entropy alloy composite material prepared in this embodiment is as follows: the measured tensile strength is 790 MPa, the hardness is 428 HV, and the elongation is 23.2%.

[0025] Implementation Case 3

[0026] Take 20mg of graphene oxide and 200ml of N-methylpyrrolidone (NMP), stir them thoroughly, and then add 75ml of ammonia water. Put the resulting mixture into a microwave oven with a power of 200W and heat it for 3 minutes. The resulting dispersion is deposited on the surface of the high entropy alloy by electrodeposition for 1 minute. Stack them together and put them into a hot pressing device. First, cold pressing and exhaust treatment are performed for 30 minutes, followed by hot pressing treatment, setting the temperature to 700 degrees, hot pressing time to 2h, and pressing rate to 50%. Finally, vacuum annealing temperature is 800 degrees and kept warm for 1h.

[0027] The test performance of the graphene-high entropy alloy composite material prepared in this embodiment is as follows: the measured tensile strength is 800 MPa, the hardness is 443 HV, and the elongation is 25.6%.

[0028] The core advantages of this technology lie in the following aspects: First, the material is treated with microwave radiation technology, which can effectively protect the surface structure of graphene and prevent its performance from being damaged. Secondly, the composite material is prepared through a lamination process, which not only improves production efficiency but also ensures the high performance of the final product. Finally, vacuum annealing technology is used, which helps prevent the surface oxidation of graphene. These innovations together ensure that the present invention improves the comprehensive performance of the material while maintaining the original performance.

Claims

1. A method for preparing uniform and dense graphene / high entropy alloy composite materials by stacking hot pressing, characterized in that: The specific steps include: (1) First, the high entropy alloy sheet is polished to remove surface pollutants and oxides; (2) adding graphene to N-methylpyrrolidone (NMP) and stirring thoroughly, and then adding an appropriate amount of ammonia water to mix; (3) subjecting the obtained mixed solution to microwave radiation treatment. After the microwave radiation is completed, the mixed solution is allowed to stand for a period of time; (4) pouring the supernatant of the graphene dispersion into an electrodeposition device, connecting the positive electrode to the steel sheet, and connecting the negative electrode to the high entropy alloy; (5) stacking the electro-deposited high entropy alloy sheets in multiple layers and cold pressing and exhausting them to avoid the introduction of oxidized inclusions; (6) hot pressing the cold pressed sample; (7) The hot pressed sample is subjected to vacuum annealing.

2. The method for preparing a uniform and dense graphene / high entropy alloy composite material by stacking hot pressing according to claim 1, characterized in that: Step (1) Surface treatment of the high entropy alloy sheet: first, pickling is used to remove the surface oxide layer, and then sanding is used to ensure that the sheet layer is smooth and flat.

3. The method for preparing a uniform and dense graphene-high entropy alloy composite material by stacking hot pressing according to claim 1, characterized in that: The thickness of the high entropy alloy sheet is 0.1 to 1 mm, and the diameter is more than 5 mm.

4. The method for preparing a uniform and dense graphene / high entropy alloy composite material by stacking hot pressing according to claim 1, characterized in that: Take 20-50 mg of graphene oxide, 200-250 ml of N-methylpyrrolidone, and 50-75 ml of ammonia water.

5. The method for preparing a uniform and dense graphene / high entropy alloy composite material by stacking hot pressing according to claim 1, characterized in that: In step (3), the microwave heating power is 100 to 500 W and the time is 1 to 5 minutes.

6. The method for preparing uniform and dense graphene / high entropy alloy composite material by stacking hot pressing method according to claim 1, characterized in that: In step (4), the electrodeposition parameters are as follows: the stainless steel sheet is used as the positive electrode, the high entropy alloy is used as the negative electrode, the distance between the cathode and the anode is maintained at 30 to 50 mm, the voltage is 20 to 40 V, and the deposition time is 0.5 to 3 minutes.

7. The method for preparing a uniform and dense graphene-high entropy alloy composite material by stacking hot pressing according to claim 1, characterized in that: The cold pressing pressure in step (5) is 100-500 MPa.

8. The method for preparing uniform and dense graphene / high entropy alloy composite material by stacking hot pressing method according to claim 1, characterized in that: In step (6), the hot pressing temperature is 400 to 800 degrees, the time is 2 to 4 hours, and the pressing rate is 40 to 60%.

9. The method for preparing a uniform and dense graphene-high entropy alloy composite material by stacking hot pressing according to claim 1, characterized in that: The vacuum annealing temperature in step (7) is 700-1000 degrees, and the holding time is 1 hour. The method for preparing a uniform and dense graphene-high entropy alloy composite material by stacking hot pressing according to claim 1 is characterized in that The hardness of the composite material can reach more than 400 HV, the tensile strength can reach 780 MPa, and the elongation after fracture can reach more than 18%.

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