Graphene aluminum conductor and industrialized preparation method thereof

Abstract

This invention relates to a graphene-aluminum conductor and its industrial-scale preparation method. The preparation method involves: uniformly mixing an aqueous solution of graphene oxide, an aluminum powder dispersion, and PTB protein; drying and compressing the mixed solution into a block; adding this block to molten aluminum; and casting to obtain an aluminum-based graphene intermediate alloy rod. Alternatively, molten aluminum is obtained by melting aluminum ingots, and an AlB8 aluminum-boron intermediate alloy ingot is added to the molten aluminum. A composite refining agent is blown into the molten aluminum using nitrogen gas to refine it, and the mixture is allowed to settle to obtain a mixed molten aluminum. The aluminum-based graphene intermediate alloy rod is added to a flow channel between the casting gate and the casting machine, and the mixed molten aluminum is rolled into a graphene aluminum rod, which is then drawn into graphene aluminum wire. Multiple graphene aluminum wires are concentrically stranded to prepare graphene aluminum conductors. This invention prepares graphene into an aluminum-based graphene intermediate alloy rod, and then adds graphene to the continuous casting and rolling process through a wire feeding method, achieving large-scale continuous production of graphene aluminum rods.

Description

Technical Field

[0001] This invention relates to the technical field of aluminum conductors, and in particular to a graphene aluminum conductor and its industrial preparation method. Background Technology

[0002] Aluminum-based composites have gradually become a key research focus in metal matrix composites due to their lightweight, strong corrosion resistance, and good electrical and thermal conductivity. Graphene, with its high Young's modulus, high tensile strength, and high electron mobility, is considered the best reinforcement for metal matrix composites. Currently, powder metallurgy methods exist for adding graphene to aluminum matrices; however, these methods result in small batch sizes and low production efficiency. In the electrical industry, aluminum conductors are primarily manufactured using continuous casting and rolling processes to produce aluminum rods. Experiments have been conducted in the industry to add graphene into continuous casting and rolling furnaces, but these attempts have failed because graphene, with its low density, floats on the surface of the molten aluminum and eventually carbonizes.

[0003] Therefore, there is an urgent need to develop a method that can achieve industrial-scale production of graphene aluminum conductors. Summary of the Invention

[0004] To address the above technical problems, this invention provides a graphene aluminum conductor and its industrial-scale preparation method. This invention prepares graphene into an aluminum-based graphene intermediate alloy rod, and then adds the graphene to the continuous casting and rolling process via wire feeding, enabling large-scale continuous production of graphene aluminum rods and solving the industry problem of the inability to produce graphene aluminum conductors in large quantities continuously.

[0005] The first objective of this invention is to provide an industrial-scale preparation method for graphene-aluminum wires, comprising the following steps: S1. Mix the graphene oxide aqueous solution, aluminum powder dispersion and PTB protein evenly, dry the mixed solution and compress it into a block, then add it into the aluminum liquid at 750-770℃ and cast it to obtain the aluminum-based graphene intermediate alloy rod. S2. Using aluminum ingots to melt and obtain aluminum liquid, add AlB8 aluminum boron intermediate alloy ingots to the aluminum liquid and stir evenly. Use nitrogen to blow a composite refining agent into the aluminum liquid to refine the aluminum liquid. Let it stand to obtain mixed aluminum liquid. Add aluminum-based graphene intermediate alloy rods to the trough between the casting gate and the casting machine, and roll the mixed aluminum liquid into graphene aluminum rods. S3. Graphene aluminum rods are drawn into graphene aluminum wires through multi-dial drawing, and then multiple graphene aluminum wires are concentrically twisted together using a frame stranding machine to prepare graphene aluminum wires. During the stranding process, bakelite molds are used as compression molds.

[0006] In some embodiments of the present invention, in step S1, the mass ratio of graphene oxide, aluminum powder, and PTB protein is (1~2):(10~12):1. Since the ratio of aluminum powder to graphene oxide in the present invention is greater than 10:1, it is equivalent to adding aluminum blocks to molten aluminum, and therefore carbonization will not occur.

[0007] In some embodiments of the present invention, in step S1, the mass ratio of the block to the molten aluminum liquid is 1:(20~30).

[0008] In some embodiments of the present invention, in step S1, the diameter of the aluminum-based graphene intermediate alloy rod is 3.0~10.0 mm.

[0009] In some embodiments of the present invention, the melting temperature in step S2 is 830~850°C.

[0010] In some embodiments of the present invention, in step S2, the amount of AlB8 aluminum boron master alloy ingot used is 4 kg / ton to 6 kg / ton.

[0011] In some embodiments of the present invention, in step S2, the composite refining agent includes a chloride-fluoride composite refining agent, which is a conventional substance in the art; the refining conditions are: at a temperature of 775-785°C, the composite refining agent is blown into the bottom of the furnace by nitrogen; the settling time is 30 min to 40 min.

[0012] In some embodiments of the present invention, in step S2, the aluminum-based graphene intermediate alloy rod is added to the casting gate at a speed of 80~85mm / min; the diameter of the graphene aluminum rod is 9.5mm~15mm, preferably 9.5mm, 12mm or 15mm.

[0013] In some embodiments of the present invention, in step S3, the diameter of the graphene aluminum wire is 3.63±0.03mm.

[0014] In some embodiments of the present invention, in step S3, the number of graphene aluminum wires is at least 61.

[0015] The second objective of this invention is to provide a graphene-aluminum wire prepared by the aforementioned preparation method.

[0016] A third objective of this invention is to provide a graphene-aluminum conductor, comprising the graphene-aluminum wire.

[0017] The technical solution of the present invention has the following advantages compared with the prior art: 1. Currently, there are methods for adding graphene to aluminum matrices using powder metallurgy. However, these methods result in small batch sizes and cannot be used for continuous production. In the electrical industry, aluminum conductors are primarily manufactured using continuous casting and rolling processes to produce aluminum rods. This invention is the first to achieve the addition of graphene to aluminum conductors using a continuous casting and rolling process, forming aluminum-based graphene intermediate alloy rods. This enables the industrial-scale and continuous production of graphene-aluminum conductors, solving a major industry challenge that prevented continuous casting and rolling addition due to graphene's low density and susceptibility to burn-off.

[0018] 2. Aqueous solutions of graphene oxide, aluminum powder dispersion, and a small amount of PTB protein are uniformly mixed. The mixture is dried and compressed into a block. The aluminum-graphene mixture is then added to molten aluminum and cast into an 8.0 mm diameter aluminum-based graphene intermediate alloy rod. This invention is based on the fact that the mixture of aqueous solution of graphene oxide and aluminum powder dispersion will separate into layers. PTB protein, with its excellent interfacial activity and good wettability for both aluminum and carbon, effectively improves the interfacial bonding between aluminum and carbon.

[0019] 3. This invention uses a trough feeding method to add aluminum-based graphene intermediate alloy rods to the trough between the casting gate and the casting machine during continuous casting and rolling processes, which greatly reduces the burning loss of graphene.

[0020] 4. The graphene conductor prepared by this invention has a DC resistance of 0.0439 Ω / km and a breaking force of 116.8 kN (the DC resistance of conventional aluminum stranded wire of the same specification is 0.0458 Ω / km and the breaking force is 101.0 kN). It has the advantages of low DC resistance and high breaking force, which can reduce line resistance loss by more than 3% in the application of overhead transmission lines and improve the safety of line operation. Attached Figure Description

[0021] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein... Figure 1 This is a cross-sectional view of the graphene aluminum wire obtained in Example 1 of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0023] Example 1 This embodiment provides a graphene aluminum conductor and its preparation method, including the following steps: 1. Preparation of aluminum-based graphene intermediate alloy rod: 2 mg / mL of graphene oxide aqueous solution, 10 mg / mL of aluminum powder dispersion, and 1 ppm of PTB protein (commercially available product, Shanghai Yanqi Biotechnology Co., Ltd., plant phosphobutyryl transferase PTB protein) were uniformly mixed in a mass ratio of 1:10:1. The mixed solution was dried at 60°C and compressed into a block. The aluminum and graphene mixed block was added to molten aluminum at 750°C and then cast into an aluminum-based graphene intermediate alloy rod with a diameter of 8.0 mm.

[0024] 2. Preparation of Graphene Aluminum Rods by Continuous Casting and Rolling: Using Al99.85 aluminum ingots as raw material, the ingots are melted in a cupola furnace at 830℃. After melting, the ingots flow into a holding furnace where the temperature is controlled at 775℃ to obtain molten aluminum. AlB8 aluminum-boron master alloy ingots are added to the molten aluminum at a rate of 4 kg / ton, and then stirred evenly. A composite refining agent of 2 kg / ton is blown into the molten aluminum using nitrogen gas. The refining agent is a commercially available product in the field: a basic molten salt of chloride NaCl + KCl (80wt%), and fluorides NaF, Na3AlF6, and K3AlF6 (20wt%). This refining agent is then allowed to stand for 30 minutes to obtain a mixed molten aluminum. During the continuous casting and rolling process, aluminum-based graphene master alloy rods are added to the runner between the gating gate and the casting machine at a speed of 80 mm / min. The mixed molten aluminum is then rolled into graphene aluminum rods with a diameter of 12 mm. The prepared graphene-aluminum rod has the following properties: diameter 12.0±0.5mm, conductor resistivity ≤0.027066Ω•mm at 20℃. 2 / m, tensile strength 110~120MPa, conductivity ≥63.7%IACS. The refining process involves: blowing the refining agent into the molten aluminum using nitrogen gas, stirring back and forth for 5 minutes to maintain the reaction, letting it stand for 5 minutes after stirring, and then using a slag rake to remove the loose, grayish-white, non-sticky refining slag from the surface of the molten aluminum. The slag should be removed until no white flux is visible and the surface of the liquid is bright.

[0025] 3. Graphene aluminum rods are drawn into graphene aluminum wires using a multi-die drawing process. Multiple graphene aluminum wires are then concentrically stranded to prepare graphene aluminum conductors. The graphene aluminum rods are drawn into graphene aluminum wires with a diameter of 3.63±0.03mm using a multi-die drawing process. Sixty-one graphene aluminum wires are then concentrically stranded using a frame stranding machine to prepare graphene aluminum conductors. A bakelite mold is used as a clamping die during the stranding process. The tested performance of the obtained graphene aluminum conductors is: conductor resistivity at 20℃ ≤0.027108Ω•mm. 2 The graphene-aluminum wire exhibits the following properties: diameter 3.63 ± 0.03 mm, tensile strength 185~210 MPa, and conductivity ≥ 63.6% IACS. The tested properties are: conductor resistivity of 0.027052~0.027108 Ω•mm at 20℃. 2 / m, tensile strength 185~210MPa, conductivity ≥63.6%IACS. The stranded graphene wire has the following properties: diameter 32.67±0.32mm, DC resistance ≤0.0439Ω / km, and total tensile strength ≥116.8kN.

[0026] Comparative Example 1 Similar to Example 1, the difference lies in the absence of PTB protein in step one. The resulting graphene-aluminum wire exhibited the following properties: diameter 3.63 ± 0.03 mm, conductor resistivity at 20°C 0.027095~0.027356 Ω•mm. 2 / m, tensile strength 172~216MPa. Due to the lack of PTB protein, large agglomerates are formed when graphene oxide and aluminum powder are mixed, resulting in uneven graphene distribution and poor performance stability of the prepared graphene aluminum wire.

[0027] Comparative Example 2 (Preparation of graphene-aluminum rods by powder metallurgy) Raw material preparation: 99.9% pure aluminum powder, particle size 50-100 μm; graphene powder, 1-5 layers, carbon content ≥99%; 0.3 wt% graphene by weight. The graphene powder and aluminum powder are placed in a planetary ball mill and mixed under argon protection for 2 h to obtain graphene-aluminum composite powder. The mixed powder is loaded into a steel mold and cold-pressed into a rod-shaped blank under 300 MPa pressure, with a blank size of Φ20 mm × 150 mm. The pressed blank is placed in a vacuum sintering furnace and heated to 580-600℃, held for 3 h for sintering and densification. The sintered blank is cold-drawn, straightened, and turned to finally produce a graphene-aluminum rod with a diameter of Φ12 mm. Comparison with Example 1 of this invention: This comparative example uses a powder metallurgy method to prepare graphene aluminum rods by directly mixing graphene powder and aluminum powder. This method suffers from problems such as small batch yields, inability to produce continuously, easy graphene agglomeration, complex processes, and high costs, and cannot be applied to continuous casting and rolling production lines. In contrast, this invention, by first preparing aluminum-based graphene intermediate alloy rods and then continuously adding them online to the continuous casting and rolling mill, achieves for the first time the continuous and industrialized production of graphene aluminum conductors in continuous casting and rolling processes. This fundamentally solves the industry problems of low graphene density, easy floating, easy burning, and difficulty in stable addition.

[0028] Comparative Example 3 Similar to Example 1, the difference lies in that, in step one, during the continuous casting and rolling of the aluminum rod, a conventional aluminum-titanium-boron alloy rod is added via wire feeding instead of an aluminum-based graphene intermediate alloy rod. The AlTi5B1 aluminum-titanium-boron alloy rod is added to the runner between the gating gate and the casting machine at a speed of 80 mm / min. The AlTi5B1 aluminum-titanium-boron alloy rod contains 5.0 wt% Ti, 1.0 wt% B, and the remainder is Al. The molten aluminum is then rolled into an aluminum rod with a diameter of 12 mm. The aluminum rod prepared in step two has the following properties: diameter 12.0 ± 0.5 mm, conductor resistivity at 20℃ ≤ 0.028056 Ω•mm. 2 / m, tensile strength 112~123MPa, conductivity ≥61.45%IACS. Comparison shows that adding aluminum-based graphene intermediate alloy rods does not significantly change strength compared to aluminum-titanium-boron alloy rods, but can improve conductivity by 2.25%IACS.

[0029] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An industrial-scale preparation method for graphene-aluminum wires, characterized in that, Includes the following steps: S1. Mix the graphene oxide aqueous solution, aluminum powder dispersion and PTB protein evenly, dry the mixed solution and compress it into a block, then add it into the aluminum liquid at 750-770℃ and cast it to obtain the aluminum-based graphene intermediate alloy rod. S2. Using aluminum ingots to melt and obtain aluminum liquid, add AlB8 aluminum boron intermediate alloy ingots to the aluminum liquid and stir evenly. Use nitrogen to blow a composite refining agent into the aluminum liquid to refine the aluminum liquid. Let it stand to obtain mixed aluminum liquid. Add aluminum-based graphene intermediate alloy rods to the trough between the casting gate and the casting machine, and roll the mixed aluminum liquid into graphene aluminum rods. S3. Graphene aluminum rods are drawn into graphene aluminum wires through multi-dye drawing, and then multiple graphene aluminum wires are concentrically twisted together to prepare graphene aluminum conductors.

2. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of graphene oxide, aluminum powder and PTB protein is (1~2):(10~12):

1.

3. The preparation method according to claim 1, characterized in that, In step S1, the mass ratio of the block to the molten aluminum liquid is 1:(20~30).

4. The preparation method according to claim 1, characterized in that, In step S1, the diameter of the aluminum-based graphene intermediate alloy rod is 3.0~10.0 mm.

5. The preparation method according to claim 1, characterized in that, In step S2, the melting temperature is 830~850℃; The addition amount of AlB8 aluminum boron master alloy ingot is 4 kg / ton to 6 kg / ton.

6. The preparation method according to claim 1, characterized in that, In step S2, the composite refining agent includes a chloride-fluoride composite refining agent; the refining conditions are: at a temperature of 775-785℃, the composite refining agent is blown into the bottom of the furnace by nitrogen; the settling time is 30min~40min.

7. The preparation method according to claim 1, characterized in that, In step S2, the aluminum-based graphene intermediate alloy rod is added to the casting gate at a speed of 80~85mm / min; the diameter of the graphene aluminum rod is 9.5mm~15mm.

8. The preparation method according to claim 1, characterized in that, In step S3, the diameter of the graphene aluminum wire is 3.63±0.03mm; the number of graphene aluminum wires is at least 61.

9. A graphene-aluminum wire, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 8.

10. A graphene-aluminum conductor, characterized in that, Includes the graphene-aluminum wire as described in claim 9.

Images