High-conductivity high-strength aluminum alloy wire and method for manufacturing the same

Abstract

The application relates to the technical field of aluminum alloy wires, and discloses a high-conductivity high-strength aluminum alloy wire and a preparation method thereof, which comprises the following steps: weighing raw materials, and the aluminum alloy comprises the following components: Mg 0.4-0.9%, Si 0.3-0.8%, Zr 0.1%-0.25%, Ag 0.05-0.12%, B 0.01%-0.05%, RE 0.03-0.08% and GR 0.07-0.14%; the GR is modified graphene, and the modified graphene is obtained by the following steps: adding an oxidized graphene mixed solution into a titanium source solution to react, drying, vacuum heat treatment and obtaining modified graphene powder; mixing the modified graphene powder and aluminum powder, pressing into small blocks; adding the small blocks into an aluminum-based alloy liquid to smelt, casting, rolling, drawing and double-stage aging. Through the modification of the graphene and micro-alloy strengthening measures, the strength and conductivity of the aluminum alloy wire are improved, and a good balance between the conductivity and the mechanical performance is achieved.

Description

Technical Field

[0001] This invention relates to the field of aluminum alloy conductor technology, and in particular to a high-conductivity, high-strength aluminum alloy conductor and its preparation method. Background Technology

[0002] With the sustained and rapid development of the social economy, the demand for electricity resources continues to rise. The requirements and demands for long-distance, large-span transmission lines are becoming increasingly stringent. The safe and reliable operation of overhead transmission lines is crucial for the demanding service environments of large spans and high currents. Overhead conductors are important electrical products in overhead transmission lines, and their comprehensive performance directly determines the transmission efficiency, operational safety, and economy of the power grid. Currently, the overhead conductors widely used in long-distance, large-span transmission lines are still mainly steel-cored aluminum stranded wires made of aluminum alloy conductors stranded with steel wires. While this approach balances the conductivity of aluminum with the high strength of steel to some extent, its inherent limitations are becoming increasingly apparent: on the one hand, the presence of the steel core significantly increases the conductor's self-weight and sag, restricting the tower's load-bearing capacity and the span of the erection; on the other hand, the electrochemical corrosion between aluminum and steel, as well as the magnetic loss effect of the steel core, leads to significant power loss in the lines, making it difficult to fully meet the requirements of energy conservation, emission reduction, and efficient operation in power transmission under the new circumstances.

[0003] Aluminum alloy conductors are characterized by low resistance loss, light weight, and low price, which can save energy, reduce costs, and extend the service life of lines. They can be used in general overhead transmission and distribution lines as well as long-span transmission lines. Ideal high-performance conductors should simultaneously possess high conductivity, high tensile strength, excellent resistance to high-temperature creep, and good plasticity. This is to reduce line loss, support long spans, and resist wind loads. High tensile strength improves the conductor's tensile-to-weight ratio, ensuring the reliability of crimping during construction and installation, supporting long spans and resisting wind loads. High conductivity improves the power transmission efficiency of transmission lines and reduces transmission losses. High-temperature creep resistance ensures long-term operational stability. However, there is a trade-off between mechanical and electrical properties, limiting the widespread application of high-strength aluminum alloy conductors.

[0004] Currently, aluminum alloy properties are mainly improved through microalloying, optimized heat treatment, and deformation treatment, but there are still limitations in achieving a synergistic improvement in strength and conductivity. The emergence of graphene has provided more possibilities for the strength and conductivity of aluminum alloys. Compared with copper and aluminum, graphene has high conductivity, low density, and high mechanical strength, which can improve the conductivity and mechanical properties of aluminum alloys. Current research has disclosed the introduction of nano-graphene into the aluminum alloy preparation process, mainly through ball milling and melting. However, graphene and the aluminum matrix have problems such as agglomeration and interfacial bonding. Specifically, graphene has a large specific surface area and high surface energy, making it easy to agglomerate in the aluminum matrix; the wettability between molten aluminum and graphene is extremely poor, making it difficult to form a strong metallurgical bond; graphene and aluminum easily react at high temperatures to form brittle aluminum carbide (Al4C3), which destroys the interfacial bond, affecting the conductivity, mechanical properties, and long-term stability of aluminum alloys, making it difficult to achieve high strength and high conductivity. Summary of the Invention

[0005] To address the above shortcomings, this invention provides a high-conductivity, high-strength aluminum alloy wire and its preparation method. Through modified graphene, combined with multi-element micro-alloying, and measures such as rolling parameters and two-stage aging, the tensile strength, conductivity, and creep resistance of the aluminum alloy wire are comprehensively improved. The specific technical solution is as follows: A method for preparing a high-conductivity, high-strength aluminum alloy wire includes the following steps: (1) Prepare raw materials: Weigh the raw materials according to the composition of the aluminum alloy; The aluminum alloy, by weight percentage, comprises the following components: Mg 0.4-0.9%, Si 0.3-0.8%, Zr 0.1%-0.25%, Ag 0.05-0.12%, B 0.01%-0.05%, RE 0.03-0.08%, GR 0.07-0.14%, with the balance being Al and unavoidable impurities; wherein GR is modified graphene. The preparation of the modified graphene includes: adding a mixed solution of graphene oxide to a solution containing a titanium source, stirring and reacting at 70-90℃ for 1-3 hours to obtain a gel; drying the gel to obtain a solid substance; heat-treating the solid substance under vacuum, first holding it at 800-1100℃ for 1-2 hours, and then raising the temperature to 1400-1500℃ and holding it for 0.5-1 hour; and grinding it after cooling to obtain modified graphene powder. (2) Prefabricated graphene blocks: Modified graphene powder and aluminum powder are ball-milled and mixed to obtain mixed powder, and the mixed powder is pressed into small blocks; (3) Smelting: Aluminum ingots and other elemental raw materials are smelted into aluminum-based alloy liquid, and then the small blocks prepared in step (2) are added to the aluminum-based alloy liquid for smelting to obtain graphene aluminum alloy liquid; (4) Casting and rolling: The graphene aluminum alloy liquid is cast and rolled, and the processing rate of the rolling pass is controlled to be 15~50% to obtain the aluminum alloy rod. (5) Drawing: The rolled aluminum alloy rod is drawn to obtain aluminum alloy wire; (6) Aging: The aluminum alloy wire is subjected to two-stage aging to obtain a high-conductivity and high-strength aluminum alloy wire.

[0006] The technical solution of this invention is based on the following technical principles: First, graphene is modified: titanium dioxide is coated on the surface of graphene oxide (GO) using a sol-gel method. Then, it is treated at 800~1100℃ for a period of time to remove oxygen-containing functional groups, water vapor, CO and CO2, and thermally reduced to reduced graphene oxide (rGO), which significantly improves conductivity. Then, the temperature is raised to 1400~1500℃, and through heat treatment, CO and other substances are used to partially convert titanium dioxide into titanium carbon compounds. The modified graphene surface is mainly coated with titanium carbon compounds and titanium oxides. On the one hand, it can improve the wettability of graphene, enhance the graphene / aluminum interface bonding and inhibit the aluminum-carbon reaction to produce brittle phases, thereby improving the conductivity and strength of aluminum alloys. On the other hand, titanium carbon compounds and titanium oxides can synergistically refine grains and optimize the microstructure during the melting and casting of aluminum alloys, strengthen the aluminum alloys, and improve the strength and creep resistance of aluminum alloys. Furthermore, the combined effect of multiple trace alloying elements enhances the overall performance. Among them, Mg and Si can form the main strengthening phase Mg2Si in aluminum alloys; Zr can refine grains and inhibit recrystallization, precipitating nanoscale, dispersed semi-coherent strengthening phases and pinning dislocations to improve strength; B can eliminate the influence of impurity elements such as V and Cr on electrical conductivity, thus improving the electrical conductivity of aluminum conductors; Ag can refine precipitates and change their distribution, enabling the alloy to achieve better strengthening effects during aging and improving electrical conductivity; RE has a microalloying effect, which can refine grains, purify the alloy, make the microstructure more uniform, improve the strength and thermal stability of aluminum alloys, and further improve strength when matched with large deformation rolling.

[0007] Preferably, in the above-mentioned method for preparing high-conductivity, high-strength aluminum alloy wires, each unavoidable impurity element in the aluminum alloy is less than 0.03% and the total amount is less than 0.1%.

[0008] Preferably, in the above-mentioned method for preparing high-conductivity and high-strength aluminum alloy wires, the graphene oxide mixed solution is prepared by dispersing graphene oxide in water to obtain a graphene oxide dispersion with a concentration of 1~2 mg / mL, and then adding acetic acid to the graphene oxide dispersion and mixing to obtain a graphene oxide mixed solution, wherein the volume ratio of acetic acid to graphene oxide dispersion is 1:(1~4). The titanium-containing solution is prepared by adding tetrabutyl titanate to ethanol and mixing them evenly, with a volume ratio of tetrabutyl titanate to ethanol of 1:(8~12), to obtain a tetrabutyl titanate solution, which is the titanium-containing solution; the volume ratio of the graphene oxide mixed solution to the titanium-containing solution is 1:(2~5).

[0009] Preferably, in the above-mentioned method for preparing high-conductivity, high-strength aluminum alloy wires, in step (1), during the preparation of modified graphene, the solid material is heat-treated under vacuum, first held at 1000℃ for 1 hour, and then heated to 1500℃ and held for 0.5 hours. By controlling the vacuum heat treatment regime, some titanium dioxide is converted into titanium carbide, and the graphene surface is coated with titanium carbide and titanium oxide. In addition to improving the bonding with the aluminum alloy interface, titanium carbide and titanium oxide can jointly improve the strength of the aluminum alloy.

[0010] Preferably, in the above-mentioned method for preparing high-conductivity and high-strength aluminum alloy wires, in step (2), the mass ratio of modified graphene powder to aluminum powder is 1:(10~20), and stearic acid is added for mixing, wherein the amount of stearic acid is 10~20% of the weight of the modified graphene powder.

[0011] Preferably, in the above-mentioned method for preparing high-conductivity, high-strength aluminum alloy wires, in step (2), the pressing pressure is 100~300MPa, and the volume of the pressed small block is less than 1cm. 3 ~100cm 3 The shape of the block can be any one or more of the following: cube, cuboid, and cylinder.

[0012] Preferably, in the above-mentioned method for preparing high-conductivity, high-strength aluminum alloy wires, in step (3), the melting temperature is 750~800℃, and the purity of the aluminum ingot is not less than 99.85%. The magnesium raw material is magnesium ingot with a purity of not less than 99.9%. The RE raw material is a rare earth mixed rare earth with a rare earth content of 10% lanthanum and cerium, in which the Ce content is 6.5% and the La content is 3.5%. Other element raw materials are intermediate alloys, such as aluminum-silicon intermediate alloy, aluminum-boron intermediate alloy, aluminum-zirconium intermediate alloy, and aluminum-silver intermediate alloy.

[0013] Preferably, in the above-mentioned method for preparing high-conductivity, high-strength aluminum alloy wires, in step (4), the deformation amount per rolling pass is controlled to be 20-35%. By precisely controlling the rolling pass processing rate, the aluminum alloy grain structure is made fine, improving the strength and creep resistance of the aluminum alloy, while maintaining high electrical conductivity.

[0014] Preferably, in the above-mentioned method for preparing high-conductivity, high-strength aluminum alloy wires, the two-stage aging process is as follows: the first-stage aging temperature is 170~180℃ and the holding time is 10~15h; the second-stage aging temperature is 200~220℃ and the holding time is 1~3h.

[0015] Preferably, in the above-mentioned method for preparing high-conductivity, high-strength aluminum alloy wires, the two-stage aging process is as follows: the first-stage aging temperature is 180°C and the holding time is 12 hours, and the second-stage aging temperature is 210°C and the holding time is 2 hours.

[0016] On the other hand, the present invention also provides a high-conductivity, high-strength aluminum alloy wire, which is prepared by the above-described preparation method.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention prepares aluminum alloy conductors with high tensile strength through measures such as modified graphene strengthening and microalloying strengthening. Simultaneously, the addition of boron effectively removes impurities such as V, Ti, and Cr in solid solution in the aluminum matrix, which severely reduce electrical conductivity, thus purifying the matrix. The high conductivity of modified graphene and the matching rolling process construct an efficient electron transport channel, enabling the material to maintain high conductivity while improving strength. This achieves a good balance between conductivity and mechanical properties, meeting the requirements of long-span, long-gap lines for both mechanical and electrical performance of the conductors.

[0018] 2. This invention coats graphene oxide with a titanium source while simultaneously subjecting it to vacuum high-temperature treatment, forming a transition layer of titanium carbon compound and titanium oxide on the graphene surface. This solves the problem of weak interfacial bonding between graphene and the aluminum matrix. The modified graphene, as a heterogeneous reinforcing phase, forms an effective pinning effect at grain boundaries and within grains. Under long-term stress and temperature, it can effectively hinder grain boundary slippage, significantly improve the creep resistance of the alloy, and thus greatly extend the service life of the material.

[0019] 3. The Zr element added in this invention forms fine and dispersed Al3Zr particles with Al. These particles have high thermal stability and work synergistically with modified graphene to effectively inhibit recrystallization and softening, ensuring that the conductor can maintain geometrical stability under high temperature operation or overload conditions, and preventing excessive creep from causing sag increase, insufficient distance to ground, and other situations. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of the method for preparing the aluminum alloy conductor of the present invention; Figure 2 This diagram illustrates the effect of different rolling pass rates on tensile strength and electrical conductivity in this invention. Figure 3 This diagram illustrates the effect of different aging regimes on tensile strength and electrical conductivity in this invention. Detailed Implementation

[0022] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. Unless otherwise defined, all technical terms used below have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of the present invention. Unless otherwise specifically stated, all raw materials, reagents, instruments, and equipment used in the present invention are commercially available or can be prepared by existing methods.

[0023] The graphene oxide used in the following examples and comparative examples is monolayer graphene oxide with a sheet diameter of 0.5~5μm. The graphene used is monolayer graphene with a sheet diameter of 1~5μm.

[0024] The purity of the aluminum ingot is not less than 99.85%, the magnesium element raw material is magnesium ingot with a purity of not less than 99.9%, the silver element raw material is silver ingot with a purity greater than 99.9%, the RE raw material is a lanthanum-cerium mixed rare earth with a rare earth content of 10%, the Ce content in the mixed rare earth is 6.5% and the La content is 3.5%, and the other element raw materials are master alloys, aluminum-silicon master alloy, aluminum-boron master alloy, and aluminum-zirconium master alloy.

[0025] Example 1 A method for preparing a high-conductivity, high-strength aluminum alloy conductor, as follows: Figure 1 As shown, it includes the following steps: (1) Prepare raw materials: Weigh the raw materials according to the composition of the aluminum alloy; The aluminum alloy, by weight percentage, comprises the following components: Mg 0.6%, Si 0.5%, Zr 0.18%, Ag 0.1%, B 0.03%, RE 0.05%, GR 0.11%, with the balance being Al and unavoidable impurities, each of which is less than 0.03% and the total amount is less than 0.1%; wherein GR is modified graphene. (2) Prefabricated graphene blocks: Modified graphene powder, aluminum powder and stearic acid are ball-milled and mixed at a speed of 300 r / min for 2 h in the absence of air to obtain mixed powder. The mass ratio of modified graphene powder to aluminum powder is 1:15 and the amount of stearic acid is 18% of the weight of modified graphene powder. The mixed powder is pressed into small cubic blocks with a side length of 2 cm under a pressure of 150 MPa at room temperature to obtain graphene blocks. (3) Smelting: Aluminum ingots and other trace alloying elements are smelted at 780°C into aluminum-based alloy liquid, slag is removed, and the graphene blocks prepared in step (2) are added to the aluminum-based alloy liquid for smelting, refining, degassing and filtration. After uniform melting, graphene aluminum alloy liquid is obtained. (4) Casting and rolling: The graphene aluminum alloy liquid is fed into the continuous casting and rolling mill for continuous casting and rolling. The rolling pass processing rate is controlled at 30% to roll into an aluminum alloy rod with a diameter of 9.5mm. The aluminum alloy round rod is then cooled to room temperature by water and quenched online. (5) Drawing: The rolled aluminum alloy rod is drawn with a deformation of 2% per pass and a drawing speed of 9m / s to obtain an aluminum alloy wire with a diameter of 3mm. (6) The aluminum alloy wire is subjected to two-stage aging. The first-stage aging temperature is 180℃ and the holding time is 12h. The second-stage aging temperature is 210℃ and the holding time is 2h, to obtain a high-conductivity and high-strength aluminum alloy wire.

[0026] The preparation of modified graphene includes: dispersing graphene oxide in deionized water and ultrasonically dispersing it evenly to obtain a graphene oxide dispersion with a concentration of 1 mg / mL; then pouring 3 mL of acetic acid into 5 mL of the graphene oxide dispersion and stirring evenly to obtain a mixed graphene oxide solution; slowly pouring 2 mL of tetrabutyl titanate into 20 mL of anhydrous ethanol and stirring evenly to form a tetrabutyl titanate ethanol solution; slowly adding the mixed graphene oxide solution dropwise to the tetrabutyl titanate ethanol solution while magnetically stirring; after the addition is complete, placing it in an 80°C water bath and continuing to stir for 2 hours to obtain a gel; drying the obtained gel at 75°C for 24 hours, then heating it to 130°C and holding it at that temperature for 10 minutes to obtain a solid substance; subjecting the solid substance to heat treatment under vacuum (pressure less than 50 Pa), first holding it at 1000°C for 1 hour, then raising the temperature to 1500°C and holding it at that temperature for 0.5 hours, and then grinding it after cooling to obtain modified graphene powder.

[0027] Example 2 A method for preparing a high-conductivity, high-strength aluminum alloy wire includes the following steps: (1) Raw material preparation: Weigh the raw materials according to the composition of the aluminum alloy; The aluminum alloy, by weight percentage, comprises the following components: Mg 0.6%, Si 0.5%, Zr 0.25%, Ag 0.05%, B 0.04%, RE 0.03%, GR 0.14%, with the balance being Al and unavoidable impurities, each of which is less than 0.03% and the total amount is less than 0.1%; wherein GR is modified graphene. (2) Prefabricated graphene blocks: Modified graphene powder, aluminum powder and stearic acid are ball-milled and mixed at a speed of 300 r / min for 2 h in the absence of air to obtain mixed powder. The mass ratio of modified graphene powder to aluminum powder is 1:20, and the amount of stearic acid is 15% of the weight of the modified graphene powder. The mixed powder is pressed into small cubic blocks with a side length of 2 cm under a pressure of 150 MPa at room temperature to obtain graphene blocks. (3) Smelting: Aluminum ingots and other trace alloying elements are smelted at 780°C into aluminum-based alloy liquid, slag is removed, and the graphene blocks prepared in step (2) are added to the aluminum-based alloy liquid for smelting, refining, degassing and filtration. After uniform melting, graphene aluminum alloy liquid is obtained. (4) Continuous casting and rolling: The graphene aluminum alloy liquid is fed into the continuous casting and rolling mill for continuous casting and rolling. The rolling pass processing rate is controlled at 25% to roll into an aluminum alloy rod with a diameter of 9.5 mm. The aluminum alloy round rod is cooled to room temperature by water and then quenched online. (5) Drawing: The rolled aluminum alloy rod is drawn with a deformation of 2% per pass and a drawing speed of 9m / s to obtain an aluminum alloy wire with a diameter of 3mm. (6) The aluminum alloy wire is subjected to two-stage aging. The first-stage aging temperature is 170℃ and the holding time is 15h. The second-stage aging temperature is 220℃ and the holding time is 1h, to obtain a high-conductivity and high-strength aluminum alloy wire.

[0028] Preparation of modified graphene: Graphene oxide was dispersed in deionized water and ultrasonically dispersed to obtain a graphene oxide dispersion with a concentration of 1 mg / mL. Then, 3 mL of acetic acid was poured into 5 mL of the graphene oxide dispersion and stirred evenly to obtain a mixed graphene oxide solution. 2 mL of tetrabutyl titanate was slowly poured into 20 mL of anhydrous ethanol and stirred evenly to form a tetrabutyl titanate ethanol solution. The mixed graphene oxide solution was slowly added dropwise to the tetrabutyl titanate ethanol solution while magnetically stirring. After the addition was complete, the solution was placed in an 80°C water bath and stirred for 2 hours to obtain a gel. The gel was then dried at 75°C for 24 hours, heated to 130°C and held for 10 minutes to obtain a solid substance. The solid substance was subjected to high-temperature heat treatment under vacuum (pressure less than 50 Pa), first held at 1000°C for 1 hour, then heated to 1400°C and held for 1 hour. After cooling, the solid substance was ground to obtain modified graphene powder.

[0029] Example 3 A method for preparing a high-conductivity, high-strength aluminum alloy conductor, as follows: Figure 1 As shown, it includes the following steps: (1) Raw material preparation: Weigh the raw materials according to the composition of the aluminum alloy; The aluminum alloy, by weight percentage, comprises the following components: Mg 0.8%, Si 0.7%, Zr 0.1%, Ag 0.10%, B 0.02%, RE 0.08%, GR 0.07%, with the balance being Al and unavoidable impurities, each of which is less than 0.03% and the total amount is less than 0.1%; wherein GR is modified graphene. (2) Pre-made graphene blocks: Modified graphene powder, aluminum powder and stearic acid are ball-milled and mixed. The ball milling speed is 300 r / min and the ball milling time is 2 h. The ball milling is carried out in the absence of air. The mass ratio of modified graphene powder to aluminum powder is 1:12. The amount of stearic acid is 20% of the weight of the modified graphene powder. The mixed powder is pressed into small cubic blocks with a side length of 2 cm under a pressure of 150 MPa at room temperature to obtain graphene blocks. (3) Smelting: Aluminum ingots and other trace alloying elements are smelted at 780°C into aluminum-based alloy liquid, slag is removed, and the graphene blocks prepared in step (3) are added to the aluminum-based alloy liquid for smelting, refining, degassing and filtration. After uniform melting, graphene aluminum alloy liquid is obtained. (4) Continuous casting and rolling: The graphene aluminum alloy liquid is fed into the continuous casting and rolling mill for continuous casting and rolling. The rolling pass processing rate is controlled at 40% to roll into an aluminum alloy rod with a diameter of 9.5 mm. The aluminum alloy round rod is then cooled to room temperature by water and quenched online. (5) Drawing: The rolled aluminum alloy rod is drawn with a deformation of 2% per pass and a drawing speed of 9m / s to obtain an aluminum alloy wire with a diameter of 3mm. (6) The aluminum alloy wire is subjected to two-stage aging. The first-stage aging temperature is 180℃ and the holding time is 12h. The second-stage aging temperature is 200℃ and the holding time is 3h, to obtain a high-conductivity and high-strength aluminum alloy wire.

[0030] The preparation of modified graphene includes: dispersing graphene oxide in deionized water and ultrasonically dispersing it evenly to obtain a graphene oxide dispersion with a concentration of 1 mg / mL; then pouring 3 mL of acetic acid into 8 mL of the graphene oxide dispersion and stirring evenly to obtain a mixed graphene oxide solution; slowly pouring 2 mL of tetrabutyl titanate into 20 mL of anhydrous ethanol and stirring evenly to form a tetrabutyl titanate ethanol solution; slowly adding the mixed graphene oxide solution dropwise to the tetrabutyl titanate ethanol solution while magnetically stirring; after the addition is complete, placing it in an 80°C water bath and continuing to stir for 2 hours to obtain a gel; drying the obtained gel at 75°C for 24 hours, then heating it to 130°C and holding it at that temperature for 10 minutes to obtain a solid substance; subjecting the solid substance to heat treatment under vacuum (pressure less than 50 Pa), first holding it at 1100°C for 0.5 hours, then raising the temperature to 1400°C and holding it at that temperature for 1 hour; and finally grinding it after cooling to obtain modified graphene powder.

[0031] Comparative Example 1 This comparative example differs from Example 1 in that graphene is used directly in the preparation of modified graphene without heat treatment. Specifically, graphene is dispersed in a 70% ethanol aqueous solution and ultrasonically dispersed to obtain a graphene dispersion with a concentration of 1 mg / mL. Then, 3 mL of acetic acid is poured into 5 mL of the graphene dispersion and stirred evenly to obtain a graphene mixed solution. 2 mL of tetrabutyl titanate is slowly poured into 20 mL of anhydrous ethanol and stirred evenly to form a tetrabutyl titanate ethanol solution. The graphene mixed solution is slowly added dropwise to the tetrabutyl titanate ethanol solution while magnetically stirring. After the addition is complete, the solution is placed in an 80°C water bath and stirred for 2 hours to obtain a gel. The gel is then dried at 75°C for 24 hours, heated to 130°C and held at that temperature for 10 minutes to obtain a solid substance. The solid substance is directly ground to obtain titanium dioxide-modified graphene powder, which is then added to the aluminum alloy. Other steps are the same as in Example 1.

[0032] Comparative Example 2 The difference between this comparative example and Example 1 is that the modified graphene preparation process does not involve high-temperature heat treatment, but otherwise it is the same as Example 1.

[0033] Comparative Example 3 The difference between this comparative example and Example 1 is that the high-temperature heat treatment during the preparation of modified graphene is: holding at 1000℃ for 1.5h, while the rest is the same as in Example 1.

[0034] Comparative Example 4 The difference between this comparative example and Example 1 is that the high-temperature heat treatment during the preparation of modified graphene is: holding at 1500℃ for 1.5h, while the rest is the same as in Example 1.

[0035] The performance of the aluminum alloy conductors in Examples 1-3 and Comparative Examples 1-4 was tested. The conductivity was tested according to GB / T 12966-2022, the tensile strength was tested according to GB / T 228.1-2021, and the creep performance of the specimens was tested according to GB / T 11546.1-2008. The experimental temperature was 150℃ and the stress was 30MPa. The test results are shown in Table 1.

[0036] As shown in Table 1, the aluminum alloy conductors prepared by the method of the present invention have significantly improved strength and conductivity, which are superior to those of EN 50183-2002. The room temperature tensile strength is greater than >325MPa and the conductivity is >57%IACS. This achieves a good balance between conductivity and mechanical properties, meeting the high requirements of long-span and long-span overhead lines for conductor mechanical properties and conductivity.

[0037] Currently, it has been published in the literature that titanium dioxide-coated graphene is pressed and sintered with Al-Zn-Mg aluminum alloy powder to prepare aluminum-based composite materials, which can improve the strength and hardness of aluminum-based composite materials. Using titanium dioxide-coated graphene in the melting and casting of aluminum alloys (Comparative Example 1) can improve strength and conductivity, but the improvement in strength of the melting and casting aluminum alloy is relatively small compared with pressing and sintering (the tensile strength of the aluminum alloy without modified graphene (270.1 MPa) is increased by 14.6%). This invention further optimizes the modified graphene by using graphene oxide (GO) as raw material. First, titanium dioxide is coated on the surface of graphene oxide, and then it is reacted at high temperature to obtain reduced graphene oxide (rGO). At the same time, the surface titanium dioxide reacts to generate titanium oxide compounds and titanium carbon compounds, which can synergistically refine the grain and optimize the microstructure during the melting and casting of aluminum alloys, thereby significantly improving the strength by 25.3% compared with the aluminum alloy without graphene. Comparing Example 1 and Comparative Example 2, it can be seen that high-temperature heat treatment during graphene modification can significantly improve the strength of aluminum alloys, increasing both tensile strength and electrical conductivity. This invention, by controlling heat treatment process parameters, promotes the transformation of graphene oxide into reduced graphene oxide, thereby improving electrical conductivity, while simultaneously converting titanium dioxide into titanium oxide and titanium carbon compounds, synergistically enhancing the strength of aluminum alloys.

[0038] Table 1 Performance data of aluminum alloy wires prepared in Examples 1-3 and Comparative Examples 1-4

[0039] Further analysis was conducted on the influence of the rolling pass processing rate. Aluminum alloy wires were prepared according to the method in Example 1. In step (4), the rolling pass processing rate was controlled at 10%, 20%, 30%, 40%, and 50%, respectively. The influence of the rolling pass processing rate on the strength and conductivity of the aluminum alloy wire was analyzed. The results are shown in […]. Figure 2As shown in the figure, the pass rate affects strength and electrical conductivity. As the pass rate increases, strength increases and electrical conductivity decreases. A good balance between strength and electrical conductivity can be achieved at 30%.

[0040] Further analysis of the aging regime was conducted. Aluminum alloy conductors were prepared according to the method in Example 1, with the difference being the aging regime. The effect of the aging regime on the strength and conductivity of the aluminum alloy conductors was analyzed, and the results are shown below. Figure 3 As shown in the figure, the aging regime affects both strength and electrical conductivity. Single-stage aging results in high tensile strength but low electrical conductivity, which fails to meet the requirements. Double-stage aging increases electrical conductivity to over 57% IACS. The aging regime is 180℃ / 12h + 210℃ / 2h, which achieves a better balance between strength and electrical conductivity.

[0041] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for preparing a high-conductivity, high-strength aluminum alloy wire, characterized in that, Includes the following steps: (1) Prepare raw materials: Weigh the raw materials according to the composition of the aluminum alloy; The aluminum alloy, by weight percentage, comprises the following components: Mg 0.4%~0.9%, Si 0.3%~0.8%, Zr 0.1%~0.25%, Ag 0.05%~0.12%, B 0.01%~0.05%, RE 0.03%~0.08%, GR 0.07%~0.14%, with the balance being Al and unavoidable impurities; wherein GR is modified graphene. The preparation of modified graphene includes: adding a mixed solution of graphene oxide to a solution containing a titanium source, stirring and reacting at 70-90℃ for 1-3 hours to obtain a gel; drying the gel to obtain a solid substance; heat-treating the solid substance under vacuum, first holding it at 800-1100℃ for 0.5-2 hours, then raising the temperature to 1400-1500℃ and holding it for 0.5-1 hour; and grinding it after cooling to obtain modified graphene powder. The graphene oxide mixed solution is prepared by dispersing graphene oxide in water to obtain a graphene oxide dispersion with a concentration of 1~2 mg / mL, and then adding acetic acid to the graphene oxide dispersion and mixing to obtain a graphene oxide mixed solution. The volume ratio of acetic acid to graphene oxide dispersion is 1:(1~4). The titanium source-containing solution is prepared by adding tetrabutyl titanate to ethanol and mixing them evenly, with the volume ratio of tetrabutyl titanate to ethanol being 1:(8~12), to obtain a tetrabutyl titanate solution, which is the titanium source-containing solution; the volume ratio of the graphene oxide mixed solution to the titanium source-containing solution is 1:(2~5). (2) Prefabricated graphene blocks: Modified graphene powder and aluminum powder are ball-milled and mixed to obtain mixed powder, and the mixed powder is pressed into small blocks; (3) Smelting: Aluminum ingots and other elemental raw materials are smelted into aluminum-based alloy liquid, and then the small blocks prepared in step (2) are added to the aluminum-based alloy liquid for smelting to obtain graphene aluminum alloy liquid; (4) Casting and rolling: The graphene aluminum alloy liquid is cast and rolled, and the processing rate of the rolling pass is controlled to be 15~50% to obtain the aluminum alloy rod. (5) Drawing: The rolled aluminum alloy rod is drawn to obtain aluminum alloy wire; (6) Aging: The aluminum alloy wire is subjected to two-stage aging, wherein the first-stage aging temperature is 170~180℃ and the holding time is 10~15h, and the second-stage aging temperature is 200~220℃ and the holding time is 1~3h; thus, a high-conductivity and high-strength aluminum alloy wire is obtained.

2. The method for preparing a high-conductivity, high-strength aluminum alloy wire according to claim 1, characterized in that, In step (2), the mass ratio of modified graphene powder to aluminum powder is 1:(10~20), and stearic acid is added for mixing. The amount of stearic acid used is 10~20% of the weight of the modified graphene powder.

3. The method for preparing a high-conductivity, high-strength aluminum alloy wire according to claim 1, characterized in that, In step (2), the pressing pressure is 100~300MPa, and the volume of the pressed small block is 1cm. 3 ~100cm 3 .

4. The method for preparing a high-conductivity, high-strength aluminum alloy wire according to claim 1, characterized in that, In step (3), the melting temperature is 750~800℃ and the purity of the aluminum ingot is not less than 99.85%.

5. The method for preparing a high-conductivity, high-strength aluminum alloy wire according to claim 1, characterized in that, In step (4), the rolling pass processing rate is controlled to be 20-35%.

6. The method for preparing a high-conductivity, high-strength aluminum alloy wire according to claim 1, characterized in that, The two-stage aging process is as follows: the first-stage aging temperature is 180℃ and the holding time is 12 hours; the second-stage aging temperature is 210℃ and the holding time is 2 hours.

7. A high-conductivity, high-strength aluminum alloy wire, characterized in that, The aluminum alloy wire is prepared by the preparation method according to any one of claims 1 to 6.

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