Aluminum-clad copper micro-arc oxidation wire for high-temperature-resistant motor and preparation method of aluminum-clad copper micro-arc oxidation wire

Abstract

The invention discloses an aluminum-clad copper micro-arc oxidation wire for a high-temperature-resistant motor and a preparation method of the aluminum-clad copper micro-arc oxidation wire. The wire sequentially comprises an aluminum oxide film, a composite layer and a copper conductor from outside to inside, and the composite layer is a copper-nickel-aluminum composite layer. The preparation method comprises the processes of raw material cleaning, nickel middle layer deposition, aluminum layer coating, vacuum rolling compounding, annealing, isothermal rolling, drawing shaping, micro-arc oxidation treatment and the like. According to the lead, the characteristics of conductivity, insulation and high temperature resistance can be considered, the requirements for slot fullness, mechanical flexibility and bonding strength during winding of a motor winding are met, the problem that the shape of the lead is limited is solved, and the preparation method can ensure the uniformity and consistency of an aluminum plating layer.

Description

Technical Field

[0001] This invention belongs to the technical field of micro-arc oxidation conductors for motors, specifically referring to a high-temperature resistant aluminum-clad copper micro-arc oxidation conductor for motors and its preparation method. Background Technology

[0002] The heat resistance of an electric motor is primarily limited by the temperature tolerance of its electrical insulation system (EIS). Currently, the heat resistance of organic enameled wires is between 180-200℃, while enameled wires based on polyimide insulation can reach 240℃.

[0003] To further improve the heat resistance of motors and overcome the problem of rapid aging and decomposition of organic insulation systems at high temperatures, inorganic EIS using ceramics, which are stable in high-temperature environments, has become a popular research and development direction. Copper-aluminum composite conductors, possessing the combined physicochemical properties of copper and aluminum, exhibit excellent electrical and thermal conductivity, and are widely used in power transmission and distribution, signal transmission, building wiring, and electrical equipment manufacturing. Micro-arc oxidation, as an advanced technology for treating metal surfaces, can prepare ceramic films on the surfaces of metals such as aluminum, magnesium, and titanium, giving the metals excellent wear resistance, corrosion resistance, high-temperature resistance, and electrical insulation properties. Currently, ceramic insulated wires for motors mainly focus on single-metal combinations with metal surface treatment technologies, while copper-aluminum composite conductors, using copper and aluminum as separate outer cladding layers, are primarily used in power transmission and distribution, signal transmission, and motor manufacturing where conductor cost is a consideration.

[0004] Chinese Patent CN111627592A discloses a high-temperature resistant and corona-resistant ceramic film-coated wire and its preparation method. This patent describes a micro-arc alumina conductor that utilizes the good conductivity of aluminum, the high temperature resistance of alumina, and its high breakdown voltage, allowing the conductor to withstand temperatures up to 350℃. However, a problem with micro-arc alumina conductors is that aluminum has a higher resistivity and temperature coefficient of resistivity than copper. This means that although the aluminum ceramic wire has higher temperature resistance, the heating of the conductor becomes more severe with increasing current density.

[0005] Chinese Patent CN112117023A discloses a copper-aluminum composite conductor and its preparation method. This method utilizes copper, which has high conductivity, as the outer layer, effectively mitigating the skin effect. The reduced copper content also decreases the overall weight of the conductor. However, because small and medium-sized motors have smaller conductor diameters and lower frequencies, they do not exhibit a significant skin effect. This results in a larger current flow through the aluminum core, increasing winding losses. Furthermore, copper, as the outer cladding layer, cannot generate an insulation layer through micro-arc oxidation, requiring additional organic insulation. It also cannot withstand temperatures exceeding 240°C.

[0006] Chinese Patent CN103952742B: Copper Conductor with Insulation Layer and its Preparation Method, discloses a hot-dip aluminized copper-clad composite conductor with an inner copper as the conductive body and an outer thin alumina layer as insulation, enabling the conductor to possess both high conductivity and high-temperature resistance. However, the hot-dip aluminizing process for the copper conductor with the aluminized insulation layer makes it difficult to ensure the uniformity of the aluminized layer, potentially leading to uneven aluminum layer thickness and difficulty in effectively controlling the aluminum layer thickness, thus affecting the slot fill factor of the motor. The bonding strength between the plating layer and the substrate is less than the inherent shear strength of aluminum (80 MPa), and the aluminum-copper composite layer is prone to porosity and cracks, making the aluminum layer easily detach. Furthermore, copper and aluminum begin to form brittle compounds (IMCS) at 120°C. Due to the high operating temperature of hot-dip aluminizing (700-720°C), a large amount of brittle compounds are easily generated between the copper and aluminum composite layers, making the conductor unable to withstand bending. Therefore, this type of hot-dip aluminized copper conductor with the aluminized insulation layer is suitable for applications where slot fill factor and bending are not a concern, such as power transmission lines. Finally, the quality and yield of hot-dip aluminum-insulated copper wires are difficult to guarantee, and mass production is also limited by the size of the aluminum molten pool.

[0007] In summary, existing motor winding conductors cannot simultaneously achieve both conductivity and high-temperature insulation properties, and they cannot meet the requirements for slot fill factor, mechanical flexibility, and bonding strength during motor winding, nor can they satisfy the limitations on conductor shape; the manufacturing process of the conductors makes it difficult to ensure the uniformity of the aluminum plating layer. Summary of the Invention

[0008] The purpose of this invention is to provide a high-temperature resistant aluminum-clad copper micro-arc oxidation conductor for motors and its preparation method. This conductor can take into account the characteristics of conductivity and high-temperature insulation, meet the requirements of slot fill factor, mechanical flexibility and bonding strength when winding motor windings, and solve the problem of limited conductor shape. This preparation method can ensure the uniformity of the aluminum plating layer.

[0009] To achieve the above objectives, the present invention provides a high-temperature resistant aluminum-clad copper micro-arc oxidation conductor for motors, comprising, from the outside in, an alumina film, a composite layer, and a copper conductor, wherein the copper conductor is a battery cell, and the composite layer is a copper-nickel-aluminum composite layer; comprising the following three forms: composite round wire, wherein the composite round wire comprises, from the outside in, an alumina film on the outer side of the round wire conductor, a composite layer on the round wire conductor, and a copper conductor on the round wire conductor; composite flat wire, wherein the composite flat wire comprises, from the outside in, an alumina film on the outer side of the flat wire conductor, a composite layer on the flat wire conductor, and a copper conductor on the flat wire conductor; and composite metal foil, wherein the composite metal foil comprises, from the outside in, an alumina layer on the outer side of the metal foil, a composite layer on the metal foil, and a copper conductor on the metal foil.

[0010] As a further aspect of the present invention: the copper-nickel-aluminum composite layer comprises a copper-nickel solid solution and a nickel-aluminum compound, with a shear strength ≥80MPa and a peel strength ≥10N / mm.

[0011] A method for preparing a high-temperature resistant aluminum-clad copper micro-arc oxidation conductor for electric motors includes the following steps:

[0012] Step A1, Raw material cleaning: The high-purity copper rods, copper strips and aluminum strips required for preparation are degreased, alkaline washed, sanded to remove rust, rinsed with deionized water and dried in sequence to obtain raw materials with no oxide layer on the surface and meeting the surface roughness requirements. The whole process is carried out under the protection of inert gas to prevent the high-purity copper rods, copper strips and aluminum strips from being oxidized again.

[0013] Step A2, Nickel Intermediate Layer Deposition: Electroplating is used to deposit a nickel layer with a thickness of 10-30μm on the surface of a high-purity copper rod or copper strip to obtain a copper substrate with a nickel plating layer. The electroplating method is DC constant current electroplating or pulse electroplating.

[0014] Step A3, Aluminum cladding: Before preparing composite round wire or composite flat wire, aluminum strip is clad onto copper substrate under inert gas protection, and the aluminum strip is welded to form an aluminum-clad copper profile with an outer sealed aluminum cladding layer and an inner copper substrate; Before preparing composite metal foil, aluminum strip is sandwiched on copper substrate under inert gas protection and then the aluminum strip is welded to form an aluminum-clad copper profile with a copper substrate in the middle layer and aluminum strips on the top and bottom layers.

[0015] Step A4, Vacuum Rolling Composite: The aluminum-clad copper profile is vacuum-pressed for 10-60 minutes using a hot isostatic press at 600-750℃, with a vacuum degree of 4.0 × 10⁻⁶. -3 Pa; Subsequently, the aluminum-clad copper profile is pressed in a hot isostatic press at a temperature of 600-710℃. High-pressure gas is used to apply pressure uniformly in all directions, so that the air gap between the three metals, copper, nickel and aluminum, can be eliminated and the contact surfaces between the metals become tightly fitted. The pressure is 20-40MPa, and an aluminum-clad copper composite profile is obtained. After the above steps A1, A2, A3 and A4, for the composite round wire (1), a structure is initially formed in which the round wire conductor composite layer (5) covers the round wire conductor copper conductor (6); for the composite flat wire (2), a structure is initially formed in which the flat wire conductor composite layer (8) covers the flat wire conductor copper conductor (9); for the composite metal foil (3), a structure is initially formed in which the metal foil composite layer (11) covers the metal foil copper conductor (12).

[0016] Step A5, Annealing: Set the annealing temperature to 200–300℃ and the annealing time to 30–60 minutes under an inert gas or vacuum atmosphere to promote the formation of a stable diffusion layer at the composite interface of the aluminum-clad copper composite profile, while refining the microstructure of the diffusion area, eliminating internal stress generated during processing, and improving the consistency of subsequent plastic processing.

[0017] Step A6, isothermal rolling: The annealed aluminum-clad copper composite profile is subjected to multi-pass isothermal rolling at a temperature of 320-380℃, a rolling speed of 0.2-1.0m / min, a single-pass relative reduction of 5%-20%, and a rolling pressure of 10-100MPa to obtain aluminum-clad copper composite conductors.

[0018] Step A7, drawing and shaping: When preparing composite flat wire (2) or composite metal foil (3), the drawing and shaping step is not required; when preparing composite round wire (1), the aluminum-clad copper composite wire after multiple rolling is first annealed, and then continuously drawn into aluminum-clad copper composite round wire of the required diameter by a wire drawing machine. The temperature of the wire drawing die is 320-380℃ during wire drawing; after the wire drawing is completed, annealing is performed, and then it is naturally cooled to room temperature in an inert gas or vacuum atmosphere.

[0019] Step A8, Micro-arc oxidation treatment: Composite round wire (1), composite flat wire (2), or composite metal foil (3) all undergo a motor winding process first, followed by micro-arc oxidation treatment of the aluminum layer. Winding first and then micro-arc oxidation can ensure the integrity of the hard and brittle aluminum oxide, avoid mechanical damage caused by winding, improve the overall thermal stability and insulation performance of the winding, and at the same time improve the yield of the final product.

[0020] As a further aspect of the present invention: the DC constant current electroplating in step A2 includes the following steps: adding an electroplating solution comprising NiSO4, NiCl2, H3BO3, 4-butynediol and sodium dodecyl sulfate (SDS) to pure water, wherein the mass ratio of pure water, NiSO4, NiCl2, H3BO3, 4-butynediol and sodium dodecyl sulfate (SDS) is 1000:300:40:35:0.28:0.1; placing the electroplating solution in a polypropylene tank, placing a high-purity copper rod or copper strip after cleaning in the electroplating solution as the cathode, and placing pure nickel or electroplating-grade nickel anode material in the electroplating solution as the anode; connecting the anode and cathode to a power source and performing electroplating treatment for 2-10 minutes to obtain a copper substrate with a nickel plating layer; storing the copper substrate with the nickel plating layer in an inert gas at 100-150℃ for 10-30 minutes to remove moisture and improve the bonding strength between the nickel plating layer and the copper substrate. During the electroplating process, the current density is 0.5-2.5 A / dm³. 2 The temperature range is 25-55℃, and the pH value is 2.5-4.5.

[0021] The pulse electroplating includes the following steps: adding NiSO4·6H2O, NiCl2, H3BO3, C6H8O7·H2O and C to pure water. 12 H 25The electroplating solution for SO4Na contains pure water, NiSO4·6H2O, NiCl2, H3BO3, C6H8O7·H2O, and C 12 H 25 The mass ratio of SO4 to Na is 1000:200:30:30:5:0.1. The pH of the electroplating solution is adjusted to 5.5-7.5 using 10% NaOH, and the temperature is 40-60℃. The electroplating solution is placed in a polypropylene tank. A high-purity copper rod or strip, after cleaning, is placed in the solution as the cathode, and pure nickel or electroplating-grade nickel anode material or an inert platinum electrode is placed in the solution as the anode. The anode and cathode are connected to a power source, and electroplating is performed for 2-20 minutes to obtain a copper substrate with a nickel plating layer. The copper substrate with the nickel plating layer is then stored in an inert gas atmosphere at 100-150℃ for 10-30 minutes to remove moisture and improve the bonding strength between the nickel plating layer and the copper substrate. During the electroplating process, the pulse power supply duty cycle is 20%-80%, the frequency is 800-1500Hz, and the current density is 2-8 A / dm³. 2 .

[0022] As a further aspect of the present invention: after step A4, the air gap between the three metals, copper, nickel, and aluminum, is eliminated, and the contact surfaces between the metals become tightly bonded; simultaneously, under the combined action of temperature and pressure, atomic diffusion occurs between copper and nickel, and between aluminum and nickel, forming a copper-nickel-aluminum composite layer with a maximum shear strength exceeding the inherent shear strength of aluminum; this composite layer ensures that the bonding strength of the composite interface of the aluminum-clad copper composite profile is greater than the inherent shear strength of aluminum, ensuring that the aluminum layer will not fall off during subsequent processing; in addition, the intermediate nickel layer effectively prevents the interdiffusion of copper and aluminum to form a brittle copper-aluminum compound, and relying on the high-temperature stability and toughness of the nickel-aluminum compound, the outer aluminum layer will not fall off due to internal thermal stress even when exposed to high-temperature environments for a long time.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. Through metallurgical diffusion bonding between nickel as an intermediate layer and copper and aluminum respectively, nickel acts as a bridge between copper and aluminum, significantly inhibiting the formation of brittle copper-aluminum compounds. The composite layer mainly consists of copper-nickel solid solution and nickel-aluminum compounds, with a shear strength ≥80MPa and a peel strength ≥10N / mm, fully meeting the requirements for motor winding. 2. The copper-nickel solid solution and nickel-aluminum compounds in the composite layer are stable and reliable at high temperatures, with high bonding strength and strong flexibility. At the same time, due to the presence of nickel as an intermediate layer, the manufactured winding will not fail due to insulation breakage and peeling caused by the large amount of brittle compounds even if it operates in a high-temperature environment for a long time. 3. The multi-pass isothermal rolling, drawing and annealing process makes the microstructure of nickel-copper solid solution, nickel and nickel-aluminum compounds in the composite layer more compact, effectively improving the interfacial bonding strength and overall flexibility. At the same time, the dense nickel plays a better role in hindering the mutual diffusion between copper and aluminum. 4. The dense alumina ceramic insulation formed by micro-arc oxidation, combined with the nickel layer as an intermediate layer to suppress brittle compounds, enables the composite conductor to withstand the thermal stress generated during long-term use in high-temperature environments, allowing it to operate continuously at temperatures ranging from 240°C to 400°C. 5. The aluminum layer coating method used in this invention employs standard high-purity aluminum strips with uniform thickness. During the hot isostatic pressing process, high-pressure gas is applied uniformly in all directions, eliminating air gaps between the copper, nickel, and aluminum metals and ensuring a tight fit between the metal surfaces. Subsequently, during multi-pass isothermal rolling and drawing, the die working surface is uniform, the reduction rate is precisely controlled, and the appropriate pressing temperature ensures good ductility of the aluminum, allowing for uniform flow during rolling and drawing. This ultimately ensures the uniformity of the composite conductor's dimensions, meeting the motor slot fill factor requirements. Furthermore, the prepared composite conductor can be used in complex wiring environments such as high-temperature motor windings, meeting the requirements for long-term high-temperature insulation and high conductivity. Attached Figure Description

[0024] Figure 1 This is a cross-sectional view of the composite circular line in Embodiment 1 of the present invention.

[0025] Figure 2 This is a cross-sectional view of the composite flat wire in Embodiment 2 of the present invention.

[0026] Figure 3 This is a cross-sectional view of the composite metal foil in Embodiment 3 of the present invention.

[0027] Figure 4 This is a flowchart of the preparation method of the present invention.

[0028] Figure 5 This is a shear strength curve of the aluminum-clad copper composite profile under different heat preservation times in step A4 of this invention.

[0029] Figure 6 This is a peel strength curve of aluminum-clad copper composite profiles under different annealing conditions in step A5 of this invention.

[0030] In the diagram: 1. Composite round wire, 2. Composite flat wire, 3. Composite metal foil, 4. Alumina film on the outer side of the round wire conductor, 5. Composite layer of the round wire conductor, 6. Copper conductor of the round wire conductor, 7. Alumina film on the outer side of the flat wire conductor, 8. Composite layer of the flat wire conductor, 9. Copper conductor of the flat wire conductor, 10. Alumina layer on the outer side of the metal foil, 11. Composite layer of the metal foil, 12. Copper conductor of the metal foil. Detailed Implementation

[0031] The invention will now be further described with reference to the accompanying drawings.

[0032] High-temperature resistant aluminum-clad copper micro-arc oxidation conductors for motors are composed of copper, nickel, and aluminum, with nickel acting as an intermediate layer between copper and aluminum. The direct diffusion between copper and aluminum is blocked by nickel, which metallurgically diffuses with both copper and aluminum. Nickel acts as a bridge between copper and aluminum, resulting in solid solutions of nickel and copper, and compounds of nickel and aluminum (NiAl, Ni3Al, etc.). These products exhibit stable and reliable performance at high temperatures, with good flexibility and bonding strength. The bonding strength of copper, nickel, and aluminum is greater than the inherent shear strength of aluminum, and significantly greater than that of hot-dip aluminizing. The aluminum-clad copper micro-arc oxidation conductor consists of an alumina film, a composite layer, and a copper conductor (the copper conductor is the battery core). The composite layer is a copper-nickel-aluminum composite layer. By appropriately adjusting the manufacturing process, it can be produced in three forms: composite round wire 1, composite flat wire 2, and composite metal foil 3, to meet the needs of different application scenarios. Figure 1 As shown, the composite round wire 1, from the outside in, includes, in sequence, an alumina film 4 on the outer side of the round wire conductor, a composite layer 5 of the round wire conductor, and a copper conductor 6 of the round wire conductor. Figure 2 As shown, the composite flat wire 2 comprises, from the outside in, an alumina film 7 on the outer side of the flat wire conductor, a composite layer 8 of the flat wire conductor, and a copper conductor 9 of the flat wire conductor. Figure 3 As shown, the composite metal foil 3 includes, from the outside to the inside, an outer aluminum oxide layer 10, a composite metal foil layer 11, and a copper conductor 12.

[0033] like Figure 4 As shown, the preparation method of aluminum-clad copper micro-arc oxidation conductor for high-temperature motors specifically includes the following steps:

[0034] Step A1, Raw Material Cleaning: The high-purity copper rods, copper strips, and aluminum strips required for preparation are sequentially subjected to degreasing, alkaline washing, sandpaper rust removal, deionized water rinsing, and drying to obtain raw materials with no oxide layer on the surface and meeting the surface roughness requirements. The entire process is carried out under inert gas protection to prevent secondary oxidation of the high-purity copper rods, copper strips, and aluminum strips;

[0035] Step A2, Nickel Intermediate Layer Deposition: Electroplating is used to deposit a nickel layer with a thickness of 10-30μm on the surface of a high-purity copper rod or copper strip to obtain a copper substrate with a nickel plating layer. The electroplating method is traditional DC constant current electroplating. If it is necessary to further improve the density and adhesion, pulse electroplating can be used.

[0036] DC constant current electroplating: An electroplating solution comprising NiSO4, NiCl2, H3BO3, 4-butynediol, and sodium dodecyl sulfate (SDS) is added to pure water, wherein the mass ratio of pure water, NiSO4, NiCl2, H3BO3, 4-butynediol, and sodium dodecyl sulfate (SDS) is 1000:300:40:35:0.28:0.1. The electroplating solution is placed in a polypropylene tank. A high-purity copper rod or strip, after cleaning, is placed in the electroplating solution as the cathode, and pure nickel or electroplating-grade nickel anode material is placed in the electroplating solution as the anode. The anode and cathode are connected to a power source, and electroplating is performed for 2-10 minutes to obtain a copper substrate with a nickel plating layer. The copper substrate with the nickel plating layer is then stored in an inert gas atmosphere at 100-150℃ for 10-30 minutes to remove moisture and improve the bonding strength between the nickel plating layer and the copper substrate. During the electroplating process, the current density is 0.5-2.5 A / dm³. 2 The temperature range is 25-55℃, and the pH value is 2.5-4.5.

[0037] Pulse electroplating: Adding NiSO4·6H2O, NiCl2, H3BO3, C6H8O7·H2O and C to pure water. 12 H 25 The electroplating solution for SO4Na contains pure water, NiSO4·6H2O, NiCl2, H3BO3, C6H8O7·H2O, and C 12 H 25 The mass ratio of SO4 to Na is 1000:200:30:30:5:0.1. The pH of the electroplating solution is adjusted to 5.5-7.5 using 10% NaOH, and the temperature is 40-60℃. The electroplating solution is placed in a polypropylene tank. A high-purity copper rod or strip, after cleaning, is placed in the solution as the cathode, and pure nickel or electroplating-grade nickel anode material or an inert platinum electrode is placed in the solution as the anode. The anode and cathode are connected to a power source, and electroplating is performed for 2-20 minutes to obtain a copper substrate with a nickel plating layer. The copper substrate with the nickel plating layer is then stored in an inert gas atmosphere at 100-150℃ for 10-30 minutes to remove moisture and improve the bonding strength between the nickel plating layer and the copper substrate. During the electroplating process, the pulse power supply duty cycle is 20%-80%, the frequency is 800-1500Hz, and the current density is 2-8 A / dm³. 2 .

[0038] Step A3, Aluminum cladding: Before preparing composite round wire 1 or composite flat wire 2, aluminum strip is clad onto copper substrate under inert gas protection, and aluminum strip is welded to form an aluminum-clad copper profile with an outer sealed aluminum cladding layer and an inner copper substrate; before preparing composite metal foil 3, aluminum strip is sandwiched on copper substrate under inert gas protection and then aluminum strip is welded to form an aluminum-clad copper profile with a copper substrate in the middle layer and aluminum strips on the top and bottom layers.

[0039] Step A4, Vacuum Rolling Composite: The aluminum-clad copper profile is vacuum-pressed for 10-60 minutes using a hot isostatic press (HIP) at a temperature of 600-750℃, with a vacuum degree of 4.0 × 10⁻⁶. -3 Pa. Subsequently, the aluminum-clad copper profile is pressed in a hot isostatic press at a temperature of 600-710℃. High-pressure gas is applied uniformly in all directions to eliminate the air gaps between the three metals (copper, nickel, and aluminum), making the contact surfaces between the metals tightly bonded. The pressure is 20-40 MPa, thus obtaining the aluminum-clad copper composite profile.

[0040] like Figure 5 The figure shows the shear strength curves of the aluminum-clad copper composite profile under different insulation times. This step eliminates the air gaps between the three metals (copper, nickel, and aluminum), resulting in a tighter fit between the metal surfaces. Simultaneously, under the combined effects of temperature and pressure, atomic diffusion occurs between copper and nickel, and between aluminum and nickel, forming a copper-nickel-aluminum composite layer with a maximum shear strength exceeding the inherent shear strength of aluminum. The formation of this composite layer is crucial, ensuring that the interfacial bonding strength of the aluminum-clad copper composite profile exceeds the inherent shear strength of aluminum, thus preventing the aluminum layer from detaching during subsequent processing. Furthermore, the intermediate nickel layer effectively prevents the interdiffusion of copper and aluminum to form brittle copper-aluminum compounds. Moreover, due to the high-temperature stability and toughness of nickel-aluminum compounds, the outer aluminum layer will not detach due to internal thermal stress even under long-term exposure to high temperatures. After the above steps A1, A2, A3 and A4, for the composite round wire 1, a structure is initially formed in which the round wire conductor composite layer 5 covers the round wire conductor copper conductor 6; for the composite flat wire 2, a structure is initially formed in which the flat wire conductor composite layer 8 covers the flat wire conductor copper conductor 9; for the composite metal foil 3, a structure is initially formed in which the metal foil composite layer 11 covers the metal foil copper conductor 12.

[0041] Step A5, Annealing: Set the annealing temperature to 200–300℃ and the annealing time to 30–60 minutes under an inert gas or vacuum atmosphere. This promotes the further formation of a stable diffusion layer at the composite interface of the aluminum-clad copper composite profile, while refining the microstructure of the diffusion area, eliminating internal stress generated during processing, and improving the consistency of subsequent plastic processing. Figure 6 The figure shows the peel strength curves of aluminum-clad copper composite profiles under different annealing conditions.

[0042] Step A6, isothermal rolling: The annealed aluminum-clad copper composite profile is subjected to multi-pass isothermal rolling at a temperature of 320-380℃, a rolling speed of 0.2-1.0m / min, a single-pass relative reduction of 5%-20%, and a rolling pressure of 10-100MPa to obtain aluminum-clad copper composite conductors.

[0043] Step A7, Drawing and Shaping: When preparing composite flat wire 2 or composite metal foil 3, the drawing and shaping step is not required. When preparing composite round wire 1, the aluminum-clad copper composite conductor after multiple rolling passes is first annealed, and then continuously drawn into aluminum-clad copper composite round wire of the required diameter using a wire drawing machine. The temperature of the wire drawing die during wire drawing is 320-380℃. After wire drawing, annealing is performed, and then it is naturally cooled to room temperature in an inert gas or vacuum atmosphere.

[0044] Step A8, Micro-arc oxidation treatment: In the actual use of the composite conductor made by this invention, the motor winding process is performed first, and then the aluminum layer is subjected to micro-arc oxidation treatment. Winding first and then micro-arc oxidation can ensure the integrity of the hard and brittle aluminum oxide, avoid mechanical damage caused by winding, improve the overall thermal stability and insulation performance of the winding, and at the same time improve the yield of the final product.

[0045] In the preparation of composite round wire 1, composite flat wire 2, or composite metal foil 3, the aluminum-clad copper composite wire, after isothermal rolling or drawing, undergoes surface cleaning to remove residual lubricant from rolling or drawing. The wound aluminum-clad copper composite wire is then placed in an electrolyte containing Na2SiO3 and KOH, wherein the mass ratio of purified water, Na2SiO3, and NaOH in the electrolyte is 1000:10:2. The conductivity of the electrolyte is 6-12 mS·cm. -1 The pH value is 9-15. The electrolyte is placed in a polypropylene tank. An aluminum-clad copper composite wire is placed in the electrolyte as the anode, and a graphite rod as the cathode. The anode and cathode are connected to a pulse power supply, and the aluminum-clad copper composite wire is subjected to micro-arc oxidation treatment for 15-40 minutes to obtain composite round wire 1, composite flat wire 2, and composite metal foil 3, all with insulating layers. A bipolar pulse current generator is used as the pulse power supply, with a frequency of 200-300Hz, a positive and negative pulse duration of 2-4ms, equal pulse intervals, and a current density set to 10-20A / dm³. 2 After the above A8 steps, for the composite round wire 1, an alumina film 4 on the outer side of the round wire conductor, a composite layer 5 of the round wire conductor, and a copper conductor 6 of the round wire conductor are formed. Figure 1 The final structure shown; for the composite flat wire 2, an alumina film 7 on the outer side of the flat wire conductor, a composite layer 8 of the flat wire conductor, and a copper conductor 9 of the flat wire conductor are formed as shown. Figure 2The final structure shown; for the composite metal foil 3, an outer aluminum oxide layer 10, a composite metal foil layer 11, and a copper conductor 12 are formed as shown. Figure 3 The final structure shown.

[0046] Example 1:

[0047] Prepare a composite round wire 1 with a diameter of 1.2 mm, such as... Figure 4 As shown, it includes the following steps:

[0048] Step A1, Raw material cleaning: Surface treatment of high-purity copper rods and aluminum strips. After degreasing, the aluminum strips are immersed in alkaline solution. The alkali can remove the oxide film on the surface of the aluminum strips. The aluminum strips are then purged with nitrogen gas. The copper rods are degreased, sanded to remove rust, rinsed with deionized water, and dried before use.

[0049] Step A2, Nickel Intermediate Layer Deposition: Add the following components to 1L of purified water: 300g NiSO4, 40g NiCl2, 35g H3BO3, 0.28g 4-butynediol, and 0.1g sodium dodecyl sulfate. Stir until fully dissolved to prepare the electroplating solution. Place the electroplating solution in a polypropylene tank. Place a cleaned copper rod in the electroplating solution as the cathode, and place pure nickel or electroplating-grade nickel anode material in the electroplating solution as the anode. Connect the anode and cathode to a power source and perform electroplating for 2 minutes to obtain a copper substrate with a nickel plating layer. The copper substrate with the nickel plating layer is then stored in an inert gas atmosphere at 100°C for 10 minutes to remove moisture and improve the bonding strength between the nickel layer and the copper substrate. Electroplating conditions include a current density of 0.5A / dm³. 2 The temperature is 25℃ and the pH value is 2.5.

[0050] Step A3, Aluminum cladding: Under the protection of inert gas, aluminum strip is clad with copper substrate and then welded to form an aluminum-clad copper profile with an outer sealed aluminum cladding layer and an inner copper substrate; the aluminum layer thickness in the aluminum-clad copper profile is 0.83mm, the copper rod diameter is 8.33mm, the diameter of the formed aluminum-clad copper profile is 10mm, and the nickel plating layer thickness is 25μm.

[0051] Step A4, Vacuum Rolling Composite: The aluminum-clad copper profile is vacuum-insulated for 20 minutes using a hot isostatic press (HIP) at 710℃, with a vacuum degree of 4.0 × 10⁻⁶. -3 Pa. Subsequently, the aluminum-clad copper profile is pressed in a hot isostatic press at 620℃ under a pressure of 20MPa to obtain the aluminum-clad copper composite profile. After steps A1, A2, A3, and A4, a preliminary structure is formed for the composite round wire 1, where the round wire conductor composite layer 5 covers the round wire conductor copper conductor 6. After step A4, the maximum shear strength of the obtained aluminum-clad copper composite profile is 86MPa.

[0052] Step A5 involves annealing the aluminum-clad copper composite profile under an inert gas or vacuum atmosphere at a temperature of 200°C for 30 minutes. After step A5, the maximum peel strength of the resulting aluminum-clad copper composite profile is 11 N·mm.

[0053] Step A6, isothermal rolling: The annealed aluminum-clad copper composite profile is subjected to multi-pass isothermal rolling at a temperature of 320℃, a rolling speed of 0.2m / min, a single-pass relative reduction of 5%, and a rolling pressure of 10MPa. After 13 passes of rolling, the aluminum-clad copper composite round wire with a diameter of 3mm is obtained.

[0054] Step A7, Drawing and Shaping: The composite wire after multiple rolling passes is first annealed, then continuously drawn into a circular shape using a wire drawing machine. It undergoes eight passes of drawing deformation with an average single-pass end-face reduction rate of 5%, ultimately producing an aluminum-clad copper composite round wire 1 of the required diameter. The temperature of the drawing die during drawing is 320℃, and the diameter of the aluminum-clad copper composite round wire is 1.2mm. After drawing, it undergoes annealing and then naturally cools to room temperature in an inert gas or vacuum atmosphere.

[0055] Step A8, Micro-arc Oxidation Treatment: The drawn and shaped aluminum-clad copper composite round wire undergoes surface cleaning to remove residual lubricant from rolling or drawing. Then, the aluminum-clad copper composite round wire is wound into motor windings, and the wound windings are placed in an electrolyte containing Na₂SiO₃ and KOH, where the mass ratio of pure water, Na₂SiO₃, and KOH is 1000:10:2. The conductivity of the electrolyte is approximately 6 mS·cm. -1 The pH value was approximately 9. The electrolyte was placed in a polypropylene tank. An aluminum-clad copper composite round wire was placed in the electrolyte as the anode, and a graphite rod as the cathode. The anode and cathode were connected to a pulse power supply for 15 minutes of micro-arc oxidation treatment to obtain a composite round wire 1 with an insulating layer. A bipolar pulse current generator was used as the pulse power supply, with a frequency of 200Hz, a positive and negative pulse duration of 2ms, equal pulse intervals, and a current density of 10A / dm³. 2 .

[0056] After the above A8 steps, the final result is as follows: Figure 1 The composite round wire 1 shown comprises, from the outside in, an alumina film 4 on the outer side of the round wire conductor, a composite layer 5 on the round wire conductor, and a copper conductor 6 on the round wire conductor. The composite round wire 1 prepared using the method and process parameters of this embodiment has a conductivity of 100% IACS, a thickness of 25 μm for the composite layer 5, and a thickness of 45 μm for the alumina film 4 on the outer side of the round wire conductor. It has a power frequency breakdown voltage of 320V and can operate continuously at temperatures below 400℃.

[0057] Example 2:

[0058] Prepare composite flat wire 2 with dimensions of 1.5mm*2.0mm, such as... Figure 4 As shown, it includes the following steps:

[0059] Step A1, Raw material cleaning: Surface treatment of high-purity copper rods and aluminum strips. After degreasing, the aluminum strips are immersed in alkaline solution to remove the surface oxide film and are then purged with nitrogen. The copper rods are degreased, sanded to remove rust, rinsed with deionized water, and dried before use.

[0060] Step A2, Nickel Intermediate Layer Deposition: Add NiSO4·6H2O, NiCl2, H3BO3, C6H8O7·H2O and C to pure water. 12 H 25 The electroplating solution for SO4Na consists of pure water, NiSO4·6H2O, NiCl2, H3BO3, C6H8O7·H2O, and C 12 H 25 The mass ratio of SO4 to Na was 1000:200:30:30:5:0.1. The pH of the electroplating solution was adjusted to 6 using 10% NaOH, and the temperature was 50℃. The electroplating solution was placed in a polypropylene tank. A cleaned copper rod was placed in the solution as the cathode, and a pure nickel or electroplating-grade nickel anode material or an inert platinum electrode was placed in the solution as the anode. The anode and cathode were connected to a power source and electroplated for 11 minutes to obtain a copper substrate with a nickel plating layer. The copper substrate with the nickel plating layer was then stored in an inert gas atmosphere at 125℃ for 20 minutes to remove moisture and improve the bonding strength between the nickel layer and the copper substrate. During the electroplating process, the pulse power supply duty cycle was 50%, the frequency was 1100Hz, and the current density was 5A / dm³. 2 The thickness of the nickel plating layer obtained by electroplating is 22 μm.

[0061] Step A3, Aluminum cladding: Under the protection of inert gas, aluminum strip is clad with copper substrate and then welded to form an aluminum-clad copper profile with an outer sealed aluminum cladding layer and an inner copper substrate. The aluminum layer thickness is 0.7mm, the copper substrate diameter is 8.6mm, and the diameter of the formed aluminum-clad copper profile is 10mm.

[0062] Step A4, Vacuum Rolling Composite: The aluminum-clad copper profile is vacuum-insulated for 40 minutes using a hot isostatic press (HIP) at 710℃, with a vacuum degree of 4.0 × 10⁻⁶. -3Pa. Subsequently, the aluminum-clad copper profile is pressed in a hot isostatic press at 620℃ under a pressure of 30 MPa to obtain the aluminum-clad copper composite profile. After steps A1, A2, A3, and A4, a structure is initially formed for the composite flat wire 2, where the flat wire conductor composite layer 8 covers the flat wire conductor copper conductor 9. After step A4, the maximum shear strength of the obtained aluminum-clad copper composite profile is 90 MPa.

[0063] Step A5 involves annealing the aluminum-clad copper composite profile under an inert gas or vacuum atmosphere at a temperature of 300°C for 60 minutes to promote the formation of a stable diffusion layer at the composite interface. After step A5, the maximum peel strength of the resulting aluminum-clad copper composite profile is 10.6 N·mm.

[0064] Step A6, isothermal rolling: The annealed aluminum-clad copper composite profile is subjected to multiple passes of isothermal rolling to obtain aluminum-clad copper composite flat wire. The rolling temperature is 360℃, the rolling speed is 0.6m / min, the single pass relative reduction is 6%, and the rolling pressure is 60MPa. After twenty passes of rolling reduction, the size of the aluminum-clad copper composite flat wire is 1.5mm×2.0mm.

[0065] Step A8, Micro-arc oxidation treatment: The aluminum-clad copper composite flat wire after isothermal rolling is surface-cleaned to remove residual lubricant from rolling. Then, the aluminum-clad copper composite flat wire is wound into a motor winding. The wound aluminum-clad copper composite flat wire winding is placed in an electrolyte containing Na2SiO3 and KOH, where the mass ratio of pure water, Na2SiO3, and KOH is 1000:10:2. The electrolyte has a conductivity of 9 mS·cm⁻¹ and a pH of 12. The electrolyte is placed in a polypropylene tank, and the aluminum-clad copper composite flat wire is placed in the electrolyte as the anode, with a graphite rod as the cathode. The anode and cathode are connected to a pulse power supply and subjected to micro-arc oxidation treatment for 25 minutes to obtain composite flat wire 2 with an insulating layer. The pulse power supply uses a bipolar pulse current generator with a frequency of 250 Hz, a positive and negative pulse duration of 3 ms, equal pulse intervals, and a current density of 10 A / dm². 2 .

[0066] After the above A8 steps, the following is formed: Figure 2 The composite flat wire 2 shown comprises, from the outside in, an alumina film 7 on the outer side of the flat wire conductor, a composite layer 8 on the flat wire conductor, and a copper conductor 9 on the flat wire conductor. The composite flat wire 2 prepared using the preparation method and process parameters of this embodiment has a conductivity of 100% IACS, a thickness of 22 μm for the composite layer 8 on the flat wire conductor, a thickness of 91 μm for the alumina film 7 on the outer side of the flat wire conductor, a power frequency breakdown voltage of 327V, and can operate continuously at temperatures below 400℃.

[0067] Example 3:

[0068] A composite metal foil 3 with a thickness of 0.29 mm was prepared, such as... Figure 4 As shown, it includes the following steps:

[0069] Step A1, Raw material cleaning: Surface treatment of high-purity copper rods and aluminum strips. After degreasing, the aluminum strip is immersed in alkaline solution to remove the surface oxide film and is then purged with nitrogen gas. The copper strip is degreased, sanded to remove rust, rinsed with deionized water and dried before use.

[0070] Step A2, Nickel Intermediate Layer Deposition: Add 300g NiSO4, 40g NiCl2, and 35g H2O to 1L of purified water. c BO3, 0.28g of 4-butynediol, and 0.1g of sodium dodecyl sulfate were dissolved by stirring to prepare an electroplating solution. The solution was placed in a polypropylene tank. A cleaned copper strip was placed in the solution as the cathode, and pure nickel or electroplating-grade nickel anode material was placed in the solution as the anode. The anode and cathode were connected to a power source and electroplated for 10 minutes to obtain a copper substrate with a nickel plating layer. The nickel-plated copper substrate was then stored in an inert gas atmosphere at 150°C for 30 minutes to remove moisture and improve the bonding strength between the nickel layer and the copper substrate. Electroplating conditions included a current density of 2.5 A / dm³. 2 The temperature was 55℃, the pH value was 4.5, and the thickness of the nickel plating layer obtained by electroplating was 30μm.

[0071] Step A3, Aluminum cladding: Under the protection of inert gas, aluminum strips are wrapped around copper substrates on both sides, and aluminum strips are welded to form an aluminum-clad copper profile with an outer sealed aluminum cladding layer and an inner copper substrate; the aluminum strip thickness in the aluminum-clad copper profile is 0.25mm, the copper strip thickness is 0.45mm, and the resulting aluminum-clad copper profile thickness is 0.95mm.

[0072] Step A4, Vacuum Rolling Composite: The aluminum-clad copper profile is vacuum-insulated for 20 minutes using a hot isostatic press (HIP) at 710℃, with a vacuum degree of 4.0 × 10⁻⁶. -3 Pa. Subsequently, the aluminum-clad copper profile is pressed in a hot isostatic press at 620℃ under a pressure of 20 MPa to obtain the aluminum-clad copper composite profile. After steps A1, A2, A3, and A4, a structure is initially formed for the composite metal foil 3, where the metal foil composite layer 11 covers the metal foil copper conductor 12. After step A4, the maximum shear strength of the obtained aluminum-clad copper composite profile is 86 MPa.

[0073] Step A5 involves annealing the aluminum-clad copper composite profile under an inert gas or vacuum atmosphere at a temperature of 200°C for 60 minutes to promote the formation of a stable diffusion layer at the composite interface. After step A5, the maximum peel strength of the resulting aluminum-clad copper composite profile is 12 N·mm.

[0074] Step A6, isothermal rolling: The annealed aluminum-clad copper composite profile is subjected to multiple passes of isothermal rolling at a temperature of 380℃, a rolling speed of 1.0m / min, a single pass relative reduction of 7%, and a rolling pressure of 100MPa. After seven passes of rolling reduction, aluminum-clad copper composite metal foil with a thickness of 0.29mm is obtained.

[0075] Step A8, Micro-arc oxidation treatment: The aluminum-clad copper composite metal foil after isothermal rolling is surface-cleaned to remove residual lubricant from the rolling process. Then, the aluminum-clad copper composite metal foil is wound into a motor winding. The wound aluminum-clad copper composite metal foil winding is then placed in an electrolyte containing Na2SiO3 and KOH, where the mass ratio of pure water, Na2SiO3, and KOH is 1000:10:2. The electrolyte has a conductivity of 12 mS·cm⁻¹ and a pH of 15. The electrolyte is placed in a polypropylene tank, and the aluminum-clad copper composite metal foil is placed in the electrolyte as the anode, with a graphite rod as the cathode. The anode and cathode are connected to a pulse power supply and subjected to micro-arc oxidation treatment for 40 minutes to obtain a composite metal foil 3 with an insulating layer. The pulse power supply uses a bipolar pulse current generator with a frequency of 300 Hz, a positive and negative pulse duration of 4 ms, equal pulse intervals, and a current density of 10 A / dm³. 2 .

[0076] After the above A8 steps, the final result is as follows: Figure 3 The composite metal foil 3 shown includes, from the outside in, an outer aluminum oxide layer 10, a composite metal foil layer 11, and a copper conductor 12.

[0077] The composite metal foil 3 prepared using the preparation method and process parameters of this embodiment has an electrical conductivity of 100% IACS, a thickness of 30 μm for the metal foil composite layer 11, and a thickness of 120 μm for the outer alumina film 10 of the metal foil. It has a power frequency breakdown voltage of 334 V and can operate continuously at temperatures below 400°C.

[0078] The composite round wire 1, composite flat wire 2, and composite metal foil 3 provided in Examples 1 to 3 form a copper-nickel-aluminum composite layer between the conductive copper core and the alumina ceramic insulation layer. Nickel, as an intermediate layer, effectively suppresses the formation of brittle copper-aluminum compounds. During winding or prolonged exposure to high temperatures, the copper-nickel-aluminum composite layer will not crack or peel off, preventing insulation failure and making it suitable for various high-temperature applications of coils. The copper-nickel-aluminum composite layer is metallurgically bonded to the copper core and to the outer alumina ceramic insulation layer, effectively increasing the bonding strength between the Al2O3 insulation layer and the copper substrate to over 80 MPa. The high-temperature resistance of the alumina ceramic and the stable performance of the copper-nickel-aluminum composite layer at high temperatures ensure that the composite round wire 1, composite flat wire 2, and composite metal foil 3 maintain good insulation even at temperatures below 400°C. This insulation layer more than doubles the temperature resistance of the motor windings compared to ordinary copper enameled wire.

[0079] The methods for preparing composite round wire 1, composite flat wire 2, and composite metal foil 3 provided in Examples 1 to 3 can produce composite round wire 1, composite flat wire 2, and composite metal foil 3 with good heat resistance, high bonding strength, bending resistance, and thermal stress impact resistance by using conventional processes in composite metal processing, such as electroplating nickel, annealing, isothermal rolling, drawing, and micro-arc oxidation. Relying on mature processes in the field of composite metal processing, the preparation method proposed in this invention is simple, low-cost, and has good practical application value.

[0080] Furthermore, in the method for preparing high-temperature resistant aluminum-clad copper micro-arc oxidation conductors for motors provided by this invention, the electroplating nickel processing time can be any value between 2 and 30 minutes, and the current density is 0.5-2.5 A / dm². 2 The thickness of the nickel plating layer can be any value, ranging from 10 to 30 μm. For vacuum rolling composite, the holding temperature of the hot isostatic pressing (HIP) mill can be any value between 600 and 750℃, the holding time can be any value between 10 and 60 minutes, the pressing temperature can be any value between 600 and 710℃, and the pressing pressure can be any value between 20 and 40 MPa. The temperature for isothermal rolling and drawing can be any value between 320 and 380℃. The micro-arc oxidation treatment time can be any value between 15 and 40 minutes, the frequency can be any value between 200 and 300 Hz, and the current density can be any value between 10 and 20 A / dm³. 2 Any value of . Although the prepared composite round wire 1, composite flat wire 2 and composite metal foil 3 differ in the thickness of the composite layer and the thickness of the alumina ceramic layer, they still have good high temperature resistance, bending resistance, thermal stress impact resistance and good bonding strength, which can meet the requirements of motor windings in high temperature environments.

Claims

1. A high-temperature resistant aluminum-clad copper micro-arc oxidation conductor for motors, characterized in that, From the outside in, it includes an alumina film, a composite layer, and a copper conductor, where the copper conductor is the battery cell and the composite layer is a copper-nickel-aluminum composite layer. The following three forms are included: composite round wire (1), which includes, from the outside to the inside, an alumina film (4) on the outer side of the round wire conductor, a composite layer (5) on the round wire conductor, and a copper conductor (6) on the round wire conductor; composite flat wire (2), which includes, from the outside to the inside, an alumina film (7) on the outer side of the flat wire conductor, a composite layer (8) on the flat wire conductor, and a copper conductor (9) on the flat wire conductor; and composite metal foil (3), which includes, from the outside to the inside, an alumina layer (10) on the outer side of the metal foil, a composite layer (11) on the metal foil, and a copper conductor (12) on the metal foil.

2. The high-temperature resistant aluminum-clad copper micro-arc oxidation conductor for motors according to claim 1, characterized in that, The copper-nickel-aluminum composite layer comprises a copper-nickel solid solution and a nickel-aluminum compound, with a shear strength ≥80MPa and a peel strength ≥10N / mm.

3. The method for preparing high-temperature resistant aluminum-clad copper micro-arc oxidation conductors for motors according to claim 1 or 2, characterized in that, Includes the following steps: Step A1, Raw material cleaning: The high-purity copper rods, copper strips and aluminum strips required for preparation are degreased, alkaline washed, sanded to remove rust, rinsed with deionized water and dried in sequence to obtain raw materials with no oxide layer on the surface and meeting the surface roughness requirements. The whole process is carried out under the protection of inert gas to prevent the high-purity copper rods, copper strips and aluminum strips from being oxidized again. Step A2, Nickel Intermediate Layer Deposition: Electroplating is used to deposit a nickel layer with a thickness of 10-30μm on the surface of a high-purity copper rod or copper strip to obtain a copper substrate with a nickel plating layer. The electroplating method is DC constant current electroplating or pulse electroplating. Step A3, aluminum cladding: Before preparing the composite round wire (1) or composite flat wire (2), aluminum strip is clad on the copper substrate under the protection of inert gas, and the aluminum strip is welded to form an aluminum-clad copper profile with a sealed aluminum cladding layer on the outside and a copper substrate on the inside; Before preparing the composite metal foil (3), aluminum strip is sandwiched on the copper substrate under the protection of inert gas and then the aluminum strip is welded to form an aluminum-clad copper profile with a copper substrate in the middle and aluminum strips on the top and bottom; Step A4, Vacuum Rolling Composite: The aluminum-clad copper profile is vacuum-pressed for 10-60 minutes using a hot isostatic press at 600-750℃, with a vacuum degree of 4.0 × 10⁻⁶. -3 Pa; then the aluminum-clad copper profile is pressed in a hot isostatic press at a temperature of 600-710℃, and high pressure gas is used to apply pressure uniformly in all directions at a pressure of 20-40MPa to obtain the aluminum-clad copper composite profile; after the above steps A1, A2, A3 and A4, for the composite round wire (1), a structure is initially formed in which the round wire conductor composite layer (5) covers the round wire conductor copper conductor (6); for the composite flat wire (2), a structure is initially formed in which the flat wire conductor composite layer (8) covers the flat wire conductor copper conductor (9); for the composite metal foil (3), a structure is initially formed in which the metal foil composite layer (11) covers the metal foil copper conductor (12); Step A5, Annealing: Set the annealing temperature to 200–300℃ and the annealing time to 30–60 minutes under an inert gas or vacuum atmosphere to promote the formation of a stable diffusion layer at the composite interface of the aluminum-clad copper composite profile, while refining the microstructure of the diffusion area, eliminating internal stress generated during processing, and improving the consistency of subsequent plastic processing. Step A6, isothermal rolling: The annealed aluminum-clad copper composite profile is subjected to multi-pass isothermal rolling at a temperature of 320-380℃, a rolling speed of 0.2-1.0m / min, a single-pass relative reduction of 5%-20%, and a rolling pressure of 10-100MPa to obtain aluminum-clad copper composite conductors. Step A7, drawing and shaping: When preparing composite flat wire (2) or composite metal foil (3), the drawing and shaping step is not required; when preparing composite round wire (1), the aluminum-clad copper composite wire after multiple rolling is first annealed, and then continuously drawn into aluminum-clad copper composite round wire of the required diameter by a wire drawing machine. The temperature of the wire drawing die is 320-380℃ during wire drawing; after the wire drawing is completed, annealing is performed, and then it is naturally cooled to room temperature in an inert gas or vacuum atmosphere; Step A8, micro-arc oxidation treatment: Composite round wire (1), composite flat wire (2), or composite metal foil (3) are all first wound into motor windings, and then the aluminum layer is micro-arc oxidized to form dense alumina ceramic, that is, the outermost alumina film of the composite wire.

4. The preparation method according to claim 3, characterized in that, The DC constant current electroplating in step A2 includes the following steps: adding an electroplating solution containing NiSO4, NiCl2, H3BO3, 4-butynediol, and sodium dodecyl sulfate (SDS) to pure water, wherein the mass ratio of pure water, NiSO4, NiCl2, H3BO3, 4-butynediol, and sodium dodecyl sulfate (SDS) is 1000:300:40:35:0.28:0.1; placing the electroplating solution in a polypropylene tank and cleaning it. A high-purity copper rod or strip is placed in the electroplating solution as the cathode, and pure nickel or electroplating-grade nickel anode material is placed in the electroplating solution as the anode. The anode and cathode are connected to a power source and electroplating is performed for 2-10 minutes to obtain a copper substrate with a nickel plating layer. The copper substrate with the nickel plating layer is then stored in an inert gas atmosphere at 100-150℃ for 10-30 minutes to remove moisture and improve the bonding strength between the nickel plating layer and the copper substrate. During the electroplating process, the current density is 0.5-2.5 A / dm³. 2 The temperature range is 25-55℃, and the pH value is 2.5-4.

5. The pulse electroplating includes the following steps: adding NiSO4·6H2O, NiCl2, H3BO3, C6H8O7·H2O and C to pure water. 12 H 25 The electroplating solution for SO4Na contains pure water, NiSO4·6H2O, NiCl2, H3BO3, C6H8O7·H2O, and C 12 H 25 The mass ratio of SO4 to Na is 1000:200:30:30:5:0.

1. The pH of the electroplating solution is adjusted to 5.5-7.5 using 10% NaOH, and the temperature is 40-60℃. The electroplating solution is placed in a polypropylene tank. A high-purity copper rod or strip, after cleaning, is placed in the solution as the cathode, and pure nickel or electroplating-grade nickel anode material or an inert platinum electrode is placed in the solution as the anode. The anode and cathode are connected to a power source, and electroplating is performed for 2-20 minutes to obtain a copper substrate with a nickel plating layer. The copper substrate with the nickel plating layer is then stored in an inert gas atmosphere at 100-150℃ for 10-30 minutes to remove moisture and improve the bonding strength between the nickel plating layer and the copper substrate. During the electroplating process, the pulse power supply duty cycle is 20%-80%, the frequency is 800-1500Hz, and the current density is 2-8 A / dm³. 2 .

5. The preparation method according to claim 3, characterized in that, After step A4, the air gaps between the three metals, copper, nickel, and aluminum, are eliminated, and the contact surfaces between the metals become tightly bonded. At the same time, under the combined action of temperature and pressure, atomic diffusion occurs between copper and nickel, and between aluminum and nickel, forming a copper-nickel-aluminum composite layer with a maximum shear strength exceeding the inherent shear strength of aluminum. This composite layer ensures that the bonding strength of the composite interface of the aluminum-clad copper composite profile is greater than the inherent shear strength of aluminum, ensuring that the aluminum layer will not fall off during subsequent processing. In addition, the intermediate nickel layer effectively prevents the interdiffusion of copper and aluminum to form brittle copper-aluminum compounds, and the outer aluminum layer will not fall off due to internal thermal stress when exposed to high temperatures for a long time.

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