Preparation process of high-strength and high-toughness copper wire

Abstract

The application belongs to the technical field of copper wire preparation, and discloses a preparation process of high-strength and high-toughness copper wire. The preparation process comprises the following steps: mixing Ni, Co and Al element powders according to a molar ratio of 0.95-1.05:0.95-1.05:0.95-1.05, and then high-energy ball milling to obtain Ni-Co-Al middle-entropy alloy micro powder, and then vacuum arc melting or discharge plasma sintering to obtain Ni-Co-Al middle-entropy alloy; mixing the Ni-Co-Al middle-entropy alloy with tungsten copper alloy and copper ingot for melting, cooling the molten copper water through a condensing device, drawing out by a traction mechanism, annealing treatment, winding by a rewinding machine after cooling, and obtaining the copper wire. The application takes the copper ingot as a base material, the tungsten copper alloy as a reinforcing phase, and the Ni-Co-Al middle-entropy alloy as a bonding phase, and the copper wire is prepared by conventional mixed melting, so that the application has the advantages of simple processing method and low production cost.

Description

Technical Field

[0001] This invention belongs to the field of copper conductor preparation technology, specifically relating to a preparation process for high-strength and high-toughness copper conductors. Background Technology

[0002] Copper conductors are linear conductors made primarily of copper. They possess excellent toughness, conductivity second only to silver, and good corrosion resistance, making them a core material for power transmission and electronic equipment. However, pure copper alloy conductors have low mechanical strength, thus the development of copper conductors with higher mechanical strength holds great market potential. Replacing pure copper with aluminum-copper alloys can improve conductor strength and reduce costs, but the addition of high aluminum content reduces conductivity and corrosion resistance in acidic or electrolyte environments.

[0003] Patent document CN 118595447 B discloses a high-strength copper alloy conductor for new energy motors and its preparation method. It uses Fe-Co-Al medium-entropy alloy and Ni3Al alloy as reinforcing and binding phases to improve the metallographic structure of the copper-aluminum alloy, refine the alloy grains, and enhance the strength and conductivity of the copper-aluminum alloy. However, the introduction of Fe element reduces the corrosion resistance of the copper alloy conductor, and the strength, toughness, and corrosion resistance of the aluminum alloy-reinforced copper conductor still need further improvement to meet the demands of more demanding applications.

[0004] Copper-tungsten alloy wires play a vital role in various fields such as power and electronics due to their excellent conductivity, high temperature resistance, high stability, and reliability. However, the significant difference in the thermal expansion coefficients of copper and tungsten, coupled with the high melting point of tungsten, makes the processing of copper-tungsten alloy wires difficult and the production cost relatively high, which to some extent limits their widespread application. Summary of the Invention

[0005] In view of the shortcomings and deficiencies of the existing technology, the primary objective of this invention is to provide a manufacturing process for high-strength and high-toughness copper wires.

[0006] Another object of the present invention is to provide a high-strength and high-toughness copper wire prepared by the above process.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A process for manufacturing high-strength and high-toughness copper wire includes the following steps:

[0009] (1) Ni, Co and Al elemental powders were mixed in a molar ratio of 0.95~1.05:0.95~1.05:0.95~1.05 and then ball-milled at high energy to obtain Ni-Co-Al medium-entropy alloy micro powder;

[0010] (2) The obtained Ni-Co-Al medium-entropy alloy micro powder is subjected to vacuum arc melting or discharge plasma sintering to obtain Ni-Co-Al medium-entropy alloy;

[0011] (3) The Ni-Co-Al medium entropy alloy, tungsten copper alloy and copper ingot are mixed and smelted. The molten copper is cooled by a condenser and then pulled out by a traction mechanism. Then it is annealed and cooled before being wound by a rewinding machine to obtain copper wire.

[0012] Preferably, the average particle size of the Ni, Co, and Al elemental powders in step (1) is ≤50μm and the purity is >99.9%.

[0013] Preferably, the high-energy ball milling in step (1) refers to ball milling for 4 to 12 hours under the conditions of a ball-to-material ratio of 8 to 15:1 and a rotation speed of 300 to 500 r / min.

[0014] Preferably, the temperature of vacuum arc melting in step (2) is 1200~1400℃; the temperature of discharge plasma sintering is 1100~1200℃.

[0015] Preferably, the mass percentage ratio of the Ni-Co-Al medium-entropy alloy, tungsten-copper alloy and copper ingot mixed and smelted in step (3) is: 2%~5% Ni-Co-Al medium-entropy alloy, 5%~25% tungsten-copper alloy and 70%~93% copper ingot.

[0016] More preferably, the tungsten-copper alloy uses tungsten-copper alloy powder with a copper content ≥30% by mass and a particle size of 0.1~0.2mm. This invention uses a tungsten-copper alloy with a copper content ≥30% by mass, which has good plasticity and can achieve a good bond between tungsten and copper under the smelting conditions of this invention. The tungsten-copper alloy powder is a conventional industrial raw material, prepared using powder metallurgy technology.

[0017] More preferably, the tungsten content in the copper wire is controlled to be 3% to 12% by mass. Too low a tungsten content has limited effect on improving strength and corrosion resistance, while too high a tungsten content leads to a poorer bonding effect with copper under conventional mixed smelting conditions, resulting in a comprehensive reduction in the improvement effect.

[0018] Preferably, the mixing and melting in step (3) is completed in a melting furnace at a temperature of 1400~1600℃.

[0019] Preferably, the annealing temperature in step (3) is 500~700℃.

[0020] A high-strength and high-toughness copper wire is prepared by the above process.

[0021] The principle of this invention is as follows: Conventional tungsten-copper alloys are produced by powder metallurgy, with tungsten content as high as 50%~90%. Directly using them to prepare wires is costly (low processing efficiency of powder metallurgy, high cost of tungsten), has low toughness, is difficult to process (high tungsten alloys have high melting points and poor plasticity), and has low conductivity (tungsten has high resistivity, and the conductivity of tungsten-copper alloys produced by existing powder metallurgy methods is generally 30%~60% IACS). This invention introduces a tungsten reinforcing phase by adding a tungsten-copper alloy through conventional mixing and melting methods, achieving good plastic mixing with the copper substrate. At the same time, a low-melting-point Ni-Co-Al medium-entropy alloy is used as a binder phase. Ni-Co-Al medium-entropy alloy has good fluidity in the molten state and good compatibility with both tungsten and copper. Through melt infiltration, it repairs defects at the copper-tungsten interface, improving the alloy strength while maintaining high toughness. Meanwhile, the introduction of Ni-Co-Al has little impact on the corrosion resistance and conductivity of the copper alloy. Through the above combined effects, the requirements of high strength, high toughness, high corrosion resistance, and high conductivity are achieved simultaneously.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] (1) The copper alloy material of the present invention is prepared by conventional mixing and melting with copper ingot as base material, tungsten copper alloy as reinforcing phase and Ni-Co-Al medium entropy alloy as binder phase. It has the advantages of simple processing method and low production cost.

[0024] (2) The copper alloy material of the present invention can significantly improve the strength and corrosion resistance of copper wires, while maintaining high conductivity and toughness. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to embodiments, but the implementation of the present invention is not limited thereto.

[0026] Example 1

[0027] A method for preparing a copper alloy wire includes the following steps:

[0028] (1) Ni, Co and Al elemental powders with an average particle size ≤50μm and a purity >99.9% were mixed at a molar ratio of 1:1:1 and added to a high-energy ball mill. The mixture was ball-milled for 8 hours at a ball-to-material ratio of 10:1 and a rotation speed of 400r / min to obtain Ni-Co-Al medium-entropy alloy micro powder.

[0029] (2) The obtained Ni-Co-Al medium-entropy alloy powder was added to a vacuum electric arc furnace for melting. The melting temperature was 1250~1300℃ and the melting time was 90min. After melting, the furnace was cooled to obtain Ni-Co-Al medium-entropy alloy.

[0030] (3) Based on mass percentage, 4% Ni-Co-Al medium entropy alloy, 16% copper-containing 50wt% tungsten copper alloy powder (80 mesh) and 80% copper ingots are added to a horizontal furnace for smelting at a smelting temperature of 1500~1550℃. The molten copper is cooled by a condenser and then pulled out by a traction mechanism. It is then annealed at 600~650℃ and cooled before being wound by a rewinding machine to obtain copper alloy wire.

[0031] The copper alloy wire obtained in this embodiment has a tensile strength of 356 MPa and an elongation at break of 27% after a tensile test (GB / T 228-2010). Its corrosion resistance in the 24-hour acetic acid salt spray test (AASS) is grade 9 (based on the corrosion area rating established in GB / T6461-2002 "Rating of specimens and pieces of metals and other inorganic coatings on a metallic substrate after corrosion testing"). The conductivity test (International Standard for Conductive Copper) result is 88.5% IACS.

[0032] Examples 2-6 and Comparative Examples 1-2

[0033] Compared with Example 1, Examples 2-6 and Comparative Examples 1-2 were performed according to the raw material ratios shown in Table 1, while the remaining steps and conditions were the same as in Example 1. The performance test results of the obtained copper alloy wires are shown in Table 1 below.

[0034] Table 1. Performance test results of copper alloy wires with different raw material ratios

[0035] Example Ni-Co-Al medium-entropy alloy Tungsten copper alloy powder copper ingots tensile strength Elongation at break Corrosion resistance conductivity Example 2 1% 4% 95% 236MPa 39% Level 7 93.7% Example 3 2% 6% 92% 280MPa 36% Level 8 92.3% Example 4 3% 10% 87% 327MPa 31% Level 9 90.5% Example 5 5% 24% 71% 384MPa 22% Level 9 79.2% Example 6 6% 30% 64% 312MPa 15% Level 8 68.4% Comparative Example 1 0 16% 84% 305MPa 18% Level 8 83.0% Comparative Example 2 4% 0 96% 219MPa 42% Level 7 96.8%

[0036] As shown in Table 1, when the amount of tungsten-copper alloy powder added does not exceed 24% (tungsten content not exceeding 12%), the tensile strength and corrosion resistance of the resulting copper alloy wires increase with the increase of tungsten-copper alloy powder addition. However, when the amount of tungsten-copper alloy powder added reaches 30% (tungsten content 15%), the tensile strength and corrosion resistance decrease significantly, indicating that the structural defects of the copper alloy obtained by conventional smelting increase significantly after the tungsten content exceeds a certain proportion. Furthermore, the comparison results of Comparative Examples 1 and 2 show that the addition of tungsten-copper alloy powder can significantly improve the tensile strength and corrosion resistance of the resulting copper alloy wires, and the Ni-Co-Al medium-entropy alloy has a synergistic effect on the reinforcement of the tungsten-copper alloy. The elongation at break results of Examples 1-6 and Comparative Example 2 show that the wire toughness tends to decrease with the increase of tungsten-copper alloy powder addition; however, the comparison with the data of Comparative Example 1 shows that the addition of Ni-Co-Al medium-entropy alloy can reduce the decrease in toughness caused by the addition of tungsten-copper alloy. This invention achieves good reinforcement and corrosion resistance while ensuring good toughness and electrical conductivity through the synergistic effect of the Ni-Co-Al medium-entropy alloy binder phase and the tungsten-copper alloy reinforcing phase.

[0037] Example 7

[0038] A method for preparing a copper alloy wire includes the following steps:

[0039] Steps (1) and (2) are the same as in Example 1;

[0040] (3) Based on mass percentage, 4% Ni-Co-Al medium entropy alloy, 11.4% copper-containing 30wt% tungsten copper alloy powder (80 mesh), and 84.6% copper ingots are added to a horizontal furnace for smelting at a temperature of 1500~1550℃. The molten copper is cooled by a condenser and then pulled out by a traction mechanism. It is then annealed at 600~650℃ and cooled before being wound by a rewinding machine to obtain copper alloy wire.

[0041] The copper alloy wire obtained in this embodiment has a tensile strength of 344 MPa and an elongation at break of 26% as tested by tensile testing; its corrosion resistance is rated at level 9 in the acetic acid salt spray test (AASS) for 24 hours; and its conductivity (international standard for conductive copper) is 87.6% IACS.

[0042] Example 8

[0043] A method for preparing a copper alloy wire includes the following steps:

[0044] Steps (1) and (2) are the same as in Example 1;

[0045] (3) Based on mass percentage, 4% Ni-Co-Al medium entropy alloy, 10% copper-containing 20wt% tungsten copper alloy powder (80 mesh) and 86% copper ingots are added to a horizontal furnace for smelting at a smelting temperature of 1500~1550℃. The molten copper is cooled by a condenser and then pulled out by a traction mechanism. It is then annealed at 600~650℃ and cooled before being wound by a rewinding machine to obtain copper alloy wire.

[0046] The copper alloy wire obtained in this embodiment has a tensile strength of 321 MPa and an elongation at break of 24% as tested by tensile testing; its corrosion resistance is rated at level 8 in the acetic acid salt spray test (AASS) for 24 hours; and its conductivity (international standard for conductive copper) is 83.8% IACS.

[0047] The comparison between Examples 7-8 and Example 1 shows that, under the same tungsten content, the lower the copper content of the tungsten-copper alloy powder, the worse the reinforcing effect of the resulting copper alloy. When the copper content of the tungsten-copper alloy powder is below 30 wt%, the tensile strength, corrosion resistance, and electrical conductivity of the resulting copper alloy all decrease significantly. This is because the lower the copper content of the tungsten-copper alloy powder, the worse its plasticity, leading to a poorer mixing and melting effect with the copper substrate and an increase in structural defects.

[0048] Comparative Example 3

[0049] A method for preparing a copper alloy wire includes the following steps:

[0050] Steps (1) and (2) are the same as in Example 1;

[0051] (3) Based on mass percentage, 4% Ni-Co-Al medium entropy alloy, 8% pure copper powder (80 mesh), 8% pure tungsten powder (80 mesh) and 80% copper ingot are added to a horizontal furnace for smelting at a smelting temperature of 1500~1550℃. The molten copper is cooled by a condenser and then pulled out by a traction mechanism. It is then annealed at 600~650℃ and cooled before being wound by a rewinding machine to obtain copper alloy wire.

[0052] The copper alloy wire obtained in this comparative example has a tensile strength of 270 MPa and an elongation at break of 19% as tested by tensile testing; its corrosion resistance is rated at level 7 in the acetic acid salt spray test (AASS) for 24 hours; and its conductivity (International Standard for Conductive Copper) result is 80.4% IACS.

[0053] The comparison results between this comparative example and Examples 1 and 7-8 show that the tensile strength, elongation at break, corrosion resistance, and conductivity of the copper alloy wires obtained by directly mixing and melting pure tungsten powder are significantly reduced. This indicates that directly mixing and melting pure tungsten powder with copper substrate yields poor results.

[0054] Comparative Example 4

[0055] A method for preparing copper alloy wires, compared with Example 1, does not pre-prepare Ni-Co-Al medium-entropy alloy micro powder, but directly uses elemental powder mixing and melting. The specific preparation steps are as follows:

[0056] (1) Mix Ni, Co and Al elemental powders with an average particle size ≤50μm and a purity >99.9% at a molar ratio of 1:1:1 to obtain mixed powder.

[0057] (2) By mass percentage, 4% of mixed powder, 16% of tungsten copper alloy powder (80 mesh) with a copper content of 50wt% and 80% of copper ingots are added to a horizontal furnace for smelting at a smelting temperature of 1500~1550℃. The molten copper is cooled by a condenser and then pulled out by a traction mechanism. It is then annealed at 600~650℃ and cooled before being wound by a rewinding machine to obtain copper alloy wire.

[0058] The copper alloy wire obtained in this comparative example has a tensile strength of 309 MPa and an elongation at break of 21% as tested in a tensile test; its corrosion resistance is rated at level 8 in the acetic acid salt spray test (AASS) for 24 hours; and its conductivity (International Standard for Conductive Copper) result is 81.6% IACS.

[0059] The comparison results between this comparative example and Example 1 show that without prior high-energy ball milling followed by melting to prepare Ni-Co-Al medium-entropy alloy, the compatibility of the elemental powder with tungsten and copper is reduced, resulting in a significant decrease in the strengthening effect and toughness improvement effect on the copper alloy.

[0060] Example 9

[0061] A method for preparing a copper alloy wire includes the following steps:

[0062] (1) Ni, Co and Al elemental powders with an average particle size ≤50μm and a purity >99.9% were mixed at a molar ratio of 1:1:0.95 and added to a high-energy ball mill. The mixture was ball-milled for 6 hours at a ball-to-material ratio of 8:1 and a rotation speed of 500r / min to obtain Ni-Co-Al medium-entropy alloy micro powder.

[0063] (2) The obtained Ni-Co-Al medium-entropy alloy powder was added to a vacuum electric arc furnace for melting. The melting temperature was 1300~1350℃ and the melting time was 120min. After melting, the furnace was cooled to obtain Ni-Co-Al medium-entropy alloy.

[0064] (3) Based on mass percentage, 4% Ni-Co-Al medium entropy alloy, 16% copper-containing 50wt% tungsten copper alloy powder (80 mesh) and 80% copper ingots are added to a horizontal furnace for smelting at a smelting temperature of 1400~1450℃. The molten copper is cooled by a condenser and then pulled out by a traction mechanism. It is then annealed at 500~550℃ and cooled before being wound by a rewinding machine to obtain copper alloy wire.

[0065] Example 10

[0066] A method for preparing a copper alloy wire includes the following steps:

[0067] (1) Ni, Co and Al elemental powders with an average particle size ≤50μm and a purity >99.9% were mixed at a molar ratio of 0.95:1:1.05 and added to a high-energy ball mill. The mixture was ball-milled for 6 hours at a ball-to-material ratio of 10:1 and a rotation speed of 500r / min to obtain Ni-Co-Al medium-entropy alloy micro powder.

[0068] (2) The obtained Ni-Co-Al medium-entropy alloy micro powder was added into the heating chamber of the discharge plasma sintering system. After evacuation, one-step liquid phase sintering was performed by discharge plasma. The sintering temperature was 1150~1200℃ and the holding time was 5min. After sintering, the Ni-Co-Al medium-entropy alloy was obtained by cooling with the furnace.

[0069] (3) Based on mass percentage, 4% Ni-Co-Al medium entropy alloy, 16% copper-containing 50wt% tungsten copper alloy powder (80 mesh) and 80% copper ingots are added to a horizontal furnace for smelting at a smelting temperature of 1450~1500℃. The molten copper is cooled by a condenser and then pulled out by a traction mechanism. It is then annealed at 550~600℃ and cooled before being wound by a rewinding machine to obtain copper alloy wire.

[0070] Example 11

[0071] A method for preparing a copper alloy wire includes the following steps:

[0072] (1) Ni, Co and Al elemental powders with an average particle size ≤50μm and a purity >99.9% were mixed in a molar ratio of 1.05:0.95:1.05 and added to a high-energy ball mill. The mixture was ball-milled for 8 hours at a ball-to-material ratio of 12:1 and a rotation speed of 400r / min to obtain Ni-Co-Al medium-entropy alloy micro powder.

[0073] (2) The obtained Ni-Co-Al medium-entropy alloy micro powder was added into the heating chamber of the discharge plasma sintering system. After evacuation, one-step liquid phase sintering was performed by discharge plasma. The sintering temperature was 1100~1150℃ and the holding time was 10min. After sintering, the Ni-Co-Al medium-entropy alloy was obtained by cooling with the furnace.

[0074] (3) Based on mass percentage, 4% Ni-Co-Al medium entropy alloy, 16% copper-containing 50wt% tungsten copper alloy powder (80 mesh) and 70% copper ingots are added to a horizontal furnace for smelting at a smelting temperature of 1550~1600℃. The molten copper is cooled by a condenser and then pulled out by a traction mechanism. It is then annealed at 650~700℃ and cooled before being wound by a rewinding machine to obtain copper alloy wire.

[0075] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A manufacturing process for a high-strength, high-toughness copper conductor, characterized in that, Includes the following steps: (1) Ni, Co and Al elemental powders were mixed in a molar ratio of 0.95~1.05:0.95~1.05:0.95~1.05 and then ball-milled at high energy to obtain Ni-Co-Al medium-entropy alloy micro powder; (2) The obtained Ni-Co-Al medium-entropy alloy micro powder is subjected to vacuum arc melting or discharge plasma sintering to obtain Ni-Co-Al medium-entropy alloy; (3) Ni-Co-Al medium entropy alloy, tungsten copper alloy and copper ingot are mixed and smelted. The molten copper is cooled by a condenser and then pulled out by a traction mechanism. Then it is annealed and cooled before being wound by a rewinding machine to obtain copper wire. The mass percentage ratio of the Ni-Co-Al medium-entropy alloy, tungsten-copper alloy and copper ingots mixed and smelted in step (3) is: Ni-Co-Al medium-entropy alloy 2%~5%, tungsten-copper alloy 5%~25%, and copper ingot 70%~93%; The tungsten-copper alloy uses tungsten-copper alloy powder with a copper content of ≥30% by mass and a particle size of 0.1~0.2mm; The tungsten mass content in the copper wire is controlled to be 3%~12%; The mixing and melting are completed in a melting furnace at a temperature of 1400~1600℃.

2. The manufacturing process of a high-strength, high-toughness copper conductor according to claim 1, characterized in that, The average particle size of the Ni, Co, and Al elemental powders mentioned in step (1) is ≤50μm and the purity is >99.9%; the high-energy ball milling refers to ball milling for 4~12h under the conditions of ball-to-material ratio of 8~15:1 and rotation speed of 300~500r / min.

3. The manufacturing process of a high-strength, high-toughness copper conductor according to claim 1, characterized in that, The temperature of vacuum arc melting in step (2) is 1200~1400℃; the temperature of discharge plasma sintering is 1100~1200℃.

4. The manufacturing process of a high-strength, high-toughness copper conductor according to claim 1, characterized in that, The annealing temperature in step (3) is 500~700℃.

5. A high-strength, high-toughness copper conductor, characterized in that, It is prepared by the process described in any one of claims 1 to 4.