Preparation method and application of electroplated copper tungsten wire for cold drawing process

Abstract

The invention provides a preparation method of an electroplating copper tungsten wire for a cold drawing process, which comprises the following steps: placing a tungsten wire in an alkaline cleaning solution for ultrasonic cleaning, washing after cleaning, then placing a copper plate with the mass purity not lower than 99.95% as an anode and the tungsten wire as a cathode in an electroplating solution for electroplating, and controlling the current density to be 1.6-2.2 A / dm < 2 > in the electroplating process, the temperature is kept at 20-30 DEG C, the electroplating time is 68 min, and the electroplating liquid is stirred at the rotating speed of 250-300 r / min; and finally, after electroplating is finished, the tungsten wire is placed in flowing deionized water with the electrical resistivity not lower than 15 M omega cm to be washed clean, after low-temperature drying, the electroplated copper tungsten wire is obtained, and the average thickness of an electroplated copper layer on the surface of the tungsten wire is 0.75-1.25 microns. The uniform, compact and firmly combined copper plating layer is formed before cold drawing of the tungsten filament, and is matched with specific cold drawing process parameters for use, so that the filament breakage rate of the small-diameter tungsten filament is remarkably reduced, the surface quality and the production efficiency are improved, and the method is suitable for industrial continuous preparation of the high-performance tungsten filament.

Description

Technical Field

[0001] This invention belongs to the field of metal processing and surface treatment technology, specifically relating to a method and application of copper electroplating in the cold drawing process of tungsten wire. Background Technology

[0002] Tungsten wire is a typical refractory metal wire with a high melting point, high strength, excellent electrical and thermal conductivity, and good chemical stability. It is widely used in electric light source manufacturing, high-temperature heating elements, electronic devices, and aerospace. Cold drawing is a key step in achieving precision forming of tungsten wire, improving dimensional accuracy and mechanical properties. Its process stability and surface treatment effect directly affect the performance and service life of the finished product.

[0003] In the cold drawing production of fine-diameter tungsten wires (<0.10 mm in diameter), frictional heat and stress concentration are more severe. If lubrication and protection measures are insufficient, the wire breakage rate can reach 20-30%, not only reducing output but also leading to increased die wear and production interruptions. Currently, the industry commonly uses a graphite emulsion coating lubrication process, which involves forming a graphite emulsion coating on the tungsten wire surface before cold drawing to reduce friction. However, this method has the following significant drawbacks: 1. Poor coating uniformity: The physical properties of graphite emulsion and coating conditions are prone to fluctuation, resulting in uneven coating thickness, uneven distribution of friction coefficient during cold drawing, and local stress concentration, which is especially prone to wire breakage in fine-diameter tungsten wires. 2. Surface contamination and cleaning difficulty: Graphite residue on the surface of tungsten wire after cold drawing is difficult to remove completely, increasing the cost of subsequent cleaning processes; In high-temperature applications, graphite is easily oxidized, and the resulting oxides will reduce surface properties. 3. Insufficient high temperature resistance and bonding strength: During multi-pass cold drawing, the graphite emulsion coating is easily worn or peeled off, losing its lubrication and protection functions; 4. Poor process compatibility: Graphite emulsion processes are difficult to reliably match with high-precision cold drawing parameters (such as high-speed drawing and low-roughness dies), which limits production efficiency and yield.

[0004] To address the aforementioned issues, existing technologies have attempted to replace graphite emulsions with chemical plating, electroplating with other metals, or organic lubricating films. However, these methods still have shortcomings in the cold drawing of fine-diameter tungsten wires. 1. Although electroless nickel or copper plating can form a metallic coating, the adhesion is insufficient and it is easy to fall off during high-stress cold drawing; 2. The organic lubricating film has poor temperature resistance and is prone to decomposition or failure under frictional heat. 3. Although existing electroplating technology has improved the uniformity of the coating, it lacks systematic matching with cold drawing parameters under the condition of fine-diameter tungsten wire, making it difficult to stably achieve low wire breakage rate and high surface quality.

[0005] Therefore, there is an urgent need for a surface treatment method for fine-diameter tungsten wires that can ensure uniform and dense coating and strong adhesion, while achieving parameter synergy with the cold drawing process, thereby significantly reducing wire breakage rate, improving surface quality and production efficiency, and possessing industrial feasibility. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a method for preparing electroplated copper-tungsten wire for cold drawing process, which addresses the shortcomings of the prior art. This method can form a uniform, dense and firmly bonded copper plating layer before cold drawing of tungsten wire, and can be used in conjunction with specific cold drawing process parameters to significantly reduce the breakage rate of fine-diameter tungsten wire, improve surface quality and production efficiency, and is suitable for the industrial continuous preparation of high-performance tungsten wire.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a method for preparing electroplated copper-tungsten wire for cold drawing process, characterized in that the method includes the following steps: S1. The tungsten wire is placed in an alkaline cleaning solution for ultrasonic cleaning, and then rinsed to remove the alkaline cleaning solution after cleaning; the alkaline cleaning solution is prepared from sodium hydroxide, sodium carbonate, sodium silicate, and deionized water; the diameter of the tungsten wire is less than 0.1 mm; S2. Using a copper plate with a purity of not less than 99.95% as the anode and the tungsten wire cleaned in S1 as the cathode, electroplating is performed in the electroplating solution. During the electroplating process, the current density is controlled at 1.6-2.2 A / dm³. 2 The temperature is maintained at 20-30℃, the electroplating time is 6-8 min, and the electroplating solution is stirred at a speed of 250-300 r / min. After electroplating, an electroplated copper layer with an average thickness of 0.75-1.25 μm is formed on the surface of the tungsten wire. Then, it is rinsed clean in flowing deionized water with a resistivity of not less than 15 MΩ・cm, and dried at low temperature to obtain electroplated copper tungsten wire. The electroplating solution is prepared by copper sulfate, sulfuric acid, polyethylene glycol and deionized water, wherein the concentration of copper sulfate is 180-200 g / L, the concentration of sulfuric acid is 55-60 g / L, and the concentration of polyethylene glycol is 0.3-0.5 g / L.

[0008] Preferably, the ultrasonic cleaning in S1 has a frequency of 25-35kHz and a power of 400-500W.

[0009] Preferably, the power fluctuation range of the ultrasonic cleaning does not exceed ±30W.

[0010] Preferably, the alkaline cleaning solution contains 8-10% sodium hydroxide, 4-5% sodium carbonate, and 2-3% sodium silicate by mass.

[0011] Preferably, in the electroplating process described in S2, the concentration of copper sulfate in the electroplating solution fluctuates within a range of ±3 g / L, and the concentration of sulfuric acid fluctuates within a range of ±2 g / L.

[0012] Preferably, the flow rate of the deionized water rinsing in S2 is 0.4-0.8 L / min, and the rinsing time is 4-5 min.

[0013] Preferably, the low-temperature drying in S2 is performed at a temperature of 70-80°C for 15-20 minutes.

[0014] This invention also discloses the application of electroplated copper-tungsten wire in a cold drawing process. The electroplated copper-tungsten wire prepared above undergoes multiple cold drawing and annealing processes. During the cold drawing process, the drawing speed is 4-6 m / min, the annealing temperature between drawing passes is 750-800℃, and the annealing time is 8-12 min. A polycrystalline diamond drawing die is used, and the surface roughness Ra of the inner hole of the drawing die is ≤0.03 μm.

[0015] Preferably, the annealing process is carried out in an inert gas protective atmosphere with a volume purity of not less than 99.99%.

[0016] Compared with the prior art, the present invention has the following advantages: 1. The electroplated copper-tungsten wire prepared by this invention has a uniform electroplated copper layer on the surface of the tungsten wire, which is firmly bonded to the tungsten wire and can withstand the high stress during cold drawing without falling off, overcoming the defects of weak coating adhesion in processes such as electroless nickel plating. At the same time, it also avoids the surface contamination problem caused by traditional graphite emulsion residue, reducing the cost and complexity of subsequent cleaning processes.

[0017] 2. The copper plating on the surface of the tungsten wire in this invention directly ensures that the copper plating does not fail during the cold drawing and annealing process (750-800℃), thus ensuring the stability of the cold drawing process. At the same time, it provides performance support for the cold-drawn tungsten wire in subsequent applications in high-temperature scenarios such as electric light sources and high-temperature heating elements, ultimately achieving the effect of "extending service life". Both of these aspects together demonstrate the technical value of the high-temperature stability of the copper plating on the tungsten wire.

[0018] 3. This invention involves electroplating copper onto the tungsten wire before cold drawing, forming a uniform copper plating layer on the wire surface. This alters the surface properties of the tungsten wire, thereby reducing the friction and adhesion between the tungsten wire and the drawing die during cold drawing. Under the same cold drawing process parameters, compared to the traditional graphite emulsion hot drawing process, it can significantly reduce the wire breakage rate, by more than 50%. In practical production applications, using the electroplated copper tungsten wire prepared by this invention for cold drawing, supplemented by a matching cold drawing process (drawing speed of 4-6 m / min, annealing temperature between drawing passes of 750-800℃, annealing time of 8-12 min, and a polycrystalline diamond drawing die with an inner hole surface roughness Ra≤0.03μm), can increase the production efficiency of tungsten wire cold drawing by more than 20% and improve the product qualification rate to over 97%.

[0019] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 This is a bar graph comparing the breakage rate of fine-diameter tungsten wires prepared by conventional hot drawing of graphite emulsion in the embodiments and comparative examples of the present invention.

[0021] Figure 2 This is a physical image of the tungsten wire in S101 in Embodiment 1 of the present invention.

[0022] Figure 3 This is a physical image of the electroplated copper-tungsten wire obtained in S205 of Embodiment 1 of the present invention.

[0023] Figure 4 This is an SEM image of the tungsten wire selected in S101 of Embodiment 1 of the present invention.

[0024] Figure 5 This is a SEM image of the electroplated copper-tungsten wire prepared in S205 in Example 1 of the present invention. Detailed Implementation

[0025] Example 1 This embodiment discloses a method for preparing electroplated copper-tungsten wire for cold drawing process, characterized in that the method includes the following steps: S1, Pre-treated tungsten wire: S101. Select 100 tungsten wires with a diameter of 63μm, a length of 20m, and no scratches or oxide spots on the surface.

[0026] S102. The selected qualified tungsten wires are suspended in a stainless steel basket, completely immersed in the alkaline cleaning solution without contact with each other. An ultrasonic cleaner is used at 500W power and 30kHz frequency for 8 minutes, with power fluctuations controlled within ±20W during the cleaning process. The alkaline cleaning solution is prepared from sodium hydroxide (analytical grade), sodium carbonate (analytical grade), sodium silicate (analytical grade), and deionized water. The mass concentration of sodium hydroxide in the alkaline cleaning solution is 10%, the mass concentration of sodium carbonate is 5%, and the mass concentration of sodium silicate is 3%. The cleaning tank of the ultrasonic cleaner is made of 50L 304 stainless steel. S103. After cleaning, immediately rinse with flowing deionized water with a resistivity ≥15MΩ・cm for 30 seconds to remove residual alkaline cleaning solution from the surface.

[0027] S2, tungsten wire electroplated copper: S201. The electroplating tank is made of 100L PVC material and has a built-in titanium alloy cathode bracket and anode support. The anode is a copper plate with a purity of 99.95%. The copper plate has a size of 100mm×50mm×5mm and a total of 4 pieces, which are symmetrically distributed on both sides of the electroplating tank.

[0028] S202. The process for preparing the electroplating solution is as follows: Add 100L of deionized water to a 200L stirring tank, then add 20kg of copper sulfate (analytical grade), 6kg of sulfuric acid (analytical grade), and 50g of polyethylene glycol (molecular weight 8000) sequentially. Stir at 300r / min for 1 hour until completely dissolved, and check the pH value to be 1.2±0.1. (That is, the concentration of copper sulfate in the electroplating solution is 200g / L, the concentration of sulfuric acid is 60g / L, and the concentration of polyethylene glycol is 0.5g / L.) S203. The tungsten wire pretreated in S1 is evenly wound around the cathode hanger, ensuring that the distance between the tungsten wire and the anode is 60mm±5mm. The wire is then immersed in the electroplating solution, with the liquid level 5cm above the electrode. S204. Turn on the DC regulated power supply and set the current density to 2A / dm. 2 (Fluctuation ≤ ±0.1A / dm) 2 The temperature of the electroplating solution is controlled at 25℃±0.5℃ by a constant temperature circulation device; the paddle stirrer is started at a speed of 300r / min to keep the solution uniform; the fluctuation range of copper sulfate concentration in the electroplating solution during the electroplating process is ±3g / L, and the fluctuation range of sulfuric acid concentration is ±2g / L. S205, after 7 minutes of electroplating, the power is turned off to complete the electroplating and obtain electroplated copper-tungsten wire.

[0029] S3. Post-treatment of electroplated copper-tungsten wire: S301. Suspend the electroplated copper-tungsten wire on the rinsing rack and rinse with deionized water with a resistivity of 18 MΩ·cm at a flow rate of 0.8 L / min. Turn the wire over once every 1 minute and continue rinsing for 5 minutes.

[0030] S302. After rinsing, place in a hot air circulating oven, set the temperature to 80℃, the drying time to 15 min, and the air velocity inside the oven to 0.5 m / s. Collect after cooling to room temperature.

[0031] S4, Cold drawing of electroplated copper-tungsten wire: S401 uses a WLD-5 type horizontal cold drawing machine (drawing speed accuracy ±0.1m / min) and is equipped with a drawing die made of polycrystalline diamond material with an inner diameter of 0.15mm and a surface roughness Ra of 0.03μm.

[0032] S402. Pass one end of the electroplated copper-tungsten wire through the drawing die and fix it to the traction mechanism. Set the drawing speed to 5m / min and perform multiple cold drawing and annealing treatments. Specifically, after each 3 drawing passes, place the electroplated copper-tungsten wire in a tube annealing furnace, introduce argon gas with a volume concentration of 99.99% at a flow rate of 1L / min, heat it to 800℃ at a rate of 10℃ / min, hold it at that temperature for 11 min, and then continue cold drawing after cooling it to below 50℃ in the furnace.

[0033] After each round of annealing is completed and the electroplated copper-tungsten wire cools to below 50°C, its performance is tested to ensure that the coating does not peel off after a 180° bending test (bending radius 0.5mm), and there is no wire breakage within two consecutive "3-pass drawing + annealing" cycles, and that the mechanical properties (tensile strength, ductility) are no longer optimized; at the same time, when the tungsten wire diameter meets the usage requirements, such as reaching 30μm, cold drawing is stopped.

[0034] Figure 2 This is a photograph of the tungsten wire in S101 in this embodiment. Figure 3 This is a photograph of the electroplated copper-tungsten wire obtained in S205 of this embodiment. Figure 2 and Figure 3 The comparison shows that the tungsten wire surface has a purplish-red luster after being electroplated with copper.

[0035] Figure 4 The image shows an SEM image of the tungsten wire selected in S101 of this embodiment. As can be seen from the image, the diameter of the tungsten wire is 63 μm, and there are some fine particles or spot-like structures on the surface of the tungsten wire. The overall surface is not completely smooth and flat. Figure 5The image shows an SEM image of the electroplated copper-tungsten wire prepared in S205 of this embodiment. As can be seen from the image, the diameter of the electroplated copper-tungsten wire is 65.4 μm and the average thickness of the electroplated copper layer is 1.2 μm. After electroplating copper on the surface of the tungsten wire, the surface becomes uniform and smooth, which is beneficial to reduce the wear of the polycrystalline diamond mold during subsequent cold drawing.

[0036] Testing revealed that only one of the 100 electroplated copper-tungsten wires in S402 broke during the cold drawing process, resulting in a breakage rate of 1.0%.

[0037] Example 2 The method for preparing electroplated copper-tungsten wire and the method for cold-drawing electroplated copper-tungsten wire in this embodiment are the same as those in Example 1, except that: In S102, power fluctuations during the cleaning process are controlled within ±25W; The electroplating solution described in S202 contains 198 g / L copper sulfate, 58 g / L sulfuric acid, 0.4 g / L polyethylene glycol, and the balance is deionized water.

[0038] The drawing speed in S402 is 5.8 m / min.

[0039] Comparative Example 1 This comparative example discloses a traditional hot-drawing process for graphite emulsion tungsten wire, specifically: S1. Select 100 tungsten wires of the same batch as in Example 1, with a diameter of 0.08 mm, a length of 20 m, and no scratches or oxide spots on the surface. Wipe them with 95% industrial alcohol and let them air dry. Dilute WS-3 type graphite emulsion with water at a mass ratio of 1:5 and stir at 500 r / min for 30 minutes to prepare a graphite emulsion with a viscosity of 25 mPa·s. Then, dip the dried tungsten wires into the graphite emulsion for 5 seconds, scrape off the excess coating with a 0.22 mm nylon mold, and dry at 120°C for 10 minutes to obtain graphite-coated tungsten wires. S2. Hot drawing process: Use RHL-6 hot drawing machine, cemented carbide die (inner hole 0.15mm, Ra0.1μm), die temperature 300℃, drawing speed 5m / min; after every 2 drawing passes, heat to 850℃ in air at a heating rate of 15℃ / min, and anneal for 10 minutes.

[0040] Testing revealed that the thickness of the graphite coating on the tungsten wire surface was 1-3 μm and not uniform. In the bending test of the graphite-coated tungsten wire, 30% of the graphite coating peeled off. Of 100 graphite-coated tungsten wires subjected to hot drawing, 9 broke, resulting in a breakage rate of 9%.

[0041] Example 3 The method for preparing electroplated copper-tungsten wire and the method for cold-drawing electroplated copper-tungsten wire in this embodiment are the same as those in Example 1, except that: The alkaline cleaning solution described in S102 has a sodium hydroxide mass concentration of 8%, a sodium carbonate mass concentration of 4%, and a sodium silicate mass concentration of 2%. The ultrasonic cleaning described in S402 has a frequency of 35kHz, a power of 400W, and a time of 6min. The electroplating solution described in S202 contains 180 g / L copper sulfate, 55 g / L sulfuric acid, and 0.3 g / L polyethylene glycol, with the balance being deionized water. The current density is controlled at 2.2 A / dm³ during the electroplating process. 2 The temperature was maintained at 30℃, the electroplating time was 8 minutes, and the electroplating solution was stirred at a speed of 280 r / min. The drawing speed in S402 is 5.8 m / min.

[0042] The flow rate of deionized water rinsing in S301 is 0.4 L / min; The low-temperature drying described in S302 is at a temperature of 70°C for 20 minutes.

[0043] In S402, the drawing speed during cold drawing is 4 m / min, the annealing temperature between drawing passes is 750℃, and the annealing time is 12 min. Testing revealed that the average thickness of the electroplated copper layer on the surface of the copper-tungsten wire prepared in S205 was 0.75 μm, with a thickness deviation of ±0.3 μm. In S402, 3 out of 100 electroplated copper-tungsten wires broke during cold drawing, resulting in a breakage rate of 3.0%. The 180° bending test (radius 0.5 mm) after cold drawing showed no plating peeling off.

[0044] Example 4 The method for preparing electroplated copper-tungsten wire and the method for cold-drawing electroplated copper-tungsten wire in this embodiment are the same as those in Example 1, except that: The electroplating solution described in S202 contains 180 g / L copper sulfate, 55 g / L sulfuric acid, and 0.3 g / L polyethylene glycol, with the balance being deionized water. The current density is controlled at 1.6 A / dm³ during the electroplating process. 2 The temperature was maintained at 20℃, the electroplating time was 6 minutes, and the electroplating solution was stirred at a speed of 250 r / min. The flow rate of deionized water rinsing in S301 is 0.6 L / min; The low-temperature drying described in S302 is at a temperature of 75°C for 18 minutes.

[0045] In S402, the drawing speed during cold drawing is 6 m / min, the annealing temperature between drawing passes is 780℃, and the annealing time is 8 min. Testing revealed that the average thickness of the electroplated copper layer on the surface of the copper-tungsten wire prepared in S205 was 1.25 μm, with a thickness deviation of ±0.3 μm. In S402, 2 out of 100 electroplated copper-tungsten wires broke during cold drawing, resulting in a breakage rate of 2.0%. A 180° bending test (radius 0.5 mm) after cold drawing showed no plating peeling.

[0046] Table 1. Comparison of Production Performance between Examples 1-4 and Comparative Examples Figure 1 This is a bar graph comparing the wire breakage rate of fine-diameter tungsten wires prepared by conventional graphite emulsion hot drawing in Examples 1 and 2 of the present invention and Comparative Example 1. Compared with the conventional graphite emulsion coating and lubrication process in Comparative Example 1, the methods in Examples 1-4 of the present invention have significant improvements in production efficiency, product qualification rate, wire breakage rate control, and surface quality, making them very suitable for industrial mass production.

[0047] The copper plating on the surface of the tungsten wire in this invention directly ensures that the copper plating does not fail during cold drawing and annealing (750-800℃), thus ensuring the stability of the cold drawing process. Simultaneously, it provides performance support for the cold-drawn tungsten wire in subsequent applications in high-temperature environments such as electric light sources and high-temperature heating elements, ultimately achieving the effect of "extended service life." Both aspects together demonstrate the technical value of the high-temperature stability of the copper plating on the tungsten wire. Furthermore, the copper plating on the tungsten wire in this invention reduces the friction and adhesion between the tungsten wire and the drawing die during cold drawing. Under the same cold drawing process parameters, compared to the traditional graphite emulsion hot drawing process, it can significantly reduce the wire breakage rate, decreasing it by more than 50% compared to the traditional process. In practical production applications, the electroplated copper-tungsten wire prepared by this invention is used for cold drawing, supplemented by a matching cold drawing process (the drawing speed during cold drawing is 4-6 m / min, the annealing temperature between drawing passes is 750-800℃, the annealing time is 8-12 min, and a drawing die made of polycrystalline diamond material is used, with the surface roughness Ra of the inner hole of the die being ≤0.03μm), which can increase the production efficiency of tungsten wire cold drawing by more than 20% and the product qualification rate to more than 97%.

[0048] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A method for preparing electroplated copper-tungsten wire for cold drawing process, characterized in that, The method includes the following steps: S1. The tungsten wire is placed in an alkaline cleaning solution for ultrasonic cleaning, and then rinsed to remove the alkaline cleaning solution after cleaning; the alkaline cleaning solution is prepared from sodium hydroxide, sodium carbonate, sodium silicate, and deionized water; the diameter of the tungsten wire is less than 0.1 mm; S2. Using a copper plate with a purity of not less than 99.95% as the anode and the tungsten wire cleaned in S1 as the cathode, electroplating is performed in the electroplating solution. During the electroplating process, the current density is controlled at 1.6-2.2 A / dm³. 2 The temperature is maintained at 20-30℃, the electroplating time is 6-8 min, and the electroplating solution is stirred at a speed of 250-300 r / min. After the electroplating is completed, an electroplated copper layer with an average thickness of 0.75-1.25 μm is formed on the surface of the tungsten wire. Then, it is rinsed clean in flowing deionized water with a resistivity of not less than 15 MΩ・cm, and dried at low temperature to obtain electroplated copper tungsten wire. The electroplating solution is prepared from copper sulfate, sulfuric acid, polyethylene glycol and deionized water, wherein the concentration of copper sulfate is 180-200 g / L, the concentration of sulfuric acid is 55-60 g / L, and the concentration of polyethylene glycol is 0.3-0.5 g / L.

2. The method according to claim 1, characterized in that, The ultrasonic cleaning described in S1 has a frequency of 25-35kHz, a power of 400-500W, and a duration of 6-8 minutes.

3. The method according to claim 2, characterized in that, The power fluctuation range of the ultrasonic cleaning process shall not exceed ±30W.

4. The method according to claim 1, characterized in that, The alkaline cleaning solution contains 8-10% sodium hydroxide, 4-5% sodium carbonate, and 2-3% sodium silicate by mass.

5. The method according to claim 1, characterized in that, In the electroplating process described in S2, the fluctuation range of copper sulfate concentration in the electroplating solution is ±3g / L, and the fluctuation range of sulfuric acid concentration is ±2g / L.

6. The method according to claim 1, characterized in that, The flow rate of the deionized water used for rinsing in S2 is 0.4-0.8 L / min, and the rinsing time is 4-5 min.

7. The method according to claim 1, characterized in that, The low-temperature drying described in S2 is at a temperature of 70-80℃ and a time of 15-20 minutes.

8. An application of electroplated copper-tungsten wire in a cold drawing process, characterized in that, The electroplated copper-tungsten wire prepared according to claims 1-7 is subjected to multiple cold drawing and annealing processes; the drawing speed during the cold drawing process is 4-6 m / min, the annealing temperature between drawing passes is 750-800℃, the annealing time is 8-12 min, and a drawing die made of polycrystalline diamond is used, with the surface roughness Ra of the inner hole of the drawing die being ≤0.03μm.

9. The method according to claim 8, characterized in that, The annealing process is carried out in an inert gas protective atmosphere with a purity of not less than 99.99%.

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