A copper-plated composite molybdenum alloy wire and a method for manufacturing the same

Abstract

The application provides a copper-plated composite molybdenum alloy wire and a preparation method thereof, and belongs to the technical field of molybdenum alloy materials, and comprises the following steps: firstly, molybdenum powder, La(OH)3 powder, titanium dihydride powder and zirconium hydride powder are mixed, and a molybdenum alloy inner core is prepared through cold pressing, sintering, rolling, annealing, swaging and drawing; and the molybdenum alloy inner core is subjected to electrolytic polishing, alkali washing, rinsing and drying to obtain a pretreated molybdenum alloy inner core; then, the pretreated molybdenum alloy inner core is activated, and is sequentially subjected to continuous electroplating in a Ni composite plating solution, a Cu composite plating solution and a Zn-Co alloy plating solution to form a Ni composite primer layer, a Cu composite plating layer and a Zn-Co alloy layer; and the copper-plated composite molybdenum alloy wire is obtained through short-time thermal diffusion under inert atmosphere protection, phosphoric acid cleaning and drying. The application can improve the tensile strength, the electrical conductivity and the stability of electrical discharge machining.

Description

Technical Field

[0001] This invention relates to the field of molybdenum alloy materials technology, specifically to a copper-plated composite molybdenum alloy wire and its preparation method. Background Technology

[0002] Molybdenum alloys possess characteristics such as high density, high melting point, low vapor pressure, low coefficient of thermal expansion, and good high-temperature strength, making them valuable for applications in high-temperature heating elements, radiation shielding components, high-temperature molds, integrated circuit connectors, and coating materials. As an important form of molybdenum products, molybdenum alloy wire can be used in wire EDM wire, heating elements, and automotive parts coating, and is particularly suitable for fast-wire and medium-wire EDM machines.

[0003] Electrical discharge wire cutting (EDM) is a common special machining method that utilizes pulsed discharge between the electrode wire and the workpiece to generate instantaneous high temperatures, causing the surface material of the workpiece to melt, vaporize, and be gradually removed, thus achieving the cutting of the target material. In actual processing, long-term stable cutting is crucial for ensuring processing quality and improving production efficiency. Besides process factors such as electrical parameters and wire feed speed, the mechanical properties of the molybdenum wire itself, especially its tensile strength, significantly affect the stability, breakage risk, and service life during the cutting process. To improve the strength of molybdenum wire, existing technologies have proposed alloying to enhance its mechanical properties. For example, patent application CN115505809A discloses a high-strength, durable molybdenum wire for wire cutting and its manufacturing process. Its chemical composition, by weight percentage, is Cr 0.13~0.25%, Ni 0.08~0.14%, ZrO2 0.15~0.26%, Mn 0.06~0.15%, with the balance being Mo and unavoidable impurities. The final tensile strength of the molybdenum wire is only 546~603MPa; in addition, this type of technical solution mainly focuses on optimizing the composition and microstructure of the molybdenum alloy matrix, and the improvement of the material surface's resistance to melting and corrosion under pulse discharge, transient thermal shock and processing fluid erosion conditions is still relatively limited.

[0004] On the other hand, while molybdenum wire possesses good high-temperature and mechanical properties, its electrical conductivity is relatively limited, restricting its application in high-precision, high-efficiency machining. Its performance in wire electrical discharge machining (EDM) is not particularly ideal. To improve conductivity, existing technologies combine molybdenum with copper, aiming to enhance conductivity while maintaining the mechanical properties of molybdenum-based materials. However, due to significant differences in physicochemical properties between molybdenum and copper, integral alloying or composite preparation can easily lead to problems such as uneven microstructure distribution, insufficient interfacial compatibility, and performance fluctuations. In contrast, copper-plated molybdenum wire can effectively improve surface conductivity while maintaining the strength and heat resistance of the molybdenum alloy matrix, and offers advantages such as flexible processing and relatively low cost.

[0005] Therefore, there is a need to provide a copper-plated composite molybdenum alloy wire and its preparation method to solve the above-mentioned technical problems. Summary of the Invention

[0006] In view of this, the present invention provides a copper-plated composite molybdenum alloy wire and its preparation method, which can improve tensile strength while improving electrical conductivity and electrical discharge processing stability.

[0007] To achieve the above objectives, the present invention provides a copper-plated composite molybdenum alloy wire and its preparation method, comprising the following steps:

[0008] S1. Molybdenum powder, La(OH)3 powder, titanium dihydrogen hydride powder and zirconium hydride powder are mixed and then cold-pressed, sintered, rolled, annealed, forged and drawn to obtain a molybdenum alloy core. The core is then electrolytically polished, alkali washed, rinsed and dried to obtain a pretreated molybdenum alloy core.

[0009] S2. After mixing glucose and ethanol aqueous solution, nickel powder is added for dispersion, heated and stirred, dried, and then pyrolyzed under a mixed atmosphere of Ar and H2 to obtain Ni@graphitized carbon composite powder. Nickel salt, boric acid, additives and deionized water are added and mixed, pH is adjusted, ultrasonic treatment and mechanical stirring are performed to obtain Ni composite plating solution.

[0010] S3. After activating the pretreated molybdenum alloy core, it is continuously electroplated in Ni composite plating solution, Cu composite plating solution and Zn-Co alloy plating solution to form Ni composite underlayer, Cu composite plating layer and Zn-Co alloy layer. After short-term thermal diffusion under inert atmosphere protection, phosphoric acid cleaning and drying, copper-plated composite molybdenum alloy wire is obtained.

[0011] This invention first employs La(OH)3, titanium dihydrogen hydride, and zirconium hydride to composite-dope molybdenum powder. The resulting molybdenum alloy core matrix is ​​obtained through cold pressing, high-temperature sintering, rolling, rotary forging, and drawing. The use of La(OH)3 powder instead of directly adding conventional rare earth oxide powder during the molybdenum substrate preparation stage improves the dispersion uniformity of rare earth components in the molybdenum powder system. During subsequent sintering and heating, La(OH)3 can decompose in situ and transform into a fine, dispersed lanthanum oxide reinforcing phase. This helps alleviate the particle agglomeration and local enrichment problems that easily occur when directly adding rare earth oxides, resulting in a more uniform distribution of the rare earth phase in the molybdenum matrix and grain boundary regions. This is more conducive to the grain boundary pinning, microstructure refinement, and high-temperature stabilization effects. Meanwhile, titanium dihydrogen hydride powder and zirconium hydride powder decompose and release Ti and Zr elements during high-temperature process. Ti is conducive to diffusion into the molybdenum matrix and produces solid solution strengthening effect, while Zr helps to improve the grain boundary state and promote microstructure stabilization. The two, together with the rare earth oxides generated in situ, can effectively improve the microstructure and grain boundary state of the molybdenum alloy core, thereby improving its tensile strength, thermal stability and softening resistance.

[0012] Furthermore, this invention first forms a graphitized carbon-containing coating structure in situ on the surface of Ni powder through glucose pyrolysis, thus obtaining Ni@graphitized carbon composite powder. This powder is then introduced into a nickel plating system to form a Ni composite underlayer. This composite underlayer retains the function of the Ni layer as a transition layer between the molybdenum alloy substrate and the outer copper-based plating layer, which is beneficial for improving the interfacial bonding strength and reducing the tendency for interfacial cracking and peeling during subsequent heat treatment and service as a cutting wire. Simultaneously, the graphitized carbon phase in the Ni@graphitized carbon composite powder is dispersed in the Ni-based deposition structure, which helps reduce the thermal resistance and electron transport impedance in the interfacial region and constructs dispersed heat transfer and conduction channels in the plating layer. This improves the thermal conduction, thermal diffusion, and electrical continuity in the interfacial region, alleviating to some extent the problems of localized heat accumulation, uneven current distribution, and excessive temperature gradients on the surface during wire cutting discharge, thereby reducing thermal stress concentration and the resulting tendency for microcrack initiation and propagation. In addition, the introduction of graphitized carbon phase is beneficial to maintaining the structural integrity of the composite underlayer, making the interface transport more uniform during the discharge process, reducing the risk of local overheating, abnormal discharge and interface failure, thereby improving the service stability of the overall coating system.

[0013] On the outer side of the Cu composite coating, this invention further introduces a Zn-Co alloy layer, which undergoes a short-term thermal diffusion treatment to create a gradient transition zone with a more gradual compositional distribution on the surface. This outer layer structure is beneficial for improving the surface stability of the wire in the processing fluid environment and reducing the tendency for localized corrosion. After short-term thermal diffusion, Zn and Co elements undergo a certain degree of interdiffusion towards the near-surface of the copper layer, which helps to reduce interlayer property differences and interfacial stress concentration, while improving the surface stability and ablation resistance during the discharge process.

[0014] Optionally, in step S1, molybdenum powder, La(OH)3 powder, titanium dihydrogen hydride powder, and zirconium hydride powder are added to a fly knife mixer and mixed for 3-4 hours at a fly knife speed of 1200 r / min and a stirring blade speed of 150 r / min. Then, the mixture is transferred to a dual-motion mixer and mixed for 4-6 hours. After cold pressing at 200 MPa for 3-5 minutes, it is sintered at 1950-2050℃ for 5-6 hours, held at 1250-1350℃ for 50-60 minutes, and then rolled into a 7-9 mm wire rod. The material is annealed online at 1500~1550℃, then forged into a 4mm rod at 1100~1300℃, then drawn to 1.0~1.2mm on a turntable, vacuum annealed at 1000~1050℃ for 2~3h, and then hot-drawn into a 0.08~0.2mm molybdenum alloy core at 650~900℃ using multiple dies. The core is then electropolished in a 10wt% potassium hydroxide electrolyte, cleaned with a low-foaming water-based alkaline degreasing agent for 3~5min, rinsed with deionized water and dried to obtain the pretreated molybdenum alloy core.

[0015] This invention combines a fly-knife mixing and a dual-motion mixing method to achieve a synergistic dispersion of the alloy powder, enabling the dopant components to be more uniformly distributed within the molybdenum powder system. Following cold pressing, high-temperature sintering, rolling, rotary forging, and drawing, a molybdenum alloy core matrix with a relatively uniform microstructure and high density is obtained. Simultaneously, KOH electrolytic polishing and degreasing treatment with a low-foaming water-based alkaline degreaser effectively remove oxides, residual lubricants, and adhering impurities from the wire surface, resulting in a cleaner and more activated substrate surface. This facilitates the uniform deposition and stable interfacial bonding of subsequent composite coatings.

[0016] Optionally, the Ni@graphitized carbon composite powder is obtained by mixing and stirring 0.2-0.5 parts by weight of glucose and 100-150 parts by weight of 75 vol% ethanol aqueous solution for 20-30 min, adding 10-15 parts by weight of nickel powder, ultrasonically dispersing for 30-50 min, stirring at 400 r / min at 70-80℃ for 2-2.5 h, drying in an oven at 70-80℃ for 2-3 h, placing it in a tube furnace, heating to 650-700℃ in a mixed atmosphere of Ar / H2 volume ratio of 9:1, holding at that temperature for 30-40 min, cooling, grinding, and passing through a 200-mesh sieve.

[0017] Optionally, the Ni composite plating solution is prepared by mixing and stirring nickel salt, 30-40 parts by weight of boric acid, 1-2 parts by weight of Ni@graphitized carbon composite powder, additives, and 800-1000 parts by weight of deionized water for 10-20 minutes, adjusting the pH to 3.8-4.0 with 10wt% dilute sulfuric acid, ultrasonically treating at 40-50°C for 10-20 minutes, and mechanically stirring at 350 r / min for 20-30 minutes.

[0018] Optionally, the nickel salt is 300-350 parts by weight of nickel aminosulfonate and 10-15 parts by weight of nickel chloride hexahydrate; the auxiliary agent is 0.3-0.5 parts by weight of polyvinylpyrrolidone, 0.1-0.2 parts by weight of PEG-4000 and 0.1-0.2 parts by weight of wetting agent; the wetting agent is one of sodium dodecyl sulfate and sodium dodecylbenzenesulfonate.

[0019] This invention uses nickel aminosulfonate and nickel chloride hexahydrate to construct a nickel salt system, which can provide a stable source of nickel ions for the electrodeposition process and improve the conductivity of the plating solution. Combined with boric acid to buffer the pH of the plating solution, PVP, PEG-4000 and wetting agents synergistically improve the dispersion stability of Ni@graphitized carbon composite powder, which is beneficial to improving the continuity of the underlayer and the interfacial bonding force.

[0020] Optionally, in step S3, the pretreated molybdenum alloy core is first activated in 5wt% hydrochloric acid for 10-15s, rinsed with deionized water, and then continuously electroplated in a Ni composite plating solution to form a Ni composite underlayer. After rinsing with deionized water, it is then continuously electroplated in a Cu composite plating solution to form a Cu composite coating. After rinsing with deionized water, it is further continuously electroplated in a Zn-Co alloy plating solution to form a Zn-Co alloy layer. After rinsing with deionized water, it is placed in a N2 protective atmosphere and kept at 340-360℃ for 5-10s. Then, it is cleaned with 28wt% phosphoric acid solution for 10-15s, rinsed with deionized water, and dried with hot air at 80-90℃ for 15-30min to obtain copper-plated composite molybdenum alloy wire.

[0021] The present invention uses rapid cleaning with phosphoric acid after short-time thermal diffusion treatment to remove residual components on the surface, avoiding loose oxides, unstable reaction products and residual salts from remaining on the surface and affecting the integrity of the coating.

[0022] Optionally, the Cu composite plating solution is prepared by adding 210-240 parts by weight of copper sulfate pentahydrate, 50-65 parts by weight of 98 wt% sulfuric acid, 0.05-0.1 parts by weight of 37 wt% hydrochloric acid, 4-8 parts by weight of high-entropy alloy precursor composite powder, 0.4-0.6 parts by weight of polyvinylpyrrolidone, and 0.05-0.1 parts by weight of hexadecyltrimethylammonium bromide to 800-1000 parts by weight of deionized water, mechanically stirring for 20-30 minutes, and then ultrasonically dispersing for 20-30 minutes.

[0023] This invention uses a copper sulfate system to construct a Cu composite plating solution, which can provide a stable source of copper ions. The high-entropy alloy precursor composite powder works synergistically with polyvinylpyrrolidone and hexadecyltrimethylammonium bromide, which is conducive to the uniform dispersion of composite particles and co-deposition with copper substrate, thereby obtaining a Cu composite coating with better conductivity and denser structure, further improving the conductivity and stability of the wire surface.

[0024] Optionally, the high-entropy alloy precursor composite powder is obtained by ball milling 30-35 parts by weight of tungsten powder, 26-30 parts by weight of tantalum powder, 13-15 parts by weight of molybdenum powder, 13-15 parts by weight of niobium powder, 5-10 parts by weight of vanadium powder, 2-5 parts by weight of titanium powder and 0.8-1.2 parts by weight of stearic acid for 30-36 hours, then heating to 850-900℃ at 10℃ / min under Ar atmosphere and holding for 1-1.5 hours, cooling, dispersing with anhydrous ethanol, allowing to stand and separate into layers, collecting the upper fine powder, and vacuum drying at 60-70℃ for 8-10 hours.

[0025] This invention further constructs a Cu composite coating on top of a Ni composite underlayer, wherein the high-entropy alloy particles are refractory high-entropy alloy micro / nano particles composed of W, Ta, Mo, Nb, V, and Ti. This composite coating, while ensuring the existence of a continuous conductive phase in copper, uniformly introduces high-entropy alloy particles with high melting point, high hardness, and high thermal stability into the copper matrix, thereby improving the structural stability of the Cu composite coating. During wire cutting, traditional copper layers are prone to melting, softening, and spattering under localized high temperatures. The introduction of high-entropy alloy particles helps improve the coating's resistance to thermal shock and localized erosion, thus mitigating surface pitting and rapid surface wear to some extent. Simultaneously, the high-entropy alloy particles, as a hard, dispersed reinforcing phase, also improve the coating's wear resistance, further enhancing the stability of the cutting process and extending its service life.

[0026] Optionally, the Zn-Co alloy plating solution is prepared by adding 80-120 parts by weight of zinc sulfate heptahydrate, 13-16 parts by weight of cobalt sulfate heptahydrate, 35-40 parts by weight of sodium citrate, 20-30 parts by weight of boric acid, 35-45 parts by weight of sodium sulfate, and 0.8-1.5 parts by weight of sodium saccharin to 800-1000 parts by weight of deionized water, mixing and stirring for 20-30 minutes, and then adjusting the pH to 4-4.5 with 10wt% dilute sulfuric acid.

[0027] The present invention also provides a copper-plated composite molybdenum alloy wire, comprising a pretreated molybdenum alloy core, and a Ni composite underlayer, a Cu composite plating layer, and a Zn-Co alloy layer sequentially disposed on the surface of the pretreated molybdenum alloy core; wherein the thickness of the Ni composite underlayer is 0.10~0.12μm, the thickness of the Cu composite plating layer is 0.4~0.7μm, and the thickness of the Zn-Co alloy layer is 0.2~0.4μm; the pretreated molybdenum alloy core comprises the following raw materials in parts by weight: 1900~2000 parts of molybdenum powder, 20~30 parts of La(OH)3 powder, 2~4 parts of titanium dihydrogen phosphate powder, and 3~4 parts of zirconium hydride powder.

[0028] This invention achieves a balance between interfacial bonding, conductive transport, and surface stability protection by sequentially constructing a Ni composite underlayer, a Cu composite coating, and a Zn-Co alloy layer on the surface of a molybdenum alloy core. Furthermore, by combining a molybdenum alloy core doped with La(OH)3, titanium dihydrogen hydride, and zirconium hydride, the tensile strength and stability of the wire can be further improved.

[0029] The above-described technical solution of the present invention has at least the following beneficial effects:

[0030] 1. This invention uses La(OH)3, titanium dihydrogenase and zirconium hydride to composite dope molybdenum powder, so that the rare earth strengthening phase and Ti and Zr elements are more evenly distributed in the molybdenum matrix. This is beneficial to refine the grains, stabilize the grain boundaries and enhance the strengthening effect of the matrix, thereby improving the tensile strength, thermal stability and softening resistance of the molybdenum alloy core, and providing a stable bearing foundation for subsequent composite coating.

[0031] 2. The present invention uses Ni composite underlayer as a transition layer between the molybdenum alloy inner core and the outer copper base plating layer. This not only improves the interfacial bonding strength, but also improves the heat conduction and current distribution uniformity in the interfacial area by utilizing the thermal and electrical conductivity of graphitized carbon. This reduces local heat accumulation, thermal stress concentration and interfacial cracking and peeling tendency, thereby improving service stability.

[0032] 3. The present invention sets a Zn-Co alloy layer on the outside of the Cu composite coating and forms a gradient transition zone by combining short-time thermal diffusion treatment, which helps to slow down the sudden change in surface composition, reduce the stress concentration at the interface, and improve the corrosion resistance, surface stability and ablation resistance of the wire in the processing fluid environment. This helps to improve the long-term processing stability of the overall coating system and extend its service life. Attached Figure Description

[0033] Figure 1 A scanning electron microscope image of the cut surface of tungsten material obtained using the copper-plated molybdenum composite alloy wire prepared in Example 1 of the present invention;

[0034] Figure 2 This is a scanning electron microscope image of the surface of the copper-plated composite molybdenum alloy wire prepared in Example 1 of the present invention after continuous use. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0036] Example 1

[0037] 1975g of molybdenum powder (Fairwood particle size 4.2μm), 25g of La(OH)3 powder (average particle size 2μm), 3g of titanium dihydrogen hydride powder (average particle size 5μm), and 3.5g of zirconium hydride powder (average particle size 5μm) were added to a fly knife mixer and mixed for 3.6h at a fly knife speed of 1200r / min and a stirring blade speed of 150r / min. The mixture was then transferred to a double-motion mixer and mixed for 5.2h. After cold pressing at 200MPa for 4.2min, sintering at 2000℃ for 5.5h, and holding at 1300℃ for 55min, the mixture was rolled to... 8mm wire rod was annealed online at 1530℃, then forged into 4mm rod at 1250℃, drawn to 1.10mm on a turntable, vacuum annealed at 1030℃ for 2.5h, and then hot-drawn into 0.14mm molybdenum alloy core at 780℃ using multiple dies. The core was then electropolished in 10wt% potassium hydroxide electrolyte, cleaned with a low-foaming water-based alkaline degreaser (purchased from Shanghai Qianhong Chemical Technology Co., Ltd.) for 4.5min, rinsed with deionized water and dried to obtain the pretreated molybdenum alloy core.

[0038] 0.35g glucose and 125g 75vol% ethanol aqueous solution were mixed and stirred for 25min. Then, 13g nickel powder (average particle size of 800nm) was added and ultrasonically dispersed for 42min. After stirring at 400r / min for 2.3h at 76℃, the mixture was dried in an oven at 76℃ for 2.5h to obtain Ni-glucose composite powder. The Ni-glucose composite powder was placed in a tube furnace and heated to 680℃ in a mixed atmosphere of Ar / H2 volume ratio of 9:1. The temperature was held for 35min, cooled, ground, and passed through a 200-mesh sieve to obtain Ni@graphitized carbon composite powder.

[0039] The following ingredients were added: 330g nickel aminosulfonate, 13g nickel chloride hexahydrate, 36g boric acid, 1.5g Ni@graphitized carbon composite powder, 0.42g polyvinylpyrrolidone, and 0.15g... PEG-4000, 0.15g sodium dodecyl sulfate, and 920g deionized water were mixed and stirred for 15 min. The pH was adjusted to 3.9 with 10wt% dilute sulfuric acid, ultrasonicated at 46℃ for 15 min, and mechanically stirred at 350 r / min for 25 min to obtain a Ni composite plating solution. 33g tungsten powder, 28g tantalum powder, 14g molybdenum powder, 14g niobium powder, 8g vanadium powder, 3.5g titanium powder, and 1.0g stearic acid were mixed and ball-milled for 34 h. The mixture was then heated to 880℃ at 10℃ / min and held at that temperature for 1.25 h under an Ar atmosphere. After cooling, it was dispersed with anhydrous ethanol, allowed to stand and separate into layers, and the upper fine powder was collected and vacuum dried at 66℃ for 9.2 h to obtain a high-entropy alloy precursor composite powder. 228g copper sulfate pentahydrate, 58g 98wt% sulfuric acid, and 0.08g... 37wt% hydrochloric acid, 6.5g high-entropy alloy precursor composite powder, 0.52g polyvinylpyrrolidone, and 0.08g hexadecyltrimethylammonium bromide were added to 920g deionized water and mechanically stirred for 25min, followed by ultrasonic dispersion for 25min to obtain a Cu composite plating solution. 100g zinc sulfate heptahydrate, 14.5g cobalt sulfate heptahydrate, 37g sodium citrate, 25g boric acid, 40g sodium sulfate, and 1.15g sodium saccharin were added to 920g deionized water, mixed and stirred for 25min, and then the pH was adjusted to 4.25 with 10wt% dilute sulfuric acid to obtain a Zn-Co alloy plating solution.

[0040] The pretreated molybdenum alloy core was first activated in 5wt% hydrochloric acid for 13s, rinsed with deionized water, and then continuously electroplated in a Ni composite plating solution until the Ni composite underlayer thickness reached 0.11μm. It was then rinsed with deionized water, followed by continuous electroplating in a Cu composite plating solution until the Cu composite coating thickness reached 0.55μm. It was then rinsed with deionized water, and further continuously electroplated in a Zn-Co alloy plating solution until the Zn-Co alloy layer thickness reached 0.30μm. After rinsing with deionized water, it was placed in a N2 protective atmosphere and held at 352℃ for 7s. It was then cleaned with a 28wt% phosphoric acid solution for 13s, rinsed with deionized water, and finally dried with hot air at 86℃ for 22min to obtain the copper-plated molybdenum composite alloy wire. Throughout the continuous electroplating process, the plating solution was continuously circulated and stirred to maintain the composite powder in a suspended and dispersed state.

[0041] Example 2

[0042] 1920g of molybdenum powder (Fairwood particle size 3.7μm), 22g of La(OH)3 powder (average particle size 2μm), 2.4g of titanium dihydrogen hydride powder (average particle size 5μm), and 3.2g of zirconium hydride powder (average particle size 5μm) were added to a fly knife mixer and mixed for 3.2h at a fly knife speed of 1200r / min and a stirring blade speed of 150r / min. The mixture was then transferred to a double-motion mixer and mixed for 4.5h. After cold pressing at 200MPa for 3.5min, it was sintered at 1970℃ for 5.2h, held at 1270℃ for 52min, and then rolled. The wire rod was annealed online at 1510℃ to a thickness of 7.5mm, then forged into a 4mm rod at 1150℃, and then drawn to 1.05mm on a turntable. After vacuum annealing at 1010℃ for 2.2h, it was hot-drawn into a 0.10mm molybdenum alloy core at 700℃ using multiple dies. The core was then electropolished in a 10wt% potassium hydroxide electrolyte, cleaned for 4min with a low-foaming water-based alkaline degreaser (purchased from Shanghai Qianhong Chemical Technology Co., Ltd.), rinsed with deionized water, and dried to obtain the pretreated molybdenum alloy core.

[0043] 0.25 g of glucose and 110 g of 75 vol% ethanol aqueous solution were mixed and stirred for 22 min. Then, 11 g of nickel powder (average particle size of 800 nm) was added and ultrasonically dispersed for 35 min. After stirring at 400 r / min for 2.1 h at 72 °C, the mixture was dried in an oven at 72 °C for 2.2 h to obtain Ni-glucose composite powder. The Ni-glucose composite powder was placed in a tube furnace and heated to 660 °C in a mixed atmosphere of Ar / H2 volume ratio of 9:1. The temperature was held for 32 min, cooled, ground, and passed through a 200 mesh sieve to obtain Ni@graphitized carbon composite powder.

[0044] The following ingredients were added: 310g nickel aminosulfonate, 11g nickel chloride hexahydrate, 32g boric acid, 1.2g Ni@graphitized carbon composite powder, 0.35g polyvinylpyrrolidone, and 0.12g... PEG-4000, 0.12g sodium dodecyl sulfate, and 850g deionized water were mixed and stirred for 12 min. The pH was adjusted to 3.85 with 10wt% dilute sulfuric acid. The mixture was ultrasonically treated at 42℃ for 12 min and mechanically stirred at 350 r / min for 22 min to obtain a Ni composite plating solution. 31g tungsten powder, 27g tantalum powder, 13.5g molybdenum powder, 13.5g niobium powder, 6g vanadium powder, 2.5g titanium powder, and 0.9g stearic acid were mixed and ball-milled for 31 h. The mixture was then heated to 860℃ at 10℃ / min and held at that temperature for 1.1 h under an Ar atmosphere. After cooling, it was dispersed with anhydrous ethanol, allowed to stand and separate into layers, and the upper fine powder was collected and vacuum dried at 62℃ for 8.5 h to obtain a high-entropy alloy precursor composite powder. 215g copper sulfate pentahydrate, 53g 98wt% sulfuric acid, and 0.06g... 37wt% hydrochloric acid, 5g high-entropy alloy precursor composite powder, 0.45g polyvinylpyrrolidone, and 0.06g hexadecyltrimethylammonium bromide were added to 850g deionized water and mechanically stirred for 22min, followed by ultrasonic dispersion for 22min to obtain a Cu composite plating solution. 88g zinc sulfate heptahydrate, 13.5g cobalt sulfate heptahydrate, 36g sodium citrate, 22g boric acid, 37g sodium sulfate, and 0.9g sodium saccharin were added to 850g deionized water, mixed and stirred for 22min, and then the pH was adjusted to 4.1 with 10wt% dilute sulfuric acid to obtain a Zn-Co alloy plating solution.

[0045] The pretreated molybdenum alloy core was first activated in 5wt% hydrochloric acid for 11s, rinsed with deionized water, and then continuously electroplated in a Ni composite plating solution until the Ni composite underlayer thickness reached 0.105μm. It was then rinsed with deionized water, followed by continuous electroplating in a Cu composite plating solution until the Cu composite coating thickness reached 0.45μm. It was then rinsed with deionized water, and further continuously electroplated in a Zn-Co alloy plating solution until the Zn-Co alloy layer thickness reached 0.25μm. After rinsing with deionized water, it was placed in a N2 protective atmosphere and held at 345℃ for 6s. It was then cleaned with a 28wt% phosphoric acid solution for 12s, rinsed with deionized water, and finally dried with hot air at 82℃ for 18min to obtain the copper-plated molybdenum composite alloy wire. Throughout the continuous electroplating process, the plating solution was continuously circulated and stirred to maintain the composite powder in a suspended and dispersed state.

[0046] Example 3

[0047] 1950g of molybdenum powder (Fairwood particle size 4.0μm), 23.5g of La(OH)3 powder (average particle size 2μm), 2.8g of titanium dihydrogen hydride powder (average particle size 5μm), and 3.4g of zirconium hydride powder (average particle size 5μm) were added to a fly knife mixer and mixed for 3.5h at a fly knife speed of 1200r / min and a stirring blade speed of 150r / min. The mixture was then transferred to a double-motion mixer and mixed for 5h. After cold pressing at 200MPa for 4min, it was sintered at 1990℃ for 5.4h, held at 1290℃ for 54min, and then rolled to 8mm. The wire rod was annealed online at 1525℃, then forged into a 4mm rod at 1200℃, and then drawn to 1.08mm on a turntable. After vacuum annealing at 1020℃ for 2.4h, it was hot-drawn into a 0.12mm molybdenum alloy core at 750℃ using multiple dies. The core was then electropolished in a 10wt% potassium hydroxide electrolyte, cleaned for 3.5min with a low-foaming water-based alkaline degreasing agent (purchased from Shanghai Qianhong Chemical Technology Co., Ltd.), rinsed with deionized water, and dried to obtain the pretreated molybdenum alloy core.

[0048] 0.30 g of glucose and 120 g of 75 vol% ethanol aqueous solution were mixed and stirred for 24 min. Then, 12 g of nickel powder (average particle size of 800 nm) was added and ultrasonically dispersed for 40 min. After stirring at 400 r / min for 2.2 h at 75 °C, the mixture was dried in an oven at 75 °C for 2.4 h to obtain Ni-glucose composite powder. The Ni-glucose composite powder was placed in a tube furnace and heated to 670 °C in a mixed atmosphere of Ar / H2 volume ratio of 9:1. The temperature was maintained for 34 min, cooled, ground, and passed through a 200-mesh sieve to obtain Ni@graphitized carbon composite powder.

[0049] 325g nickel aminosulfonate, 12g nickel chloride hexahydrate, 35g boric acid, 1.4g Ni@graphitized carbon composite powder, 0.40g polyvinylpyrrolidone, and 0.14g... PEG-4000, 0.14g sodium dodecylbenzenesulfonate, and 900g deionized water were mixed and stirred for 14 min. The pH was adjusted to 3.9 with 10wt% dilute sulfuric acid, ultrasonicated at 45℃ for 14 min, and mechanically stirred at 350 r / min for 24 min to obtain a Ni composite plating solution. 32g tungsten powder, 28g tantalum powder, 14g molybdenum powder, 14g niobium powder, 7g vanadium powder, 3g titanium powder, and 1.0g stearic acid were mixed and ball-milled for 33 h. The mixture was then heated to 875℃ at 10℃ / min and held at that temperature for 1.2 h under an Ar atmosphere. After cooling, it was dispersed with anhydrous ethanol, allowed to stand and separate into layers, and the upper fine powder was collected and vacuum dried at 65℃ for 9 h to obtain a high-entropy alloy precursor composite powder. 222g copper sulfate pentahydrate, 56g 98wt% sulfuric acid, and 0.07g... 37wt% hydrochloric acid, 6g high-entropy alloy precursor composite powder, 0.50g polyvinylpyrrolidone, and 0.07g hexadecyltrimethylammonium bromide were added to 900g deionized water and mechanically stirred for 24min, followed by ultrasonic dispersion for 24min to obtain a Cu composite plating solution. 96g zinc sulfate heptahydrate, 14g cobalt sulfate heptahydrate, 37g sodium citrate, 24g boric acid, 39g sodium sulfate, and 1.1g sodium saccharin were added to 900g deionized water, mixed and stirred for 24min, and then the pH was adjusted to 4.2 with 10wt% dilute sulfuric acid to obtain a Zn-Co alloy plating solution.

[0050] The pretreated molybdenum alloy core was first activated in 5wt% hydrochloric acid for 12s, rinsed with deionized water, and then continuously electroplated in a Ni composite plating solution until the Ni composite underlayer thickness reached 0.11μm. It was then rinsed with deionized water, followed by continuous electroplating in a Cu composite plating solution until the Cu composite coating thickness reached 0.52μm. It was then rinsed with deionized water, and further continuously electroplated in a Zn-Co alloy plating solution until the Zn-Co alloy layer thickness reached 0.30μm. After rinsing with deionized water, it was placed in a N2 protective atmosphere and held at 350℃ for 7s. It was then cleaned with a 28wt% phosphoric acid solution for 13s, rinsed with deionized water, and finally dried with hot air at 85℃ for 20min to obtain the copper-plated molybdenum composite alloy wire. Throughout the continuous electroplating process, the plating solution was continuously circulated and stirred to maintain the composite powder in a suspended and dispersed state.

[0051] Example 4

[0052] 1900g of molybdenum powder (Fairwood particle size 3.5μm), 20g of La(OH)3 powder (average particle size 2μm), 2g of titanium dihydrogen hydride powder (average particle size 5μm), and 3g of zirconium hydride powder (average particle size 5μm) were added to a fly knife mixer and mixed for 3 hours at a fly knife speed of 1200 rpm and a stirring blade speed of 150 rpm. The mixture was then transferred to a double-motion mixer and mixed for 4 hours. After cold pressing at 200 MPa for 3 minutes, it was sintered at 1950℃ for 5 hours, held at 1250℃ for 50 minutes, and then rolled to 7mm. The wire rod was annealed online at 1500℃, then forged into a 4mm rod at 1100℃, and then drawn to 1.0mm on a turntable. After vacuum annealing at 1000℃ for 2 hours, it was hot-drawn into a 0.08mm molybdenum alloy core at 650℃ using multiple dies. The core was then electropolished in a 10wt% potassium hydroxide electrolyte, cleaned for 3 minutes with a low-foaming water-based alkaline degreasing agent (purchased from Shanghai Qianhong Chemical Technology Co., Ltd.), rinsed with deionized water, and dried to obtain the pretreated molybdenum alloy core.

[0053] 0.2g of glucose and 100g of 75vol% ethanol aqueous solution were mixed and stirred for 20min. Then, 10g of nickel powder (average particle size of 800nm) was added and ultrasonically dispersed for 30min. After stirring at 400r / min for 2h at 70℃, the mixture was dried in an oven at 70℃ for 2h to obtain Ni-glucose composite powder. The Ni-glucose composite powder was placed in a tube furnace and heated to 650℃ in a mixed atmosphere of Ar / H2 volume ratio of 9:1. The temperature was held for 30min, cooled, ground, and passed through a 200-mesh sieve to obtain Ni@graphitized carbon composite powder.

[0054] The following ingredients were added: 300g nickel aminosulfonate (CAS No.: 13770-89-3), 10g nickel chloride hexahydrate, 30g boric acid, 1g Ni@graphitized carbon composite powder, 0.3g polyvinylpyrrolidone, and 0.1g... PEG-4000, 0.1g sodium dodecylbenzenesulfonate, and 800g deionized water were mixed and stirred for 10 min. The pH was adjusted to 3.8 with 10wt% dilute sulfuric acid, ultrasonicated at 40℃ for 10 min, and mechanically stirred at 350 r / min for 20 min to obtain a Ni composite plating solution. 30g tungsten powder, 26g tantalum powder, 13g molybdenum powder, 13g niobium powder, 5g vanadium powder, 2g titanium powder, and 0.8g stearic acid were mixed and ball-milled for 30 h. The mixture was heated to 850℃ at 10℃ / min and held for 1 h under Ar atmosphere. After cooling, it was dispersed with anhydrous ethanol, allowed to stand and separate into layers, and the upper fine powder was collected and vacuum dried at 60℃ for 8 h to obtain a high-entropy alloy precursor composite powder. 210g copper sulfate pentahydrate, 50g 98wt% sulfuric acid, and 0.05g... 37wt% hydrochloric acid, 4g high-entropy alloy precursor composite powder, 0.4g polyvinylpyrrolidone, and 0.05g hexadecyltrimethylammonium bromide were added to 800g deionized water and mechanically stirred for 20min, followed by ultrasonic dispersion for 20min to obtain a Cu composite plating solution. 80g zinc sulfate heptahydrate, 13g cobalt sulfate heptahydrate, 35g sodium citrate, 20g boric acid, 35g sodium sulfate, and 0.8g sodium saccharin were added to 800g deionized water, mixed and stirred for 20min, and then the pH was adjusted to 4 with 10wt% dilute sulfuric acid to obtain a Zn-Co alloy plating solution.

[0055] The pretreated molybdenum alloy core was first activated in 5wt% hydrochloric acid for 10s, rinsed with deionized water, and then continuously electroplated in a Ni composite plating solution until the Ni composite underlayer thickness reached 0.10μm. It was then rinsed with deionized water, followed by continuous electroplating in a Cu composite plating solution until the Cu composite coating thickness reached 0.4μm. It was then rinsed with deionized water, and further continuously electroplated in a Zn-Co alloy plating solution until the Zn-Co alloy layer thickness reached 0.2μm. After rinsing with deionized water, it was placed in a N2 protective atmosphere and held at 340℃ for 5s. It was then cleaned with a 28wt% phosphoric acid solution for 10s, rinsed with deionized water, and finally dried with hot air at 80℃ for 15min to obtain the copper-plated composite molybdenum alloy wire. Throughout the continuous electroplating process, the plating solution was continuously circulated and stirred to maintain the composite powder in a suspended and dispersed state.

[0056] Example 5

[0057] 2000g of molybdenum powder (Fairwood particle size 4.5μm), 30g of La(OH)3 powder (average particle size 2μm), 4g of titanium dihydrogen hydride powder (average particle size 5μm), and 4g of zirconium hydride powder (average particle size 5μm) were added to a fly knife mixer and mixed for 4 hours at a fly knife speed of 1200r / min and a stirring blade speed of 150r / min. The mixture was then transferred to a double-motion mixer and mixed for 6 hours. After cold pressing at 200MPa for 5 minutes, it was sintered at 2050℃ for 6 hours, held at 1350℃ for 60 minutes, and then rolled to 9mm. The wire rod was annealed online at 1550℃, then forged into a 4mm rod at 1300℃, and then drawn to 1.2mm on a turntable. After vacuum annealing at 1050℃ for 3 hours, it was hot-drawn into a 0.20mm molybdenum alloy core at 900℃ using multiple dies. The core was then electropolished in a 10wt% potassium hydroxide electrolyte, cleaned for 5 minutes with a low-foaming water-based alkaline degreasing agent (purchased from Shanghai Qianhong Chemical Technology Co., Ltd.), rinsed with deionized water, and dried to obtain the pretreated molybdenum alloy core.

[0058] 0.5g glucose and 150g 75vol% ethanol aqueous solution were mixed and stirred for 30min. Then, 15g nickel powder (average particle size of 800nm) was added and ultrasonically dispersed for 50min. After stirring at 400r / min for 2.5h at 80℃, the mixture was dried in an oven at 80℃ for 3h to obtain Ni-glucose composite powder. The Ni-glucose composite powder was placed in a tube furnace and heated to 700℃ in a mixed atmosphere of Ar / H2 volume ratio of 9:1. The temperature was maintained for 40min, cooled, ground, and passed through a 200-mesh sieve to obtain Ni@graphitized carbon composite powder.

[0059] 350g nickel aminosulfonate, 15g nickel chloride hexahydrate, 40g boric acid, 2g Ni@graphitized carbon composite powder, 0.5g polyvinylpyrrolidone, and 0.2g... PEG-4000, 0.2g sodium dodecyl sulfate, and 1000g deionized water were mixed and stirred for 20 min. The pH was adjusted to 4.0 with 10wt% dilute sulfuric acid. The mixture was ultrasonically treated at 50℃ for 20 min and mechanically stirred at 350 r / min for 30 min to obtain a Ni composite plating solution. 35g tungsten powder, 30g tantalum powder, 15g molybdenum powder, 15g niobium powder, 10g vanadium powder, 5g titanium powder, and 1.2g stearic acid were mixed and ball-milled for 36 h. The mixture was heated to 900℃ at 10℃ / min and held at that temperature for 1.5 h under an Ar atmosphere. After cooling, it was dispersed with anhydrous ethanol, allowed to stand and separate into layers, and the upper fine powder was collected and vacuum dried at 70℃ for 10 h to obtain a high-entropy alloy precursor composite powder. 240g copper sulfate pentahydrate, 65g 98wt% sulfuric acid, and 0.1g... 37wt% hydrochloric acid, 8g high-entropy alloy precursor composite powder, 0.6g polyvinylpyrrolidone, and 0.1g hexadecyltrimethylammonium bromide were added to 1000g deionized water and mechanically stirred for 30min, followed by ultrasonic dispersion for 30min to obtain a Cu composite plating solution. 120g zinc sulfate heptahydrate, 16g cobalt sulfate heptahydrate, 40g sodium citrate, 30g boric acid, 45g sodium sulfate, and 1.5g sodium saccharin were added to 1000g deionized water, mixed and stirred for 30min, and then the pH was adjusted to 4.5 with 10wt% dilute sulfuric acid to obtain a Zn-Co alloy plating solution.

[0060] The pretreated molybdenum alloy core was first activated in 5wt% hydrochloric acid for 15s, rinsed with deionized water, and then continuously electroplated in a Ni composite plating solution until the Ni composite underlayer thickness reached 0.12μm. It was then rinsed with deionized water, followed by continuous electroplating in a Cu composite plating solution until the Cu composite coating thickness reached 0.7μm. It was then rinsed with deionized water, and further continuously electroplated in a Zn-Co alloy plating solution until the Zn-Co alloy layer thickness reached 0.4μm. After rinsing with deionized water, it was placed in a N2 protective atmosphere and held at 360℃ for 10s. It was then cleaned with a 28wt% phosphoric acid solution for 15s, rinsed with deionized water, and finally dried with hot air at 90℃ for 30min to obtain the copper-plated molybdenum composite alloy wire. Throughout the continuous electroplating process, the plating solution was continuously circulated and stirred to maintain the composite powder in a suspended and dispersed state.

[0061] The present invention also includes comparative examples and related experiments.

[0062] Comparative Example 1

[0063] Compared with Example 1, the only difference is that lanthanum oxide powder, titanium dioxide powder, and zirconium oxide powder are used instead of La(OH)3 powder, titanium dihydrogen hydride powder, and zirconium hydride powder. The other preparation methods and components are completely consistent, and copper-plated composite molybdenum alloy wire is finally obtained.

[0064] Comparative Example 2

[0065] Compared with Example 1, the only difference is that Ni plating solution is used instead of Ni composite plating solution, while the other preparation methods and components are completely consistent, and copper-plated composite molybdenum alloy wire is finally obtained.

[0066] Comparative Example 3

[0067] Compared with Example 1, the only difference is that a Ni composite underlayer was not prepared, but the other preparation methods and components were completely consistent, and a copper-plated composite molybdenum alloy wire was finally obtained.

[0068] Comparative Example 4

[0069] Compared with Example 1, the only difference is that no Zn-Co alloy layer was prepared. The other preparation methods and compositions are completely consistent, and copper-plated composite molybdenum alloy wire is finally obtained.

[0070] Performance testing

[0071] The copper-plated molybdenum composite alloy wires prepared in Examples 1-5 and Comparative Examples 1-4 of this invention were subjected to performance testing and analysis in accordance with GB / T228.1. Tensile strength tests were conducted according to GB / T3048.2-2007 "Metallic materials, tensile testing - Part 1: Test method at room temperature" to evaluate tensile strength; and resistivity tests were conducted according to GB / T3048.2-2007 "Electrical properties test method for wires and cables - Part 2: Test for resistivity of metallic materials" to evaluate conductivity; the specific performance test results are shown in Table 1.

[0072] Table 1

[0073]

[0074] As shown in Table 1, the tensile strength and resistivity of the copper-plated composite molybdenum alloy wires prepared in Examples 1-5 of this invention are superior to those in Comparative Examples 1-4. Compared to Comparative Example 1, Example 1 significantly improved the tensile strength of the molybdenum alloy core by using La(OH)3, titanium dihydrogen hydride, and zirconium hydride for composite doping; Comparative Examples 2 and 3 lacked Ni@graphitized carbon, resulting in a significant increase in resistivity, which also indicates that the introduction of Ni@graphitized carbon improved the conductivity continuity of the underlying layer, forming a highly efficient conductive path.

[0075] In addition, copper-plated molybdenum composite alloy wires prepared in Examples 1-5 and Comparative Examples 1-4 were used to continuously cut tungsten material at a current of 7A. The occurrence of wire breakage during continuous use was tested, and the state of the tungsten material cutting surface and the surface state of the wire after continuous use were observed by scanning electron microscopy to evaluate its cutting effect as an electrode wire for electrical discharge cutting. The specific performance test results are shown in Table 2.

[0076] Table 2

[0077]

[0078] As shown in Table 2, the continuous cutting life before the first wire breakage of the copper-plated composite molybdenum alloy wires prepared in Examples 1-5 of this invention is 54-62 hours, which is significantly higher than the 36-44 hours of comparative examples 1-4. This indicates that the wires prepared in this invention have better stability and longer service life in actual wire EDM operations. Meanwhile, the tungsten material cutting surfaces corresponding to Examples 1-5 all exhibit good surface finish. The scanning electron microscope image of the tungsten material cutting surface obtained using the copper-plated composite molybdenum alloy wire prepared in Example 1 is shown below. Figure 1 It can also be seen that the cut surface of the tungsten material has no obvious striations and a good surface finish; in addition, the copper-plated composite molybdenum alloy wires prepared in Examples 1-5 of this invention can still maintain a relatively smooth wire surface, a relatively complete coating, and no obvious erosion pits after continuous use. The scanning electron microscope image of the surface of the copper-plated composite molybdenum alloy wire prepared in Example 1 after continuous use is shown in the figure. Figure 2 This further demonstrates that the copper-plated molybdenum composite alloy wire prepared by this invention can maintain good surface integrity and corrosion resistance after long-term electrical discharge machining, thereby reducing abnormal discharge and early wire breakage. In contrast, the cutting life of Comparative Examples 1-4 is significantly shortened, and phenomena such as deepened stripes, decreased surface uniformity, local roughness, erosion pits, and coating peeling occur, indicating that surface damage accumulates faster under continuous discharge and thermal shock conditions, making it difficult to maintain a stable cutting state for a long time. In particular, Comparative Example 4, although some basic properties are close to those of the embodiment, shows a decrease in stripe uniformity and an increase in wire surface roughness in the later stages, indicating that when the outermost layer only has a Cu composite coating and lacks the interface control of a Zn-Co alloy layer, the long-term service performance of the wire is still limited.

[0079] To further evaluate the corrosion resistance of the copper-plated molybdenum alloy wire of the present invention in the processing fluid environment, a simulated wire EDM processing fluid was first prepared. The fluid, by mass concentration, included 2.5 g / L emulsified soap, 1.0 g / L disodium hydrogen phosphate, 0.5 g / L boric acid, and the balance deionized water, with the pH controlled at 8.5 ± 0.5. This system was used to simulate, to a certain extent, the weakly alkaline water-based working fluid environment in which the wire was subjected during wire EDM. The copper-plated molybdenum alloy wire samples prepared in Examples 1-5 and Comparative Examples 1-4 were immersed in the simulated wire EDM processing fluid at a constant temperature for 36 hours. After removal, they were cleaned, and the surface corrosion spots, cracks, and peeling were observed. Specific test results are shown in Table 3.

[0080] Table 3

[0081]

[0082] As shown in Table 3, the copper-plated composite molybdenum alloy wires prepared in Examples 1-5 of this invention showed no obvious corrosion spots after corrosion testing, and exhibited no cracks or peeling, with the coating remaining intact. In contrast, Comparative Examples 1 and 2 showed a small number of dotted or shallow corrosion spots, accompanied by a slight tendency to blister; Comparative Example 3 further showed more corrosion spots, local microcracks, and coating peeling; Comparative Example 4 showed a large number of corrosion spots and obvious coating peeling, exhibiting the worst corrosion resistance. The above results indicate that the wires prepared by this invention can maintain good surface integrity and corrosion resistance stability in a weakly alkaline water-based working environment, which plays a positive role in reducing the accumulation of surface damage during long-term processing and maintaining continuous processing stability.

[0083] The above are preferred embodiments of the present invention. Those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing copper-plated composite molybdenum alloy wire, characterized in that, Includes the following steps: S1. Molybdenum powder, La(OH)3 powder, titanium dihydrogen hydride powder and zirconium hydride powder are mixed and then cold-pressed, sintered, rolled, annealed, forged and drawn to obtain a molybdenum alloy core. The core is then electrolytically polished, alkali washed, rinsed and dried to obtain a pretreated molybdenum alloy core. S2. After mixing glucose and ethanol aqueous solution, nickel powder is added for dispersion, heated and stirred, dried, and then pyrolyzed under a mixed atmosphere of Ar and H2 to obtain Ni@graphitized carbon composite powder. Nickel salt, boric acid, additives and deionized water are added and mixed, pH is adjusted, ultrasonic treatment and mechanical stirring are performed to obtain Ni composite plating solution. S3. After activating the pretreated molybdenum alloy core, it is continuously electroplated in Ni composite plating solution, Cu composite plating solution and Zn-Co alloy plating solution to form Ni composite underlayer, Cu composite plating layer and Zn-Co alloy layer. After short-term thermal diffusion under inert atmosphere protection, phosphoric acid cleaning and drying, copper-plated composite molybdenum alloy wire is obtained.

2. The method for preparing a copper-plated composite molybdenum alloy wire according to claim 1, characterized in that, In step S1, molybdenum powder, La(OH)3 powder, titanium dihydrogen hydride powder, and zirconium hydride powder are added to a fly knife mixer and mixed for 3-4 hours at a fly knife speed of 1200 r / min and a stirring blade speed of 150 r / min. The mixture is then transferred to a dual-motion mixer and mixed for 4-6 hours. After cold pressing at 200 MPa for 3-5 minutes, it is sintered at 1950-2050℃ for 5-6 hours, held at 1250-1350℃ for 50-60 minutes, and then rolled into 7-9 mm wire rods. The material is annealed online at 00~1550℃, then forged into a 4mm rod at 1100~1300℃, then drawn to 1.0~1.2mm on a turntable, vacuum annealed at 1000~1050℃ for 2~3h, and then hot-drawn into a 0.08~0.2mm molybdenum alloy core at 650~900℃ using multiple dies. The core is then electropolished in a 10wt% potassium hydroxide electrolyte, cleaned with a low-foaming water-based alkaline degreasing agent for 3~5min, rinsed with deionized water and dried to obtain the pretreated molybdenum alloy core.

3. The method for preparing a copper-plated composite molybdenum alloy wire according to claim 1, characterized in that, The Ni@graphitized carbon composite powder is obtained by mixing and stirring 0.2-0.5 parts by weight of glucose and 100-150 parts by weight of 75 vol% ethanol aqueous solution for 20-30 min, then adding 10-15 parts by weight of nickel powder, ultrasonically dispersing for 30-50 min, stirring at 400 r / min at 70-80℃ for 2-2.5 h, drying in an oven at 70-80℃ for 2-3 h, placing it in a tube furnace, heating to 650-700℃ in a mixed atmosphere of Ar / H2 volume ratio of 9:1, holding at that temperature for 30-40 min, cooling, grinding, and passing through a 200 mesh sieve.

4. The method for preparing a copper-plated composite molybdenum alloy wire according to claim 1, characterized in that, The Ni composite plating solution is prepared by mixing and stirring nickel salt, 30-40 parts by weight of boric acid, 1-2 parts by weight of Ni@graphitized carbon composite powder, additives, and 800-1000 parts by weight of deionized water for 10-20 minutes, adjusting the pH to 3.8-4.0 with 10wt% dilute sulfuric acid, ultrasonically treating at 40-50℃ for 10-20 minutes, and mechanically stirring at 350 r / min for 20-30 minutes.

5. The method for preparing a copper-plated composite molybdenum alloy wire according to claim 4, characterized in that, The nickel salt comprises 300-350 parts by weight of nickel aminosulfonate and 10-15 parts by weight of nickel chloride hexahydrate; the auxiliary agent comprises 0.3-0.5 parts by weight of polyvinylpyrrolidone, 0.1-0.2 parts by weight of PEG-4000 and 0.1-0.2 parts by weight of wetting agent; the wetting agent is one of sodium dodecyl sulfate and sodium dodecylbenzenesulfonate.

6. The method for preparing a copper-plated composite molybdenum alloy wire according to claim 1, characterized in that, In step S3, the pretreated molybdenum alloy core is first activated in 5wt% hydrochloric acid for 10-15s, rinsed with deionized water, and then continuously electroplated in a Ni composite plating solution to form a Ni composite underlayer. After rinsing with deionized water, it is then continuously electroplated in a Cu composite plating solution to form a Cu composite coating. After rinsing with deionized water, it is further continuously electroplated in a Zn-Co alloy plating solution to form a Zn-Co alloy layer. After rinsing with deionized water, it is placed in a N2 protective atmosphere and kept at 340-360℃ for 5-10s. Then, it is cleaned with 28wt% phosphoric acid solution for 10-15s, rinsed with deionized water, and dried with hot air at 80-90℃ for 15-30min to obtain copper-plated composite molybdenum alloy wire.

7. The method for preparing a copper-plated composite molybdenum alloy wire according to claim 1, characterized in that, The Cu composite plating solution is prepared by adding 210-240 parts by weight of copper sulfate pentahydrate, 50-65 parts by weight of 98 wt% sulfuric acid, 0.05-0.1 parts by weight of 37 wt% hydrochloric acid, 4-8 parts by weight of high-entropy alloy precursor composite powder, 0.4-0.6 parts by weight of polyvinylpyrrolidone, and 0.05-0.1 parts by weight of hexadecyltrimethylammonium bromide to 800-1000 parts by weight of deionized water, mechanically stirring for 20-30 minutes, and then ultrasonically dispersing for 20-30 minutes.

8. The method for preparing a copper-plated composite molybdenum alloy wire according to claim 7, characterized in that, The high-entropy alloy precursor composite powder is obtained by ball milling 30-35 parts by weight of tungsten powder, 26-30 parts by weight of tantalum powder, 13-15 parts by weight of molybdenum powder, 13-15 parts by weight of niobium powder, 5-10 parts by weight of vanadium powder, 2-5 parts by weight of titanium powder and 0.8-1.2 parts by weight of stearic acid for 30-36 hours. Then, the mixture is heated to 850-900℃ at 10℃ / min under Ar atmosphere and held for 1-1.5 hours. After cooling, it is dispersed with anhydrous ethanol, allowed to stand and separate into layers, and the upper fine powder is collected and vacuum dried at 60-70℃ for 8-10 hours.

9. The method for preparing a copper-plated composite molybdenum alloy wire according to claim 1, characterized in that, The Zn-Co alloy plating solution is prepared by adding 80-120 parts by weight of zinc sulfate heptahydrate, 13-16 parts by weight of cobalt sulfate heptahydrate, 35-40 parts by weight of sodium citrate, 20-30 parts by weight of boric acid, 35-45 parts by weight of sodium sulfate, and 0.8-1.5 parts by weight of sodium saccharin to 800-1000 parts by weight of deionized water, mixing and stirring for 20-30 minutes, and then adjusting the pH to 4-4.5 with 10wt% dilute sulfuric acid.

10. A copper-plated composite molybdenum alloy wire, characterized in that, The material is prepared using the method described in any one of claims 1 to 9, comprising a pretreated molybdenum alloy core, and a Ni composite underlayer, a Cu composite coating, and a Zn-Co alloy layer sequentially placed on the surface of the pretreated molybdenum alloy core; wherein the thickness of the Ni composite underlayer is 0.10~0.12μm, the thickness of the Cu composite coating is 0.4~0.7μm, and the thickness of the Zn-Co alloy layer is 0.2~0.4μm; the pretreated molybdenum alloy core comprises the following raw materials in parts by weight: 1900~2000 parts of molybdenum powder, 20~30 parts of La(OH)3 powder, 2~4 parts of titanium dihydrogen phosphate powder, and 3~4 parts of zirconium hydride powder.

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