Method for producing a metallurgically bonded nickel-coated copper rod or wire

Abstract

The application relates to the technical field of composite material preparation, in particular to a metallurgical bonding nickel-coated copper rod and wire manufacturing method, which comprises the following steps of: copper core preparation, stirring T1 oxygen-free copper powder and borax adhesive, extruding and polishing to complete copper core preparation; shell preparation, selecting a nickel rod to cut and process into a nickel shell and a nickel back cover; smelting treatment, preparing a reinforcing agent, cleaning the inside of the nickel shell, smearing the reinforcing agent, putting the copper core into the nickel shell, and sending the nickel shell into a vacuum smelting furnace for sealed smelting treatment. In the application, various components in the reinforcing agent are mutually synergistic and mutually promoting, a dense metallurgical bonding layer is formed on the bonding interface of the nickel-coated copper rod, the atomic arrangement of the bonding layer is close and orderly, the bonding strength between copper and nickel is greatly enhanced, and the two kinds of metals are no longer simply mechanically bonded, but are firmly metallurgically bonded through mutual diffusion and chemical bonding between atoms.

Description

Technical Field

[0001] This invention relates to the field of composite material preparation technology, specifically to a metallurgically bonded method for manufacturing nickel-coated copper rods and wires. Background Technology

[0002] With the rapid development of modern industry, the requirements for material performance are becoming increasingly stringent. In the fields of electronics and electrical engineering, products are constantly developing towards miniaturization and high performance. This requires conductive materials to not only have good conductivity, but also certain strength, corrosion resistance and stability. Although copper has excellent conductivity, it is insufficient in terms of strength and corrosion resistance. Nickel has good corrosion resistance and stability, but its conductivity is not as good as copper. Combining nickel and copper to make nickel-coated copper rods can combine the advantages of both and meet the diverse material needs of industrial development.

[0003] In existing technologies, nickel-plated copper is manufactured using an interference fit process, either through cold extrusion or nickel plating on a copper core. However, nickel-plated copper produced by interference fit does not form a metallurgical bond between the two metals; they are merely in close contact. After a period of use, oxidation will occur between the two metals, leading to an increase in the resistance of the contact surface. Furthermore, when used at temperatures exceeding 100°C, the different coefficients of thermal expansion and contraction of the two metals will cause gaps to form between them after repeated expansion and contraction, eventually leading to the separation of the two metals. Summary of the Invention

[0004] The purpose of this invention is to provide a method for manufacturing metallurgically bonded nickel-coated copper rods and wires. The method for manufacturing metallurgically bonded nickel-coated copper rods and wires prepared by this invention not only has good bonding strength and high-temperature stability, but also effectively improves the performance of the method for manufacturing metallurgically bonded nickel-coated copper rods and wires.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for manufacturing a metallurgically bonded nickel-coated copper rod or wire, comprising the following steps:

[0006] Step 1: Copper core preparation. Select T1 oxygen-free copper powder and borax binder, mix, extrude and polish to complete the copper core preparation;

[0007] Step 2: Shell preparation: Select a nickel rod, cut it, and process it into shape to obtain a nickel shell and a nickel back cover;

[0008] Step 3: Smelting treatment. The reinforcing agent is prepared, and after cleaning the inside of the nickel shell and applying the reinforcing agent, the copper core is inserted into the nickel shell and sent into a vacuum smelting furnace for sealed smelting treatment.

[0009] Step 4: Welding process. The nickel shell after smelting is inspected for flaws, and then the inspected nickel shell is vacuum welded to the nickel back cover using a vacuum welding box.

[0010] Step 5: Extrusion process. The welded nickel shell is placed in a high-temperature resistance furnace for heating and then extruded through an extruder to obtain a nickel-coated copper rod. After cooling, the nickel-coated copper rod is cut at both ends and then drawn to the required size through a cold drawing process to complete the preparation.

[0011] Furthermore, the copper core preparation step involves stirring T1 oxygen-free copper powder and borax binder to obtain a mixed powder, wherein the mass ratio of T1 oxygen-free copper powder to borax binder is 20:3. The mixed powder is then added to the molding die of a hydraulic press for extrusion molding, and after removal, it is polished with 800-grit sandpaper to complete the copper core preparation.

[0012] Furthermore, the outer shell preparation includes the following steps: the nickel outer shell is selected from a 125mm diameter nickel rod, cut and processed to a length of 290mm; one end of the nickel outer shell is machined with an R87.5 arc head, and the tangent point between the arc and the machined outer diameter surface is a R32.5 arc chamfer; the other end of the nickel outer shell has a 75mm diameter hole machined at one end of the cross section, the front end of the hole has the same shape as the outer diameter, and a 20×25° chamfer is machined on the outer diameter of the drilled end; the nickel back cover is selected from a 125mm nickel rod, cut and processed to a length of 30mm, a diameter of 120mm, a length of 25mm, and a 20×25° chamfer on one end.

[0013] Further, the melting process involves wiping the inner hole of the nickel shell with industrial alcohol 3-5 times, and applying a reinforcing agent to the inner hole of the nickel shell using a spraying device. The coating thickness is 80-100 micrometers. After inserting the copper core into the nickel shell, the shell is placed into a vacuum melting furnace. Argon gas is continuously injected into the vacuum melting furnace until the argon gas occupies 99.8% of the furnace space. The argon gas purity is greater than 99.9%. The vacuum melting furnace is heated to 1280°C at a rate of 5-10°C / min and maintained for 3 hours, followed by cooling to room temperature. During the cooling process, if the temperature is above 80°C, argon gas is continuously filled until the temperature of the vacuum melting furnace is below 60°C. Argon gas filling is then stopped, and the nickel shell is removed, completing the melting process.

[0014] Furthermore, the preparation method of the reinforcing agent is as follows: foundry waste sand, aluminum ash, and borax are selected for pretreatment. The foundry waste sand is crushed and sieved, then soaked in a 10% dilute hydrochloric acid solution for 30-40 minutes. After washing with deionized water until neutral, it is dried using a dryer for later use. The aluminum ash is placed in a muffle furnace and forged at 800℃ for 2 hours at a temperature of 5-10℃ / min. After cooling, the forged aluminum ash is ball-milled in a planetary ball mill at a speed of 250-350 r / min for 4 hours and then sieved through a 200-mesh sieve. The medium is zirconia balls, and the mass ratio of zirconia balls to aluminum ash is 4:1. Industrial-grade borax is dehydrated at 200℃ and sieved through a 200-mesh sieve, thus completing the pretreatment of foundry waste sand, aluminum ash, and borax.

[0015] Further, the pretreated foundry waste sand, aluminum ash, and borax are added to a V-type mixer and stirred at 20-40 r / min for 15 min to obtain a mixture. The mass ratio of the foundry waste sand, aluminum ash, and borax is 6:3:1. The mixture is then placed in a ball mill, and anhydrous ethanol is added, accounting for 15% of the mass of the mixture. The mixture is stirred at 200-300 r / min for 6 h to obtain a slurry. The slurry is then dried in a vacuum drying oven. After drying, it is placed in a small crusher for crushing and sieved through a 200-mesh sieve to obtain a composite powder. The composite powder and PVA solution are stirred using a magnetic stirrer. During the stirring process, the composite powder is continuously added at 500-600 r / min for 30-40 min to complete the preparation of the reinforcing agent.

[0016] Furthermore, the mass ratio of the composite powder to the PVA solution is 1:1, the concentration of the PVA solution is 5%, and the vacuum drying oven is set to a temperature of 60°C and a vacuum degree of -0.1 MPa during the preparation of the reinforcing agent.

[0017] Furthermore, the welding process involves: coarsely grinding the smelted nickel shell with a silicon carbide grinding wheel, then finely grinding it with 800-grit sandpaper. After grinding, UT flaw detection is performed to remove defective products. The nickel back cover is then cleaned and placed on the end face of a qualified nickel shell. The shell is placed inside a vacuum welding box, and the nickel shell and back cover are welded together using argon arc welding with the same welding wire as the nickel back cover. After cooling, the shell is removed and the weld bead is ground to match the outer diameter of the nickel shell, thus completing the welding process of the nickel shell.

[0018] Furthermore, the extrusion process involves placing the welded nickel shell in a high-temperature resistance furnace, heating it to 920°C at a rate of 5-10°C / min, holding it at that temperature for 2 hours, then removing it and placing it in a 1500T extruder to extrude it from a die to obtain a nickel-clad copper rod. The die opening diameter is 28mm. After the nickel-clad copper rod cools, the ends of the rod are cut off, and the rod is then drawn to the required dimensions using a cold drawing process, thus completing the extrusion process.

[0019] Furthermore, the cold drawing process reduces the diameter by less than 6.3% per drawing, with a drawing speed of 2-5 m / min, and after every 2-4 drawing cycles, the material is annealed in a high-temperature annealing furnace at a temperature of 680-720℃ for 2 hours.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. In this invention, by adding a reinforcing agent, borax will fully contact and react with silicates in foundry waste sand under high temperature environment to generate a low-melting-point glass phase, which significantly improves the wettability of molten copper to the nickel wall and reduces the surface tension between the molten copper and the nickel wall, allowing the copper to adhere more uniformly and tightly to the inner wall of the nickel shell. At the same time, the aluminum metal will remove oxygen from the interface oxide and be oxidized, while the interface oxide will be reduced to a pure metallic state, ensuring the cleanliness of the bonding surface and eliminating key obstacles affecting metallurgical bonding. With mutual synergy and promotion, a dense metallurgical bonding layer is formed at the bonding interface of the nickel-clad copper rod. The atoms of this bonding layer are arranged in a tight and orderly manner, which greatly enhances the bonding strength between copper and nickel, so that the two metals are no longer simply mechanically bonded, but form a strong metallurgical bond through interatomic diffusion and chemical bonding.

[0022] 2. In this invention, the iron oxide in the foundry waste sand interacts with the boron oxide decomposed from borax at high temperatures to form complex salts. These salts adhere tightly to the surface of nickel-clad copper rods and wires, forming part of a protective film that effectively blocks the erosion of oxygen and moisture, enhancing the corrosion resistance of the product. At the same time, borax forms boron trioxide at high temperatures and reacts with metallic aluminum and aluminum oxide in aluminum ash, creating a transition layer at the interface between copper and nickel. The composition and structure of this transition layer are between those of copper and nickel, which can alleviate the thermal stress caused by the difference in thermal expansion coefficients between the two metals, improving the stability of nickel-clad copper rods and wires under different temperature conditions.

[0023] 3. In this invention, foundry waste sand and aluminum ash are used as reinforcing agent raw materials, realizing the resource utilization of industrial waste and reducing raw material costs. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that the raw materials used in the following embodiments are all commercially available.

[0026] Example 1:

[0027] A metallurgically bonded method for manufacturing nickel-coated copper rods and wires includes the following steps:

[0028] Step 1: Copper core preparation. Select T1 oxygen-free copper powder and borax binder, mix, extrude and polish to complete the copper core preparation;

[0029] Step 2: Shell preparation: Select a nickel rod, cut it, and process it into shape to obtain a nickel shell and a nickel back cover;

[0030] Step 3: Smelting treatment. The reinforcing agent is prepared, and after cleaning the inside of the nickel shell and applying the reinforcing agent, the copper core is inserted into the nickel shell and sent into a vacuum smelting furnace for sealed smelting treatment.

[0031] Step 4: Welding process. The nickel shell after smelting is inspected for flaws, and then the inspected nickel shell is vacuum welded to the nickel back cover using a vacuum welding box.

[0032] Step 5: Extrusion process. The welded nickel shell is placed in a high-temperature resistance furnace for heating and then extruded through an extruder to obtain a nickel-coated copper rod. After cooling, the nickel-coated copper rod is cut at both ends and then drawn to the required size through a cold drawing process to complete the preparation.

[0033] The steps for preparing the copper core are as follows: T1 oxygen-free copper powder and borax binder are stirred to obtain a mixed powder. The mass ratio of T1 oxygen-free copper powder to borax binder is 20:3. The mixed powder is added to the forming mold of a hydraulic press for extrusion molding. After being taken out, it is polished with 800-grit sandpaper to complete the preparation of the copper core.

[0034] The outer shell preparation includes the following steps: the nickel outer shell is made by cutting and machining a 125mm diameter nickel rod to a length of 290mm. One end of the nickel outer shell is machined with an R87.5 arc head, and the tangent point between the arc and the machined outer diameter surface is a R32.5 arc chamfer. The other end of the nickel outer shell has a 75mm diameter hole machined at one end of the cross section. The shape of the front end of the hole is consistent with the outer diameter. A 20×25° chamfer is machined on the outer diameter of the drilled end. The nickel back cover is made by cutting and machining a 125mm nickel rod to a cutting length of 30mm, machining the diameter to 120mm, and the length to 25mm. One end is chamfered at 20×25°.

[0035] The melting process is as follows: the inner hole of the nickel shell is wiped three times with industrial alcohol, and the reinforcing agent is applied to the inner hole of the nickel shell using a spraying device with a coating thickness of 80 micrometers. After the copper core is installed inside the nickel shell, it is sent into a vacuum melting furnace. Argon gas is continuously injected into the vacuum melting furnace so that the argon gas occupies 99.8% of the furnace space and the argon gas purity is greater than 99.9%. The vacuum melting furnace is heated to 1250℃ at 5℃ / min and maintained for 3 hours, and then cooled to room temperature. During the cooling process, when the temperature is above 80℃, argon gas is continuously filled until the temperature of the vacuum melting furnace is below 60℃. Argon gas filling is then stopped, and the nickel shell is removed to complete the melting process.

[0036] The preparation method of the reinforcing agent is as follows: Foundry waste sand, aluminum ash, and borax are selected for pretreatment. The foundry waste sand is crushed and screened, then soaked in a 10% dilute hydrochloric acid solution for 30 minutes. After washing with deionized water until neutral, it is dried in a dryer for later use. The aluminum ash is placed in a muffle furnace and forged at 800℃ for 2 hours at a temperature of 5℃ / min. After cooling, the forged aluminum ash is ball-milled in a planetary ball mill at a speed of 250 r / min for 4 hours and then sieved through a 200-mesh sieve. The medium is zirconia balls, and the mass ratio of zirconia balls to aluminum ash is 4:1. Industrial-grade borax is dehydrated at 200℃ and sieved through a 200-mesh sieve. This completes the pretreatment of foundry waste sand, aluminum ash, and borax.

[0037] Pretreated foundry waste sand, aluminum ash, and borax were added to a V-type mixer and stirred at 20 r / min for 15 min to obtain a mixture. The mass ratio of foundry waste sand, aluminum ash, and borax was 6:3:1. The mixture was then placed in a ball mill, and anhydrous ethanol (15% of the mixture mass) was added. The mixture was stirred at 200 r / min for 6 h to obtain a slurry. The slurry was then dried in a vacuum drying oven. After drying, it was placed in a small crusher and crushed. The slurry was then sieved through a 200-mesh sieve to obtain a composite powder. The composite powder and PVA solution were stirred using a magnetic stirrer. During the stirring process, the composite powder was continuously added, and the mixture was stirred at 500 r / min for 30 min to complete the preparation of the reinforcing agent.

[0038] The mass ratio of composite powder to PVA solution is 1:1, the concentration of PVA solution is 5%, and the vacuum drying oven is set at 60℃ and vacuum degree is -0.1MPa during the preparation of the reinforcing agent.

[0039] The welding process involves first coarsely grinding the smelted nickel shell using a silicon carbide grinding wheel, then finely grinding it with 800-grit sandpaper. After grinding, UT flaw detection is performed to remove defective products. The nickel back cover is then cleaned and placed on the end face of the qualified nickel shell. The shell is then placed inside a vacuum welding box, and the nickel shell and back cover are welded together using argon arc welding with the same welding wire as the nickel back cover. After cooling, the shell is removed, and the weld bead is ground to match the outer diameter of the nickel shell, thus completing the welding process of the nickel shell.

[0040] The extrusion process involves placing the welded nickel shell in a high-temperature resistance furnace, heating it to 920°C at a rate of 5°C / min, holding it at that temperature for 2 hours, then removing it and placing it in a 1500T extruder to extrude it from the die to obtain a nickel-clad copper rod. The die opening diameter is 28mm. After the nickel-clad copper rod cools, the ends of the rod are cut off, and the rod is then drawn to the required dimensions using a cold drawing process, thus completing the extrusion process.

[0041] The cold drawing process reduces the diameter by less than 6.3% per drawing, with a drawing speed of 2 m / min. After every two drawing cycles, the material is annealed in a high-temperature annealing furnace at 680℃ for 2 hours.

[0042] Example 2:

[0043] A metallurgically bonded method for manufacturing nickel-coated copper rods and wires includes the following steps:

[0044] Step 1: Copper core preparation. Select T1 oxygen-free copper powder and borax binder, mix, extrude and polish to complete the copper core preparation;

[0045] Step 2: Shell preparation: Select a nickel rod, cut it, and process it into shape to obtain a nickel shell and a nickel back cover;

[0046] Step 3: Smelting treatment. The reinforcing agent is prepared, and after cleaning the inside of the nickel shell and applying the reinforcing agent, the copper core is inserted into the nickel shell and sent into a vacuum smelting furnace for sealed smelting treatment.

[0047] Step 4: Welding process. The nickel shell after smelting is inspected for flaws, and then the inspected nickel shell is vacuum welded to the nickel back cover using a vacuum welding box.

[0048] Step 5: Extrusion process. The welded nickel shell is placed in a high-temperature resistance furnace for heating and then extruded through an extruder to obtain a nickel-coated copper rod. After cooling, the nickel-coated copper rod is cut at both ends and then drawn to the required size through a cold drawing process to complete the preparation.

[0049] The steps for preparing the copper core are as follows: T1 oxygen-free copper powder and borax binder are stirred to obtain a mixed powder. The mass ratio of T1 oxygen-free copper powder to borax binder is 20:3. The mixed powder is added to the forming mold of a hydraulic press for extrusion molding. After being taken out, it is polished with 800-grit sandpaper to complete the preparation of the copper core.

[0050] The outer shell preparation includes the following steps: the nickel outer shell is made by cutting and machining a 125mm diameter nickel rod to a length of 290mm. One end of the nickel outer shell is machined with an R87.5 arc head, and the tangent point between the arc and the machined outer diameter surface is a R32.5 arc chamfer. The other end of the nickel outer shell has a 75mm diameter hole machined at one end of the cross section. The shape of the front end of the hole is consistent with the outer diameter. A 20×25° chamfer is machined on the outer diameter of the drilled end. The nickel back cover is made by cutting and machining a 125mm nickel rod to a cutting length of 30mm, machining the diameter to 120mm, and the length to 25mm. One end is chamfered at 20×25°.

[0051] The melting process is as follows: Wipe the inner hole of the nickel shell with industrial alcohol 3-5 times, and apply the reinforcing agent to the inner hole of the nickel shell using a spraying device. The coating thickness is 80-100 micrometers. After inserting the copper core into the nickel shell, it is sent into a vacuum melting furnace. Argon gas is continuously injected into the vacuum melting furnace so that the argon gas occupies 99.8% of the furnace space and the argon gas purity is greater than 99.9%. The vacuum melting furnace is heated to 1300℃ at 7.5℃ / min and maintained for 3 hours, and then cooled to room temperature. During the cooling process, when the temperature is above 80℃, argon gas is continuously filled until the temperature of the vacuum melting furnace is below 60℃. Argon gas filling is then stopped, and the nickel shell is removed to complete the melting process.

[0052] The preparation method of the reinforcing agent is as follows: Foundry waste sand, aluminum ash, and borax are selected for pretreatment. The foundry waste sand is crushed and screened, then soaked in a 10% dilute hydrochloric acid solution for 40 minutes. After washing with deionized water until neutral, it is dried in a dryer for later use. The aluminum ash is placed in a muffle furnace and forged at 800℃ for 2 hours at a temperature of 10℃ / min. After cooling, the forged aluminum ash is ball-milled in a planetary ball mill at a speed of 350 r / min for 4 hours and then sieved through a 200-mesh sieve. The medium is zirconia balls, and the mass ratio of zirconia balls to aluminum ash is 4:1. Industrial-grade borax is dehydrated at 200℃ and sieved through a 200-mesh sieve. This completes the pretreatment of foundry waste sand, aluminum ash, and borax.

[0053] Pretreated foundry waste sand, aluminum ash, and borax were added to a V-type mixer and stirred at 30 r / min for 15 min to obtain a mixture. The mass ratio of foundry waste sand, aluminum ash, and borax was 6:3:1. The mixture was then placed in a ball mill, and anhydrous ethanol (15% of the mixture mass) was added. The mixture was stirred at 250 r / min for 6 h to obtain a slurry. The slurry was then dried in a vacuum drying oven. After drying, it was placed in a small crusher and crushed. The slurry was then sieved through a 200-mesh sieve to obtain a composite powder. The composite powder and PVA solution were stirred using a magnetic stirrer. During the stirring process, the composite powder was continuously added, and the mixture was stirred at 550 r / min for 35 min to complete the preparation of the reinforcing agent.

[0054] The mass ratio of composite powder to PVA solution is 1:1, the concentration of PVA solution is 5%, and the vacuum drying oven is set at 60℃ and vacuum degree is -0.1MPa during the preparation of the reinforcing agent.

[0055] The welding process involves first coarsely grinding the smelted nickel shell using a silicon carbide grinding wheel, then finely grinding it with 800-grit sandpaper. After grinding, UT flaw detection is performed to remove defective products. The nickel back cover is then cleaned and placed on the end face of the qualified nickel shell. The shell is then placed inside a vacuum welding box, and the nickel shell and back cover are welded together using argon arc welding with the same welding wire as the nickel back cover. After cooling, the shell is removed, and the weld bead is ground to match the outer diameter of the nickel shell, thus completing the welding process of the nickel shell.

[0056] The extrusion process involves placing the welded nickel shell in a high-temperature resistance furnace, heating it to 920°C at a rate of 7.5°C / min, holding it at that temperature for 2 hours, then removing it and placing it in a 1500T extruder to extrude it from the die to obtain a nickel-clad copper rod. The die opening diameter is 28mm. After the nickel-clad copper rod cools, the ends of the rod are cut off, and the rod is then drawn to the required dimensions using a cold drawing process, thus completing the extrusion process.

[0057] The cold drawing process reduces the diameter by less than 6.3% per drawing, with a drawing speed of 3.5 m / min. After every 3 drawing cycles, the material is annealed in a high-temperature annealing furnace at 700℃ for 2 hours.

[0058] Example 3:

[0059] A metallurgically bonded method for manufacturing nickel-coated copper rods and wires includes the following steps:

[0060] Step 1: Copper core preparation. Select T1 oxygen-free copper powder and borax binder, mix, extrude and polish to complete the copper core preparation;

[0061] Step 2: Shell preparation: Select a nickel rod, cut it, and process it into shape to obtain a nickel shell and a nickel back cover;

[0062] Step 3: Smelting treatment. The reinforcing agent is prepared, and after cleaning the inside of the nickel shell and applying the reinforcing agent, the copper core is inserted into the nickel shell and sent into a vacuum smelting furnace for sealed smelting treatment.

[0063] Step 4: Welding process. The nickel shell after smelting is inspected for flaws, and then the inspected nickel shell is vacuum welded to the nickel back cover using a vacuum welding box.

[0064] Step 5: Extrusion process. The welded nickel shell is placed in a high-temperature resistance furnace for heating and then extruded through an extruder to obtain a nickel-coated copper rod. After cooling, the nickel-coated copper rod is cut at both ends and then drawn to the required size through a cold drawing process to complete the preparation.

[0065] The steps for preparing the copper core are as follows: T1 oxygen-free copper powder and borax binder are stirred to obtain a mixed powder. The mass ratio of T1 oxygen-free copper powder to borax binder is 20:3. The mixed powder is added to the forming mold of a hydraulic press for extrusion molding. After being taken out, it is polished with 800-grit sandpaper to complete the preparation of the copper core.

[0066] The outer shell preparation includes the following steps: the nickel outer shell is made by cutting and machining a 125mm diameter nickel rod to a length of 290mm. One end of the nickel outer shell is machined with an R87.5 arc head, and the tangent point between the arc and the machined outer diameter surface is a R32.5 arc chamfer. The other end of the nickel outer shell has a 75mm diameter hole machined at one end of the cross section. The shape of the front end of the hole is consistent with the outer diameter. A 20×25° chamfer is machined on the outer diameter of the drilled end. The nickel back cover is made by cutting and machining a 125mm nickel rod to a cutting length of 30mm, machining the diameter to 120mm, and the length to 25mm. One end is chamfered at 20×25°.

[0067] The melting process is as follows: the inner hole of the nickel shell is wiped five times with industrial alcohol, and a reinforcing agent is applied to the inner hole of the nickel shell using a spraying device with a coating thickness of 100 micrometers. After the copper core is installed inside the nickel shell, it is sent into a vacuum melting furnace. Argon gas is continuously injected into the vacuum melting furnace so that the argon gas occupies 99.8% of the furnace space and the argon gas purity is greater than 99.9%. The vacuum melting furnace is heated to 1350℃ at 10℃ / min and maintained for 3 hours, and then cooled to room temperature. During the cooling process, when the temperature is above 80℃, argon gas is continuously filled until the temperature of the vacuum melting furnace is below 60℃. Argon gas filling is then stopped, and the nickel shell is removed to complete the melting process.

[0068] The preparation method of the reinforcing agent is as follows: Foundry waste sand, aluminum ash, and borax are selected for pretreatment. The foundry waste sand is crushed and screened, then soaked in a 10% dilute hydrochloric acid solution for 30-40 minutes. After washing with deionized water until neutral, it is dried in a dryer for later use. The aluminum ash is placed in a muffle furnace and forged at 800℃ for 2 hours at a temperature of 10℃ / min. After cooling, the forged aluminum ash is ball-milled in a planetary ball mill at a speed of 350 r / min for 4 hours and then sieved through a 200-mesh sieve. The medium is zirconia balls, and the mass ratio of zirconia balls to aluminum ash is 4:1. Industrial-grade borax is dehydrated at 200℃ and sieved through a 200-mesh sieve. This completes the pretreatment of foundry waste sand, aluminum ash, and borax.

[0069] Specifically, foundry waste sand contains silicon dioxide and aluminum oxide, while aluminum ash contains elemental aluminum, aluminum nitride, and aluminum oxide.

[0070] Pretreated foundry waste sand, aluminum ash, and borax were added to a V-type mixer and stirred at 40 r / min for 15 min to obtain a mixture. The mass ratio of foundry waste sand, aluminum ash, and borax was 6:3:1. The mixture was then placed in a ball mill, and anhydrous ethanol (15% of the mixture mass) was added. The mixture was stirred at 300 r / min for 6 h to obtain a slurry. The slurry was then dried in a vacuum drying oven. After drying, it was placed in a small crusher and crushed. The slurry was then sieved through a 200-mesh sieve to obtain a composite powder. The composite powder and PVA solution were stirred using a magnetic stirrer. During the stirring process, the composite powder was continuously added, and the mixture was stirred at 600 r / min for 40 min to complete the preparation of the reinforcing agent.

[0071] The mass ratio of composite powder to PVA solution is 1:1, the concentration of PVA solution is 5%, and the vacuum drying oven is set at 60℃ and vacuum degree is -0.1MPa during the preparation of the reinforcing agent.

[0072] The welding process involves first coarsely grinding the smelted nickel shell using a silicon carbide grinding wheel, then finely grinding it with 800-grit sandpaper. After grinding, UT flaw detection is performed to remove defective products. The nickel back cover is then cleaned and placed on the end face of the qualified nickel shell. The shell is then placed inside a vacuum welding box, and the nickel shell and back cover are welded together using argon arc welding with the same welding wire as the nickel back cover. After cooling, the shell is removed, and the weld bead is ground to match the outer diameter of the nickel shell, thus completing the welding process of the nickel shell.

[0073] The extrusion process involves placing the welded nickel shell in a high-temperature resistance furnace, heating it to 920°C at a rate of 10°C / min, and holding it at that temperature for 2 hours. The shell is then removed and placed in a 1500T extruder to extrude it from the die to obtain a nickel-clad copper rod with a die diameter of 28mm. After the nickel-clad copper rod cools, its ends are cut off, and it is then drawn to the required dimensions using a cold drawing process, thus completing the extrusion process.

[0074] The cold drawing process reduces the diameter by less than 6.3% per drawing, with a drawing speed of 5 m / min. After every 4 drawing cycles, the material is annealed in a high-temperature annealing furnace at 720℃ for 2 hours.

[0075] The difference between Comparative Example 1 and Example 1 is that no foundry waste sand was added to the reinforcing agent in this comparative example.

[0076] The difference between Comparative Example 2 and Example 1 is that no aluminum ash was added to the reinforcing agent in this comparative example.

[0077] The difference between Comparative Example 3 and Example 1 is that aluminum ash and foundry waste sand were not added to the reinforcing agent in this comparative example.

[0078] The difference between Comparative Example 4 and Example 1 is that a nickel-plated copper rod made with conventional interference fit is used in this comparative example.

[0079] Performance testing: The metallurgically bonded nickel-coated copper rods and wires prepared in Examples 1, 2, 3, 1, 2, 3, and 4 were subjected to performance tests. Bond strength test: The interface hardness was evaluated by nanoindentation test. High temperature performance test: The interface was observed to have cracks or peeling after 100 hours of aging test at 400°C. Conductivity test: The resistivity of the nickel-coated copper rods was measured by four-probe method.

[0080] The obtained test data is recorded in the table below:

[0081]

[0082] It is evident that the bonding strength, high-temperature stability, and conductivity of the metallurgically bonded nickel-coated copper rods and wires prepared in Comparative Examples 1, 2, 3, and 4 are all lower than those in Examples 1, 2, and 3. This indicates that the metallurgically bonded nickel-coated copper rods and wires prepared by the present invention not only possess better bonding strength but also excellent high-temperature stability and conductivity. Therefore, the metallurgically bonded nickel-coated copper rods and wires prepared by the present invention have a broader market prospect and are more suitable for widespread application.

[0083] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0084] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for manufacturing a metallurgically bonded nickel-coated copper rod or wire, characterized in that: Includes the following steps: Step 1: Copper core preparation. Select T1 oxygen-free copper powder and borax binder, mix, extrude and polish to complete the copper core preparation; Step 2: Shell preparation: Select a nickel rod, cut it, and process it into shape to obtain a nickel shell and a nickel back cover; Step 3: Smelting treatment. The reinforcing agent is prepared, and after cleaning the inside of the nickel shell and applying the reinforcing agent, the copper core is inserted into the nickel shell and sent into a vacuum smelting furnace for sealed smelting treatment. Step 4: Welding process. The nickel shell after smelting is inspected for flaws, and then the inspected nickel shell is vacuum welded to the nickel back cover using a vacuum welding box. Step 5: Extrusion process. The welded nickel shell is placed in a high-temperature resistance furnace for heating and then extruded through an extruder to obtain a nickel-coated copper rod. After cooling, the nickel-coated copper rod is cut at both ends and then drawn to the required size through a cold drawing process to complete the preparation. The preparation method of the reinforcing agent is as follows: Foundry waste sand, aluminum ash, and borax are selected for pretreatment. The foundry waste sand is crushed and screened, then soaked in a 10% dilute hydrochloric acid solution for 30-40 minutes. After washing with deionized water until neutral, it is dried in a dryer for later use. The aluminum ash is placed in a muffle furnace and forged at 800℃ for 2 hours at a temperature of 5-10℃ / min. After cooling, the forged aluminum ash is ball-milled in a planetary ball mill at a speed of 250-350 r / min for 4 hours and then sieved through a 200-mesh sieve. The medium is zirconia balls, and the mass ratio of zirconia balls to aluminum ash is 4:

1. Industrial-grade borax is dehydrated at 200℃ and sieved through a 200-mesh sieve to complete the pretreatment of foundry waste sand, aluminum ash, and borax. The pretreated foundry waste sand, aluminum ash, and borax are added to a V-type mixer and stirred at 20-40 r / min for 15 min to obtain a mixture. The mass ratio of the foundry waste sand, aluminum ash, and borax is 6:3:

1. The mixture is then placed in a ball mill, and anhydrous ethanol is added, accounting for 15% of the mass of the mixture. The mixture is stirred at 200-300 r / min for 6 h to obtain a slurry. The slurry is then dried in a vacuum drying oven. After drying, it is placed in a small crusher for crushing and sieved through a 200-mesh sieve to obtain a composite powder. The composite powder and PVA solution are stirred using a magnetic stirrer. During the stirring process, the composite powder is continuously added at 500-600 r / min for 30-40 min to complete the preparation of the reinforcing agent.

2. The method for manufacturing metallurgically bonded nickel-coated copper rods and wires according to claim 1, characterized in that, The copper core preparation steps are as follows: T1 oxygen-free copper powder and borax binder are stirred to obtain a mixed powder. The mass ratio of T1 oxygen-free copper powder to borax binder is 20:

3. The mixed powder is added to the molding die of a hydraulic press for extrusion molding. After removal, it is polished with 800-grit sandpaper to complete the copper core preparation.

3. The method for manufacturing metallurgically bonded nickel-coated copper rods and wires according to claim 1, characterized in that, The outer shell preparation includes the following steps: the nickel outer shell is selected from a 125mm diameter nickel rod, cut and processed to a length of 290mm. One end of the nickel outer shell is machined with an R87.5 arc head, and the tangent point between the arc and the machined outer diameter surface is a R32.5 arc chamfer. The other end of the nickel outer shell has a 75mm diameter hole machined at one end of the cross section. The shape of the front end of the hole is consistent with the outer diameter. A 20×25° chamfer is machined on the outer diameter of the drilled end. The nickel back cover is selected from a 125mm nickel rod, cut and processed to a length of 30mm, a diameter of 120mm, a length of 25mm, and a 20×25° chamfer on one end.

4. The method for manufacturing metallurgically bonded nickel-coated copper rods and wires according to claim 1, characterized in that, The melting process is as follows: the inner hole of the nickel shell is wiped with industrial alcohol 3-5 times, and a reinforcing agent is applied to the inner hole of the nickel shell using a spraying device. The coating thickness is 80-100 micrometers. After the copper core is installed inside the nickel shell, it is sent into a vacuum melting furnace. Argon gas is continuously injected into the vacuum melting furnace so that the argon gas occupies 99.8% of the furnace space. The purity of the argon gas is greater than 99.9%. The vacuum melting furnace is heated to 1250-1350℃ at 5-10℃ / min and maintained for 3 hours, and then cooled to room temperature. During the cooling process, when the temperature is above 80℃, argon gas is continuously filled until the temperature of the vacuum melting furnace is below 60℃. Argon gas filling is then stopped, and the nickel shell is removed to complete the melting process.

5. The method for manufacturing metallurgically bonded nickel-coated copper rods and wires according to claim 1, characterized in that, The mass ratio of the composite powder to the PVA solution is 1:1, the concentration of the PVA solution is 5%, and the vacuum drying oven is set at 60°C and the vacuum degree is -0.1MPa during the preparation of the reinforcing agent.

6. The method for manufacturing metallurgically bonded nickel-coated copper rods and wires according to claim 1, characterized in that, The welding process involves first coarsely grinding the smelted nickel shell with a silicon carbide grinding wheel, then finely grinding it with 800-grit sandpaper. After grinding, UT flaw detection is performed to remove defective products. The nickel back cover is then cleaned and placed on the end face of the qualified nickel shell. The shell is then placed inside a vacuum welding box and welded to the nickel back cover using argon arc welding with the same welding wire as the nickel back cover. After cooling, the shell is removed and the weld bead is ground to match the outer diameter of the nickel shell, thus completing the welding process of the nickel shell.

7. The method for manufacturing metallurgically bonded nickel-coated copper rods and wires according to claim 1, characterized in that, The extrusion process involves placing the welded nickel shell in a high-temperature resistance furnace, heating it to 920°C at a rate of 5-10°C / min, holding it at that temperature for 2 hours, then removing it and placing it in a 1500T extruder to extrude it from a die to obtain a nickel-coated copper rod. The die opening diameter is 28mm. After the nickel-coated copper rod cools, the ends of the rod are cut off, and the rod is then drawn to the required dimensions using a cold drawing process, thus completing the extrusion process.

8. The method for manufacturing metallurgically bonded nickel-coated copper rods and wires according to claim 7, characterized in that, The cold drawing process reduces the diameter by less than 6.3% per drawing, with a drawing speed of 2-5 m / min. After every 2-4 drawing cycles, the material is annealed in a high-temperature annealing furnace at a temperature of 680-720℃ for 2 hours.

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