Copper alloy material for high-voltage direct-current relay contact and preparation method of copper alloy material

Abstract

The invention provides a copper alloy material for a high-voltage direct-current relay contact and a preparation method of the copper alloy material, and belongs to the technical field of preparation of alloy materials. The copper alloy material for the high-voltage direct-current relay contact, provided by the invention, contains 0.6%-0.7% of tellurium, 0.004%-0.012% of lanthanum, 0.002%-0.006% of boron and the balance of copper and inevitable impurities. The properties of the copper alloy material prepared by the method are as follows: the conductivity is greater than or equal to 90% IACS, the hardness is 110-130 HV, the tensile strength Rm is greater than or equal to 350 MPa, the percentage elongation after fracture is greater than or equal to 8%, and the high-temperature softening resistance temperature is greater than or equal to 420 DEG C. The material has excellent conductivity, arc ablation resistance, fusion welding resistance, high mechanical strength and high-temperature softening resistance, and can meet the application requirements of high-voltage direct-current relays in the fields of new energy automobiles and the like.

Description

Technical Field

[0001] This invention belongs to the field of alloy material preparation technology, specifically relating to a copper alloy material for high-voltage DC relay contacts and its preparation method. Background Technology

[0002] With the rapid development of the new energy vehicle industry, high-voltage DC relays, as key components in the electrical systems of new energy vehicles, are crucial for their reliability and stability. The contacts, as the core components of high-voltage DC relays, need to possess excellent conductivity, resistance to arc erosion, resistance to welding, and high mechanical strength.

[0003] Currently, traditional high-voltage DC relay contact materials mostly use cathode copper or silver-based alloys. While cathode copper has good electrical and thermal conductivity, its resistance to arc erosion and welding is poor. During high-current switching, the contacts are easily eroded and welded by the arc, leading to a shortened contact life and affecting the relay's reliability. Although silver-based alloys have better resistance to arc erosion and welding, their high cost and scarcity limit their large-scale application.

[0004] To improve the performance of high-voltage DC relay contacts, researchers have prepared copper alloys by adding other elements to the copper matrix. For example, adding tellurium can effectively improve the arc erosion resistance of copper alloys because tellurium has extremely low solid solubility in copper and disperses in the copper matrix as fine second-phase particles. These second-phase particles can hinder arc erosion and play a role in arc extinguishing. However, copper alloys with only tellurium addition still have certain limitations in terms of overall performance, such as mechanical strength and resistance to high-temperature softening, which need further improvement.

[0005] In addition, the application of rare earth elements such as lanthanum in copper alloys is gradually attracting attention. Rare earth elements can purify the composition of molten alloys, refine grains, and improve grain boundaries, thereby enhancing the overall performance of copper alloys. However, how to precisely control the amount of rare earth elements added to copper alloys and how to make them synergistic with other elements to obtain high-performance copper alloy materials remains a key research focus and challenge.

[0006] Therefore, how to select rare earth elements to prepare copper alloy materials in order to obtain a copper alloy material with excellent electrical conductivity, resistance to arc erosion, resistance to welding, as well as high mechanical strength and resistance to high temperature softening, so as to meet the application requirements of high voltage DC relays in new energy vehicles and other fields, has become an urgent technical problem to be solved. Summary of the Invention

[0007] The present invention aims to solve the aforementioned technical problems by providing a copper alloy material for high-voltage DC relay contacts and its preparation method. The technical objective of this invention is to provide a copper alloy material for high-voltage DC relay contacts and its preparation method. This material possesses excellent electrical conductivity, resistance to arc erosion, resistance to welding, as well as high mechanical strength and resistance to high-temperature softening, meeting the application requirements of high-voltage DC relays in fields such as new energy vehicles. Furthermore, this invention also provides a simple, easy-to-operate method for preparing the copper alloy material, enabling large-scale industrial production.

[0008] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0009] This invention first provides a method for preparing copper alloy material for high-voltage DC relay contacts. The elemental composition of the copper alloy material for high-voltage DC relay contacts, by mass percentage, includes: 0.6-0.7% tellurium, 0.004-0.012% lanthanum, 0.002-0.006% boron, with the balance being copper and unavoidable impurities.

[0010] The method for preparing the copper alloy material for the high-voltage DC relay contacts includes the following steps:

[0011] (1) Ingredients: Weigh out the cathode copper, tellurium, lanthanum copper master alloy and boron copper master alloy according to the mass percentage;

[0012] (2) Smelting: Add the cathode copper to the vacuum induction melting furnace and heat it to 1150-1200℃ to completely melt the cathode copper; then add tellurium, stir evenly, and keep it at the temperature for 10-15 minutes; add lanthanum copper master alloy, continue to stir evenly, and keep it at the temperature for 5-10 minutes; finally add boron copper master alloy, continue to stir evenly, and keep it at the temperature for 5-10 minutes to obtain copper alloy melt.

[0013] (3) Casting: The temperature of the molten copper alloy is controlled at 1170-1190℃, and poured into a high-purity graphite mold preheated to 300-350℃ for casting to obtain copper alloy ingots.

[0014] (4) Homogenization annealing: The copper alloy ingot is placed in an annealing furnace for homogenization annealing, and then cooled to room temperature with the furnace to eliminate compositional segregation and residual stress inside the ingot.

[0015] (5) Hot extrusion molding: The copper alloy ingot after homogenization and annealing in step (4) is heated to 800℃±10℃ and hot extruded to obtain the extruded billet.

[0016] (6) Pickling + First cold drawing: The extruded billet from step (5) is soaked in acid for 15 minutes, then washed with high pressure water to remove the residual acid and its oxides on the surface, and then hydraulically drawn.

[0017] (7) Aging treatment: The copper alloy material after cold drawing in step (6) is placed in an aging furnace for aging treatment, and then air-cooled to room temperature to allow the second phase particles in the copper alloy to be fully released, thereby improving the strength and hardness of the alloy.

[0018] (8) Pickling + Second cold drawing: The aged billet from step (7) is soaked in acid for 15 minutes, then the residual acid and its oxides are washed away with high pressure water, and then hydraulic drawing is performed again.

[0019] (9) Straighten, polish and cut to length the bar after drawing deformation in step (8).

[0020] Furthermore, in step (1), the purity of the cathode copper is: copper content ≥ 99.95%; the purity of tellurium is: tellurium content ≥ 99.99%; the lanthanum content in the lanthanum copper master alloy is 20% ± 2%; and the boron content in the boron copper master alloy is 5% ± 1%.

[0021] Furthermore, the vacuum degree of the vacuum induction melting furnace described in step (2) is ≤10. -3 Pa.

[0022] Furthermore, the casting temperature in step (3) is 1170℃~1190℃.

[0023] Furthermore, in step (4), the homogenization annealing temperature is 750-850℃ and the holding time is 5-8h.

[0024] Furthermore, in step (5), a horizontal extrusion press of type 850 is used for hot extrusion molding.

[0025] Furthermore, in step (6), the hydraulic drawing process uses a total deformation of 50% ± 1% and a single-pass deformation of 15% to 25%.

[0026] Furthermore, the aging treatment in step (7) is carried out at a temperature of 300–350°C for 2–4 hours.

[0027] Furthermore, in step (8), hydraulic drawing is performed again with a total deformation of 50% ± 1% and a single-pass deformation of 15% to 25%.

[0028] A second objective of this invention is to provide a copper alloy material for high-voltage DC relay contacts prepared by the method described in any of the preceding claims. At room temperature, it exhibits a conductivity ≥90% IACS, a hardness of 110–130 HV, a tensile strength Rm ≥350 MPa, an elongation after fracture ≥8%, and a high-temperature softening temperature ≥420℃, demonstrating extremely excellent overall performance.

[0029] The beneficial effects of this invention are as follows:

[0030] (1) This invention utilizes the excellent comprehensive properties of copper alloy materials prepared by adding appropriate amounts of tellurium, lanthanum, and boron to a copper matrix, taking advantage of tellurium's resistance to arc erosion and lanthanum and boron's effects of purifying the alloy liquid, refining grains, and improving grain boundaries. Tellurium, dispersed in the copper matrix as fine second-phase particles, effectively hinders arc erosion and improves the alloy's resistance to arc erosion. Lanthanum purifies the alloy liquid, reducing the influence of impurities, while refining grains, improving the alloy's strength and toughness, improving grain boundary properties, and enhancing the alloy's resistance to high-temperature softening. Boron also refines grains, improves strength and corrosion resistance, and acts as a deoxidizer or additive, reducing porosity defects during copper processing and improving material purity.

[0031] (2) The preparation method of the present invention is simple and easy to operate. By reasonably controlling the process parameters such as melting, casting, homogenization annealing, hot extrusion molding, cold drawing molding and aging treatment, the microstructure and properties of copper alloy materials can be precisely controlled, ensuring the stability and consistency of product quality, and making it suitable for large-scale industrial production.

[0032] (3) The copper alloy material prepared by the present invention has high conductivity, which can meet the requirements of high voltage DC relay for conductivity performance; at the same time, it has good anti-arc erosion performance, anti-welding performance, high mechanical strength and high temperature softening performance, which can effectively improve the service life and reliability of high voltage DC relay, and has broad application prospects in the fields of new energy vehicles, smart grids and the like. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention is described in detail below with reference to embodiments. It should be noted that the following embodiments are for explanation and illustration only and are not intended to limit the invention. Non-essential improvements and adjustments made by those skilled in the art based on the above description are still within the scope of protection of this invention.

[0034] Example 1

[0035] A method for preparing copper alloy material for high-voltage DC relay contacts includes the following steps:

[0036] (1) Ingredients: Weigh 99.26 kg of cathode copper with a purity of 99.95%, 0.62 kg of tellurium with a purity of 99.99%, 0.04 kg of copper-lanthanum master alloy containing lanthanum (20%), and 0.08 kg of copper-boron master alloy containing boron (5%).

[0037] (2) Smelting: Cathode copper is added to a vacuum induction melting furnace, and smelting is carried out under a vacuum of 10... -3 Under the condition of Pa, heat to 1150℃±10℃ to completely melt the cathode copper; then add tellurium, stir evenly, and keep warm for 15 min; add lanthanum copper master alloy, continue to stir evenly, keep warm for 10 min; add copper boron master alloy, continue to stir evenly, and keep warm for 10 min to obtain copper alloy melt.

[0038] (3) Casting: The molten copper alloy is poured into a high-purity graphite mold preheated to 300°C at a casting temperature of 1180°C to form a copper alloy ingot.

[0039] (4) Homogenization annealing: Place the copper alloy ingot into the annealing furnace, hold it at 750°C for 8 hours, and then cool it to room temperature with the furnace.

[0040] (5) Hot extrusion forming: The homogenized and annealed copper alloy ingot is heated to 800℃±10℃ and hot extruded using an 850-type horizontal extrusion press. mm, extruded billet size

[0041] (6) Pickling + First Cold Drawing: The extruded billet is immersed in acid for 15 minutes, and then washed with high-pressure water to remove residual acid and its oxides. Then, hydraulic drawing is performed. The drawing process is as follows: Pulling at a constant speed.

[0042] (7) Aging treatment: The cold-drawn copper alloy bar is placed in an aging furnace and held at 300°C for 4 hours, and then air-cooled to room temperature.

[0043] (8) Pickling + Second Cold Drawing: The aged billet is immersed in acid for 15 minutes, and then washed with high-pressure water to remove residual acid and its oxides. Then, hydraulic drawing is performed. The drawing process is as follows: Pull out at a constant speed and straighten.

[0044] According to the test results, the copper alloy rods prepared by the production method described above have the following properties: tensile strength Rm = 365 MPa, elongation 11%, HV = 120, conductivity 91% IACS, and high temperature softening temperature 420℃.

[0045] Example 2

[0046] A method for preparing copper alloy material for high-voltage DC relay contacts includes the following steps:

[0047] (1) Ingredients: Weigh 99.20 kg of cathode copper with a purity of 99.95%, 0.65 kg of tellurium with a purity of 99.99%, 0.05 kg of copper-lanthanum master alloy containing lanthanum (20%), and 0.10 kg of copper-boron master alloy containing boron (5%).

[0048] (2) Smelting: Add the cathode copper to the vacuum induction melting furnace and heat it to 1150℃±10℃ under a vacuum of 10-3Pa to completely melt the cathode copper; then add tellurium, stir evenly, and keep warm for 15min; add copper lanthanum master alloy, continue to stir evenly, keep warm for 10min, add copper boron master alloy, continue to stir evenly, keep warm for 10min to obtain copper alloy melt.

[0049] (3) Casting: The molten copper alloy is poured into a high-purity graphite mold preheated to 350°C at a casting temperature of 1190°C to form a copper alloy ingot.

[0050] (4) Homogenization annealing: Place the copper alloy ingot into the annealing furnace, hold it at 800℃ for 6 hours, and then cool it to room temperature with the furnace.

[0051] (5) Hot extrusion forming: The homogenized and annealed copper alloy ingot is heated to 800℃±10℃ and hot extruded using an 850-type horizontal extrusion press. Extruded billet dimensions

[0052] (6) Pickling + First Cold Drawing: The extruded billet is immersed in acid for 15 minutes, and then washed with high-pressure water to remove residual acid and its oxides. Then, hydraulic drawing is performed. The drawing process is as follows: Pulling at a constant speed.

[0053] (7) Aging treatment: The cold-drawn copper alloy bar is placed in an aging furnace and held at 300°C for 4 hours, and then air-cooled to room temperature.

[0054] (8) Pickling + Second Cold Drawing: The aged billet is immersed in acid for 15 minutes, and then washed with high-pressure water to remove residual acid and its oxides. Then, hydraulic drawing is performed. The drawing process is as follows: Pull out at a constant speed and straighten.

[0055] According to the test, the copper alloy rod prepared by the production method described above has the following properties: tensile strength Rm = 370 MPa, elongation 11%, HV = 119, conductivity 91% IACS, and high temperature softening temperature 425℃.

[0056] Example 3

[0057] A method for preparing copper alloy material for high-voltage DC relay contacts includes the following steps:

[0058] (1) Ingredients: Weigh 99.14 kg of cathode copper with a purity of 99.95%, 0.68 kg of tellurium with a purity of 99.99%, 0.06 kg of copper-lanthanum master alloy containing lanthanum (20%), and 0.12 kg of copper-boron master alloy containing boron (5%).

[0059] (2) Smelting: Add the cathode copper to the vacuum induction melting furnace and heat it to 1150℃±10℃ under a vacuum of 10-3Pa to completely melt the cathode copper; then add tellurium, stir evenly, and keep warm for 15min; add copper lanthanum master alloy, continue to stir evenly, keep warm for 10min, add copper boron master alloy, continue to stir evenly, keep warm for 10min to obtain copper alloy melt.

[0060] (3) Casting: The molten copper alloy liquid is poured into a high-purity graphite mold preheated to 300°C at a casting temperature of 1175°C to form a copper alloy ingot.

[0061] (4) Homogenization annealing: Place the copper alloy ingot into the annealing furnace, hold it at 850°C for 5 hours, and then cool it to room temperature with the furnace.

[0062] (5) Hot extrusion forming: The homogenized and annealed copper alloy ingot is heated to 800℃±10℃ and hot extruded using an 850-type horizontal extrusion press. Extruded billet dimensions

[0063] (6) Pickling + First Cold Drawing: The extruded billet is immersed in acid for 15 minutes, and then washed with high-pressure water to remove residual acid and its oxides. Then, hydraulic drawing is performed. The drawing process is as follows: Pulling at a constant speed.

[0064] (7) Aging treatment: The cold-drawn copper alloy bar is placed in an aging furnace and held at 300°C for 4 hours, and then air-cooled to room temperature.

[0065] (8) Pickling + Second Cold Drawing: The aged billet is immersed in acid for 15 minutes, and then washed with high-pressure water to remove residual acid and its oxides. Then, hydraulic drawing is performed. The drawing process is as follows: Pulling at a constant speed.

[0066] According to the test, the copper alloy rod prepared by the production method described above has the following properties: tensile strength Rm = 371 MPa, elongation 12%, HV+118, conductivity 91% IACS, and high temperature softening temperature 420℃.

[0067] The test results show that the copper alloy material prepared by this invention has excellent electrical conductivity, high hardness and tensile strength, good plasticity and high high temperature softening temperature, which can meet the performance requirements of high voltage DC relay contacts.

[0068] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a copper alloy material for high-voltage DC relay contacts, characterized in that, The elemental composition of the copper alloy material used for the high-voltage DC relay contacts, by mass percentage, includes: 0.6-0.7% tellurium, 0.004-0.012% lanthanum, 0.002-0.006% boron, with the balance being copper and unavoidable impurities; The method for preparing the copper alloy material for the high-voltage DC relay contacts includes the following steps: (1) Ingredients: Weigh out the cathode copper, tellurium, lanthanum copper master alloy and boron copper master alloy according to the mass percentage; (2) Smelting: Add the cathode copper to the vacuum induction melting furnace and heat it to 1150-1200℃ to completely melt the cathode copper; then add tellurium, stir evenly, and keep it at the temperature for 10-15 minutes; add lanthanum copper master alloy, continue to stir evenly, and keep it at the temperature for 5-10 minutes; finally add boron copper master alloy, continue to stir evenly, and keep it at the temperature for 5-10 minutes to obtain copper alloy melt. (3) Casting: The temperature of the molten copper alloy is controlled at 1170-1190℃, and poured into a high-purity graphite mold preheated to 300-350℃ for casting to obtain copper alloy ingots. (4) Homogenization annealing: The copper alloy ingot is placed in an annealing furnace for homogenization annealing, and then cooled to room temperature with the furnace to eliminate compositional segregation and residual stress inside the ingot. (5) Hot extrusion molding: The copper alloy ingot after homogenization and annealing in step (4) is heated to 800℃±10℃ and hot extruded to obtain the extruded billet. (6) Pickling + First cold drawing: The extruded billet from step (5) is soaked in acid for 15 minutes, then washed with high pressure water to remove the residual acid and its oxides on the surface, and then hydraulically drawn. (7) Aging treatment: The copper alloy material after cold drawing in step (6) is placed in an aging furnace for aging treatment, and then air-cooled to room temperature to allow the second phase particles in the copper alloy to be fully released, thereby improving the strength and hardness of the alloy. (8) Pickling + Second cold drawing: The aged billet from step (7) is soaked in acid for 15 minutes, then the residual acid and its oxides are washed away with high pressure water, and then hydraulic drawing is performed again. (9) Straighten, polish and cut to length the bar after drawing deformation in step (8).

2. The method for preparing the copper alloy material for high-voltage DC relay contacts according to claim 1, characterized in that, In step (1), the purity of the cathode copper is: copper content ≥ 99.95%; the purity of tellurium is: tellurium content ≥ 99.99%; the lanthanum content in the lanthanum copper master alloy is 20% ± 2%; and the boron content in the boron copper master alloy is 5% ± 1%.

3. The method for preparing copper alloy material for high-voltage DC relay contacts according to claim 1, characterized in that, The vacuum degree of the vacuum induction melting furnace mentioned in step (2) is ≤10. -3 Pa.

4. The method for preparing copper alloy material for high-voltage DC relay contacts according to claim 1, characterized in that, In step (3), the casting temperature is 1170℃~1190℃.

5. The method for preparing the copper alloy material for high-voltage DC relay contacts according to claim 1, characterized in that, In step (4), the homogenization annealing temperature is 750-850℃ and the holding time is 5-8h.

6. The method for preparing the copper alloy material for high-voltage DC relay contacts according to claim 1, characterized in that, In step (5), a horizontal extrusion press of type 850 is used for hot extrusion molding.

7. The method for preparing the copper alloy material for high-voltage DC relay contacts according to claim 1, characterized in that, In step (6), the hydraulic drawing process uses a total deformation of 50% ± 1% and a single-pass deformation of 15% to 25%.

8. The method for preparing copper alloy material for high-voltage DC relay contacts according to claim 1, characterized in that, The aging treatment in step (7) is carried out at a temperature of 300-350°C for 2-4 hours.

9. The method for preparing copper alloy material for high-voltage DC relay contacts according to claim 1, characterized in that, In step (8), hydraulic drawing is performed again with a total deformation of 50% ± 1% and a single-pass deformation of 15% to 25%.

10. A copper alloy material for high-voltage DC relay contacts prepared by the method according to any one of claims 1-9.