Copper-tungsten boron-containing diamond electric resistance welding electrode and preparation method thereof

Abstract

The invention is suitable for the field of metal matrix composite materials, and provides a copper-tungsten boron-containing diamond electric resistance welding electrode and a preparation method thereof, and the electrode material is composed of a copper phase, a tungsten phase and boron-containing diamond powder; the preparation method comprises the following steps: carrying out step-by-step metallization treatment of chemical copper plating and magnetron sputtering nickel on boron-containing diamond powder; the boron-containing diamond powder with the metalized surface and tungsten powder are mixed, subjected to ball milling and then subjected to cold isostatic pressing forming, and a tungsten prefabricated body is obtained; sintering the tungsten preform in a hydrogen or vacuum environment to form a porous tungsten skeleton; and filling pores of the tungsten skeleton through copper infiltration to obtain the copper-tungsten boron-containing diamond electrode material, and finally processing and forming. Through introduction of the conductive boron-containing diamond and a step-by-step metallization process, the contradiction between the conductivity and the wear resistance of a traditional electrode is broken through, meanwhile, the adhesion rate is remarkably reduced, and the method is suitable for welding high-strength steel, plated plates, copper alloys and other easy-adhesion working conditions.

Description

Technical Field

[0001] The present invention belongs to the field of metal matrix composite materials, and in particular relates to a copper-tungsten boron-containing diamond resistance welding electrode and a preparation method thereof. Background Art

[0002] Resistance welding electrode materials are widely used in the automotive, aerospace, and electronics industries. They must simultaneously meet the core performance requirements of high conductivity (to ensure welding efficiency), high hardness and wear resistance (to extend electrode life), and low adhesion (to prevent adhesion between the welding material and the electrode surface). Currently, mainstream technologies include copper-tungsten composites, metal oxide-reinforced copper-based materials, and graphene-reinforced copper-based materials. Copper-tungsten composites have become the industry's leading choice, combining the high conductivity of copper with the high melting point and hardness of tungsten.

[0003] However, traditional copper-tungsten electrodes, hardened by adding metal oxides (such as aluminum oxide) or rare earth oxides, significantly reduce their electrical conductivity, making them difficult to meet the demands of efficient welding. Furthermore, while graphene-enhanced copper matrix materials partially improve conductivity, they suffer from poor wear resistance, making the electrodes susceptible to wear. When welding highly conductive materials (such as copper alloys and plated sheets), the electrode surface easily adheres to the workpiece, reducing weld quality and shortening electrode life. Summary of the Invention

[0004] The purpose of the present invention is to provide a copper-tungsten boron-containing diamond resistance welding electrode and a preparation method thereof, aiming to solve

[0005] The present invention is achieved by providing a copper-tungsten boron-containing diamond resistance welding electrode, comprising:

[0006] Matrix phase: a composite matrix of copper phase and tungsten phase, wherein the copper phase is 10-40wt% and the tungsten phase is 60-90wt%;

[0007] Reinforcement phase: boron-containing diamond powder with a boron doping concentration of 10¹ 9 -10²¹atoms / cm³, mass fraction is 0.5-3%, particle size is 50-400 mesh;

[0008] Metallization layer: A copper-nickel composite metallization layer covering the surface of boron-containing diamond powder, with a total thickness of 0.5-2μm, of which the copper layer accounts for 30-50% of the thickness, and the nickel layer is deposited by magnetron sputtering.

[0009] The method for preparing the copper-tungsten boron-containing diamond resistance welding electrode as described above comprises the following steps:

[0010] S1. Performing a step-by-step metallization treatment on the boron-containing diamond powder: first, immersing the boron-containing diamond powder in a copper sulfate solution and reacting it at 60°C for 30 minutes to deposit a 0.2-0.5 μm copper layer; then, in an argon atmosphere, using a pure nickel target and a sputtering power of 200W, depositing a 0.3-1.5 μm nickel layer to obtain a surface-metallized boron-containing diamond powder;

[0011] S2, mixing the boron-containing diamond powder with the surface metallization treatment in S1 with tungsten powder and ball milling, and cold isostatically pressing to form a preform to obtain a tungsten preform;

[0012] S3, sintering the tungsten preform in S2 in a vacuum environment at a temperature of 1250-1380°C for 2-4 hours to form a tungsten skeleton with a porosity of 18-25%, and placing an electrolytic copper plate under the tungsten skeleton, and performing pressure infiltration in a vacuum environment at 1080-1180°C and a pressure of 15-25 MPa to obtain a copper-tungsten boron-containing diamond electrode material;

[0013] S4. Wire cutting is performed on the electrode material obtained after infiltration, and the surface of the formed object is laser polished.

[0014] The present invention provides a copper-tungsten boron-containing diamond resistance welding electrode and a preparation method thereof, which has the following beneficial effects:

[0015] This copper-tungsten boron-containing diamond resistance welding electrode combines conductive boron-containing diamond with copper-tungsten for the first time, maintaining high conductivity while improving hardness, and limiting the boron doping concentration range to ensure that diamond is transformed from an insulator to a semiconductor / conductor.

[0016] The step-by-step metallization process (copper plating followed by nickel sputtering) solves the problem of poor bonding strength of the boron-containing diamond surface coating. The interface shear strength is increased to ≥150MPa, and the sintering temperature and infiltration pressure (15-25MPa) are coordinated to achieve ultra-high densification with a porosity of ≤0.5%. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0018] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0019] Material composition:

[0020] A copper-tungsten boron-containing diamond resistance welding electrode, comprising:

[0021] Matrix phase: a composite matrix of copper phase and tungsten phase, wherein the copper phase is 10-40wt% and the tungsten phase is 60-90wt%;

[0022] Reinforcement phase: boron-containing diamond powder with a boron doping concentration of 10¹ 9 -10²¹atoms / cm³, mass fraction is 0.5-3%, particle size is 50-400 mesh;

[0023] Metallization layer: A copper-nickel composite metallization layer covering the surface of boron-containing diamond powder, with a total thickness of 0.5-2μm, of which the copper layer accounts for 30-50% of the thickness, and the nickel layer is deposited by magnetron sputtering.

[0024] Preparation method:

[0025] 1. Boron-containing diamond pretreatment

[0026] Chemical copper plating: immerse boron-containing diamond powder in copper sulfate solution, react at 60°C for 30 minutes, and deposit a 0.2-0.5μm copper layer;

[0027] Magnetron sputtering nickel: In an argon atmosphere, the target material is pure nickel, the sputtering power is 200W, and a 0.3-1.5μm nickel layer is deposited to obtain a surface metallized boron-containing diamond powder;

[0028] 2. Preform preparation:

[0029] The tungsten powder was mixed with the surface metallized boron-containing diamond powder by ball milling for 4-8 hours (ball-to-material ratio 5:1, speed 200 rpm);

[0030] Cold isostatic pressing (pressure 300-600 MPa), holding time 10 min;

[0031] 3. Sintering and infiltration:

[0032] Sintering at 1250-1380℃ for 2-4h under vacuum to form a tungsten skeleton with a porosity of 18-25%;

[0033] Copper infiltration: Place the electrolytic copper plate under the sintered tungsten skeleton and perform pressure infiltration in a vacuum or nitrogen atmosphere (pressure 15-25MPa, temperature 1080-1180℃, holding temperature for 2h);

[0034] 4. Post-processing:

[0035] Wire cutting molding, surface laser polishing (roughness Ra ≤ 0.4μm).

[0036] Example 1 (optimal solution)

[0037] Raw material ratio: tungsten powder (300 mesh, 88wt%), boron-containing diamond powder (200 mesh, boron concentration 10² 0 atoms / cm³, 2wt%), electrolytic copper (10wt%).

[0038] Preparation steps:

[0039] 1. Metallization treatment: Chemical copper plating: copper sulfate solution (20g / L), reaction at 60℃ for 30 minutes, depositing a 0.3μm copper layer; magnetron sputtering nickel: argon flow rate 50sccm, power 200W, depositing a 1.0μm nickel layer, obtaining a surface metallized boron-containing diamond powder with an interfacial shear strength of 155MPa.

[0040] 2. Preform preparation: The surface metallized boron-containing diamond powder from step 1 was mixed with tungsten powder, ball milled for 6 hours (ball-to-powder ratio 5:1, speed 200 rpm), and cold isostatically pressed at 500 MPa to obtain a preform with a porosity of 20%.

[0041] 3. Sintering and infiltration: The preform in step 2 was sintered in hydrogen at 1300°C for 3 hours to obtain a tungsten skeleton. An electrolytic copper plate was placed under the tungsten skeleton and vacuum copper infiltrated at 1150°C / 20 MPa for 2 hours to obtain the Cu10W88D2 electrode material.

[0042] 4. Post-processing: The electrode material in step 3 is subjected to wire cutting and laser polishing to Ra = 0.35μm.

[0043] 5. Comparison of electrode material life test:

[0044]

[0045] 6. Test results:

[0046] The service life of the electrode material in Example 1 is 1.8 times that of the traditional copper tungsten 90 electrode material. In addition, the surface of the base material being welded is not easily adhered during welding, and the surface finish of the product is higher than that of the comparative case product.

[0047] Example 2

[0048] Raw material ratio: tungsten powder (300 mesh, 79wt%), boron-containing diamond powder (200 mesh, boron concentration 10² 0 atoms / cm³, 1wt%), electrolytic copper (20wt%).

[0049] Preparation steps:

[0050] 1. Metallization treatment: Chemical copper plating: copper sulfate solution (20g / L), reaction at 60℃ for 30 minutes, depositing a 0.4μm copper layer; magnetron sputtering nickel: argon flow rate 60sccm, power 200W, depositing a 1.0μm nickel layer, obtaining a surface metallized boron-containing diamond powder with an interfacial shear strength of 160MPa.

[0051] 2. Preform preparation: The surface metallized boron-containing diamond powder from step 1 was mixed with tungsten powder, ball milled for 5 hours (ball-to-powder ratio 5:2, speed 300 rpm), and cold isostatically pressed at 600 MPa to obtain a preform with a porosity of 25%.

[0052] 3. Sintering and infiltration: The preform in step 2 was sintered in hydrogen at 1350°C for 3 hours to obtain a tungsten skeleton. An electrolytic copper plate was placed under the tungsten skeleton and copper infiltrated at 1180°C / 20 MPa for 2 hours to obtain the Cu20W79D1 electrode material.

[0053] 4. Post-processing: The electrode material in step 3 is subjected to wire cutting and laser polishing to Ra = 0.3 μm.

[0054] 5. Comparison of electrode material life test

[0055]

[0056] 5. Test results:

[0057] The electrode material in Example 2 has a service life 1.75 times that of conventional copper-tungsten 80 electrode materials. Furthermore, the surface of the base metal being welded is less susceptible to adhesion during welding. Conventional copper-tungsten 80 exhibits adhesion and tip failure after approximately 9,100 welds. The electrode material in Example 2 exhibited no adhesion after approximately 16,000 welds, with only surface irregularities present. However, to ensure the reliability of the welded product, failure was determined at this point. Comparative testing demonstrates that the patented product of this invention significantly improves the performance of conventional electrode materials.

[0058] 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 in the scope of protection of the present invention.

Claims

1. A copper-tungsten boron-containing diamond resistance welding electrode, characterized in that: The copper-tungsten boron-containing diamond resistance welding electrode comprises: Matrix phase: a composite matrix of copper phase and tungsten phase, wherein the copper phase is 10-40wt% and the tungsten phase is 60-90wt%; Reinforcement phase: boron-containing diamond powder with a boron doping concentration of 10¹ 9 -10²¹atoms / cm³, mass fraction 0.5-3%, particle size 50-400 mesh; Metallization layer: A copper-nickel composite metallization layer covering the surface of boron-containing diamond powder, with a total thickness of 0.5-2μm, of which the copper layer accounts for 30-50% of the thickness, and the nickel layer is deposited by magnetron sputtering; In the copper-nickel composite metallization layer, the thickness of the chemically plated copper layer is 0.2-0.5 μm, and the thickness of the magnetron sputtered nickel layer is 0.3-1.5 μm; The method for preparing the copper-tungsten boron-containing diamond resistance welding electrode comprises the following steps: S1. Performing a step-by-step metallization treatment on the boron-containing diamond powder: first, immersing the boron-containing diamond powder in a copper sulfate solution and reacting it at 60°C for 30 minutes to deposit a 0.2-0.5 μm copper layer; then, in an argon atmosphere, using a pure nickel target and a sputtering power of 200W, depositing a 0.3-1.5 μm nickel layer to obtain a surface-metallized boron-containing diamond powder; S2, mixing the surface metallized boron-containing diamond powder and tungsten powder in S1 with ball milling, and cold isostatically pressing to form a preform to obtain a tungsten preform; S3, sintering the tungsten preform in S2 in a vacuum environment at a temperature of 1250-1380°C for 2-4 hours to form a tungsten skeleton with a porosity of 18-25%, and placing an electrolytic copper plate under the tungsten skeleton, and performing pressure infiltration in a vacuum environment at 1080-1180°C and a pressure of 15-25 MPa to obtain a copper-tungsten boron-containing diamond electrode material; S4. Wire cutting is performed on the electrode material obtained after infiltration, and the surface of the formed object is laser polished.

2. The method for preparing the copper-tungsten boron-containing diamond resistance welding electrode according to claim 1, characterized in that: The ball-to-material ratio of the mixed ball mill in S2 is 5:1, the rotation speed is 200 rpm, and the mixing time is 4-8 hours.

3. The method for preparing the copper-tungsten boron-containing diamond resistance welding electrode according to claim 1, characterized in that: The cold isostatic pressing pressure in S2 is 300-600 MPa, and the holding time is 10 minutes.

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