Red copper diffusion welding method based on interface melting and welding joint

Abstract

The invention provides a red copper diffusion welding method based on interface melting and a welding joint, and relates to the technical field of welding, the diffusion welding method comprises the following steps: copper and nickel are simultaneously sputtered on a to-be-welded surface of a red copper base metal in a magnetron sputtering mode to form a Cu-Ni film on the to-be-welded surface of the red copper base metal, and a first sample is obtained; after the first sample is cleaned for the first time, the first sample is placed in an etchant solution to be heated so as to remove Ni in the Cu-Ni film, and a second sample is obtained; cleaning the second sample for the second time to obtain a third sample; the two third samples are assembled so that the to-be-welded faces of the two third samples can be attached, and an assembly part is obtained; and under the vacuum condition, the assembly part is subjected to spark plasma sintering diffusion welding, and a welding joint is obtained. By the adoption of the method, welding of the red copper base metal can be rapidly achieved at the low temperature, so that the defects that grains of the red copper base metal grow up, the red copper base metal deforms and the like are overcome, and the strength of an obtained welding joint is high.

Description

Technical Field

[0001] This invention relates to the field of welding technology, and more specifically, to a copper diffusion welding method based on interface melting and a welded joint. Background Technology

[0002] Pure copper, or industrial pure copper, is generally called "red copper" because of its rose-red color and the purple hue that forms after an oxide film on its surface. Red copper possesses excellent thermal conductivity, electrical conductivity, machinability, and weldability, and is widely used in aerospace, transportation, petrochemicals, and power electronics. In the application of red copper, the issue of joining is unavoidable. Currently, common welding methods for red copper include fusion welding, brazing, and diffusion welding. Fusion welding, due to its high temperature, can lead to grain growth during the welding process. Furthermore, fusion welding can introduce impurities and alloying elements, causing cracks in the joint. During brazing, the significant difference in composition between the filler metal and the base metal can easily lead to the formation of low-melting-point compounds in the brazed joint, weakening its mechanical properties. Traditional diffusion welding requires high temperature, high pressure, and long holding time. The excessively high welding temperature and long holding time can easily cause defects such as grain growth and deformation in the base metal, and the resulting welded joint has relatively low strength. Summary of the Invention

[0003] The problem solved by this invention is that traditional diffusion welding for copper welding requires high temperature, high pressure and long holding time, which easily leads to defects such as grain growth and deformation of the copper base material, and the strength of the welded joint is low.

[0004] To address the above problems, this invention provides a copper diffusion welding method based on interface melting, comprising: Step S1: Using copper and nickel targets as targets, copper and nickel are simultaneously sputtered on the surface of the copper substrate to be soldered by magnetron sputtering to form a Cu-Ni film on the surface of the copper substrate to be soldered, thus obtaining the first sample. Step S2: After the first sample is cleaned for the first time, it is placed in a corrosion solution for heating treatment to remove Ni from the Cu-Ni film and obtain the second sample. Step S3: The second sample is washed a second time to obtain the third sample; Step S4: Assemble the two third samples so that their surfaces to be welded fit together to obtain an assembly. Step S5: Under vacuum conditions, the assembly is subjected to discharge plasma sintering diffusion welding to obtain a welded joint.

[0005] Optionally, in step S1, the thickness of the Cu-Ni film is 0.3 μm to 5 μm.

[0006] Optionally, in step S1, the mass ratio of Cu to Ni in the Cu-Ni film is (1.5 to 2):1.

[0007] Optionally, in step S5, the temperature of the discharge plasma sintering diffusion welding is 240°C to 260°C, the pressure is 18MPa to 22MPa, and the time is 30min to 60min.

[0008] Optionally, in step S2, the corrosion solution is prepared by mixing dilute sulfuric acid solution and hydrogen peroxide solution in a volume ratio of 1:1, wherein the mass fraction of the dilute sulfuric acid solution is 20% to 30% and the mass fraction of the hydrogen peroxide solution is 6% to 7%.

[0009] Optionally, in step S2, the temperature of the heating treatment is 600°C to 700°C, and the time is 10 min to 15 min.

[0010] Optionally, in step S1, the Cu-Ni film is preferably oriented with a (111) crystal plane.

[0011] Optionally, in step S2, the first cleaning of the first sample includes: The first sample was placed in NaOH solution for alkaline washing for 10 to 15 minutes, then placed in anhydrous ethanol for ultrasonic cleaning for 10 to 15 minutes; then placed in HCl solution for acid washing for 10 to 15 minutes, and then placed in anhydrous ethanol for ultrasonic cleaning for 10 to 15 minutes.

[0012] Optionally, in step S2, the mass fraction of the NaOH solution is 8% to 12%, and the mass fraction of the HCl solution is 6% to 7%.

[0013] The present invention also provides a welded joint, which is made by the copper diffusion welding method based on interface melting as described above.

[0014] Compared with related technologies, this invention uses magnetron sputtering to deposit a mixture of nickel and copper onto the surface of a copper substrate to be welded. Subsequently, the active element nickel is etched away using an etching solution, forming a copper film with a mesh structure on the copper substrate surface. During spark plasma sintering diffusion welding, this mesh structure creates a discontinuous contact interface at the joint, resulting in a higher pulse current density at the joint interface than at the copper substrate. Simultaneously, the higher contact interface resistance creates localized high temperatures at the joint interface, melting only the mesh copper film structure at the interface and filling the gaps. This effectively avoids defects such as grain growth and deformation of the substrate. Furthermore, the use of spark plasma sintering diffusion welding allows for rapid diffusion of interfacial atoms through the synergistic effects of electromigration and electroplasticity, significantly reducing the required welding temperature and time. Additionally, experiments have shown that the welded joints obtained using the method of this invention exhibit high strength. In summary, the method of this invention enables rapid welding of copper base material at relatively low temperatures (240°C to 260°C), thereby avoiding defects such as grain growth and deformation of the copper base material, and the resulting welded joint has high strength. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the copper diffusion welding method based on interface melting in an embodiment of the present invention; Figure 2 This is a scanning electron microscope image of the welded joint obtained in Embodiment 1 of the present invention. Detailed Implementation

[0016] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the present invention. It should be understood that the accompanying drawings and embodiments of the present invention are for illustrative purposes only and are not intended to limit the scope of protection of the present invention.

[0017] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0018] The term "comprising" and its variations as used herein are open-ended, meaning "including but not limited to"; the term "based on" means "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; and the term "optionally" means "optional embodiments". Definitions of other terms will be given in the following description. It should be noted that the concepts of "first," "second," etc., mentioned in this invention are used to distinguish different objects, not to describe a specific order or hierarchy. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0019] like Figure 1 As shown, this embodiment of the invention provides a copper diffusion welding method based on interface melting, comprising: Step S1: Using copper and nickel targets as targets, copper and nickel are simultaneously sputtered on the surface of the copper substrate to be soldered by magnetron sputtering to form a Cu-Ni film on the surface of the copper substrate to be soldered, thus obtaining the first sample. Step S2: After the first sample is cleaned for the first time, it is placed in a corrosion solution for heating treatment to remove Ni from the Cu-Ni film and obtain the second sample. Step S3: The second sample is washed a second time to obtain the third sample; Step S4: Assemble the two third samples so that their surfaces to be welded fit together to obtain an assembly. Step S5: Under vacuum conditions, the assembly is subjected to discharge plasma sintering diffusion welding to obtain a welded joint.

[0020] It should be noted that the surface to be soldered for the third sample refers to the surface on which a thin film has been sputtered.

[0021] In this embodiment of the invention, nickel and copper are mixed and plated onto the surface of a copper substrate to be welded using magnetron sputtering. Subsequently, the active element nickel is etched away using an etching solution, forming a copper film with a mesh structure on the copper substrate surface. During spark plasma sintering diffusion welding, this mesh structure of the copper film creates a discontinuous contact interface at the joint, resulting in a higher pulse current density at the joint interface than at the copper substrate. Simultaneously, the contact interface resistance is higher, creating localized high temperatures at the joint interface. This melts only the mesh copper film structure at the joint interface, filling the gaps and effectively preventing defects such as grain growth and deformation of the substrate. Furthermore, the use of spark plasma sintering diffusion welding allows for rapid diffusion of interface atoms through the synergistic effects of electromigration and electroplasticity, significantly reducing the required welding temperature and time. Additionally, experiments have shown that the welded joints obtained using the method of this embodiment exhibit high strength. In summary, the method of this invention can quickly achieve welding of copper base material at a relatively low temperature (240°C to 260°C), thereby avoiding defects such as grain growth and deformation of copper base material, and the obtained weld joint has high strength.

[0022] In some embodiments of the present invention, in step S1, the thickness of the Cu-Ni film is 0.3 μm to 5 μm.

[0023] In some embodiments of the present invention, in step S1, the mass ratio of Cu to Ni in the Cu-Ni film is (1.5 to 2):1.

[0024] In some embodiments of the present invention, in step S1, the Cu-Ni film is preferably oriented with a (111) crystal plane. Since the (111) crystal plane has the highest atomic diffusion coefficient, it can promote atomic diffusion at the welding interface, further reducing the welding temperature and welding time. In some embodiments of the present invention, in step S2, the etching solution is prepared by mixing dilute sulfuric acid solution and hydrogen peroxide solution in a volume ratio of 1:1, wherein the mass fraction of the dilute sulfuric acid solution is 20% to 30%, and the mass fraction of the hydrogen peroxide solution is 6% to 7%. This etching solution can etch away the Ni in the Cu-Ni film at high temperature.

[0025] In some embodiments of the present invention, in step S2, the temperature of the heat treatment is 600°C to 700°C, and the time is 10 min to 15 min.

[0026] In some embodiments of the present invention, step S2, wherein the first sample is first cleaned, includes: The first sample was placed in NaOH solution for alkaline washing for 10 to 15 minutes, then placed in anhydrous ethanol for ultrasonic cleaning for 10 to 15 minutes; then placed in HCl solution for acid washing for 10 to 15 minutes, and then placed in anhydrous ethanol for ultrasonic cleaning for 10 to 15 minutes; the mass fraction of the NaOH solution was 8% to 12%, and the mass fraction of the HCl solution was 6% to 7%.

[0027] In some embodiments of the present invention, step S2, wherein the second sample is washed a second time, includes: The second sample was placed in NaOH solution for alkaline washing for 10 to 15 minutes, then placed in anhydrous ethanol for ultrasonic cleaning for 10 to 15 minutes; then placed in HCl solution for acid washing for 10 to 15 minutes, and then placed in anhydrous ethanol for ultrasonic cleaning for 10 to 15 minutes; the mass fraction of the NaOH solution was 8% to 12%, and the mass fraction of the HCl solution was 6% to 7%.

[0028] In some embodiments of the present invention, in step S5, the temperature of the discharge plasma sintering diffusion welding is 240°C to 260°C, the pressure is 18MPa to 22MPa, and the time is 30min to 60min.

[0029] Another embodiment of the present invention provides a welded joint, which is made by the copper diffusion welding method based on interface melting as described above.

[0030] The present invention will be further described below with reference to specific embodiments.

[0031] Example 1 A1. Use 800 grit, 1000 grit, 1500 grit and 2000 grit sandpaper to polish the T2 copper base material in sequence, then place it in anhydrous ethanol for ultrasonic cleaning for 30 minutes, and blow dry for later use.

[0032] A2. Using copper and nickel targets as targets, copper and nickel are simultaneously sputtered on the surface of the T2 copper substrate to be soldered by magnetron sputtering to form a Cu-Ni film on the surface of the T2 copper substrate to be soldered, thus obtaining a first sample; wherein the thickness of the Cu-Ni film is 5μm, and the mass ratio of Cu to Ni in the Cu-Ni film is 1.75:1.

[0033] A3. After the first sample is cleaned for the first time, it is placed in a corrosion solution for heating treatment to remove Ni from the Cu-Ni film, thereby obtaining the second sample; wherein, the first cleaning of the first sample includes: placing the first sample in NaOH solution for alkaline washing for 12 min, then placing it in anhydrous ethanol for ultrasonic cleaning for 12 min; then placing it in HCl solution for acid washing for 12 min, and then placing it in anhydrous ethanol for ultrasonic cleaning for 12 min; the mass fraction of the NaOH solution is 10%, and the mass fraction of the HCl solution is 6.5%; the corrosion solution is prepared by mixing dilute sulfuric acid solution and hydrogen peroxide solution in a volume ratio of 1:1, the mass fraction of the dilute sulfuric acid solution is 25%, and the mass fraction of the hydrogen peroxide solution is 6.5%; the heating treatment temperature is 650℃ and the time is 12.5 min.

[0034] A4. The second sample is placed in NaOH solution for alkaline washing for 12 min, then in anhydrous ethanol for ultrasonic cleaning for 12 min; then in HCl solution for acid washing for 12 min, and then in anhydrous ethanol for ultrasonic cleaning for 12 min to obtain the third sample; wherein the mass fraction of the NaOH solution is 10% and the mass fraction of the HCl solution is 6.5%.

[0035] A5. Assemble the two third samples so that their surfaces to be welded fit together to obtain an assembly. A6. Under vacuum conditions, the assembly is subjected to discharge plasma sintering diffusion welding to obtain a welded joint; the discharge plasma sintering diffusion welding temperature is 250℃, the pressure is 20MPa, and the time is 45min.

[0036] Example 2 A1. Use 800 grit, 1000 grit, 1500 grit and 2000 grit sandpaper to polish the T2 copper base material in sequence, then place it in anhydrous ethanol for ultrasonic cleaning for 30 minutes, and blow dry for later use.

[0037] A2. Using copper and nickel targets as targets, copper and nickel are simultaneously sputtered on the surface of the T2 copper substrate to be soldered by magnetron sputtering to form a Cu-Ni film on the surface of the T2 copper substrate to be soldered, thus obtaining a first sample; wherein the thickness of the Cu-Ni film is 5μm, and the mass ratio of Cu to Ni in the Cu-Ni film is 1.75:1.

[0038] A3. After the first sample is cleaned for the first time, it is placed in a corrosion solution for heating treatment to remove Ni from the Cu-Ni film, thereby obtaining the second sample; wherein, the first cleaning of the first sample includes: placing the first sample in NaOH solution for alkaline washing for 10 min, then placing it in anhydrous ethanol for ultrasonic cleaning for 10 min; then placing it in HCl solution for acid washing for 10 min, and then placing it in anhydrous ethanol for ultrasonic cleaning for 10 min; the mass fraction of the NaOH solution is 8%, and the mass fraction of the HCl solution is 6%; the corrosion solution is prepared by mixing dilute sulfuric acid solution and hydrogen peroxide solution in a volume ratio of 1:1, the mass fraction of the dilute sulfuric acid solution is 20%, and the mass fraction of the hydrogen peroxide solution is 6%; the heating treatment temperature is 600℃ and the time is 15 min.

[0039] A4. The second sample is placed in NaOH solution for alkaline washing for 10 min, then in anhydrous ethanol for ultrasonic cleaning for 10 min; then in HCl solution for acid washing for 10 min, and then in anhydrous ethanol for ultrasonic cleaning for 10 min to obtain the third sample; wherein the mass fraction of the NaOH solution is 8% and the mass fraction of the HCl solution is 6%.

[0040] A5. Assemble the two third samples so that their surfaces to be welded fit together to obtain an assembly.

[0041] A6. Under vacuum conditions, the assembly is subjected to discharge plasma sintering diffusion welding to obtain a welded joint; the discharge plasma sintering diffusion welding temperature is 240℃, the pressure is 22MPa, and the time is 60min.

[0042] Example 3 A1. Use 800 grit, 1000 grit, 1500 grit and 2000 grit sandpaper to polish the T2 copper base material in sequence, then place it in anhydrous ethanol for ultrasonic cleaning for 30 minutes, and blow dry for later use.

[0043] A2. Using copper and nickel targets as targets, copper and nickel are simultaneously sputtered on the surface of the T2 copper substrate to be soldered by magnetron sputtering to form a Cu-Ni film on the surface of the T2 copper substrate to be soldered, thus obtaining a first sample; wherein the thickness of the Cu-Ni film is 5μm, and the mass ratio of Cu to Ni in the Cu-Ni film is 1.75:1.

[0044] A3. After the first sample is cleaned for the first time, it is placed in a corrosion solution for heating treatment to remove Ni from the Cu-Ni film, thereby obtaining the second sample; wherein, the first cleaning of the first sample includes: placing the first sample in NaOH solution for alkaline washing for 15 min, then placing it in anhydrous ethanol for ultrasonic cleaning for 15 min; then placing it in HCl solution for acid washing for 15 min, and then placing it in anhydrous ethanol for ultrasonic cleaning for 15 min; the mass fraction of the NaOH solution is 12%, and the mass fraction of the HCl solution is 7%; the corrosion solution is prepared by mixing dilute sulfuric acid solution and hydrogen peroxide solution in a volume ratio of 1:1, the mass fraction of the dilute sulfuric acid solution is 30%, and the mass fraction of the hydrogen peroxide solution is 7%; the heating treatment temperature is 700℃ and the time is 10 min.

[0045] A4. The second sample is placed in NaOH solution for alkaline washing for 15 min, then in anhydrous ethanol for ultrasonic cleaning for 15 min; then in HCl solution for acid washing for 15 min, and then in anhydrous ethanol for ultrasonic cleaning for 15 min to obtain the third sample; wherein the mass fraction of the NaOH solution is 12% and the mass fraction of the HCl solution is 7%.

[0046] A5. Assemble the two third samples so that their surfaces to be welded fit together to obtain an assembly.

[0047] A6. Under vacuum conditions, the assembly is subjected to discharge plasma sintering diffusion welding to obtain a welded joint; the discharge plasma sintering diffusion welding temperature is 260℃, the pressure is 18MPa, and the time is 30min.

[0048] Comparative Example 1 (The surface of the T2 copper base material to be welded has a Cu film) The T2 copper base material was polished sequentially using 800-grit, 1000-grit, 1500-grit, and 2000-grit sandpaper, then ultrasonically cleaned in anhydrous ethanol for 30 minutes, and dried for later use.

[0049] Using a copper target as the target material, copper is sputtered onto the solderable surface of a T2 copper substrate by magnetron sputtering to form a Cu film on the solderable surface of the copper substrate, thus obtaining a first sample; wherein the thickness of the Cu film is 5 μm.

[0050] The first sample was placed in NaOH solution for alkaline washing for 10 to 15 minutes, then placed in anhydrous ethanol for ultrasonic cleaning for 10 to 15 minutes; then placed in HCl solution for acid washing for 10 to 15 minutes, and then placed in anhydrous ethanol for ultrasonic cleaning for 10 to 15 minutes to obtain the second sample; wherein the mass fraction of the NaOH solution was 10% and the mass fraction of the HCl solution was 6%.

[0051] The two second samples are assembled so that their surfaces to be welded fit together to obtain an assembly.

[0052] Under vacuum conditions, the assembly is subjected to discharge plasma sintering diffusion welding to obtain a welded joint; the discharge plasma sintering diffusion welding temperature is 250℃, the pressure is 20MPa, and the time is 45min.

[0053] Experimental Example The welded joint prepared in Example 1 was characterized by scanning electron microscopy, and the results are shown in the figure. Figure 2 ,from Figure 2 It can be seen that the welded joints obtained in Example 1 are of good quality. The shear strength and deformation rate of the welded joints obtained in Examples 1 to 3 and Comparative Example 1 were tested respectively. The results are shown in Table 1. It can be seen from Table 1 that, compared with Comparative Example 1, the welded joints obtained in Examples 1 to 3 have higher shear strength and lower deformation rate.

[0054] Table 1

[0055] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A copper diffusion welding method based on interface melting, characterized in that, include: Step S1: Using copper and nickel targets as targets, copper and nickel are simultaneously sputtered on the surface of the copper substrate to be soldered by magnetron sputtering to form a Cu-Ni film on the surface of the copper substrate to be soldered, thus obtaining the first sample. Step S2: After the first sample is cleaned for the first time, it is placed in a corrosion solution for heating treatment to remove Ni from the Cu-Ni film and obtain the second sample. Step S3: The second sample is washed a second time to obtain the third sample; Step S4: Assemble the two third samples so that their surfaces to be welded fit together to obtain an assembly. Step S5: Under vacuum conditions, the assembly is subjected to discharge plasma sintering diffusion welding to obtain a welded joint.

2. The copper diffusion welding method based on interface melting according to claim 1, characterized in that, In step S1, the thickness of the Cu-Ni film is 0.3 μm to 5 μm.

3. The copper diffusion welding method based on interface melting according to claim 1, characterized in that, In step S1, the mass ratio of Cu to Ni in the Cu-Ni film is (1.5 to 2):

1.

4. The copper diffusion welding method based on interface melting according to claim 1, characterized in that, In step S5, the temperature of the discharge plasma sintering diffusion welding is 240°C to 260°C, the pressure is 18MPa to 22MPa, and the time is 30min to 60min.

5. The copper diffusion welding method based on interface melting according to claim 1, characterized in that, In step S2, the corrosion solution is prepared by mixing dilute sulfuric acid solution and hydrogen peroxide solution in a volume ratio of 1:1, wherein the mass fraction of the dilute sulfuric acid solution is 20% to 30% and the mass fraction of the hydrogen peroxide solution is 6% to 7%.

6. The copper diffusion welding method based on interface melting according to claim 1, characterized in that, In step S2, the heating temperature is 600°C to 700°C, and the time is 10 min to 15 min.

7. The copper diffusion welding method based on interface melting according to claim 1, characterized in that, In step S1, the Cu-Ni film is preferably oriented with a (111) crystal plane.

8. The copper diffusion welding method based on interface melting according to claim 1, characterized in that, In step S2, the first cleaning of the first sample includes: The first sample was placed in NaOH solution for alkaline washing for 10 to 15 minutes, then placed in anhydrous ethanol for ultrasonic cleaning for 10 to 15 minutes; then placed in HCl solution for acid washing for 10 to 15 minutes, and then placed in anhydrous ethanol for ultrasonic cleaning for 10 to 15 minutes.

9. The copper diffusion welding method based on interface melting according to claim 8, characterized in that, In step S2, the NaOH solution has a mass fraction of 8% to 12%, and the HCl solution has a mass fraction of 6% to 7%.

10. A welded joint, characterized in that, It is made by the copper diffusion welding method based on interface melting as described in any one of claims 1 to 9.

Images