Manufacturing method of high-strength welding joint of second-generation high-temperature superconducting strip

Abstract

The invention discloses a manufacturing method of a high-strength welding joint of a second-generation high-temperature superconducting tape, and relates to the technical field of welding joints, and the manufacturing method comprises the following steps: S1, cleaning the surface of the second-generation high-temperature superconducting tape; s2, cutting a plurality of uniformly distributed holes in the surface of the second-generation high-temperature superconducting strip by using laser; and S3, the two second-generation high-temperature superconducting strips are aligned, and the surfaces of the second-generation high-temperature superconducting strips in the to-be-welded area are evenly coated with the welding agent with the uniform thickness. According to the manufacturing method of the high-strength welding joint of the second-generation high-temperature superconducting tape, the superconducting tape is punched, and the copper columns are inserted, so that the structure of a bolt-welding mixed joint can be formed, the connection strength of the joint is improved, and electrical properties such as critical current and joint resistance of the joint cannot be affected.

Description

Technical Field

[0001] The invention relates to the technical field of welded joints, and in particular to a method for manufacturing a high-strength welded joint of a second-generation high-temperature superconducting tape. Background Art

[0002] As an important part in superconducting applications, high-temperature superconducting tape joints are of great significance for the practical application and repair of high-temperature superconducting devices. At present, the manufacturing process of superconducting tape welding joints has the advantages of simple operation and rapidity, and is widely used in practical applications. Under working conditions, the joint part will also be subjected to complex loads such as temperature stress and electromagnetic force. Therefore, an improved manufacturing process is needed to produce high-temperature superconducting tape joints with low resistance, no critical current degradation, and good mechanical properties.

[0003] The main connection processes for high-temperature superconducting tapes include welding joints, diffusion joints and melt diffusion joints. Compared with the other two methods, melt diffusion joints are the most likely to achieve superconducting joints, but their manufacturing process is complex and very time-consuming. Moreover, the mechanical strength of melt diffusion joints and diffusion joints is low, and it is difficult to withstand the load under working conditions. Welded joints can achieve lower resistance at a certain welding length, but their mechanical strength still needs to be further strengthened, especially the debonding strength in the thickness direction.

[0004] The existing method for making high-strength welded joints of second-generation high-temperature superconducting tapes often only uses welding agent to weld on the surface of the second-generation high-temperature superconducting tapes. However, this will change the surface shape of the second-generation high-temperature superconducting tapes, thereby affecting the electrical properties of the tape joints, such as critical current and joint resistance. In addition, the current second-generation high-temperature superconducting tapes are only connected by welding, which will result in insufficient connection strength of the joints. Summary of the invention

[0005] 1. Technical issues to be resolved In view of the deficiencies in the prior art, the present invention provides a method for manufacturing a high-strength welded joint of a second-generation high-temperature superconducting tape, which solves the problem that when welding the second-generation high-temperature superconducting tape, only welding is often performed on the surface of the tape, which will change the surface shape of the second-generation high-temperature superconducting tape, thereby affecting the electrical properties of the tape joint, such as the critical current and joint resistance. In addition, the current second-generation high-temperature superconducting tape is only connected by welding, which will result in insufficient connection strength of the joint.

[0006] (II) Technical solution To achieve the above objectives, the present invention is implemented through the following technical solutions: A method for making a high-strength welded joint of a second-generation high-temperature superconducting tape, comprising the following steps: S1. Cleaning the surface of the second generation high temperature superconducting tape; S2, using a laser to cut multiple evenly spaced holes on the surface of the second-generation high-temperature superconducting tape; S3, aligning the two second-generation high-temperature superconducting tapes, and applying a uniform thickness of welding agent on the surface of the second-generation high-temperature superconducting tape in the area to be welded; S4, prepare a copper pillar with a size matching the hole, apply a uniform thickness of solder on its side and insert it into the hole; S5. Assemble the second-generation high-temperature superconducting tapes and copper columns coated with welding agent, and perform pressure welding on a welding table until the welding is completed.

[0007] Preferably, in step S1, 300-grit sandpaper is used to polish the surface of the second-generation high-temperature superconducting tape to remove impurities and oxides on the surface of the second-generation high-temperature superconducting tape.

[0008] Preferably, in step S1, the second-generation high-temperature superconducting tape polished with sandpaper is immersed in a diluted hydrochloric acid solution to further remove impurities and oxides on the surface of the second-generation high-temperature superconducting tape.

[0009] Preferably, in step S2, the number of holes cut by the laser is not less than 9, and the radius is small enough, so that the critical current of the second-generation high-temperature superconducting tape is reduced by no more than 10%. By designing holes with a smaller radius, the critical current of the second-generation high-temperature superconducting tape can be reduced to a relatively small extent, and the hole setting with a sufficiently small radius is selected so that the critical current of the second-generation high-temperature superconducting tape is reduced by no more than 10%, thereby preventing the hole radius from being too large and affecting the electrical properties of the tape such as the critical current and joint resistance.

[0010] Preferably, in the step S3, the solder on the surface of the second-generation high-temperature superconducting tape can be any one of tin-based solder, silver-based solder, gold-based solder, indium-tin alloy, silver-copper alloy and indium-based solder. The two end faces of the second-generation high-temperature superconducting tape 1 can be welded by any one of the above solders, and the selectivity is relatively strong when used.

[0011] Preferably, in step S4, the material of the copper column can be selected from any one of stainless steel, aluminum and silver. Stainless steel, aluminum and silver are metal materials with good conductivity. The conductivity of the second-generation high-temperature superconducting tape is reduced less by these materials, thereby having less impact on the electrical properties of its joints, such as the critical current and joint resistance.

[0012] Preferably, in step S4, a uniform thickness of solder is applied to the inner wall of the hole. By applying the uniform solder to the inside of the hole, the copper column can be welded more firmly in the hole.

[0013] Preferably, in step S5, during the welding process, the pressure applied in the welding area is maintained at about 20 MPa, and the applied pressure can ensure that the second-generation high-temperature superconducting tape is more stable and firm during welding.

[0014] (III) Beneficial effects The present invention provides a method for manufacturing a high-strength welded joint of a second-generation high-temperature superconducting tape. It has the following beneficial effects: (1) The method for making a high-strength welded joint of the second-generation high-temperature superconducting tape comprises the following steps: drilling holes in the surface of the second-generation high-temperature superconducting tape and inserting copper pillars, making their surfaces smooth, and then welding them to form a bolt-welded hybrid joint structure, which improves the strength of the joint and does not affect the electrical properties of the joint, such as the critical current and joint resistance.

[0015] (ii) The method for making a high-strength welded joint of the second-generation high-temperature superconducting tape has a small impact on the electrical properties of the joint, such as the critical current and joint resistance, because the copper column can be replaced with any one of stainless steel, aluminum and silver, that is, any metal material with good electrical conductivity. The material of the copper column can be selected and used as needed, making the method widely applicable and selectable.

[0016] (III) The method for making the high-strength welded joint of the second-generation high-temperature superconducting tape can make the welding between the tape and the copper column more firm and the connection strength stronger by evenly applying welding agent to the area to be welded of the tape, the surface of the copper column and the inner wall of the hole. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the welding joint of the present invention; Figure 2 This is a schematic diagram of the disassembled structure of the welding joint of the present invention.

[0018] In the figure: 1. Second-generation high-temperature superconducting tape; 2. Holes; 3. Copper pillars; 4. Solder layer. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] See also Figure 1-2A high-strength welding joint of a second-generation high-temperature superconducting tape comprises a second-generation high-temperature superconducting tape 1. The number of the second-generation high-temperature superconducting tapes 1 is set to two. Holes 2 are opened on the surfaces of the two second-generation high-temperature superconducting tapes 1. The number of holes 2 is set to multiple. Copper pillars 3 are inserted into the inside of the holes 2. The common contact areas of the two second-generation high-temperature superconducting tapes 1 are coated with a solder layer 4.

[0021] A method for manufacturing a high-strength welded joint of a second-generation high-temperature superconducting tape comprises the following steps: S1, cleaning the surface of the second-generation high-temperature superconducting tape 1; S2, cutting a plurality of evenly arranged holes 2 on the surface of the second-generation high-temperature superconducting tape 1 using a laser; S3, aligning two second-generation high-temperature superconducting tapes 1, and applying a uniform thickness of welding agent on the surface of the second-generation high-temperature superconducting tapes 1 in the area to be welded; S4, prepare a copper column 3 with a size matching the hole 2, apply a uniform thickness of solder on its side and insert it into the hole 2; S5. Assemble the second-generation high-temperature superconducting tape 1 and the copper column 3 coated with welding agent, and perform pressure welding on a welding table until the welding is completed.

[0022] Wherein, in step S1, the surface of the second-generation high-temperature superconducting tape 1 is polished with 300-grit sandpaper to remove impurities and oxides on the surface of the second-generation high-temperature superconducting tape 1.

[0023] Wherein, in step S1, the second-generation high-temperature superconducting tape 1 polished with sandpaper is immersed in a diluted hydrochloric acid solution to further remove impurities and oxides on the surface of the second-generation high-temperature superconducting tape 1.

[0024] Among them, in step S2, the number of holes 2 cut by laser is not less than 9, and the radius is small enough, so that the critical current of the second-generation high-temperature superconducting tape 1 is reduced by no more than 10%. By designing holes 2 with smaller radius, the critical current of the second-generation high-temperature superconducting tape 1 can be reduced to a relatively small extent, and the holes 2 with a sufficiently small radius are selected to set so that the critical current of the second-generation high-temperature superconducting tape 1 is reduced by no more than 10%, thereby preventing the radius of the holes 2 from being too large and affecting the electrical properties of the tape such as the critical current and joint resistance.

[0025] Among them, in step S3, the solder on the surface of the second-generation high-temperature superconducting tape 1 can be any one of tin-based solder, silver-based solder, gold-based solder, indium-tin alloy, silver-copper alloy and indium-based solder. The two end faces of the second-generation high-temperature superconducting tape 1 can be welded by any one of the above solders, and the selectivity is relatively strong when used.

[0026] Among them, in step S4, the material of the copper column 3 can be selected from any one of stainless steel, aluminum and silver. Stainless steel, aluminum and silver are metal materials with good conductivity. The conductivity of the second-generation high-temperature superconducting tape 1 is reduced less by these materials, thereby having less impact on the electrical properties of its joints such as critical current and joint resistance.

[0027] In step S4, a uniform thickness of solder is applied to the inner wall of the hole 2. By applying the uniform solder to the inside of the hole 2, the copper column 3 can be welded more firmly in the hole 2.

[0028] In step S5, during the welding process, the pressure applied to the welding area is maintained at about 20 MPa.

[0029] When working, select the required second-generation high-temperature superconducting tape 1 disk, take out the required length from it, and then clean the surface of the second-generation high-temperature superconducting tape 1. When processing, first use an electric grinder to grind the surface of the second-generation high-temperature superconducting tape 1 until the impurities and oxides on the surface are removed and the surface is polished. When grinding, use 300-mesh sandpaper on the electric grinder to dilute the dilute hydrochloric acid, and then soak the polished second-generation high-temperature superconducting tape 1 in the diluted dilute hydrochloric acid for about 5-10 minutes. Then take out the soaked tape and rinse its surface with running clean water. The rinsed tape is dried by a dryer to make its surface clean and dry, thereby completing the cleaning of the surface of the second-generation high-temperature superconducting tape 1. Before using the laser cutting machine to punch holes in the processed second-generation high-temperature superconducting tape 1, clean the laser head, turn on the power, check whether the working indicator light of the laser cutting machine is on, and after confirming that the laser cutting machine can work normally, adjust the correct focal length, place the second-generation high-temperature superconducting tape 1 on the platform of the laser cutting machine, so that the end face of the tape is located below the laser cutting head, and then punch it according to the distribution and size of the holes set in advance, cut the two end faces of the second-generation high-temperature superconducting tape 1 into five horizontal rows and four vertical columns, a total of 20 holes 2, so that when the two end faces overlap, the holes 2 on their surfaces can just overlap with each other; Align the end faces of two second-generation high-temperature superconducting tapes 1 so that the holes 2 on the surfaces of the two tapes completely overlap. The overlapping area of ​​the two tapes is the area to be welded. Apply a uniform thickness of flux to the surfaces of the two areas to be welded to form a solder layer 4. Then, evenly apply the flux to the inside of the hole 2 and the side of the copper pillar 3. Overlap the two tapes so that the hole 2 overlaps. Then, insert the copper pillar 3 into the inside of the hole 2. When selecting the copper pillar 3, first select the copper pillar 3 that matches the hole size. Similarly, treat the surface of the copper pillar 3 according to the surface treatment method of the second-generation high-temperature superconducting tape 1. First, polish the surface of the copper pillar 3 with 300-mesh sandpaper, then soak it in diluted hydrochloric acid for 5-10 minutes, take it out, and then rinse it with clean water and dry it. The second-generation high-temperature superconducting tape 1 and the copper column 3 coated with flux are assembled, and a roller is used to apply uniform pressure to the welding area. The pressure applied in the welding area is about 20 MPa, until the rolling welding machine completes the welding of the second-generation high-temperature superconducting tape 1 and the copper column 3.

[0030] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0031] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for manufacturing a high-strength welded joint of a second-generation high-temperature superconducting tape, characterized in that: The following steps are involved: S1. Cleaning the surface of the second generation high temperature superconducting tape; S2, using a laser to cut multiple evenly spaced holes on the surface of the second-generation high-temperature superconducting tape; S3, aligning the two second-generation high-temperature superconducting tapes, and applying a uniform thickness of welding agent on the surface of the second-generation high-temperature superconducting tape in the area to be welded; S4, prepare a copper column with a size matching the hole, apply a uniform thickness of solder on its side and insert it into the hole; S5. Assemble the second-generation high-temperature superconducting tapes and copper columns coated with welding agent, and perform pressure welding on a welding table until the welding is completed.

2. The method for manufacturing a high-strength welded joint of a second-generation high-temperature superconducting tape according to claim 1, characterized in that: In the step S1, the surface of the second-generation high-temperature superconducting tape is polished with 300-grit sandpaper to remove impurities and oxides on the surface of the second-generation high-temperature superconducting tape.

3. The method for manufacturing a high-strength welded joint of a second-generation high-temperature superconducting tape according to claim 2, characterized in that: In the step S1, the second-generation high-temperature superconducting tape polished with sandpaper is immersed in a diluted hydrochloric acid solution to further remove impurities and oxides on the surface of the second-generation high-temperature superconducting tape.

4. The method for manufacturing a high-strength welded joint of a second-generation high-temperature superconducting tape according to claim 1, characterized in that: In step S2, the number of holes cut by the laser is not less than 9, and the radius is small enough to reduce the critical current of the second-generation high-temperature superconducting tape by no more than 10%.

5. The method for manufacturing a high-strength welded joint of a second-generation high-temperature superconducting tape according to claim 1, characterized in that: In the step S3, the solder on the surface of the second-generation high-temperature superconducting tape can be any one of tin-based solder, silver-based solder, gold-based solder, indium-tin alloy, silver-copper alloy and indium-based solder.

6. The method for manufacturing a high-strength welded joint of a second-generation high-temperature superconducting tape according to claim 1, characterized in that: In step S4, the material of the copper column can be any one of stainless steel, aluminum and silver.

7. The method for manufacturing a high-strength welded joint of a second-generation high-temperature superconducting tape according to claim 1, characterized in that: In the step S4, a uniform thickness of solder is applied to the inner wall of the hole.

8. The method for manufacturing a high-strength welded joint of a second-generation high-temperature superconducting tape according to claim 1, characterized in that: In step S5, during the welding process, the pressure applied to the welding area is maintained at about 20 MPa.

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