Superconducting strip axial strain critical current testing device and manufacturing method thereof

Abstract

The invention discloses a superconducting tape axial strain critical current testing device and a manufacturing method thereof. The manufacturing method comprises the following steps: uniformly smearing soldering tin on a sample area and two outer side surfaces of a skeleton, the surface of a test sample and the surfaces of two current leads; placing a test sample in a sample area of the skeleton, placing two current leads on two outer side surfaces of the skeleton respectively, and enabling the two current leads to be in contact with two ends of the test sample respectively; providing a clamp I to fix the test sample on the framework, and providing a clamp II to fix the two current leads on the framework to obtain a semi-finished product; and heating and cooling the semi-finished product to obtain the axial strain critical current testing device for the superconducting tape. According to the manufacturing method of the axial strain critical current testing device for the superconducting tape, the problem that when a traditional welding method is used, the transmission performance of the superconducting tape is reduced due to the fact that the heating time is too long or the heating temperature is too high can be solved.

Description

Technical Field

[0001] The present invention relates to the field of superconducting technology, and particularly relates to a test device for the axial strain critical current of a superconducting tape and a manufacturing method thereof. Background Art

[0002] As the core material of modern superconducting technology, superconducting tapes have unique properties of zero resistance and perfect diamagnetism, showing revolutionary application prospects in the fields of energy, medicine, transportation, etc. In the energy field, superconducting tapes can achieve efficient power transmission, high-field magnets, and next-generation wind power generators, significantly reducing energy consumption and increasing power density; in the medical field, their high magnetic field stability promotes the development of high-resolution MRI and particle accelerators; in transportation, superconducting maglev trains and electric aircraft propulsion systems are expected to break through the speed and efficiency limits of traditional technologies. Compared with conventional materials, the core advantages of superconducting tapes are nearly zero energy loss, current-carrying capacity far exceeding that of copper conductors, and the potential for compact and lightweight designs. Although cost and cryogenic system integration remain challenges, with the maturity and large-scale production of high-temperature superconducting materials such as REBCO, superconducting tapes are accelerating from the laboratory to industrialization and becoming a key enabling technology for future green energy and high-end equipment.

[0003] Common high-temperature superconducting tapes include bismuth-based, yttrium-based, and iron-based superconducting tapes. In practical applications, high electromagnetic forces and stress-strain will significantly reduce the transmission performance of the tapes. To ensure the successful application of the tapes, it is necessary to determine the limits of the tapes under their operating conditions, so it is necessary to test the axial strain critical current of the superconducting tapes. The U-shape bending spring (U-spring) is an existing test device for the axial strain critical current of superconducting tapes. Before using this test device, it is necessary to weld the superconducting tape to the skeleton, and the steps are relatively cumbersome: first, weld the superconducting tape to the sample area on the test skeleton, and then weld one end of the current lead to the superconducting tape and the other end to the side of the test skeleton. During this process, the superconducting tape will be continuously contacted with a soldering iron. Since the superconducting tape is sensitive to temperature, excessive heating temperature or excessive heating time will cause its performance to decline or even lose superconductivity. Summary of the Invention

[0004] Based on this, the purpose of the present invention is to provide a test device for the axial strain critical current of a superconducting tape and a manufacturing method thereof, so as to ensure that the performance of the superconducting tape is not damaged after being welded to the test skeleton.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: The present invention first provides a manufacturing method of a test device for the axial strain critical current of a superconducting tape, which includes the following steps: Apply solder evenly on the sample area of the skeleton, on its two outer sides, on the surface of the test sample, and on the surfaces of the two current leads. Place the test sample in the sample area of the skeleton, and place the two current leads on the two outer sides of the skeleton respectively, making the two current leads contact the two ends of the test sample respectively. Provide fixture 1 to fix the test sample on the skeleton, and provide fixture 2 to fix the two current leads on the skeleton to obtain a semi-finished product. Heat and then cool the semi-finished product to obtain a superconducting tape axial strain critical current test device.

[0006] As a further improvement of the above solution of the present invention, the solder is 70°C solder or 145°C solder.

[0007] As a further improvement of the above solution of the present invention, a layer of solder foil is provided between the test sample and the skeleton.

[0008] As a further improvement of the above solution of the present invention, a layer of solder foil is provided between the current lead and the skeleton.

[0009] As a further improvement of the above solution of the present invention, fixture 1 includes a lower clamping plate and an upper clamping plate with a roughness ≤ 3.2; the lower clamping plate is provided with a clamping groove and the sample area of the skeleton is clamped in the clamping groove, the upper clamping plate covers the test sample and is connected to the lower clamping plate by a plurality of screws, and a rubber sheet is provided between the upper clamping plate and the test sample.

[0010] As a further improvement of the above solution of the present invention, the pressure between the upper clamping plate and the test sample is 8 - 18 MPa.

[0011] As a further improvement of the above solution of the present invention, fixture 2 includes two side clamping plates with a roughness ≤ 3.2, and the two side clamping plates respectively cover the two current leads and are both connected to the skeleton by a plurality of screws.

[0012] As a further improvement of the above solution of the present invention, after the test sample is placed in the sample area of the skeleton, polyimide winding tape is used on the skeleton to fix the test sample.

[0013] As a further improvement of the above solution of the present invention, the heating is carried out at 90 - 165°C for 25 - 30 min.

[0014] The present invention also provides a superconducting tape axial strain critical current test device, which is made by using the manufacturing method as described above.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The manufacturing method of the superconducting tape axial strain critical current testing device proposed by the present invention can avoid the problem that the superconducting tape has a reduced transmission performance due to too long heating time or too high heating temperature when using the traditional welding method, improving the success rate of the test; it can simply and quickly prepare the testing device, simplify the preparation process, and improve the test efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG. is a schematic structural diagram of a superconducting tape axial strain critical current testing device proposed by the present invention; Figure 2 FIG. is a schematic structural diagram of fixture 1 in the present invention; Figure 3 FIG. is a schematic structural diagram of fixture 2 in the present invention.

[0017] Reference numerals: 1, test sample; 2, skeleton; 3, current lead; 4, upper clamping plate; 5, lower clamping plate; 6, side clamping plate. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] For the convenience of understanding the present invention, the present invention will be described more comprehensively below in conjunction with specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0020] Aiming at the technical problem that in the current superconducting tape axial strain critical current test, the superconducting tape needs to be welded to the skeleton, and the soldering iron needs to be continuously contacted with the superconducting tape, resulting in the performance decline of the superconducting tape and even the loss of superconductivity, this embodiment proposes a superconducting tape axial strain critical current testing device, which can avoid the problem that the superconducting tape has a reduced transmission performance due to too long heating time or too high heating temperature when using the traditional welding method, improving the success rate of the test.

[0021] Refer to Figure 1 , this embodiment proposes a superconducting tape axial strain critical current testing device, and its manufacturing method includes the following steps: Step 1. Pre-tinning: Use a soldering iron to evenly apply solder to the sample area and two outer sides of the skeleton 2 (i.e., U-spring), the surface of the test sample 1, and the surfaces of the two current leads 3.

[0022] In this embodiment, the skeleton 2 adopts the prior art and will not be elaborated here. In practical applications, the skeleton 2 made of a suitable material needs to be selected according to the superconducting tape to be tested. For example, when the test sample 1 is a FeSeTe tape, when selecting the material of the skeleton 2, a material with the same or similar coefficient of thermal expansion as that of FeSeTe needs to be selected as the matrix material of the skeleton 2, such as Ti6Al4V. For example, when the test sample 1 is a FeSeTe tape, Bi2223 can be selected as the current lead 3.

[0023] Considering that different superconducting tapes have different sensitivities to temperature, too high heating temperature or too long heating time will reduce the transmission performance of the superconducting tape. Therefore, when soldering, the temperature and contact time of the soldering iron need to be controlled. For FeSeTe tapes, 70°C soldering is recommended, and for YBCO tapes, 145°C soldering is recommended; in order to avoid the phenomenon of stress concentration reducing the transmission performance of the superconducting tape, the surface is gently wiped with gauze during soldering to ensure the uniformity of the solder.

[0024] Step 2. Place the test sample 1 in the sample area of the skeleton 2, and place the two current leads 3 on the two outer sides of the skeleton 2 respectively and make the two current leads 3 contact the two ends of the test sample 1 respectively. Provide fixture one to fix the test sample 1 on the skeleton 2, and provide fixture two to fix the two current leads 3 on the skeleton 2 to obtain a semi-finished product.

[0025] In order to ensure the uniformity of the solder, a layer of solder foil is placed between the test sample 1 and the skeleton 2 and between the current lead 3 and the skeleton 2 respectively.

[0026] Combined Figure 2 , fixture one includes a lower clamping plate 5 and an upper clamping plate 4 with a surface roughness ≤ 3.2. The lower clamping plate 5 is provided with a clamping groove and the sample area of the skeleton 2 is clamped in the clamping groove, and the upper clamping plate 4 covers the test sample 1 and is connected to the lower clamping plate 5 through several screws. When fixing fixture one, a torque wrench is used to control the magnitude and uniformity of the force applied by fixture one to the test sample 1, to avoid reducing the transmission performance of the superconducting tape due to excessive lateral load or stress concentration. In this embodiment, four M3 screws are used to fix the lower clamping plate 5 and the upper clamping plate 4, and the force applied by the four M3 screws to the sample is: 4×630 / 0.01 / 0.03×10-6 = 8.4 MPa. It should be noted that after the test sample 1 is placed in the sample area of the skeleton 2, it is wrapped with polyimide tape, and after a rubber sheet is placed on the test sample 1, the upper clamping plate 4 and the lower clamping plate 5 are assembled and fixed, so as to avoid the phenomenon of stress concentration and ensure the uniformity of the applied force. The surface roughness of the lower clamping plate 5 and the upper clamping plate 4 ≤ 3.2, so as to avoid the phenomenon of stress concentration and ensure the uniformity of the applied force.

[0027] Combined Figure 3, Fixture Two includes two side clamping plates 6 with a surface roughness ≤ 3.2. The two side clamping plates 6 respectively cover the two current leads 3, and both of the two side clamping plates 6 are connected to the skeleton 2 by a plurality of screws. The surface roughness of the side clamping plate 6 is ≤ 3.2, thus avoiding the phenomenon of stress concentration and ensuring the uniformity of the applied force.

[0028] Step 3. Place the semi-finished product in a heating device for heating (set specific temperatures and heating times for different heating devices and superconducting tapes). After the sample cools to room temperature with the heating device, take it out, and then the axial strain critical current test device for the superconducting tape is obtained.

[0029] In this embodiment, a 101-4B type electrothermal blast drying oven can be used for heating. Considering the accuracy problem of the heating device, it is necessary to conduct tests before welding the test sample to determine the heating temperature and heating time suitable for the test sample. The specific method is as follows: evenly apply solder on the sample area and the two outer sides of the skeleton 2. Put the skeleton 2 coated with solder into the heating device, set different heating temperatures and heating times, observe the state of the solder on the skeleton 2, and the lowest heating temperature and the shortest heating time at which the solder melts are the heating temperature and heating time suitable for the test sample 1. Note that the heating temperature cannot exceed the highest heat-receiving temperature of the test sample 1. For example, for the FeSeTe tape, the heating temperature and heating time are 90°C and 25 min respectively, and for the YBCO tape, the heating temperature and heating time are 165°C and 25 min respectively.

[0030] Next, taking the FeSeTe tape as an example, the fabrication of the test device will be further described.

[0031] The fabrication process of the axial strain critical current test device for the FeSeTe tape 1 is as follows: Step 1: Pre-tin. Use an electric soldering iron to evenly apply 70°C solder on both sides of the FeSeTe tape, both sides of the Bi2223 current lead 3, the sample area of the skeleton 2, and the two outer sides. Step 2: Assembly. Place the FeSeTe tape in the sample area of the skeleton 2, place the two Bi2223 current leads 3 on both sides of the skeleton 2 respectively. Place a layer of solder foil between the FeSeTe tape and the skeleton 23 and between the Bi2223 current lead 3 and the skeleton 2 respectively, and use polyimide tape to wind the FeSeTe tape and the skeleton 2. Then place a layer of rubber sheet on the FeSeTe tape, and finally use Fixture One and Fixture Two to fix the FeSeTe tape and the Bi2223 current lead 3 on the skeleton 2 respectively. Step 3: Heating. Place the assembled sample in a 101-4B type electrothermal blast drying oven for heating, and set the heating temperature and heating time to 90°C and 25 min respectively. Step 4: Cooling. After the sample is cooled to room temperature with the heating device, it can be taken out, and that's it.

[0032] It should be noted that when a component is referred to as being "installed on" another component, it can be directly on the other component or there may also be an intermediate component. When a component is considered to be "arranged on" another component, it can be directly arranged on the other component or there may be an intermediate component at the same time. When a component is considered to be "fixed to" another component, it can be directly fixed to the other component or there may be an intermediate component at the same time.

[0033] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this invention belongs. The terms used in the description of the present invention in this specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "or / and" used herein includes any and all combinations of one or more of the related listed items.

[0034] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0035] The above-described embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the invention patent should be subject to the appended claims.

Claims

1. A manufacturing method of a test device for the axial strain critical current of a superconducting tape, characterized in that, It includes the following steps: Apply solder evenly on the sample area and two outer sides of the skeleton, the surface of the test sample, and the surfaces of the two current leads; Place the test sample in the sample area of the skeleton, place the two current leads on the two outer sides of the skeleton respectively, and make the two current leads contact the two ends of the test sample respectively; Provide fixture one to fix the test sample on the skeleton, provide fixture two to fix the two current leads on the skeleton, and obtain a semi-finished product; Heat and then cool the semi-finished product to obtain the axial strain critical current test device for superconducting tapes.

2. The manufacturing method of the superconducting tape axial strain critical current test device according to claim 1, characterized in that, The solder is 70°C solder or 145°C solder.

3. The manufacturing method of the superconducting tape axial strain critical current test device according to claim 1, characterized in that A layer of solder foil is provided between the test sample and the skeleton.

4. The manufacturing method of the axial strain critical current test device for superconducting tapes according to claim 1, characterized in that, A layer of solder foil is provided between the current lead and the skeleton.

5. The manufacturing method of the superconducting tape axial strain critical current test device according to claim 1, characterized in that The fixture one includes a lower clamping plate and an upper clamping plate with a roughness ≤ 3.2; a clamping groove is formed in the lower clamping plate and the sample area of the skeleton is clamped in the clamping groove, the upper clamping plate covers the test sample and the upper clamping plate is connected to the lower clamping plate by a plurality of screws, and a rubber sheet is provided between the upper clamping plate and the test sample.

6. The manufacturing method of the superconducting tape axial strain critical current test device according to claim 5, characterized in that, The pressure between the upper clamping plate and the test sample is 8 - 18 MPa.

7. The manufacturing method of the axial strain critical current test device for superconducting tapes according to claim 1, characterized in that The fixture two includes two side clamping plates with a roughness ≤ 3.2, the two side clamping plates respectively cover the two current leads and both the two side clamping plates are connected to the skeleton by a plurality of screws.

8. The manufacturing method of the superconducting tape axial strain critical current test device according to claim 1, characterized in that After the test sample is placed in the sample area of the skeleton, a polyimide tape is wound around the skeleton to fix the test sample.

9. The manufacturing method of the superconducting tape axial strain critical current testing device according to claim 1, characterized in that, The heating is carried out at 90 - 165°C for 25 - 30 min.

10. A superconducting tape axial strain critical current testing device, characterized in that, It is made by using the manufacturing method described in any one of claims 1 - 9.

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