Preparation method of second-generation high-temperature superconducting tape and superconducting tape

Abstract

The application provides a preparation method of a second-generation high-temperature superconducting tape and the superconducting tape; the method comprises the following steps: using a roll-to-roll dip coating device to immerse an original superconducting tape in an adhesive solution, uniformly pulling out the superconducting tape to form an adhesive transition layer; co-winding the superconducting tape after immersion and a polyimide film to make the polyimide film adhere to the surface of the superconducting tape; and solidifying the adhesive transition layer in the co-wound superconducting tape. The prepared second-generation high-temperature superconducting tape has a contact resistivity in liquid nitrogen of greater than 10 4 μΩ·cm 2 (@100MPa); compared with common superconducting tapes, the delamination strength of the superconducting tape in liquid nitrogen is increased by more than 40%; after working in liquid nitrogen for 3000 hours and undergoing 10,000 times of repeated thermal shocks (from 4.2K to room temperature), the polyimide film and the adhesive transition layer in the superconducting tape do not delaminate or fall off, and the superconducting tape still maintains an intact structure, thereby realizing the long-term reliability of the surface insulating layer of the superconducting tape.

Description

Technical Field

[0001] This invention relates to the field of superconducting materials technology, specifically to a method for preparing a second-generation high-temperature superconducting tape and the superconducting tape itself. Background Technology

[0002] The second-generation high-temperature superconducting tape based on rare earth barium copper oxide (REBCO, where RE represents rare earth elements) has advantages such as high transition temperature, high critical current density and excellent mechanical properties, and has been demonstrated in many fields such as power, energy and magnets.

[0003] In superconducting devices, the post-processing of commercial superconducting tapes (such as insulation or semi-insulation treatment) is of great significance for practical applications. For example, in the much-discussed uninsulated coils, semi-insulation treatment on the surface of the superconducting tape can improve inter-turn resistance and reduce coil charging and discharging delays and ramp-up losses. In the winding coils of devices such as superconducting current limiters, materials such as Kapton film need to be wound around the surface of the superconducting tape for insulation protection. However, these insulating films are prone to peeling and delamination under long-term use in cryogenic conditions at and below liquid nitrogen temperature or under repeated thermal shock conditions, which seriously affects the long-term stable operation of superconducting devices.

[0004] Furthermore, thermal stress generated during the fabrication and application of superconducting devices, as well as the Lorentz force experienced under high electromagnetic fields, can also lead to delamination and breakage within the superconducting tape. For traditional superconducting tapes, delamination typically occurs at the weakest point of the multilayer structure, namely the superconducting layer and the CeO2 buffer layer, such as... Figure 2 As shown. The superconducting layer is the most important functional layer in the entire superconducting tape. Once delamination occurs, it leads to a sharp decrease in the current-carrying capacity of the superconducting tape, causing fatal damage. The delamination strength of superconducting tapes is extremely important in practical engineering applications, but the delamination strength values ​​of existing tapes are low and the data are discrete, making it one of the worst mechanical properties among superconducting tapes with flat multilayer structures. Therefore, it is currently a hot topic in the improvement of the mechanical properties of superconducting tapes. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a second-generation high-temperature superconducting tape and the superconducting tape itself, thereby achieving surface insulation of the superconducting tape and improving its delamination strength.

[0006] To achieve the above objectives, the present invention provides a method for preparing a second-generation high-temperature superconducting tape, wherein the superconducting tape comprises a primary superconducting tape, an adhesive buffer layer on the outer side of the primary superconducting tape, and an outermost polyimide film; the preparation method comprises the following steps:

[0007] S1. Prepare the adhesive solution;

[0008] S2. The original superconducting tape is immersed in the adhesive solution using a roll-to-roll dip coating equipment, and then pulled out at a certain speed to form an adhesive buffer layer.

[0009] S3. Wrap the impregnated superconducting tape with a polyimide film, so that the polyimide film adheres to the surface of the superconducting tape.

[0010] S4, the adhesive buffer layer in the cured superconducting tape.

[0011] As one embodiment, in step S1, the adhesive solution is a mixture of fluorinated polyamic acid, propylene glycol monomethyl ether acetate, methyl ethyl ketone, and dimethylacetamide.

[0012] As one embodiment, the adhesive solution contains at least 30% fluorinated polyamic acid by mass.

[0013] As one embodiment, the adhesive solution comprises, by weight percentage, 30-50% fluorinated polyamic acid, 23-32% propylene glycol monomethyl ether acetate, 20%-28% methyl ethyl ketone, and 7%-27% dimethylacetamide.

[0014] As one implementation, in step S2, the original superconducting tape is a copper-plated superconducting tape.

[0015] As one implementation, in step S3, the thickness of the polyimide film is 10-50 μm, and the width is equal to or slightly smaller than the width of the superconducting tape.

[0016] As one implementation, the width difference between the polyimide film and the superconducting tape is less than 0.2 mm.

[0017] As one implementation scheme, in step S4, the curing method is low-vacuum curing at a temperature not exceeding 40°C.

[0018] As one implementation method, the curing temperature is 20-40℃ and the curing environment pressure is less than 30KPa.

[0019] As one implementation scheme, in step S4, the thickness of the cured adhesive buffer layer is 5-15μm, and there are no pores or defects inside the adhesive buffer layer or at the relevant interfaces.

[0020] The second-generation high-temperature superconducting tape prepared by the above-described method is also within the scope of protection of this invention.

[0021] Compared with existing technologies, the superconducting tape prepared by this invention exhibits a contact resistivity greater than 10⁻⁶ in liquid nitrogen. 4 μΩ·cm 2(@100MPa); Compared with ordinary superconducting tapes, the delamination strength of this superconducting tape in liquid nitrogen is increased by more than 40%; After working in liquid nitrogen for 3000 hours and undergoing 10,000 repeated thermal shocks (from 4.2K to room temperature), the polyimide film and adhesive buffer layer in this superconducting tape did not delaminate or fall off, and the superconducting tape still maintained its complete structure.

[0022] The second-generation high-temperature superconducting tape prepared using the aforementioned structure and preparation method exhibits the following characteristics: under transverse stress conditions, the adhesive buffer layer and its interface become the weakest part of the entire tape, most susceptible to delamination and breakage. The adhesive buffer layer, a high-molecular-weight organic material with strong adhesion and a high elastic modulus, can convert transverse stress into potential energy for storage. As a sacrificial layer, it provides some protection to the superconducting core layer, improving the delamination strength of the superconducting tape. Under repeated thermal shocks, the adhesive buffer layer does not crack or delamination, maintaining excellent adhesion in liquid nitrogen for extended periods, thus tightly bonding the polyimide film and the copper-plated superconducting tape. Attached Figure Description

[0023] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0024] Figure 1 This is a schematic diagram of the structure of the second-generation high-temperature superconducting tape prepared according to the present invention;

[0025] Figure 2 This is a microscopic image of a typical delamination interface in second-generation high-temperature superconducting tapes.

[0026] Figure 3 This invention provides a method for preparing a second-generation high-temperature superconducting tape and an example of the superconducting tape, showing (a) a bonding transition layer and (b) a partial photograph of the superconducting tape. Detailed Implementation

[0027] The present invention will be described in detail below with reference to embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0028] Example 1

[0029] This embodiment relates to a method for preparing a second-generation high-temperature superconducting tape, including the following steps:

[0030] S1: Prepare the adhesive solution. It contains 35% fluorinated polyamic acid, 30% propylene glycol monomethyl ether acetate, 25% methyl ethyl ketone, and 10% dimethylacetamide.

[0031] S2: A roll-to-roll dip coating device is used to immerse a 4mm wide copper-plated superconducting tape in the adhesive solution, and then pull it out at a uniform speed to form an adhesive buffer layer.

[0032] S3: Wrap the impregnated superconducting tape with a 4mm wide polyimide film to make the polyimide film adhere to the surface of the superconducting tape;

[0033] S4: The adhesive buffer layer in the superconducting tape was cured at 25℃ and 20 kPa. The thickness of the adhesive buffer layer was approximately 10 μm.

[0034] Testing revealed that the structure of the second-generation high-temperature superconducting tape prepared using the above method is as follows: Figure 1 As shown, it includes the original superconducting tape, an adhesive buffer layer on the outer side of the original superconducting tape, and an outermost polyimide film. This second-generation high-temperature superconducting tape (e.g.) Figure 3 The contact resistivity (as shown) in liquid nitrogen is approximately 2.7 × 10⁻⁶. 4 μΩ·cm 2 (@100MPa); Compared with the original copper-plated superconducting tape (control group), the average delamination strength of this superconducting tape in liquid nitrogen increased by 41.4%, as shown in Table 1:

[0035] Table 1 shows the delamination strength of second-generation high-temperature superconducting tapes in the liquid nitrogen temperature range.

[0036]

[0037] After working in liquid nitrogen for 3,000 hours and undergoing 10,000 repeated thermal shocks (from 4.2K to room temperature), the polyimide film and adhesive buffer layer in the superconducting tape did not delaminate or peel off, and the superconducting tape still maintained its complete structure.

[0038] Examples 2-4

[0039] This embodiment provides a method for preparing a second-generation high-temperature superconducting tape, which is basically the same as in Embodiment 1; the difference is that the formulation of the adhesive solution is shown in Table 2.

[0040] Table 2 Adhesive solution ratios for Examples 2-4

[0041] Fluoroamic acid Propylene glycol monomethyl ether acetate Methyl ethyl ketone dimethylacetamide Example 2 30％ 32％ 28％ 10％ Example 3 50％ 23％ 20％ 7％ Example 4 30％ 25％ 25％ 20％

[0042] The contact resistivity of the superconducting tapes described in Examples 2-4 in liquid nitrogen is all greater than 10. 4 μΩ·cm 2(@100MPa); Compared with the original copper-plated superconducting tape (control group), the average delamination strength of the superconducting tape in liquid nitrogen was increased by more than 40%, as shown in Table 3:

[0043] Table 3 shows the delamination strength of the second-generation high-temperature superconducting tapes in Examples 2-4 at the liquid nitrogen temperature range.

[0044]

[0045] After working in liquid nitrogen for 3,000 hours and undergoing 10,000 repeated thermal shocks (from 4.2K to room temperature), the polyimide film and adhesive buffer layer in the superconducting tape did not delaminate or peel off, and the superconducting tape still maintained its complete structure.

[0046] Comparative Example 1

[0047] The difference between Comparative Example 1 and Example 1 is that in step S1 of the Comparative Example, the proportion of fluorinated polyamic acid is 10%; and in step S4, the thickness of the adhesive buffer layer is 3 μm. Apart from these differences, all other steps are the same as in Example 1.

[0048] The second-generation high-temperature superconducting tape prepared by the above method did not have an adhesive buffer layer that completely covered the entire surface of the superconducting tape, resulting in the polyimide film not being tightly wrapped. After 500 hours of use in liquid nitrogen, the adhesive buffer layer and the polyimide interface delaminated, and part of the polyimide film fell off.

[0049] Comparative Example 2

[0050] The difference between Comparative Example 2 and Example 1 is that in step S4, the thickness of the adhesive buffer layer is 18 μm. Otherwise, all other steps are the same as in Example 1.

[0051] The second-generation high-temperature superconducting tape prepared by the above method experienced cracking of the adhesive buffer layer after 100 repeated thermal shocks (from 4.2K to room temperature), resulting in the partial detachment of the polyimide film.

[0052] Comparative Example 3

[0053] The difference between Comparative Example 3 and Example 1 is that the curing temperature in step S4 of the Comparative Example is 150°C. Apart from this, all other steps are the same as in Example 1.

[0054] The second-generation high-temperature superconducting tape prepared using the above method exhibits a critical current attenuation of more than 8% compared to the original copper-plated superconducting tape.

[0055] Comparative Example 4

[0056] The difference between Comparative Example 4 and Example 1 is that in step S4 of the Comparative Example, the curing environment pressure is 101 kPa (standard atmospheric pressure). Apart from this, the remaining steps are the same as in Example 1.

[0057] The second-generation high-temperature superconducting tape prepared by the above method has structural defects such as bubbles between the adhesive buffer layer and the polyimide film after curing. After repeated thermal shocks for 100 cycles, the polyimide film delaminates.

[0058] Comparative Example 5

[0059] The difference between Comparative Example 5 and Example 1 is that in step S1 of the Comparative Example, the adhesive solution consists of 20% acrylic resin, 25% propylene glycol monomethyl ether acetate, 25% methyl ethyl ketone, and 30% xylene. Apart from this, all other steps are the same as in Example 1.

[0060] The second-generation high-temperature superconducting tape prepared by the above method, after working in liquid nitrogen for 500 hours, most of the polyimide film fell off and no longer adhered to the adhesive buffer layer and the superconducting tape.

[0061] Comparative Example 6

[0062] The difference between Comparative Example 6 and Example 1 is that, in step S1 of Comparative Example 6, the adhesive solution does not contain propylene glycol monomethyl ether acetate. Apart from this, all other steps are the same as in Example 1.

[0063] The second-generation high-temperature superconducting tape prepared by the above method showed that the adhesive buffer layer cracked and delaminated after 100 repeated thermal shocks, and in severe cases, it completely detached from the superconducting tape.

[0064] In summary, the second-generation high-temperature superconducting tape of this invention exhibits a contact resistivity greater than 10⁻⁶ in liquid nitrogen. 4 μΩ·cm 2 (@100MPa); Compared with ordinary superconducting tapes, the delamination strength of this superconducting tape in liquid nitrogen is increased by more than 40%; After working in liquid nitrogen for 3000 hours and undergoing 10,000 repeated thermal shocks (from 4.2K to room temperature), the polyimide film and adhesive buffer layer in this superconducting tape did not delaminate or fall off, and the superconducting tape still maintained its complete structure.

[0065] Therefore, by adopting the structure and preparation method of the second-generation high-temperature superconducting tape and the second-generation high-temperature superconducting tape described above, the present invention can improve the delamination strength of the second-generation high-temperature superconducting tape and solve the problem of the insulating film falling off under repeated thermal shock, thus achieving long-term reliability of the insulating layer on the surface of the superconducting tape.

[0066] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method of making a second-generation high temperature superconducting tape, characterized by, The superconducting tape comprises a raw superconducting tape, an adhesive buffer layer outside the raw superconducting tape, and an outermost polyimide film; the preparation method comprises the following steps: S1, configuring an adhesive solution; the adhesive solution comprises: fluorine-containing polyamide acid 30-50%, propylene glycol monomethyl ether acetate 23-32%, methyl ethyl ketone 20%-28%, dimethylacetamide 7%-27%; S2, using a roll-to-roll dip coating device to immerse the raw superconducting tape in the adhesive solution, and then pulling it out at a certain speed to form an adhesive buffer layer; S3, using a polyimide film to coat the infiltrated superconducting tape, so that the polyimide film adheres to the surface of the superconducting tape; S4, curing the adhesive buffer layer in the superconducting tape.

2. The method of claim 1, wherein the second-generation high temperature superconducting tape is characterized by In step S2, the raw superconducting tape is a copper-plated superconducting tape.

3. The method of claim 1, wherein the second-generation high temperature superconducting tape is prepared by the steps of: In step S3, the thickness of the polyimide film is 10-50μm, and the width is equal to or slightly smaller than the width of the superconducting tape.

4. The method of claim 3, wherein the second-generation high temperature superconducting tape is prepared by the steps of: The width difference between the polyimide film and the superconducting tape is less than 0.2mm.

5. The method of claim 1, wherein the second-generation high temperature superconducting tape is characterized by In step S4, the curing method is low-vacuum curing at a temperature not higher than 40℃.

6. The method of claim 5, wherein the second-generation high temperature superconducting tape is prepared by the steps of: The curing temperature is 20-40℃, and the curing environmental pressure is less than 30KPa.

7. The method of claim 1, wherein the second-generation high temperature superconducting tape is characterized by In step S4, the thickness of the adhesive buffer layer after curing is 5-15μm; there are no pore defects in the adhesive buffer layer and related interfaces.

8. A second-generation high-temperature superconducting tape prepared by the method of any one of claims 1-7.

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