A REBCO tape structure and packaging process

Abstract

This invention discloses a REBCO tape structure and packaging process. The REBCO tape, from the inside out along its thickness direction, comprises a metal base layer, a buffer layer system, a REBCO superconducting functional layer, a metal stabilizing layer, an interface transition control layer, and a multi-layer composite encapsulation layer, with continuous bonding interfaces between the layers. The packaging process includes, after the formation of the superconducting functional layer and the metal stabilizing layer, surface pretreatment of the metal stabilizing layer to construct the interface transition control layer, and the formation of a multi-layer composite encapsulation layer on its outer side, followed by integral molding under controlled temperature and pressure conditions. Through the above structural design and packaging process, continuous encapsulation of the REBCO tape's interlayer structure is achieved, improving the tape's structural stability and engineering adaptability under low-temperature operating conditions.

Description

Technical Field

[0001] This invention relates to the field of high-temperature superconducting materials technology, and more specifically, to a REBCO tape structure and packaging process. Background Technology

[0002] REBCO (Rare Earth Barium Copper Oxide) high-temperature superconducting tapes have been widely used in high-field superconducting magnets, superconducting cables, superconducting current limiters, and related cryogenic engineering equipment due to their high critical current density, strong magnetic field adaptability, and stable operation in the liquid nitrogen temperature range. Existing REBCO tapes typically use a metal base tape as the carrier substrate, with a buffer layer system, a REBCO superconducting functional layer, and a metal stabilizing layer sequentially formed on its surface to meet the requirements of superconducting performance and basic electrical stability.

[0003] In practical engineering applications, REBCO tapes often undergo multiple stages, including winding, assembly, cooling, energizing, and long-term operation. These stages inevitably involve temperature changes, electromagnetic forces, and mechanical loading. Since the superconducting functional layers of REBCO are typically micron-scale thin film structures, they are inherently sensitive to external mechanical disturbances. Therefore, the overall structural stability of the tape depends not only on the superconducting functional layers themselves but also on the structural matching and bonding state between the functional layers.

[0004] In existing technologies, to improve the engineering adaptability of REBCO tapes, an encapsulation structure is typically placed outside the metal stabilizing layer. This can be achieved through methods such as resin impregnation, polymer coating, or composite material coating, to enhance the overall mechanical strength and environmental adaptability of the tape. However, in these encapsulation methods, there are often significant differences in elastic modulus and thermal expansion characteristics between the encapsulation layer material and the metal stabilizing layer. When the tape undergoes low-temperature cooling or repeated thermal cycling, additional stress can easily be generated at the interlayer interface.

[0005] Especially at low temperatures, the difference in thermal shrinkage behavior between metallic materials and polymers or composite materials becomes more pronounced. When the encapsulation structure directly acts on the metal stabilizing layer, localized stress concentration can easily occur at the interface, leading to changes in the interfacial bonding state. This can even result in structural discontinuities such as delamination and debonding under long-term operation or repeated loading conditions. Once these problems occur, they can adversely affect the overall stability and service life of the strip.

[0006] On the other hand, as the application requirements of REBCO tapes under high current density and complex operating conditions continue to increase, the requirements for maintaining interlayer bonding stability of the tape structure under multiple thermal cycles, bending and winding, and long-term service conditions are also constantly increasing. Existing solutions that rely solely on a single encapsulation layer or a simple encapsulation structure still suffer from insufficient structural matching when dealing with complex multi-field coupling conditions.

[0007] Therefore, how to improve the interface matching relationship between the metal stabilizing layer and the external packaging structure, and enhance the structural stability of the tape under low-temperature thermal cycling and mechanical loading conditions, while maintaining the original hierarchical structure and superconducting properties of REBCO tape, has become an urgent technical problem to be solved in the current engineering applications of REBCO tape.

[0008] Therefore, there is an urgent need for a REBCO tape structure and packaging process to solve these problems. Summary of the Invention

[0009] The purpose of this invention is to solve the technical problems mentioned in the background art and provide a REBCO tape structure, wherein the REBCO tape comprises, from the inside to the outside along the thickness direction: a metal base tape layer, a buffer layer, a REBCO superconducting functional layer, a metal stabilizing layer, an interface transition control layer, and a multilayer composite encapsulation layer; wherein, adjacent layers are bonded together by deposition, metallurgical bonding, or interfacial bonding to form a continuous bonding interface, so that the REBCO tape maintains its superconducting performance while possessing overall mechanical integrity and low-temperature operation stability.

[0010] As a preferred technical solution of the present invention, the metal base strip layer is a continuous strip metal substrate, formed by rolling or stretching, used to bear the axial tensile force and bending load of the entire REBCO strip, and to provide a flat and stable deposition or growth substrate for each functional layer thereon.

[0011] As a preferred technical solution of the present invention, the buffer layer system is disposed between the metal substrate layer and the REBCO superconducting functional layer. The buffer layer system includes at least one functional buffer layer, and each buffer layer is formed sequentially by thin film deposition. It is used to achieve lattice orientation control, block element diffusion, and reduce the residual stress transmitted from the metal substrate layer to the REBCO superconducting functional layer.

[0012] As a preferred technical solution of the present invention, the REBCO superconducting functional layer is disposed on the surface of the buffer layer system. The REBCO superconducting functional layer is a continuous and dense rare earth barium copper oxide thin film structure, and forms an orientation-matched bonding interface with the buffer layer system through epitaxial or preferred orientation growth.

[0013] As a preferred technical solution of the present invention, the metal stabilizing layer is disposed on the outside of the REBCO superconducting functional layer. The metal stabilizing layer forms an electrical connection interface with the REBCO superconducting functional layer by electroplating, sputtering or bonding, which is used to provide a bypass current channel when the superconducting state is unstable and to conduct heat outward to improve the thermal stability of the tape.

[0014] As a preferred technical solution of the present invention, the interface transition control layer is disposed between the metal stabilizing layer and the multilayer composite encapsulation layer. The interface transition control layer is formed by coating, impregnation or deposition, and forms a continuous bonding interface with the metal stabilizing layer and the multilayer composite encapsulation layer respectively, for buffering the difference in elastic modulus and thermal expansion between different material layers.

[0015] As a preferred technical solution of the present invention, the multi-layer composite encapsulation layer is a composite structure covering the outside of the strip, which includes a polymer encapsulation layer, a reinforcing fiber layer and a metal foil layer in sequence along the thickness direction. The layers are formed into an integral encapsulation structure by impregnation curing or hot pressing, which is used to improve the overall strength and environmental adaptability of the strip.

[0016] This invention also proposes a packaging process for manufacturing REBCO tape structures, comprising the following steps:

[0017] 1) After completing the formation of the REBCO superconducting functional layer and the metal stabilizing layer, the surface of the metal stabilizing layer is pretreated;

[0018] 2) Construct an interface transition control layer on the outside of the pretreated metal stabilization layer;

[0019] 3) Multiple composite encapsulation layers are sequentially stacked on the outside of the interface transition control layer;

[0020] 4) The multilayer composite encapsulation layer is integrally molded under controlled temperature and pressure conditions to form a stable bonding interface between the layers.

[0021] As a preferred technical solution of the present invention, the surface pretreatment includes cleaning and surface activation of the metal stabilizing layer to enhance the bonding strength and interface consistency between the interface transition control layer and the metal stabilizing layer.

[0022] As a preferred technical solution of the present invention, after the multi-layer composite packaging layer is formed, the packaged REBCO tape is subjected to controlled heating and cooling cycle treatment to release the residual stress generated during the packaging process and stabilize the bonding state between the layers.

[0023] Compared with the prior art, the intraoperative nerve localization system for thoracic sympathectomy provided by the present invention has at least the following beneficial effects:

[0024] Compared to existing REBCO tape structures and packaging methods, this invention introduces an interface transition control layer between the metal stabilizing layer and the multilayer composite packaging layer, and combines this with a multilayer composite packaging structure to achieve continuous and collaborative design of the tape layer structure, enabling a stable bonding interface between each functional layer. This structure improves the structural matching relationship between different material layers without changing the basic layer structure of the REBCO tape, thus enhancing the consistency and integrity of the overall tape structure.

[0025] Furthermore, the REBCO tape structure and packaging process described in this invention can maintain a relatively stable interlayer bonding state when the tape undergoes low-temperature cooling, thermal cycling, and mechanical loading. By rationally setting the interface transition control layer and adopting a multi-layer composite packaging method, a continuous transition is formed between the metal stabilizing layer and the external packaging structure, which helps to reduce the adverse effects of temperature changes and bending and winding processes on the interlayer interface, thereby improving the structural stability and reliability of the tape under complex working conditions.

[0026] Furthermore, the packaging process provided by this invention is well-defined and highly operable, capable of being integrated with existing REBCO tape fabrication processes. It does not rely on complex or difficult-to-achieve special conditions, making it suitable for engineering implementation. Through the synergistic design of this structure and process, REBCO tapes, while maintaining their original superconducting properties, possess better engineering adaptability, facilitating their widespread application in high-field magnets, superconducting electrical equipment, and related cryogenic engineering fields. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of the present invention;

[0028] Figure 2 This is a flowchart of the packaging process of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the following description is provided in conjunction with embodiments and appendices. Figures 1-2 The present invention will be further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0030] Example 1: This example provides a REBCO strip structure, in which multiple functional structures are arranged sequentially from the inside to the outside along the thickness direction, with each layer continuously distributed to form an integral strip structure.

[0031] In this embodiment, the innermost layer of the REBCO strip is a metal base layer 1. The metal base layer 1 is made from a continuous strip of metal substrate through a rolling process, and its thickness and width are designed according to the application requirements of the REBCO strip. This metal base layer 1 serves as the load-bearing substrate for the entire REBCO strip, providing a flat and stable forming surface for each layer on top.

[0032] A buffer layer system 2 is sequentially formed on the surface of the metal substrate layer 1. The buffer layer system 2 consists of at least one buffer thin film layer, which is formed by sequentially stacking buffer thin film layers along the thickness direction. The buffer thin film layers are directly deposited on the surface of the metal substrate layer 1 by thin film deposition, thereby forming a continuous bonding interface between the metal substrate layer 1 and its upper structure.

[0033] A REBCO superconducting functional layer 3 is formed on the surface of the buffer layer system 2. The REBCO superconducting functional layer 3 is a continuous and dense rare-earth barium copper oxide thin film structure, which is continuously distributed along the length of the strip and forms an orientation-matched bonding interface with the buffer layer system 2, thereby ensuring the continuity and structural integrity of the superconducting functional layer along the length of the strip.

[0034] A metal stabilizing layer 4 is disposed on the outside of the REBCO superconducting functional layer 3. The metal stabilizing layer 4 is formed by electroplating, sputtering or bonding, and forms an electrical connection interface with the REBCO superconducting functional layer 3, so that the metal stabilizing layer 4 continuously covers the surface of the REBCO superconducting functional layer 3 along the length of the strip.

[0035] An interface transition control layer 5 is provided on the outside of the metal stabilizing layer 4. The interface transition control layer 5 is formed by coating, impregnation or deposition. One side of it forms an adhesive interface with the metal stabilizing layer 4, and the other side forms an adhesive interface with the multilayer composite encapsulation layer 6, so that a continuous transition is formed between the metal stabilizing layer 4 and the external encapsulation structure.

[0036] A multi-layer composite encapsulation layer 6 is formed on the outside of the interface transition control layer 5. The multi-layer composite encapsulation layer 6 includes a polymer encapsulation layer, a reinforcing fiber layer and a metal foil layer in sequence along the thickness direction. Each layer is bonded to each other by impregnation curing or hot pressing, and finally forms an integral continuous composite encapsulation structure on the outside of the REBCO tape, thereby completing the overall construction of the REBCO tape structure.

[0037] Example 2: This example provides a packaging process for manufacturing the above-mentioned REBCO tape structure. This process is performed after the REBCO superconducting functional layer 3 and the metal stabilizing layer 4 are formed.

[0038] In this embodiment, the strip with the REBCO superconducting functional layer 3 and the metal stabilizing layer 4 formed thereon is first subjected to surface pretreatment. During the pretreatment process, the surface of the metal stabilizing layer 4 is cleaned to remove residual impurities and contaminants. Subsequently, the metal stabilizing layer 4 is subjected to surface activation treatment to ensure that its surface state meets the requirements for subsequent interlayer bonding.

[0039] After pretreatment, an interface transition control layer 5 is formed on the outside of the metal stabilizing layer 4. The interface transition control layer 5 is applied to the surface of the metal stabilizing layer 4 by coating, impregnation or deposition, so that it forms a continuous covering structure along the length of the strip and forms a stable bonding interface with the metal stabilizing layer 4.

[0040] Subsequently, multiple composite encapsulation layers 6 are sequentially formed on the outside of the interface transition control layer 5. In this process, a polymer encapsulation layer is first formed on the surface of the interface transition control layer 5, then a reinforcing fiber layer is laid, and finally a metal foil layer is set on the outside. The layers are stacked sequentially in a predetermined order so that the encapsulation structure is continuously distributed along the length of the strip.

[0041] After the multi-layer composite encapsulation layer 6 is stacked, the encapsulation structure is integrally molded under controlled temperature and pressure conditions. Through hot pressing or curing, a stable bonding interface is formed between the internal layers of the multi-layer composite encapsulation layer 6, thereby forming an integral encapsulation structure on the outside of the REBCO tape.

[0042] After the overall molding is completed, the encapsulated REBCO tape is subjected to heating and cooling cycles. Through multiple controlled temperature cycles, the residual stress generated during the molding process is released and the bonding state between the layers tends to be stable, thereby obtaining a REBCO tape finished product with continuous structure and stable interlayer bonding.

[0043] Experimental Example: REBCO tape samples prepared according to the structure of Example 1 and packaged according to the process of Example 2 were selected as test samples. The samples, along their thickness direction, comprise a metal base layer 1, a buffer layer system 2, a REBCO superconducting functional layer 3, a metal stabilizing layer 4, an interface transition control layer 5, and a multilayer composite encapsulation layer 6. To ensure comparability, the sample width was 12 mm and the length was 1 m, with 10 samples taken from each group for statistical analysis.

[0044] The average initial critical current Ic0 measured at 77K under DC self-field conditions was 610A, with a range of 585–635A across 10 samples. Subsequently, the samples underwent thermal cycling tests from room temperature to 77K, with the following cycle regime: 10 min at room temperature → 10 min at 77K → 10 min at room temperature, recorded as one cycle. After 300 thermal cycles, the critical current was measured again, yielding an average Ic300 of 592A, indicating an Ic retention rate of approximately 97.0%, with the inter-sample dispersion remaining within an acceptable range.

[0045] Simultaneously, bending adaptability tests were conducted: samples were wound onto winding fixtures with bending radii of 50mm, 30mm, and 20mm, held for 5 minutes, and then reset, repeated 20 times. After the test, the critical current retention rates measured under a 77K self-field condition were approximately 99.1%, 98.0%, and 95.4%, respectively, and no cracking or obvious delamination of the encapsulation layer 6 was observed. Local cross-sectional observation of the bending area showed that the metal stabilizing layer 4 and the interface transition control layer 5, as well as the interface transition control layer 5 and the multilayer composite encapsulation layer 6, maintained a continuous interface state, and no continuous peeling bands were observed.

[0046] To characterize the bonding level at the encapsulation interface, a 90° peel test was performed on the samples, measuring the peelable structure interface on the outer side of the encapsulation layer. The average peel strength was 3.6 N / cm, ranging from 3.2 to 4.0 N / cm. Regarding insulation performance, a withstand voltage test was conducted on the encapsulated tape. The withstand voltage between the outer surface of the tape and the metal stabilizing layer 4 reached 2.5 kV / 60s without breakdown, and no obvious signs of partial discharge were observed.

[0047] The above data show that the sample of the present invention exhibits stable performance in terms of thermal cycling, bending loading, and interfacial bonding stability, and the key electrical and insulation indicators remain within the engineering-usable range.

[0048] Comparative Example: The comparative example sample maintains the same layer structure as the experimental example, but the interface transition control layer 5 is removed; a multilayer composite encapsulation layer 6 is directly formed outside the metal stabilizing layer 4. Apart from this difference, the remaining layer structure, preparation conditions, and sample size (12mm × 1m) are consistent with the experimental example, and 10 samples are also taken for statistical analysis.

[0049] The average initial critical current Ic0' of the comparative samples, measured under a self-field condition of 77K, was 607A, ranging from 580 to 632A, which is close to the initial level of the experimental examples. After the same 300 thermal cycles, the average value of Ic300' was measured to be 548A, with an Ic retention rate of approximately 90.3%. Some samples showed an accelerated performance degradation trend after 200 cycles, and the dispersion between samples increased.

[0050] In terms of bending tests, the critical current retention rates of the comparative samples were approximately 97.8%, 93.6%, and 84.9% after 20 repetitions under bending radii of 50mm, 30mm, and 20mm, respectively. Under the conditions of 30mm and 20mm, some samples showed interface discontinuities in the encapsulation layer 6 in the bending area; local cross-sectional observation showed that micro-debonding bands were more likely to appear between the metal stabilizing layer 4 and the multilayer composite encapsulation layer 6.

[0051] The average 90° peel strength of the comparative examples was 2.1 N / cm, ranging from 1.7 to 2.6 N / cm, which was lower than that of the test examples. In terms of withstand voltage test, the withstand voltage level was 2.0 kV / 60s. Some samples showed signs of partial discharge, which requires further control through process consistency.

[0052] By comparing the data of the experimental examples and the comparative examples, it can be seen that, under the premise that the initial Ic is similar, the sample with the interface transition control layer 5 shows a more stable trend in terms of Ic retention rate after thermal cycling, Ic retention rate after bending, and interface peel strength.

[0053] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, but the present invention is not limited to these embodiments. Equivalent modifications made by those skilled in the art without departing from the principles of the present invention should fall within the protection scope of the present invention.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A REBCO tape structure, characterized in that, The REBCO tape, from the inside to the outside along the thickness direction, includes: a metal base layer (1), a buffer layer system (2), a REBCO superconducting functional layer (3), a metal stabilizing layer (4), an interface transition control layer (5), and a multi-layer composite encapsulation layer (6). In this process, adjacent layers form a continuous bonding interface through deposition, metallurgical bonding, or interfacial bonding.

2. The REBCO tape structure according to claim 1, characterized in that: The metal base layer (1) is a continuous strip metal substrate, formed by rolling or stretching, and is used as the supporting substrate for each layer structure thereon.

3. The REBCO tape structure according to claim 1, characterized in that: The buffer layer system (2) is disposed between the metal substrate layer (1) and the REBCO superconducting functional layer (3). The buffer layer system (2) includes at least one buffer thin film layer, and each buffer thin film layer is formed sequentially by thin film deposition.

4. The REBCO tape structure according to claim 1, characterized in that: The REBCO superconducting functional layer (3) is disposed on the surface of the buffer layer system (2). The REBCO superconducting functional layer (3) is a continuous and dense rare earth barium copper oxide thin film structure and forms an orientation-matched bonding interface with the buffer layer system (2).

5. The REBCO tape structure according to claim 1, characterized in that: The metal stabilizing layer (4) is disposed on the outside of the REBCO superconducting functional layer (3). The metal stabilizing layer (4) is formed by electroplating, sputtering or bonding and forms an electrical connection interface with the REBCO superconducting functional layer (3).

6. The REBCO tape structure according to claim 1, characterized in that: The interface transition control layer (5) is disposed between the metal stabilizing layer (4) and the multilayer composite encapsulation layer (6). The interface transition control layer (5) is formed by coating, impregnation or deposition, and forms an adhesive interface with the metal stabilizing layer (4) and the multilayer composite encapsulation layer (6) respectively.

7. The REBCO tape structure according to claim 1, characterized in that: The multi-layer composite encapsulation layer (6) is a composite structure covering the outside of the strip. It includes a polymer encapsulation layer, a reinforcing fiber layer and a metal foil layer in sequence along the thickness direction. Each layer is formed into an integral structure by impregnation curing or hot pressing.

8. A packaging process for manufacturing the REBCO tape structure according to any one of claims 1–7, characterized in that, Includes the following steps: 1) After the REBCO superconducting functional layer (3) and the metal stabilizing layer (4) are formed, the surface of the metal stabilizing layer (4) is pretreated; 2) An interface transition control layer (5) is formed on the outside of the pretreated metal stabilizing layer (4); 3) A multi-layer composite encapsulation layer (6) is formed sequentially on the outside of the interface transition control layer (5); 4) The multilayer composite encapsulation layer (6) is integrally formed under controlled temperature and pressure conditions.

9. The packaging process according to claim 8, characterized in that: The pretreatment includes cleaning and surface activation of the metal stabilizing layer (4).

10. The packaging process according to claim 8, characterized in that: After the multi-layer composite packaging layer (6) is formed, the packaged REBCO tape is subjected to heating and cooling cycle treatment.

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