High-temperature superconducting tape repairing method

Abstract

The invention discloses a method for repairing a high-temperature superconducting tape. The method comprises the following steps: S1, placing a to-be-repaired area of the high-temperature superconducting tape in a reaction container; s2, the reaction container is kept at a certain oxygen partial pressure, and annealing treatment is conducted on the to-be-repaired area; s3, after annealing treatment is completed, the high-temperature superconducting tape is taken out after the reaction container is cooled; wherein the to-be-repaired area is a dead pixel area in the high-temperature superconducting tape and an area with a certain length on two sides of the dead pixel area in the length direction of the tape. According to the repairing method, cutting treatment is not needed, that is, the original strip does not need to be damaged basically, and the dead pixel area can be repaired only by conducting proper heat treatment on the dead pixel area.

Description

Technical Field

[0001] The invention relates to the technical field of materials, and in particular to a method for repairing a high-temperature superconducting tape. Background Art

[0002] REBCO coated conductors based on thin film epitaxial growth and biaxial texturing technology are called second-generation high-temperature superconducting tapes, where RE is a rare earth element, B is a Ba element, C is a Cu element, and O is an oxygen element. The critical temperature of REBCO coated conductors is much higher than that of traditional low-temperature superconducting materials, and can reach above 90K, exceeding the temperature of liquid nitrogen (77K). This allows liquid nitrogen to be used as a coolant, thereby reducing cooling costs. The second-generation high-temperature superconducting tapes have extremely high upper critical fields, extremely strong current carrying capacity, and mechanical strength, making them more suitable for large-scale applications. At present, the manufacturing technology of the second-generation high-temperature superconducting tapes is relatively mature and has been industrialized.

[0003] REBCO coated conductors are mainly composed of a metal base tape, a multi-layer buffer layer, a superconducting layer and a protective layer. The metal base tape is generally Ni or Ni alloy (such as Hastelloy), or even stainless steel, with a thickness of 50-100μm, which is used to support the superconducting layer and provide mechanical properties. The multi-layer buffer layer is generally obtained by magnetron sputtering or pulsed laser deposition. In addition to blocking atomic diffusion, it also has the function of transferring texture to the superconducting layer. The superconducting layer is a biaxially textured REBCO based on thin film epitaxial growth. It is the core of the strip and provides the required superconductivity. The thickness is generally 1~6μm. Finally, the strip is wrapped with a silver layer and a copper layer to protect the entire structure. At high temperatures, oxygen atoms can penetrate the silver layer and react with the superconducting layer to achieve regulation of the oxygen content.

[0004] In the REBCO coated conductors produced on a large scale, the performance of a certain area of ​​the tape deteriorates due to the process stability deviation, which reduces the texture and connectivity of the superconducting layer and weakens the superconductivity such as superconducting transition temperature and critical current density. This local bad spot blocks the superconducting current and seriously reduces the current carrying capacity of the entire long tape, so the entire long tape has to be cut off from both sides of the bad spot, greatly reducing the length and yield of the product. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method for repairing a high-temperature superconducting tape, which can repair the bad spots without destroying the original tape, only requiring appropriate heat treatment of the bad spot area.

[0006] The present invention adopts the following technical solution:

[0007] A method for repairing a high-temperature superconducting tape comprises the following steps:

[0008] S1: placing the area to be repaired of the high-temperature superconducting tape in a reaction container;

[0009] S2: maintaining a certain oxygen partial pressure in the reaction container and performing annealing treatment on the area to be repaired;

[0010] S3: After the annealing treatment is completed, the reaction container is cooled and the high temperature superconducting tape is taken out;

[0011] The area to be repaired is the bad spot area in the high-temperature superconducting tape and the area of ​​a certain length on both sides of the bad spot area in the length direction of the tape.

[0012] The certain length is 5% to 15% of the length of the bad pixel area.

[0013] Wherein, the repair method does not perform truncation processing on the bad point area of ​​the high-temperature strip.

[0014] Wherein, the high temperature superconducting tape is a REBCO coated conductor, wherein RE is a rare earth element, B is a Ba element, C is a Cu element, and O is an oxygen element.

[0015] Wherein, the oxygen partial pressure is 0.5 bar-100 bar, the annealing temperature is 200°C-800°C, and the holding time is 10-1500 min.

[0016] Wherein, before step S1, step S0 is also included;

[0017] S0: a step of analyzing whether the outer layer of the area to be repaired contains oxygen-impermeable materials; wherein oxygen-impermeable materials include copper, stainless steel, nickel-based alloys and aluminum;

[0018] If no oxygen-impermeable material is included, directly proceed to step S1;

[0019] If it contains oxygen-impermeable material, execute step S01, and then proceed to step S1;

[0020] Step S01: removing the oxygen-impermeable material in the area to be repaired.

[0021] Furthermore, if the oxygen-impermeable material is included, after step S3, step S03 is further included;

[0022] S03: Restoring the oxygen-impermeable material in the area to be repaired.

[0023] Wherein, the reaction container is made of stainless steel or quartz.

[0024] The beneficial effects of the present invention are as follows:

[0025] (1) The repair method of the present invention does not require truncation, that is, it basically does not need to destroy the original strip. The bad spot area can be repaired by performing appropriate heat treatment on the bad spot area. The repair result is as follows Figure 2 As shown, the superconducting transition temperature of the bad spot is completely restored to 93K.

[0026] (2) The repair method of the present invention can improve the microstructure of the high-temperature superconducting tape through a simple process, increase the critical current of the bad point, and restore its current carrying capacity to 95%-110% of the normal value.

[0027] (3) The repair method of the present invention uses simple equipment and has extremely low repair costs, thereby greatly improving the yield rate of the strip and reducing the preparation cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the area to be repaired according to the present invention.

[0029] Figure 2 This is a diagram showing the MT change of the high-temperature superconducting tape of Example 3 after repair. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] A method for repairing a high-temperature superconducting tape comprises the following steps:

[0032] S1: placing the area to be repaired of the high-temperature superconducting tape in a reaction container; it should be noted that here only the area to be repaired is placed in the reaction container, and the other areas are located outside the reaction container; the reaction container may be sealed or not, as long as the oxygen partial pressure is guaranteed;

[0033] S2: maintaining a certain oxygen partial pressure in the reaction container and performing annealing treatment on the area to be repaired;

[0034] S3: After the annealing treatment is completed, the reaction container is cooled and the high temperature superconducting tape is taken out;

[0035] The area to be repaired is the bad spot area in the high temperature superconducting tape and the area of ​​a certain length on both sides of the bad spot area in the length direction of the tape. That is to say, the area to be repaired is not only the bad spot area, but also includes a certain area on both sides of the bad spot area (the area without bad spots), but the length of the area without bad spots should be appropriate.

[0036] See also Figure 1 , the length of the bad spot area in the strip length direction is d, then the length of the area to be repaired (in the strip length direction) = ;in is the length of the non-bad-point area on one side (along the strip length direction) of the bad-point area. It is the length of the non-bad spot area on the other side of the bad spot area (along the strip length direction); and The lengths can be the same or different.

[0037] Preferably, the certain length is 5% to 15% of the length of the bad pixel area. This setting takes into account the subsequent processing workload, so 5% to 15% is more appropriate.

[0038] It should be noted that the repair method of the present invention does not perform truncation processing on the bad point area of ​​the high-temperature strip.

[0039] Wherein, the high temperature superconducting tape is a REBCO coated conductor, wherein RE is a rare earth element, B is a Ba element, C is a Cu element, and O is an oxygen element.

[0040] Preferably, the oxygen partial pressure is 0.5 bar-100 bar, the annealing temperature is 200° C.-500° C., and the holding time is 10-1000 min.

[0041] Preferably, before step S1, step S0 is also included;

[0042] S0: a step of analyzing whether the outer layer of the area to be repaired contains oxygen-impermeable materials; wherein oxygen-impermeable materials include copper, stainless steel, nickel-based alloys and aluminum;

[0043] If no oxygen-impermeable material is included, directly proceed to step S1.

[0044] If the material contains oxygen-impermeable material, then execute step S01, and then enter step S1; the details are as follows:

[0045] Step S01: removing the oxygen-impermeable material in the area to be repaired; the removal can be carried out by corrosion; one method is to use an acidic solution (such as dilute hydrochloric acid) for anodic corrosion removal; another method is to use hydrogen peroxide plus sulfuric acid solution as a corrosive agent for chemical corrosion removal.

[0046] S1: placing the area to be repaired of the high-temperature superconducting tape in a reaction container;

[0047] S2: maintaining a certain oxygen partial pressure in the reaction container and performing annealing treatment on the area to be repaired;

[0048] S3: After the annealing treatment is completed, the reaction container is cooled and the high temperature superconducting tape is taken out;

[0049] If the material is not permeable to oxygen, after step S3, step S03 is further included;

[0050] S03: Restoring the oxygen-impermeable material in the area to be repaired, preferably by physical vapor deposition, chemical vapor deposition, electroplating, ion-assisted deposition, or magnetron sputtering; the repair is completed.

[0051] Preferably, the reaction container is made of stainless steel or quartz.

[0052] Example 1

[0053] A method for repairing a high-temperature superconducting tape comprises the following steps:

[0054] S0: The analysis shows that the outer layer of the area to be repaired is only Ag;

[0055] S1: Place the area to be repaired into an annealing furnace. The annealing furnace used is a stainless steel tube furnace; the length of the bad spot area is d=3mm, and the length of the area to be repaired is 3.3mm.

[0056] S2: high-purity oxygen is introduced into the annealing furnace, which is sealed and maintained at a pressure of 1.5 bar, and the temperature is raised to an annealing temperature of 350°C, and the annealing temperature is maintained constant for 120 minutes;

[0057] S3: After the annealing is completed and the temperature of the annealing furnace drops below 80°C, the seal of the annealing furnace is released and the strip is taken out.

[0058] After testing, the current carrying capacity at the bad point recovered to 98% of the normal value.

[0059] Example 2

[0060] A method for repairing a high-temperature superconducting tape comprises the following steps:

[0061] S0: The protective layer of the superconducting tape to be repaired is analyzed to include an inner layer of Ag and an outer layer of Cu;

[0062] S01: using hydrogen peroxide and dilute sulfuric acid solution as an etchant to chemically etch and remove the Cu layer in the area to be repaired, where the length of the bad point area is d=4mm and the length of the area to be repaired is 5.2mm;

[0063] S1: Place the area to be repaired into an annealing furnace;

[0064] S2: high-purity oxygen is introduced into the annealing furnace, which is sealed and maintained at a pressure of 10 bar, and the temperature is raised to an annealing temperature of 350°C, and the annealing temperature is maintained constant for 120 minutes;

[0065] S3: After the annealing is completed and the temperature of the annealing furnace drops below 80°C, the seal of the area to be repaired is released and the strip is taken out;

[0066] S03: A Cu layer is plated on the repaired bad pixel area by magnetron sputtering, and the repair is completed.

[0067] After testing, the current carrying capacity at the bad point recovered to 99% of the normal value.

[0068] Example 3

[0069] A method for repairing a high-temperature superconducting tape comprises the following steps:

[0070] S0: Analysis shows that the protective layer of the superconducting tape to be repaired is only Ag, where the length of the bad spot area is d=4mm, and the length of the area to be repaired is 5mm;

[0071] S1: Place the area to be repaired directly into the annealing furnace;

[0072] S2: high-purity oxygen is introduced into the annealing furnace to maintain the reaction atmosphere as flowing oxygen, the pressure (oxygen partial pressure) is 1 bar, the temperature is raised to the annealing temperature of 350°C, and the annealing temperature is maintained constant for 300 minutes;

[0073] S3: After the annealing is completed and the temperature of the annealing furnace drops below 80°C, the strip is taken out.

[0074] After testing, the current carrying capacity at the bad point recovered to 96% of the normal value.

[0075] Example 4

[0076] This embodiment is basically the same as Embodiment 1, and includes the following steps:

[0077] A method for repairing a high-temperature superconducting tape comprises the following steps:

[0078] S0: Analysis shows that the protective layer of the superconducting tape to be repaired is only Ag;

[0079] S1: The area to be repaired is directly placed in an annealing furnace, wherein the length of the bad spot area is d=5mm, and the length of the area to be repaired is 6mm; the annealing furnace used is a laser heating furnace.

[0080] S2: A nitrogen-oxygen mixture with a ratio of 1:1 is introduced into the annealing furnace, which is sealed and maintained at a pressure of 2 bar, and the temperature is raised to an annealing temperature of 400°C, and the annealing temperature is maintained constant for 120 minutes;

[0081] S3: After the annealing is completed, when the temperature of the annealing furnace drops below 80°C, the seal of the annealing furnace is released and the strip is taken out.

[0082] After testing, the current carrying capacity at the bad point recovered to 105% of the normal value.

[0083] Example 5

[0084] This embodiment is basically the same as Embodiment 1, and includes the following steps:

[0085] A method for repairing a high-temperature superconducting tape comprises the following steps:

[0086] S0: Analysis shows that the protective layer of the superconducting tape to be repaired is only Ag;

[0087] S1: Place the area to be repaired directly into an annealing furnace; the annealing furnace used is a quartz glass box furnace.

[0088] S2: A nitrogen-oxygen mixed gas with a ratio of 1:1 is introduced into the annealing furnace, the gas flow is maintained so that the oxygen partial pressure is 1 bar, the temperature is raised to the annealing temperature of 800°C, and the annealing temperature is kept constant for 10 minutes;

[0089] S3: After annealing is completed, the strip is taken out after the temperature of the annealing furnace drops below 80°C.

[0090] After testing, the current carrying capacity at the bad point recovered to 96% of the normal value.

[0091] Example 6

[0092] This embodiment is basically the same as Embodiment 1, and includes the following steps:

[0093] A method for repairing a high-temperature superconducting tape comprises the following steps:

[0094] S0: The protective layer of the superconducting tape to be repaired is analyzed to include an inner Ag layer and an outer Cu layer and a stainless steel layer;

[0095] S01: Remove the Cu layer and stainless steel layer in the area to be repaired by anodic corrosion with an acid solution (such as dilute hydrochloric acid), where the length of the bad point area is d=4mm and the length of the area to be repaired is 5.2mm;

[0096] S1: Place the area to be repaired into an annealing furnace; the annealing furnace used is a fixture heating furnace.

[0097] S2: high-purity oxygen is introduced into the annealing furnace, which is sealed and maintained at a pressure of 100 bar, and the temperature is raised to an annealing temperature of 200°C, and the annealing temperature is maintained constant for 1500 min;

[0098] S3: After the annealing is completed, when the temperature of the annealing furnace drops below 80°C, the seal of the annealing furnace is released and the strip is taken out.

[0099] S03: A Cu layer and a stainless steel layer are plated on the repaired bad pixel area by physical vapor deposition, and the repair is completed.

[0100] After testing, the current carrying capacity at the bad point was restored to 100% of the normal value.

[0101] It will be easily understood by those skilled in the art that 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 in the protection scope of the present invention.

[0102] The parts not elaborated in detail in the description of the present invention belong to the known technology in the art. The above embodiments are provided only for the purpose of describing the present invention, and are not intended to limit the scope of the present invention. The scope of the present invention is defined by the appended claims. Various equivalent substitutions and modifications made without departing from the spirit and principle of the present invention should be included in the scope of the present invention.

Claims

1. A method for repairing a high-temperature superconducting tape, characterized in that: The steps include: S1: placing the area to be repaired of the high-temperature superconducting tape in a reaction container; S2: maintaining a certain oxygen partial pressure in the reaction container and performing annealing treatment on the area to be repaired; S3: After the annealing treatment is completed, the reaction container is cooled and the high temperature superconducting tape is taken out; The area to be repaired is the bad spot area in the high-temperature superconducting tape and the area of ​​a certain length on both sides of the bad spot area in the length direction of the tape.

2. The high temperature superconducting tape repair method according to claim 1, characterized in that: The certain length is 5% to 15% of the length of the bad pixel area.

3. The high temperature superconducting tape repair method according to claim 1, characterized in that: The repair method does not perform truncation processing on the bad point area of ​​the high-temperature strip.

4. The high temperature superconducting tape repair method according to claim 1, characterized in that: The high temperature superconducting tape is a REBCO coated conductor, wherein RE is a rare earth element, B is a Ba element, C is a Cu element, and O is an oxygen element.

5. The high temperature superconducting tape repair method according to claim 1, characterized in that: The oxygen partial pressure is 0.5 bar-100 bar, the annealing temperature is 200° C.-800° C., and the holding time is 10-1500 min.

6. The high temperature superconducting tape repair method according to claim 1, characterized in that: The method further includes step S0 before step S1; S0: a step of analyzing whether the outer layer of the area to be repaired contains oxygen-impermeable materials; wherein oxygen-impermeable materials include copper, stainless steel, nickel-based alloys and aluminum; If no oxygen-impermeable material is included, directly proceed to step S1; If it contains oxygen-impermeable material, execute step S01, and then proceed to step S1; Step S01: removing the oxygen-impermeable material in the area to be repaired.

7. The high temperature superconducting tape repair method according to claim 6, characterized in that: If the material is not permeable to oxygen, after step S3, step S03 is further included; S03: Restoring the oxygen-impermeable material in the area to be repaired.

8. The high temperature superconducting tape repair method according to claim 1, characterized in that: The reaction container is made of stainless steel or quartz.

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