Rare earth barium copper oxide superconducting wire and preparation method and application thereof

Abstract

The invention relates to a rare earth barium copper oxide superconducting wire and a preparation method and application thereof, and relates to the field of superconducting materials, and the rare earth barium copper oxide superconducting wire comprises a wire core and a silver tube wrapping the wire core; the inner wall of the silver tube is a crystal face (111); the raw material powder used in the wire core preparation comprises main powder and auxiliary powder; the main powder comprises mixed powder of Re, Ba and Cu according to the atomic molar ratio of 1: 2: 3, and Re211 powder with the mass percent smaller than or equal to 20% based on the mixed powder; the auxiliary powder comprises, by mass, less than or equal to 20% of silver oxide powder, less than or equal to 5% of cerium oxide powder and / or platinum powder and less than or equal to 20% of Re123 powder on the basis of the main powder. According to the rare earth barium copper oxide superconducting wire provided by the invention, the preparation of the high-performance ReBCO wire is realized by designing the wire and adopting specific raw materials by using a melt growth method.

Description

Technical Field

[0001] The invention relates to the field of superconducting materials, and in particular to a rare earth barium copper oxide superconducting wire and a preparation method and application thereof. Background Art

[0002] Copper oxide is a well-known superconductor system, the representative of which is ReBa2Cu3O 7-x A series of superconductors, Tc is higher than the liquid nitrogen transition temperature.

[0003] As shown by the many applications of low-temperature superconductors NbTi wire and Nb3Sn wire, one of the great advantages of round wire is that it is easy to manufacture application products. Bi-2212 and Bi-2223 are the first high-temperature superconducting wires to start commercial production and are undergoing various application research. However, these two high-temperature superconducting wires face the same problem, that is, the critical current density is low in high-temperature magnetic fields.

[0004] At present, ReBCO high-temperature superconducting wires are expected to be used in various applications such as the next generation of ultra-strong magnetic field superconducting magnets and high-temperature MRI. Bi-based copper oxide superconductors cannot replace ReBCO-based materials based on YBCO in terms of performance.

[0005] For example, CN109785990A discloses a superconducting tape or wire for use in a strong magnetic field, wherein the superconducting material is a rare earth barium copper oxide material with a molecular formula of REBa2Cu3O 7-δ (abbreviated as REBCO), where RE is Yb or a rare earth ion combination containing Yb. Yb-containing rare earth barium copper oxide superconducting materials exhibit excellent strong magnetic field characteristics in temperature environments below 50K, especially in temperatures below 20K and strong magnetic fields. Yb-containing REBCO superconducting materials have higher critical current density than superconducting materials without Yb, and the critical current density decreases more slowly with increasing magnetic field strength.

[0006] However, due to the anisotropy of the crystal, the direction in which a large current can be passed is limited to the ab plane direction of the crystal. Therefore, ReBCO high-temperature superconducting superconductor materials are mostly made by thin film methods and sold in the form of strips. However, there are problems with the middle layer (thin film layer) of the current strips, changes in the conduction performance caused by changes in the magnetic field angle, and material protection in the event of a quench. Summary of the invention

[0007] In view of the problems existing in the prior art, the purpose of the present invention is to provide a rare earth barium copper oxide superconducting wire and a preparation method and use thereof, so as to solve the problems of peeling of the intermediate layer (thin film layer) of the current strip, changes in the electrical performance caused by changes in the magnetic field angle, and material protection in the case of quenching.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a rare earth barium copper oxide superconducting wire, the rare earth barium copper oxide superconducting wire comprising: a wire core and a silver tube wrapping the wire core;

[0010] The inner wall of the silver tube is a (111) crystal plane;

[0011] The raw material powder used in the preparation of the wire core includes: main powder and auxiliary powder;

[0012] The main powder comprises: a mixed powder having an atomic molar ratio of Re, Ba and Cu of 1:2:3, and Re211 powder having a mass percentage of ≤20% based on the mixed powder;

[0013] The auxiliary powder comprises, based on the main powder, in terms of mass percentage: silver oxide powder ≤ 20%, cerium oxide powder and / or platinum powder ≤ 5%, and Re123 powder ≤ 20%.

[0014] The rare earth barium copper oxide superconducting wire provided by the present invention realizes the preparation of high-performance ReBCO wire by designing the wire and adopting specific raw materials.

[0015] As a preferred technical solution of the present invention, the mixed powder includes Re211 powder, copper-barium oxide powder, copper oxide powder and barium oxide powder.

[0016] Preferably, the Re211 powder includes: Re2BaCuO5 powder and / or oxide powder obtained by mixing Re and its oxide, Ba and its oxide, Cu and its oxide in a molar ratio of 2:1:1.

[0017] Preferably, the copper-barium oxide powder includes: BaCuO2 powder and / or BaCu2O2 powder.

[0018] Preferably, the Re includes one or a combination of at least two of the Y element, the Gd element or the Yb element.

[0019] Preferably, the Re123 powder used in the auxiliary powder is 1-5% by mass based on the main powder.

[0020] As a preferred technical solution of the present invention, the particle size of the powder in the raw material for preparing the wire core is less than 1 μm.

[0021] In a second aspect, the present invention provides a method for preparing the rare earth barium copper oxide superconducting wire as described in the first aspect, the preparation method comprising:

[0022] The raw material powder is filled into a silver tube and stretched, and then preheated, pre-melted, textured, first heat treated and second heat treated are performed in sequence to obtain a rare earth barium copper oxide superconducting wire.

[0023] As a preferred technical solution of the present invention, the stretching includes at least one cold stretching and / or at least one hot stretching.

[0024] Preferably, the diameter compression ratio of the at least one cold stretching is 1-10%.

[0025] Preferably, each stretching in the at least one cold stretching is followed by firing, preferably every 2×i stretching is followed by firing, i∈N*.

[0026] Preferably, the firing temperature is 300-800°C.

[0027] Preferably, the firing time is 4-12 hours.

[0028] Preferably, the firing is carried out under an absolute vacuum degree of less than 1 Pa or in an inert atmosphere.

[0029] Preferably, the diameter compression ratio of the at least one hot stretching is 1-20%.

[0030] Preferably, the stretching temperature of the at least one thermal stretching is 300-800°C.

[0031] Preferably, the at least one thermal stretching is performed under an absolute vacuum degree of less than 1 Pa or an inert atmosphere.

[0032] As a preferred technical solution of the present invention, the preheating temperature is 800-850°C.

[0033] Preferably, the preheating time is ≤ 3 hours.

[0034] Preferably, the preheating is performed under an absolute vacuum degree of less than 1 Pa or an inert atmosphere.

[0035] Preferably, the pre-melting temperature is 900-950°C.

[0036] Preferably, the pre-melting time is 1-60 min.

[0037] Preferably, the pre-melting is carried out under an absolute vacuum degree of less than 1 Pa or in an inert atmosphere.

[0038] As a preferred technical solution of the present invention, the temperature of the texture growth is 900-950°C.

[0039] Preferably, the texture growth time is 1-72h.

[0040] Preferably, the texture growth is performed in an oxygen atmosphere with a volume content of 0.001-5%.

[0041] Preferably, a direct current or a magnetic field is applied to the wire during the texture growth.

[0042] Preferably, the magnitude of the direct current is 10μA-1A.

[0043] Preferably, the intensity of the magnetic field is ≤10T.

[0044] As a preferred technical solution of the present invention, the temperature of the first heat treatment is 500-800°C.

[0045] Preferably, the first heat treatment is performed for 5-48 hours.

[0046] Preferably, the first heat treatment is performed in an atmosphere with an oxygen volume content of ≥ 21%.

[0047] As a preferred technical solution of the present invention, the temperature of the second heat treatment is 300-600°C.

[0048] Preferably, the second heat treatment is performed for 24-200 hours.

[0049] Preferably, the second heat treatment is performed in an atmosphere with an oxygen volume content of ≥ 21%.

[0050] Preferably, the gas phase pressure is controlled to be 10-100 bar in the second treatment.

[0051] In a third aspect, the present invention provides a use of the rare earth barium copper oxide superconducting wire as described in the first aspect, the use comprising: using the rare earth barium copper oxide superconducting wire for a current density of ≥50A / mm 2 Conductive conduction below.

[0052] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0053] The rare earth barium copper oxide superconducting wire provided by the present invention realizes the preparation of high-performance ReBCO round wire by optimizing the design of raw materials and the preparation process, and utilizing the melt growth method. The critical current density of the obtained wire product at a temperature of 4.2K is ≥50A / mm 2 . BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 The IV curves of the wire product obtained in Example 1 of the present invention under different magnetic fields at a temperature of 4.2K;

[0055] Figure 2 is the critical current curve of the wire product obtained in Example 1 of the present invention at different magnetic fields at a temperature of 4.2K;

[0056] Figure 3The wire product obtained in Example 1 of the present invention has a wire cross section of 0.15 mm 2 As a benchmark, convert the critical current density curve of the sample;

[0057] Figure 4 1 is the IV curve of the wire product obtained in Example 2 of the present invention under different magnetic fields at a temperature of 4.2K;

[0058] Figure 5 is the critical current curve of the wire product obtained in Example 2 of the present invention under different magnetic fields at a temperature of 4.2K;

[0059] Figure 6 This is a comparison chart of the current densities of the wire product obtained in Example 1 of the present invention, the wire product obtained in Example 2, and existing commercially available wire products;

[0060] Figure 7 This is the IV curve of the wire product obtained in Example 3 of the present invention at a temperature of 4.2K.

[0061] The present invention is further described in detail below. However, the following examples are only simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0062] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0063] This embodiment provides a rare earth barium copper oxide superconducting wire, which includes a wire core and a silver tube wrapping the wire core.

[0064] The inner wall of the silver tube is a (111) crystal plane, the purity of the silver tube is ≥99%, and a silver tube of a commonly used shape in the art such as a columnar silver tube can be selected.

[0065] Exemplarily, the inner wall of the silver tube with a (111) crystal plane can be obtained by the following process: calcining at 700-950° C. for 4-24 h in an inert atmosphere or an absolute vacuum degree of <1 Pa.

[0066] In the present invention, the inert atmosphere includes an atmosphere that does not react with the treatment object, such as nitrogen, helium, neon, helium and other gases that meet the requirements, and gases such as carbon dioxide are not excluded.

[0067] The raw material powder used in the preparation of the wire core includes: main powder and auxiliary powder.

[0068] The main powder comprises: a mixed powder in which the atomic molar ratio of Re, Ba and Cu is 1:2:3, and Re211 powder having a mass percentage of ≤20% based on the mixed powder.

[0069] In the present invention, the mixed powder is based on the Re211 powder of ≤20% by mass percentage, which means that the main powder additionally contains Re211 powder of ≤20% by mass of the mixed powder.

[0070] Wherein, the mixed powder includes Re211 powder, copper-barium oxide powder, copper oxide powder and barium oxide powder;

[0071] In the present invention, Re211 powder refers to Re2BaCuO5 powder or oxide powder obtained by mixing Re and its oxide, Ba and its oxide, Cu and its oxide in a molar ratio of 2:1:1.

[0072] In the present invention, copper barium oxide powder refers to BaCuO2 powder and / or BaCu2O2 powder.

[0073] Wherein, the auxiliary powder includes, based on the main powder, in terms of mass percentage: silver oxide powder ≤20%, cerium oxide powder and / or platinum powder ≤5%, and Re123 powder ≤20%.

[0074] In the present invention, the proportion of the auxiliary powder is ≤% of the mass of the main powder, such as the amount of the silver oxide powder is ≤20% of the mass of the main powder, and the rest can be deduced by analogy.

[0075] In the present invention, the amount of silver oxide powder in the auxiliary powder used is ≤ 20% of the mass of the main powder, for example, it can be 20%, 18%, 16%, 14%, 12%, 10%, 8%, 6%, 4%, 2% or 1% of the mass of the main powder, but is not limited to the listed values, and other values ​​not listed within this range also meet the requirements.

[0076] In the present invention, the amount of cerium oxide powder and / or platinum powder in the auxiliary powder used is ≤5% of the mass of the main powder, for example, it can be 5%, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, 1% or 0.5% of the mass of the main powder, but is not limited to the listed values, and other values ​​not listed within this range also meet the requirements.

[0077] In the present invention, the amount of Re123 powder in the auxiliary powder used is ≤20% of the mass of the main powder, for example, it can be 20%, 18%, 16%, 14%, 12%, 10%, 8%, 6%, 4%, 2% or 1% of the mass of the main powder, but is not limited to the listed values, and other values ​​not listed within this range also meet the requirements.

[0078] In the present invention, Re123 powder refers to finished ReBCO powder, which can be a commercially available product or a powder synthesized according to the prior art.

[0079] In the present invention, the Re includes one or a combination of at least two of the Y element, the Gd element or the Yb element.

[0080] In a preferred embodiment, the Re123 powder used in the auxiliary powder is 1-5% by mass based on the main powder, for example, it can be 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, etc., but is not limited to the listed values, and other values ​​not listed within this range also meet the requirements.

[0081] Wherein, the particle size of the powder in the mixed powder is less than 1 μm.

[0082] Furthermore, this embodiment provides a method for preparing the aforementioned rare earth barium copper oxide superconducting wire, the preparation method comprising:

[0083] The raw material powder is filled into a silver tube and stretched, and then preheated, pre-melted, textured, first heat treated and second heat treated are performed in sequence to obtain a rare earth barium copper oxide superconducting wire.

[0084] Wherein, the stretching includes at least one cold stretching and / or at least one hot stretching.

[0085] In the present invention, cold stretching and hot stretching can be crossed and combined with each other during the stretching process.

[0086] Among them, the diameter compression ratio of the at least one cold stretching is 1-10%, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%, etc., but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0087] In the at least one cold stretching, each stretching is followed by firing, preferably, each 2×i stretching is followed by firing, i∈N*.

[0088] Wherein, the firing temperature is 300-800°C, for example, it can be 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, 600°C, 650°C, 700°C, 750°C or 800°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0089] Wherein, the firing time is 4-12h, for example, it can be 4h, 4.5h, 5h, 5.5h, 6h, 6.5h, 7h, 7.5h, 8h, 8.5h, 9h, 9.5h, 10h, 10.5h, 11h, 11.5h or 12h, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0090] Wherein, the firing is carried out under absolute vacuum degree <1Pa or inert atmosphere, for example, it can be 0.9Pa, 0.8Pa, 0.7Pa, 0.6Pa, 0.5Pa, 0.4Pa, 0.3Pa, 0.2Pa or 0.1Pa, etc., but not limited to the listed values, other unlisted values ​​within the range also meet the requirements.

[0091] Among them, the diameter compression ratio of the at least one hot stretching is 1-20%, for example, it can be 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%, etc., but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0092] Among them, the stretching temperature of the at least one hot stretching is 300-800℃, for example, it can be 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃ or 800℃, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0093] Wherein, the at least one hot stretching is carried out under absolute vacuum degree <1Pa or inert atmosphere, for example, it can be 0.9Pa, 0.8Pa, 0.7Pa, 0.6Pa, 0.5Pa, 0.4Pa, 0.3Pa, 0.2Pa or 0.1Pa, etc., but not limited to the listed values, other unlisted values ​​within this range also meet the requirements.

[0094] The preheating temperature is 800-850°C, for example, 800°C, 810°C, 820°C, 830°C, 840°C or 850°C, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0095] The preheating time is ≤ 3 h, for example, it can be 3 h, 2.5 h, 2 h, 1.5 h, 1 h, 0.5 h or 0.1 h, but is not limited to the listed values. Other values ​​not listed within the range also meet the requirements.

[0096] Wherein, the preheating is carried out under absolute vacuum degree <1Pa or inert atmosphere, for example, it can be 0.9Pa, 0.8Pa, 0.7Pa, 0.6Pa, 0.5Pa, 0.4Pa, 0.3Pa, 0.2Pa or 0.1Pa, etc., but not limited to the listed values, other unlisted values ​​within the range also meet the requirements.

[0097] The pre-melting temperature is 900-950°C, for example, 900°C, 910°C, 920°C, 930°C, 940°C or 950°C, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0098] The pre-melting time is 1-60 min, for example, it can be 1 min, 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0099] Wherein, the pre-melting is carried out under absolute vacuum degree <1Pa or inert atmosphere, for example, it can be 0.9Pa, 0.8Pa, 0.7Pa, 0.6Pa, 0.5Pa, 0.4Pa, 0.3Pa, 0.2Pa or 0.1Pa, etc., but not limited to the listed values, other unlisted values ​​within the range also meet the requirements.

[0100] The temperature of the texture growth is 900-950°C, for example, 910°C, 920°C, 930°C, 940°C or 950°C, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0101] In the present invention, the temperature of texture growth can be selectively controlled to be a fixed value within a range or to change within a certain subset within the range, such as when the temperature decreases from high to low, the decrease amplitude is ≤5°C, wherein when the temperature of texture growth changes within a certain subset within the range, it can be 950°C to 945°C, or 930°C to 925°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0102] Wherein, the time for texture growth is 1-72h, for example, it can be 1h, 2h, 4h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, 30h, 32h, 33h, 34h, 36h, 38h, 40h, 42h, 44h, 46h, 48h, 50h, 52h, 54h, 56h, 58h, 60h, 62h, 64h, 66h, 68h, 70h or 72h, etc., but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0103] Wherein, the texture growth is carried out in an oxygen atmosphere with a volume content of 0.001-5%, for example, it can be 0.001%, 0.002%, 0.004%, 0.006%, 0.008%, 0.01%, 0.02%, 0.04%, 0.06%, 0.08%, 0.1%, 0.2%, 0.4%, 0.6%, 0.8%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, etc., but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0104] In the present invention, the volume content of oxygen in texture growth can be selectively controlled to be a fixed value within a range or to vary in high and low within a certain subset within the range, wherein the volume content of oxygen is regulated by an inert gas such as helium, neon, nitrogen, etc., such as gradually increasing linearly from 0.001-0.5% to 1-5%, or linearly decreasing from 1-5% to 0.001-0.5%, wherein the gradual linear increase can be a linear increase from 0.001% to 1% after 10 hours, or the gas component change can be divided into stages such as 0.001%, 0.01%, 0.1%, 1%, etc., and increased in stages within a fixed time, which also belongs to a linear change.

[0105] In which, during the texture growth, while maintaining the gas composition unchanged, the pressure is controlled to be 10-100 bar to improve the crystal density and stability. For example, it can be 10 bar, 20 bar, 40 bar, 60 bar, 80 bar or 100 bar, but is not limited to the listed values. Other values ​​not listed within this range also meet the requirements.

[0106] Furthermore, in order to enhance product performance, a direct current or a magnetic field is applied to the wire during texture growth.

[0107] Among them, the size of direct current is 10μA-1A, for example, it can be 10μA, 20μA, 40μA, 60μA, 80μA, 100μA, 200μA, 400μA, 600μA, 800μA, 1mA, 2mA, 4mA, 6mA, 8mA, 10mA, 20mA, 40mA, 60mA, 80mA, 100mA, 200mA, 400mA, 600mA, 800mA or 1A, but is not limited to the listed values, and other values ​​not listed in the range also meet the requirements.

[0108] Among them, the intensity of the magnetic field is ≤10T, for example, it can be 10T, 9T, 8T, 7T, 6T, 5T, 4T, 3T, 2T, 1T, 0.5T, 0.1T, 0.05T or 0.01T, but is not limited to the listed values. Other values ​​not listed in the range also meet the requirements.

[0109] In the present invention, the direction of the magnetic field applied to the wire can be optionally perpendicular to the direction of the current in the wire, that is, perpendicular to the wire.

[0110] Among them, the temperature of the first heat treatment is 500-800℃, for example, it can be 500℃, 550℃, 600℃, 650℃, 700℃, 750℃ or 800℃, but is not limited to the listed values, and other unlisted values ​​within this range also meet the requirements.

[0111] Wherein, the time of the first heat treatment is 5-48h, for example, it can be 5h, 6h, 8h, 10h, 12h, 14h, 16h, 18h, 20h, 22h, 24h, 26h, 28h, 30h, 32h, 34h, 36h, 38h, 40h, 42h, 44h, 46h or 48h, but is not limited to the listed values, and other values ​​not listed within the range also meet the requirements.

[0112] Wherein, the first heat treatment is carried out in an atmosphere with an oxygen volume content ≥21%, for example, it can be 21%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100%, etc., but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0113] The temperature of the second heat treatment is 300-600°C, for example, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C or 600°C, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0114] Wherein, the time of the second heat treatment is 24-200h, for example, it can be 24h, 30h, 40h, 50h, 60h, 70h, 80h, 90h, 100h, 110h, 120h, 130h, 140h, 150h, 160h, 170h, 180h, 190h or 200h, but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0115] Wherein, the second heat treatment is carried out in an atmosphere with an oxygen volume content ≥21%, for example, it can be 21%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or 100%, etc., but is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0116] Among them, in the second treatment, the crystal density and stability are improved by controlling the gas phase pressure while maintaining the gas composition unchanged, and the gas phase pressure can be selected to be 10-100 bar, for example, it can be 10 bar, 20 bar, 40 bar, 60 bar, 80 bar or 100 bar, etc., but it is not limited to the listed values, and other unlisted values ​​within the range also meet the requirements.

[0117] The wire obtained after the second heat treatment can be optionally cooled to below 4.2K and slowly heated to room temperature to destroy the internal stress in the wire through thermal expansion and contraction, thereby ensuring stable performance of the wire.

[0118] In the present invention, room temperature refers to a temperature of 15-35°C.

[0119] Furthermore, after being bent or wound, the obtained wire can be subjected to one or more second heat treatments to restore the superconducting properties of the wire.

[0120] Further, in order to illustrate the superconducting effect that can be achieved by the rare earth barium copper oxide superconducting wire provided by the present invention, the following practical examples are used for illustration, as follows:

[0121] Example 1

[0122] This embodiment provides a method for preparing a Re(Y)BCO wire, which is as follows:

[0123] The silver tube used in this embodiment is a cylindrical sleeve with a purity of 99.9%. The silver tube is calcined at 880° C. for 5 h in a vacuum environment of 1 Pa to promote the secondary growth of the (111) crystal plane.

[0124] The raw materials Y211 and copper barium oxide used in this example are commercially available products, and the remaining oxides are of analytical grade (purity of 99.9%).

[0125] Y2BaCuO5 (Y211), BaCu2O2 and BaO are mixed in a molar ratio of Y:Ba:Cu=1:2:3 to obtain a mixed powder, and 10% of the mass of the mixed powder of Y211 is additionally added, and the mixture is thoroughly mixed again.

[0126] According to the total weight of the mixed powder, 5 wt% of Ag2O, 1 wt% of CeO2 and 5% of commercially available Y123 powder were added.

[0127] Fill the prepared raw materials into the silver tube and seal it with a pure silver stopper.

[0128] Then, the wire is stretched and pressed at a diameter compression ratio of 1% each time until the wire has a wall thickness of 100 μm.

[0129] The wire was fired once at each stretching interval, and the firing conditions were: firing at 800°C for 5 hours in an absolute vacuum of 0.5 Pa.

[0130] Heat the wire to 800℃ and keep it at this temperature for 1h to complete preheating.

[0131] Heat the wire to 945°C and keep it warm for 10 minutes to complete pre-melting.

[0132] During the preheating and pre-melting stages, the furnace body is kept in vacuum (absolute vacuum is 0.5Pa), and inert gas purging must be completed before vacuuming to prevent oxygen residue.

[0133] After the pre-melting, the wire was immediately cooled to 940°C, and then slowly cooled to 935°C over a 10-hour period to complete the texture growth. During the texture growth process, an Ar-O2 mixed gas was used to control the oxygen content in the furnace. During the 10-hour texture growth process, the O2 ratio in the gas increased linearly from 0.001% to 1%.

[0134] After the texture growth is completed, the furnace body is cooled to 800°C for the first heat treatment and kept warm for 24 hours, with the atmosphere in the furnace maintained as air to complete the heat treatment and crystal growth.

[0135] Afterwards, the wire is cooled to 500° C. for a second heat treatment, and the atmosphere in the furnace is changed to an oxygen-rich gas with an oxygen volume content of 60% and a heat treatment time of 72 h.

[0136] The resulting wire product is cooled to below 4.2K degrees Celsius and electrified, using thermal expansion and contraction to eliminate the excess performance of the wire itself.

[0137] The cross section of the sample in this embodiment is 0.15 mm 2 .

[0138] The obtained wire (the wire described in the embodiment is cooled by liquid helium and then restored to room temperature twice before electrical measurement) is tested for IV curves under different magnetic fields at a temperature of 4.2K, such as Figure 1 As shown in the figure, and the critical current of different magnetic fields at a temperature of 4.2K, as Figure 2 As shown, the wire cross section is 0.15mm 2 As a benchmark, the critical current density of the sample is converted, such as Figure 3 shown.

[0139] Example 2

[0140] The only difference from Example 1 is that the obtained sample was not subjected to cyclic cooling and heating, ie, liquid helium cooling, after the second heat treatment, and the crystal link was complete.

[0141] Figure 4The IV curves of the obtained samples under different magnetic fields at a temperature of 4.2K; Figure 5 The critical current under different magnetic fields at a temperature of 4.2K after the third heat treatment is shown, indicating that the obtained samples are stable and repeatable batches.

[0142] Figure 6 The critical current density of the samples obtained in Example 1 and Example 2 at 4.2K and different magnetic fields is compared, and the test results of the current mainstream materials at 4.2K are compared (taking the optimal value). The critical current density of the partially cut-off 4.2K of Example 2 can reach 3000A / mm at 0T 2 , which is close to the current best Bi-2223 wire performance. Example 2 The wire can achieve 740A / mm at 0T 2 , 550A / mm at 14T 2 .

[0143] Example 3

[0144] The only difference from Example 1 is that after the obtained wire has been wound, bent and stressed for 4 times, the critical current density has dropped significantly. At this time, the wire is subjected to a second heat treatment again, wherein the second heat treatment parameters are 600°C in an air atmosphere for 10 hours, then slowly cooled to 300°C, and switched to a pure oxygen atmosphere for the second heat treatment for 36 hours. Figure 7 The current-voltage curve at 4.2K under zero magnetic field changes before and after heat treatment. It can be seen from the figure that the wire performance is restored.

[0145] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0146] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0147] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A rare earth barium copper oxide superconducting wire, characterized in that: The rare earth barium copper oxide superconducting wire comprises: a wire core and a silver tube wrapping the wire core; The inner wall of the silver tube is a (111) crystal plane; The raw material powder used in the preparation of the wire core includes: main powder and auxiliary powder; The main powder comprises: a mixed powder having an atomic molar ratio of Re, Ba and Cu of 1:2:3, and Re211 powder having a mass percentage of ≤20% based on the mixed powder; The auxiliary powder comprises, based on the main powder, in terms of mass percentage: silver oxide powder ≤ 20%, cerium oxide powder and / or platinum powder ≤ 5%, and Re123 powder ≤ 20%.

2. The rare earth barium copper oxide superconducting wire according to claim 1, characterized in that: The mixed powder comprises Re211 powder, copper-barium oxide powder, copper oxide powder and barium oxide powder; Preferably, the Re211 powder includes: Re2BaCuO5 powder and / or oxide powder obtained by mixing Re and its oxide, Ba and its oxide, Cu and its oxide in a molar ratio of 2:1:1; Preferably, the copper-barium oxide powder comprises: BaCuO2 powder and / or BaCu2O2 powder; Preferably, the Re includes one or a combination of at least two of Y element, Gd element or Yb element; Preferably, the Re123 powder used in the auxiliary powder is 1-5% by mass based on the main powder.

3. The rare earth barium copper oxide superconducting wire according to claim 1, characterized in that: The particle size of the powder in the raw material for preparing the wire core is less than 1 μm.

4. A method for preparing a rare earth barium copper oxide superconducting wire according to any one of claims 1 to 3, characterized in that: The preparation method comprises: The raw material powder is filled into a silver tube and stretched, and then preheated, pre-melted, textured, first heat treated and second heat treated are performed in sequence to obtain a rare earth barium copper oxide superconducting wire.

5. The preparation method according to claim 4, characterized in that: The stretching comprises at least one cold stretching and / or at least one hot stretching; Preferably, the diameter compression ratio of the at least one cold stretching is 1-10%; Preferably, each stretching in the at least one cold stretching is supplemented by firing, preferably each 2×i stretching is supplemented by firing, i∈N*; Preferably, the firing temperature is 300-800°C; Preferably, the firing time is 4-12h; Preferably, the firing is carried out under an absolute vacuum degree of <1 Pa or an inert atmosphere; Preferably, the diameter compression ratio of the at least one hot stretching is 1-20%; Preferably, the stretching temperature of the at least one thermal stretching is 300-800°C; Preferably, the at least one thermal stretching is performed under an absolute vacuum degree of less than 1 Pa or an inert atmosphere.

6. The preparation method according to claim 4 or 5, characterized in that: The preheating temperature is 800-850°C; Preferably, the preheating time is ≤3h; Preferably, the preheating is carried out under an absolute vacuum degree of <1 Pa or an inert atmosphere; Preferably, the pre-melting temperature is 900-950°C; Preferably, the pre-melting time is 1-60 min; Preferably, the pre-melting is carried out under an absolute vacuum degree of less than 1 Pa or in an inert atmosphere.

7. The preparation method according to any one of claims 4 to 6, characterized in that: The temperature of the texture growth is 900-950°C; Preferably, the texture growth time is 1-72h; Preferably, the texture growth is carried out in an oxygen atmosphere with a volume content of 0.001-5%; Preferably, a direct current or a magnetic field is applied to the wire during the texture growth; Preferably, the magnitude of the direct current is 10μA-1A; Preferably, the intensity of the magnetic field is ≤10T.

8. The preparation method according to any one of claims 4 to 7, characterized in that: The temperature of the first heat treatment is 500-800°C; Preferably, the first heat treatment time is 5-48h; Preferably, the first heat treatment is performed in an atmosphere with an oxygen volume content of ≥ 21%.

9. The preparation method according to any one of claims 4 to 8, characterized in that: The temperature of the second heat treatment is 300-600°C; Preferably, the second heat treatment time is 24-200h; Preferably, the second heat treatment is carried out in an atmosphere with an oxygen volume content of ≥21%; Preferably, the gas phase pressure is controlled to be 10-100 bar in the second treatment.

10. Use of the rare earth barium copper oxide superconducting wire according to any one of claims 1 to 3, characterized in that: The application includes: using the rare earth barium copper oxide superconducting wire for current density ≥550A / mm 2 Conductive conduction below.

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