Yttrium barium copper oxide superconducting cable core wire and preparation method and application thereof

Abstract

The present invention relates to a yttrium barium copper oxide superconducting cable core wire and a preparation method and application thereof, and relates to the field of material technology. The preparation method comprises the following steps: adding a yttrium source, a barium source and a copper source to a polymer solution and stirring them to obtain a superconducting precursor spinning solution; printing the superconducting precursor spinning solution by an electrostatic spinning 3D printing method to obtain a core wire; freeze-drying the core wire, and then performing plastic removal and crystal growth treatment to obtain a superconducting core wire; protecting the surface of the superconducting core wire to obtain the yttrium barium copper oxide superconducting cable core wire. The present invention combines 3D printing with electrostatic spinning technology for the first time and applies it to the preparation of superconducting nanowires, breaking through the existing preparation method of YBCO superconducting materials, expanding the prepared product form to a one-dimensional core wire, enriching the product variety, and the obtained yttrium barium copper oxide superconducting cable core wire has the characteristics of high precision, good crystallinity and excellent superconductivity.

Description

Technical Field

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

[0002] High-temperature superconducting materials have zero resistance characteristics, Meissner effect and Josephson effect. At present, superconducting technology is widely used in major projects such as energy, information, transportation, medical treatment, scientific research and national defense and military industry. Among them, Bi-based high-temperature superconducting tapes have achieved industrial application in superconducting cables.

[0003] Yttrium barium copper oxide (YBCO) high-temperature superconducting materials have higher current carrying capacity under magnetic fields, such as high critical current density, high irreversible field and low AC loss, so they have been widely studied. At present, the most widely used are YBCO superconducting blocks, strips and superconducting films. Due to the "weak connection" of grain boundaries (that is, the non-ideality and non-completeness of the structure and components will inevitably affect the electronic structure, resulting in the weakening or even loss of high-temperature superconducting coupling between grains), it is very difficult to prepare YBCO superconducting wires using traditional methods. At present, there are some patents based on direct writing 3D printing methods in superconductor preparation, such as a method for preparing yttrium barium copper oxide superconducting strands based on 3D printing (Chinese patent number: CN201910916914.5) previously applied by the inventor, which prepares superconducting strands and blocks by gas pressure propulsion, and realizes self-supporting molding of paste slurry. The target structure is a multi-strand winding wire and a three-dimensional body, and its molding limit accuracy is only 100μm. In view of this, it is necessary to develop a yttrium barium copper oxide superconducting material with higher molding precision and better performance. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a yttrium barium copper oxide superconducting cable core wire and a preparation method and application thereof.

[0005] In a first aspect, the present invention provides a method for preparing a yttrium barium copper oxide superconducting cable core wire, the preparation method comprising the following steps:

[0006] adding a yttrium source, a barium source and a copper source into a polymer solution and stirring the solution to obtain a superconducting precursor spinning solution;

[0007] Printing the superconducting precursor spinning solution by electrospinning 3D printing to obtain a core filament;

[0008] The core wire is freeze-dried, and then subjected to plastic removal and crystal growth treatment to obtain a superconducting core wire;

[0009] The surface of the superconducting core wire is protected to obtain the yttrium barium copper oxide superconducting cable core wire.

[0010] Furthermore, the molar ratio of Y in the yttrium source, Ba in the barium source and Cu in the copper source is 1:2:3.

[0011] Furthermore, the polymer solution contains a polymer and a solvent, the mass ratio of the polymer to the solvent is 3-5wt%; the polymer includes at least one of polyvinyl pyrrolidone, polyvinyl alcohol, polyamide, polylactic acid and gelatin; the solvent is composed of methanol, acetic acid and propionic acid in a mass ratio of 2.5:1:1.5; the viscosity of the superconducting precursor spinning solution is 50-100CPS.

[0012] Furthermore, the yttrium source includes at least one of hydrated yttrium acetate and yttrium nitrate pentahydrate; the barium source includes at least one of barium acetate and barium nitrate; and the copper source includes at least one of copper acetate monohydrate and 2.5 hydrated copper nitrate.

[0013] Furthermore, the working parameters of the electrospinning 3D printing method include: a spinning solution flow rate of 0.8-1.5 ml / h; at the beginning, the voltage is increased from 0 kV to 20-25 kV, and when the spinning solution at the needle tip forms a Taylor cone, the voltage is continued to be increased until the jet is ejected into the liquid collection plate.

[0014] Furthermore, the freeze-drying working parameters include: temperature of -65°C to -30°C, and time of 30 to 50 hours.

[0015] Furthermore, the steps of the plastic removal and crystal growth treatment include the following processes:

[0016] Placing the freeze-dried core wire in a device, and sequentially operating the device according to a first operating procedure, a second operating procedure, a third operating procedure, and a fourth operating procedure to obtain the superconducting core wire;

[0017] The first operation procedure includes: heating from 0°C to 450-500°C at a heating rate of 40-60°C / h and keeping the temperature for 3-5 hours;

[0018] The second operation procedure includes: introducing oxygen at a flow rate of 100 to 200 sccm, while heating to 800 to 820°C at a heating rate of 60 to 120°C / h and keeping the temperature for 10 to 20 hours;

[0019] The third operation procedure includes: heating to 910-930°C at a heating rate of 0.3-0.5°C / h and keeping the temperature for 1-3h;

[0020] The fourth operation procedure includes: cooling the temperature to 420-450° C. at a cooling rate of 50-60° C. / h, introducing high-purity oxygen at a flow rate of 100-200 Sccm for 2-4 hours, and finally maintaining the pressure at 2 MPa for 12 hours.

[0021] Furthermore, the step of performing a protective treatment on the surface of the superconducting core wire to obtain the yttrium barium copper oxide superconducting cable core wire includes the following process:

[0022] The surface of the superconducting core wire is coated with silver to obtain a silver-coated superconducting core wire;

[0023] The surface of the silver-coated superconducting core wire is coated and armored with metal copper to obtain the yttrium barium copper oxide superconducting cable core wire.

[0024] In a second aspect, the present invention provides a yttrium barium copper oxide superconducting cable core wire, which is prepared by the preparation method described in any one of the first aspects, and the diameter of the superconducting core wire is 100nm-1um. The diameter of the yttrium barium copper oxide superconducting cable core wire after being coated with silver and armored with metal copper is 500nm-10μm.

[0025] In a third aspect, the present invention provides an application of the yttrium barium copper oxide superconducting cable core wire described in any one of the first aspect and the second aspect in lossless current transmission and preparation of superconducting equipment.

[0026] The above technical solution provided by the embodiment of the present invention has at least the following advantages compared with the prior art:

[0027] The embodiment of the present invention provides a method for preparing a yttrium barium copper oxide superconducting cable core wire. The present invention combines 3D printing with electrostatic spinning technology for the first time and applies it to the preparation of superconducting nanowires, breaking through the existing preparation method of YBCO superconducting materials, expanding the prepared product form to a one-dimensional core wire, and enriching the product variety. The obtained yttrium barium copper oxide superconducting cable core wire has the characteristics of high precision, good crystallinity, and excellent superconductivity. Specifically:

[0028] 1) Compared with the existing preparation method of YBCO superconducting materials, its main technical features are the preparation of superconducting multi-strand wires and blocks by air pressure propulsion, self-supporting molding achieved by paste slurry, and the target structure is multi-strand winding wires and three-dimensional bodies, and its molding limit accuracy is only 100μm. The technology applied for this time is to use solution ink for inkjet printing, and use the electric field Taylor cone effect to make the ink pass through the nano needle to form nanowires, with a molding accuracy range of 100nm-1μm. The structural form prepared by this technology is impossible to achieve with the existing technology, and the wire has the characteristics of high precision, good crystallinity, and excellent superconductivity.

[0029] 2) This technology combines 3D printing and electrospinning technology for the first time in the preparation of superconducting nanowires. It pioneered the design of superconducting ink materials that are compatible with inkjet technology, and personalized the 3D printing molding platform for superconducting nanowire collection tanks, breaking through the application limits of traditional 3D printing technology. It also provides an experimental basis for the customized manufacturing of superconducting nanowires.

[0030] 3) The present invention breaks through the barrier that the existing technology cannot realize nano-scale high-crystallization superconducting wires, and solves the problem of superconducting performance failure caused by the existence of large grain boundary angles inside traditional YBCO superconducting materials; at the same time, with the help of customized path setting of 3D printing technology, the orderly arrangement of superconducting core wires is achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0033] Figure 1 The present invention provides a flow chart of a method for preparing a yttrium barium copper oxide superconducting cable core wire.

[0034] Figure 2 This is a flow chart of the method for preparing the yttrium barium copper oxide superconducting cable core wire in Example 1 of the present invention.

[0035] Figure 3 Graph showing the morphology and crystallization properties of YBCO wire in an embodiment of the present invention.

[0036] Figure 4 This is a microscopic characterization diagram of the YBCO wire in an embodiment of the present invention.

[0037] Figure 5 This is a structural diagram of the electrospinning 3D printing device for the yttrium barium copper oxide superconducting cable core wire in an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0040] In a first aspect, the present invention provides a method for preparing a yttrium barium copper oxide superconducting cable core wire, such as Figure 1 As shown, the preparation method comprises the following steps:

[0041] adding a yttrium source, a barium source and a copper source into a polymer solution and stirring the solution to obtain a superconducting precursor spinning solution;

[0042] Printing the superconducting precursor spinning solution by electrospinning 3D printing to obtain a core filament;

[0043] The core wire is freeze-dried, and then subjected to plastic removal and crystal growth treatment to obtain a superconducting core wire;

[0044] The surface of the superconducting core wire is protected to obtain the yttrium barium copper oxide superconducting cable core wire.

[0045] The embodiment of the present invention provides a method for preparing yttrium barium copper oxide superconducting cable core wires. The preparation method is mainly divided into three steps: preparation of superconducting precursor spinning solution, electrospinning 3D printing, and wire post-processing. The present invention combines 3D printing with electrospinning technology for the first time and applies it to the preparation of superconducting nanowires, breaking through the existing preparation method of YBCO superconducting materials, expanding the prepared product form to one-dimensional core wires, and enriching the product variety. The obtained yttrium barium copper oxide superconducting cable core wires have the characteristics of high precision, good crystallinity, and excellent superconductivity. The superconducting core wires prepared by the advanced technology of electrospinning assisted 3D printing can be applied to emerging energy fields such as lossless transmission of current, superconducting energy storage, superconducting current limiters, winding of magnets, superconducting computers, filters, etc. Specifically:

[0046] 1) Compared with the existing preparation method of YBCO superconducting materials, its main technical features are the preparation of superconducting multi-strand wires and blocks by air pressure propulsion, self-supporting molding achieved by paste slurry, and the target structure is multi-strand winding wires and three-dimensional bodies, and its molding limit accuracy is only 100μm. The technology applied for this time is to use solution ink for inkjet printing, and use the electric field Taylor cone effect to make the ink pass through the nano needle to form nanowires, with a molding accuracy range of 100nm-1μm. The structural form prepared by this technology is impossible to achieve with the existing technology, and the wire has the characteristics of high precision, good crystallinity, and excellent superconductivity.

[0047] 2) This technology combines 3D printing and electrospinning technology for the first time in the preparation of superconducting nanowires. It pioneered the design of superconducting ink materials that are compatible with inkjet technology, and personalized the 3D printing molding platform for superconducting nanowire collection tanks, breaking through the application limits of traditional 3D printing technology. It also provides an experimental basis for the customized manufacturing of superconducting nanowires.

[0048] 3) The present invention breaks through the barrier that the existing technology cannot realize nano-scale high-crystallization superconducting wires, and solves the problem of superconducting performance failure caused by the existence of large grain boundary angles inside traditional YBCO superconducting materials; at the same time, with the help of customized path setting of 3D printing technology, the orderly arrangement of superconducting core wires is achieved.

[0049] In some specific embodiments, the electrospinning 3D printing method is a dedicated device independently developed and built, and its equipment structure is shown in the figure. The electrospinning 3D printing device is mainly composed of four parts: a direct writing 3D printer, a high-voltage power supply, a precursor liquid propeller, and a receiving device for collecting cable core filaments; among them, the direct writing 3D printer, the high-voltage power supply, the precursor liquid propeller, and the receiving device for collecting cable core filaments are all existing commercially available equipment, and no improvements have been made. The above four parts are connected in sequence. Figure 5 As shown, the receiving device is a grounded aluminum plate, and the precursor liquid propeller is a constant flow pump that controls the flow rate of the solution. The delivery flow rate is controlled by mechanically pushing the wire. After the high-voltage power supply is connected, a high-voltage potential is applied to the ejection head of the polymer solution, forming a strong electrostatic field between the spinneret and the receiving device. Under the high-voltage electrostatic field, the polymer solution is positively charged, so that the surface of the liquid is charged. When the electric field force continues to increase until it exceeds a certain critical value, the thin stream will be pulled tens of millions of times within tens of millimeters, bending and whipping along an unstable spiral trajectory. As the solvent evaporates, the thin stream solidifies to form micron to nanometer-level ultrafine fibers. At the same time, the 3D printer moves along a certain path such as a spiral or a U-shaped path, and finally deposits on the solution collector or receiving plate.

[0050] In some specific embodiments, the molar ratio of Y in the yttrium source, Ba in the barium source, and Cu in the copper source is 1:2:3. In the present application, the molar ratio of Y in the yttrium source, Ba in the barium source, and Cu in the copper source is controlled to be 1:2:3 to achieve excellent superconducting performance, which is a key parameter for realizing this scheme. If the molar ratio is adjusted to 1:2:1, 1:2:4, 1:1:3, 1:3:3, 2:2:3, etc., it will cause component segregation, causing the obtained material to lose superconductivity.

[0051] In some specific embodiments, the polymer solution contains a polymer and a solvent, the mass ratio of the polymer to the solvent is 3-5wt%, specifically referring to "the weight ratio of polymer: solvent is (0.03-0.05):1; the polymer includes at least one of polyvinyl pyrrolidone, polyvinyl alcohol, polyamide, polylactic acid and gelatin; the solvent is composed of methanol, acetic acid and propionic acid in a mass ratio of 2.5:1:1.5; the viscosity of the superconducting precursor spinning solution is 50-100CPS.

[0052] In some specific embodiments, the yttrium source includes at least one of hydrated yttrium acetate and yttrium nitrate pentahydrate; the barium source includes at least one of barium acetate and barium nitrate; and the copper source includes at least one of copper acetate monohydrate and 2.5 hydrated copper nitrate.

[0053] In some specific embodiments, the working parameters of the electrospinning 3D printing method include: a spinning solution flow rate of 0.8-1.5 ml / h; at the beginning, the voltage is increased from 0 kV to 20-25 kV, and when the spinning solution at the needle tip forms a Taylor cone, the voltage is continued to be increased until the jet is ejected into the liquid collection plate.

[0054] In some specific embodiments, the freeze-drying operating parameters include: a temperature of -65°C to -30°C and a time of 30 to 50 hours.

[0055] In some specific embodiments, the steps of molding and crystal growth treatment include the following process:

[0056] Placing the freeze-dried core wire in a device, and sequentially operating the device according to a first operating procedure, a second operating procedure, a third operating procedure, and a fourth operating procedure to obtain the superconducting core wire;

[0057] The first operation procedure includes: heating from 0°C to 450-500°C at a heating rate of 40-60°C / h and keeping the temperature for 3-5 hours;

[0058] The second operation procedure includes: introducing oxygen at a flow rate of 100 to 200 sccm, while heating to 800 to 820°C at a heating rate of 60 to 120°C / h and keeping the temperature for 10 to 20 hours;

[0059] The third operation procedure includes: heating to 910-930°C at a heating rate of 0.3-0.5°C / h and keeping the temperature for 1-3h;

[0060] The fourth operation procedure includes: cooling the temperature to 420-450° C. at a cooling rate of 50-60° C. / h, introducing high-purity oxygen at a flow rate of 100-200 Sccm and maintaining the pressure at 2 MPa for 12 hours.

[0061] In some specific embodiments, the step of performing a protective treatment on the surface of the superconducting core wire to obtain the yttrium barium copper oxide superconducting cable core wire comprises the following process:

[0062] The surface of the superconducting core wire is coated with silver to obtain a silver-coated superconducting core wire;

[0063] The surface of the silver-coated superconducting core wire is coated and armored with metal copper to obtain the yttrium barium copper oxide superconducting cable core wire.

[0064] In some specific embodiments, preferably, the method for preparing the yttrium barium copper oxide superconducting cable core wire comprises the following process:

[0065] first step:

[0066] Prepare superconducting precursor spinning solution (taking acetate as an example): use hydrated yttrium acetate (Y(CH 3 CO 2 ) 3 ·xH 2 O) (99.9%), barium acetate (Ba(CH 3 CO 2 ) 2 ) (99%), dried at 120 °C overnight before use, and copper acetate monohydrate (Cu(CH 3 CO 2 ) 2 ·H 2O) (98%), in order to obtain the correct YBCO stoichiometry, the three acetates are configured according to the molar ratio of Y:Ba:Cu=1:2:3. A polymer is added to the precursor to adjust the viscosity, and the diameter of the spun fiber is controlled by adjusting the viscosity. The polymers used are polyvinyl pyrrolidone (PVP, MW=1300000), polyvinyl alcohol (Polyvinyl Alcohol, PVA), polyamide (Polyamide), polylactic acid (Polylactic Acid, PLA), and gelatin, which are dissolved in a certain amount of methanol, acetic acid and propionic acid mixture, methanol: acetic acid: propionic acid = 2.5:1:1.5 (mass ratio), and the mass ratio of polymer to solvent is 3-5wt%. In order to make the acetate evenly distributed in the polymer solvent, the precursor spinning solution is mechanically stirred at room temperature for 12-24 hours. The viscosity of the precursor is measured using a viscometer, and the viscosity is adjusted by controlling the ratio of acetate and polymer solvent to control the viscosity at 50-100CPS. Electrospinning-assisted 3D printing technology to prepare YBCO superconducting cable core wire process and control parameters Figure 1 shown.

[0067] Step 2:

[0068] Electrospinning 3D printing: After the superconducting precursor spinning solution is prepared, it is poured into the printing barrel. The travel path in the XY plane of the printer is designed according to the needs. For example, the travel path can be spiral, U-shaped, etc. The needle movement rate and the distance from the collector in the Z-axis direction are controlled by programming. For example, the needle movement rate is 10mm / s, and the distance between the needle and the collector is 3-5cm. An external micro-propeller is used to control the flow rate of the spinning solution, and the flow rate is controlled at 0.8-1.5ml / h. The needle is selected as 23G or 25G, and the inner diameter is 0.34mm or 0.26mm respectively. The collector bottom plate is made of cadmium-plated iron plate or aluminum plate, and polytetrafluoroethylene, polyimide and polycarbonate insulating materials are used around it. The bottom surface of the collector is paved with receiving aluminum foil. After everything is ready, turn on the high-voltage power switch and slowly increase the voltage to 20-25kV. When the spinning solution at the needle forms a Taylor cone, continue to increase the voltage until the jet is ejected into the liquid collection plate. Control the printer Z-axis programmer to adjust the needle position to a suitable height, such as 3 to 5 cm, to obtain the target wire diameter. Collect the wire on the bottom plate through the designed XY path to achieve a spiral or U-shaped collection form.

[0069] Step 3:

[0070] Freeze drying: Place the printed filament core in a freeze dryer and remove excess liquid from the inside of the filament at -30 to -65°C for 30 to 50 hours, using freeze drying technology to form a complete support structure.

[0071] Step 4:

[0072] Plastic removal and crystal growth: Place the freeze-dried filament core wire on the supporting chassis, place the filament core wire and the supporting chassis in a box furnace and heat it to 450-500°C at a heating rate of 40-60°C / h, and then keep it warm for 3-5 hours to fully oxidize, decompose and volatilize the organic matter in the wire. Then, introduce oxygen with a flow rate of 100-200sccm, and heat it to 800-820°C at a heating rate of 60-120°C / h and keep it warm for 10-20h, then heat it to 910-930°C at a rate of 0.3-0.5°C / h and keep it warm for 1-3h, so that the YBCO small grains can fully react and grow into uniformly arranged and long-range ordered YBCO superconducting wires. The temperature was lowered to 420-450°C at a cooling rate of 50-60°C / h, high-purity oxygen was introduced and the pressure was maintained at 2MPa for 12 hours to fully oxygenate the YBCO crystal structure and achieve a good superconducting state.

[0073] Step 5:

[0074] Silver coating and wire reinforcement: Use physical vapor deposition, chemical vapor deposition and other methods to silver-coat the superconducting YBCO wire and provide coating protection. Use vacuum ion plating, thermal spraying, plasma spraying and other methods to coat and armor the surface of the silver-coated YBCO superconducting core wire with metal copper to form a concentric composite superconducting wire.

[0075] It should be noted that the components and raw materials involved in the yttrium barium copper oxide superconducting cable core wire and the preparation method thereof provided in the embodiments of the present invention can directly use commercially available products unless otherwise specified or described. At the same time, the operation steps and parameters involved can be carried out according to the existing 3D printing technology or using existing equipment unless otherwise specified or described, and this document will not repeat them one by one.

[0076] In the second aspect, based on a general inventive concept, the present invention provides a yttrium barium copper oxide superconducting cable core wire, which is prepared by the preparation method described in any one of the first aspects, and the diameter of the superconducting core wire is 100nm-1um. The diameter of the yttrium barium copper oxide superconducting cable core wire after being coated with silver and armored with metal copper is 500nm-10μm.

[0077] In a third aspect, based on a general inventive concept, the present invention provides an application of the yttrium barium copper oxide superconducting cable core wire described in any one of the first aspect and the second aspect in lossless current transmission and preparation of superconducting equipment.

[0078] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are usually measured according to national standards. If there is no corresponding national standard, then the conditions recommended by the manufacturer are followed.

[0079] Example 1

[0080] This example provides a yttrium barium copper oxide superconducting cable core wire, such as Figure 2 As shown, the method for preparing the yttrium barium copper oxide superconducting cable core wire comprises the following steps:

[0081] Step 1: Prepare the superconducting precursor spinning solution: 1) Use hydrated yttrium acetate (Y(CH 3 CO 2 ) 3 ·xH 2 O) (99.9%), barium acetate (Ba(CH 3 CO 2 ) 2 ) (99%), dried at 120 °C overnight before use, and copper acetate monohydrate (Cu(CH 3 CO 2 ) 2 ·H 2 O) (98%), three acetates are configured as precursors according to a molar ratio of Y:Ba:Cu=1:2:3; 2) a polymer solution is added to the precursor to adjust the viscosity, the polymer solution is prepared by dissolving polyvinyl pyrrolidone in a certain amount of solvent, the mass ratio of polymer to solvent is 4wt%, and the solvent is composed of methanol:acetic acid:propionic acid=2.5:1:1.5 (mass ratio), in order to make the acetate uniformly distributed in the polymer solvent, the precursor spinning solution is mechanically stirred at room temperature for 20 hours to obtain a superconducting precursor spinning solution, and the viscosity of the superconducting precursor spinning solution is measured by a viscometer to be 60CPS;

[0082] Step 2, electrospinning 3D printing: After the superconducting precursor spinning solution is prepared in the first step, it is poured into the printing barrel. The travel path in the XY plane of the printer is designed according to needs. For example, the travel path can be spiral, U-shaped, etc. The needle movement rate and the distance from the collector in the Z-axis direction are programmed and controlled. The needle movement rate is 10mm / s, and the distance between the needle and the collector is 3-5cm; an external micro-propeller is used to control the flow rate of the spinning solution, and the flow rate is controlled at 0.8-1.5ml / h. The needle is selected as 23G or 25G, and the inner diameter is 0.34mm or 0.2 6mm; the collector bottom plate is made of cadmium-plated iron plate, and the surrounding area is made of polytetrafluoroethylene insulation material, and the bottom of the collector is paved with receiving aluminum foil; when everything is ready, turn on the high-voltage power switch and slowly increase the voltage to 20-25kV. When the spinning solution at the needle tip forms a Taylor cone, continue to increase the voltage until the jet is ejected into the liquid collection plate; control the printer Z-axis programmer to adjust the needle position to a suitable height, such as 3-5cm, to obtain the target wire diameter; collect the wire on the bottom plate through the designed XY path to achieve spiral and U-shaped collection forms;

[0083] Step 3: Freeze drying: Place the filament core printed in the second step in a freeze dryer to remove excess liquid from the inside of the filament at -30 to -54°C for 30 to 50 hours, using freeze drying technology to form a complete support structure.

[0084] Step 4: plastic removal and crystal growth: place the filament core wire freeze-dried in the third step on the supporting chassis, place the filament core wire and the supporting chassis together in a box furnace and heat it to 480°C at a heating rate of 50°C / h, then keep it warm for 3 hours to fully oxidize, decompose and volatilize the organic matter in the wire; then introduce oxygen with a flow rate controlled at 150sccm, and heat it to 810°C at a heating rate of 80°C / h and keep it warm for 15h, then heat it to 920°C at a rate of 0.4°C / h and keep it warm for 2h, so that the YBCO small grains can fully react and grow into uniformly arranged and long-range ordered YBCO superconducting wires; cool it down to 435°C at a cooling rate of 60°C / h, introduce high-purity oxygen and keep it at a pressure of 2MPa for 12 hours to fully oxygenate the YBCO crystal structure and achieve a good superconducting state;

[0085] Step 5: Silver coating and wire reinforcement (protection treatment of the surface of the superconducting core wire): chemical vapor deposition method (specific working parameters include: (1) reaction solvent: tetraphenyl dioxoimido diphosphine silver-[Ag{(OPPh 2 ) 2 N}] 4 ·2H 2O, toluene; (2) protective gas: argon, flow rate 140-160 sccm; (3) deposition time: 120-150 min; (4) deposition temperature: 350-415 °C) to coat the superconducting YBCO wire with silver, and then coat it with a silver coating with a thickness of 1-2 μm. The vacuum ion plating method is used (the specific working parameters include: (1) vacuum requirement: 3×10 -6 Torr; (2) coating temperature: 430℃; (3) working voltage: 3~5kv; (3) shielding gas: argon; (4) coating time: 35min) The surface of the silver-coated YBCO superconducting core wire is coated and armored with metal copper to form a concentric composite superconducting wire - that is, the yttrium barium copper oxide superconducting cable core wire.

[0086] After testing, the diameter of the superconducting core wire of the Y-Ba-Cu-O superconducting cable core wire obtained in this example is 500nm, and its superconducting performance parameters include: Tc = 91K; Jc>3×10 7 A / cm 2 The Yttrium Barium Copper Oxide superconducting cable core wire obtained in this example has the characteristics of regular arrangement and high critical current. Figure 3 This is the YBCO wire morphology and crystallization performance diagram in this example. Figure 4 This is the microscopic characterization of the YBCO wire in this example.

[0087] Various embodiments of the present invention may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present invention; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0088] The foregoing is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for preparing a yttrium barium copper oxide superconducting cable core wire, characterized in that: The diameter of the YBCO superconducting cable core wire is 100nm-1um, and the preparation method comprises the following steps: adding a yttrium source, a barium source and a copper source into a polymer solution and stirring the solution to obtain a superconducting precursor spinning solution; Printing the superconducting precursor spinning solution by electrospinning 3D printing to obtain a core filament; The core wire is freeze-dried, and then subjected to plastic removal and crystal growth treatment to obtain a superconducting core wire; Performing a protective treatment on the surface of the superconducting core wire to obtain the yttrium barium copper oxide superconducting cable core wire; The molar ratio of Y in the yttrium source, Ba in the barium source and Cu in the copper source is 1:2:3; The steps of the molding and crystal growth treatment include the following processes: Placing the freeze-dried core wire in a device, and sequentially operating the device according to a first operating procedure, a second operating procedure, a third operating procedure, and a fourth operating procedure to obtain the superconducting core wire; The first operation procedure includes: heating from 0°C to 450-500°C at a heating rate of 40-60°C / h and keeping the temperature for 3-5 hours; The second operation procedure includes: introducing oxygen at a flow rate of 100 to 200 sccm, while heating to 800 to 820°C at a heating rate of 60 to 120°C / h and keeping the temperature for 10 to 20 hours; The third operation procedure includes: heating to 910-930°C at a heating rate of 0.3-0.5°C / h and keeping the temperature for 1-3h; The fourth operation procedure includes: cooling the temperature to 420-450°C at a cooling rate of 50-60°C / h, introducing high-purity oxygen at a flow rate of 100-200 Sccm for 2-4 hours, and finally maintaining the pressure at 2 MPa for 12 hours.

2. The method for preparing the YBCO superconducting cable core wire according to claim 1, characterized in that: The polymer solution contains a polymer and a solvent, wherein the mass ratio of the polymer to the solvent is 3-5wt%; the polymer includes at least one of polyvinyl pyrrolidone, polyvinyl alcohol, polyamide, polylactic acid and gelatin; the solvent is composed of methanol, acetic acid and propionic acid in a mass ratio of 2.5:1:1.5; the viscosity of the superconducting precursor spinning solution is 50-100CPS.

3. The method for preparing the YBCO superconducting cable core wire according to claim 1, characterized in that: The yttrium source includes at least one of hydrated yttrium acetate and yttrium nitrate pentahydrate; the barium source includes at least one of barium acetate and barium nitrate; and the copper source includes at least one of copper acetate monohydrate and 2.5 hydrated copper nitrate.

4. The method for preparing the YBCO superconducting cable core wire according to claim 1, characterized in that: The working parameters of the electrospinning 3D printing method include: a spinning solution flow rate of 0.8-1.5 ml / h; at the beginning, the voltage is increased from 0 kV to 20-25 kV, and when the spinning solution at the needle tip forms a Taylor cone, the voltage is continued to be increased until the jet is ejected into the liquid collection plate.

5. The method for preparing the YBCO superconducting cable core wire according to claim 1, characterized in that: The freeze-drying working parameters include: temperature of -65°C to -30°C and time of 30 to 50 hours.

6. The method for preparing the YBCO superconducting cable core wire according to claim 1, characterized in that: The step of performing a protective treatment on the surface of the superconducting core wire to obtain the yttrium barium copper oxide superconducting cable core wire comprises the following process: The surface of the superconducting core wire is coated with silver to obtain a silver-coated superconducting core wire; The surface of the silver-coated superconducting core wire is coated and armored with metal copper to obtain the yttrium barium copper oxide superconducting cable core wire.

7. A Yttrium Barium Copper Oxide superconducting cable core wire, characterized in that: The YBCO superconducting cable core wire is prepared by the preparation method described in any one of claims 1 to 6, and the diameter of the YBCO superconducting cable core wire after being coated with silver and armored with metal copper is 500nm-10μm.

8. Use of the yttrium barium copper oxide superconducting cable core wire according to any one of claims 1 to 7 in lossless current transmission and preparation of superconducting equipment.

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