A method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables

Abstract

The present invention relates to the field of materials technology, and particularly relates to a method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables. The specific technical solution is as follows: A method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables uses dual-material collaborative 3D printing technology. The inner-channel feed port controls the conductive silver paste, and the air pressure is controlled at 0.1 - 0.3 MPa. The outer-channel feed port controls the YBCO precursor printing slurry, and the flow rate is controlled at 1 - 1.5 ml / min. The printing needle is connected to the mechanical motion platform of the 3D printing platform to print the YBCO superconducting precursor wire. Subsequently, after freeze-drying, plastic removal and phase-forming annealing are carried out to obtain a metal-core YBCO superconducting wire. After hot-pressing and sintering according to a certain wiring structure, a YBCO armored superconducting cable is obtained. The present invention overcomes the extreme brittleness and high anisotropy of the YBCO superconducting material, improves the "weak connection" phenomenon at the grain boundaries caused by its polycrystalline structure, successfully prepares a metal-core YBCO superconducting wire with excellent superconducting properties, and obtains a YBCO armored superconducting cable by armoring it.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, and particularly to a method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables. Background Art

[0002] Since the discovery of high-temperature superconductivity in the late 1980s, people have been striving to create practical superconductors that meet industrial requirements and reduce costs through technological progress and large-scale production. Superconducting cables formed by high-temperature superconducting (HTS) material YBCO can achieve high-efficiency and high-power density power transmission, and have important potential and advantages in solving the energy crisis.

[0003] High-temperature superconducting cables are usually wound with round wires or flat tapes. Through multi-stage or multi-layer winding, superconducting round wires or tapes can form a compact and uniform cable structure, thereby improving their current-carrying capacity and reducing the loss of current in the conductor. However, due to the complex crystal structure and chemical properties of YBCO, it is very difficult to prepare YBCO superconducting filaments by traditional methods, not only because it is necessary to overcome its extreme brittleness and high anisotropy, but also because it is necessary to suppress the "weak connection" phenomenon at grain boundaries caused by its polycrystalline structure.

[0004] Surface coating (silver, copper) techniques generally include mechanical cladding, physical vapor deposition (PVD), chemical vapor deposition (CVD), etc. Mechanical cladding requires a rolling process and is therefore not suitable for brittle YBCO ceramics. For PVD or CVD methods, during the process of depositing metal thin films, metal ions (Ag + 、Cu 2+ ), at the beginning of deposition on the surface of YBCO, are prone to combine with O on the surface of YBCO to form metal oxides, seriously reducing the physical properties such as the mechanical, thermal, and electrical properties of the metal. On the other hand, since metal ions combine with O on the surface of YBa 2 Cu 3 O 7-x surface, the oxidation state x increases, and more oxygen vacancies are obtained in its lattice structure, resulting in a reduction in the superconducting performance of YBCO. This is because the number of oxygen defects affects the electron conduction performance between Cu-O layers, thereby affecting the superconducting performance of the material.

[0005] Therefore, it is necessary to develop a dual-material synchronous 3D printing technology and a close-packed wiring structure design to construct complex and customized structures at the mesoscopic and microscopic scales with good precision, while meeting the requirements such as tight binding and non-cracking at the YBCO-metal interface, and solving the key scientific problem of the serious attenuation of the critical current density Jc when passing through large-angle grain boundaries caused by the cold processing of traditional methods. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention provides a method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables.

[0007] To achieve the above objectives, the present invention is realized through the following technical solutions:

[0008] The present invention discloses a method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables. Using the dual-material collaborative 3D printing technology, the inner feed port controls the conductive silver paste, and the air pressure is controlled at 0.1 - 0.3 MPa. The outer feed port controls the YBCO printing paste, and the flow rate is controlled at 1 - 1.5 ml / min. The printing needle is connected to the mechanical motion platform of the 3D printing platform to print the YBCO superconducting precursor wire. Subsequently, after freeze-drying, plastic removal and phase-forming annealing are carried out to obtain the metal-core YBCO superconducting wire. After hot-pressing and sintering according to the wiring structure, the YBCO armored superconducting cable is obtained.

[0009] Preferably, the preparation process of the YBCO precursor printing paste is as follows: Mix Y 2 O 3 , CuO and BaCO 3 . After adding absolute ethanol and ball milling, dry it to obtain the YBCO precursor powder. Mix the YBCO precursor powder and the aqueous slurry in a weight ratio of 3:2 - 2:1, add epoxy soybean oil and stir evenly, and then roll mill 2 - 3 times to obtain the YBCO printing paste.

[0010] Preferably, Y 2 O 3 , CuO and BaCO 3 are in a stoichiometric molar ratio of Y:Ba:Cu = 1:2:3.

[0011] Preferably, the ball milling rotation speed range is 350 - 400 rpm, the ball milling time is 1 - 3 h, and the ball-to-powder ratio is 3:1. Add zirconia balls, and the number ratio of balls with diameters of 10 mm, 8 mm, 6 mm, and 4 mm is 1:2:4:8.

[0012] Preferably, the drying temperature is 85 - 90 °C, and the drying time is 12 - 16 h.

[0013] Preferably, dissolve sodium carboxymethyl cellulose in deionized water and mechanically stir for 2 - 3 h to obtain the aqueous slurry; the mass fraction of sodium carboxymethyl cellulose in deionized water is 6 - 6.5 wt%.

[0014] Preferably, the process of plastic removal and phase annealing is: heating to 450-500°C at a heating rate of 40-60°C / h, keeping warm for 5-6h, then introducing oxygen with a flow rate controlled at 100-200 sccm, and heating to 920-930°C at a heating rate of 50-60°C / h and keeping warm for 32-36h; then cooling to 450-500°C at a cooling rate of 60°C / h, introducing high-purity oxygen and maintaining at a pressure of 2-4 MPa for 12-15h.

[0015] Preferably, the metal core YBCO superconducting filaments are closely arranged and loaded into annular hollow aluminum tubes of different sizes, and the gaps are filled with aluminum powder to obtain single-tube wiring structures of different sizes.

[0016] Preferably, the single-tube wiring structures of different sizes are sequentially sheathed, the openings are sealed, and then hot-pressed sintering is performed. After the sintering is completed, an insulating layer is wrapped to obtain a YBCO armored superconducting cable.

[0017] Preferably, the hot pressing sintering temperature is 550-600° C., the time is 10-12 hours, and the pressure is 80 MPa.

[0018] The present invention has the following beneficial effects:

[0019] 1. The present invention provides a method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables. This technology is used to prepare YBCO superconducting monofilaments, and the monofilaments are arranged and armored in a densely packed wiring structure. This technology can significantly shorten the preparation cycle, simplify the process flow, and improve the consistency and controllability of the product. On the other hand, it meets the emerging superconducting application needs, especially strategic equipment and cutting-edge devices involving YBCO superconducting wires, such as superconducting solenoid valves, particle accelerators, and super-strong magnets, and opens up the development of the high-temperature superconducting industry chain.

[0020] Therefore, the multi-material synchronous 3D printing technology and dense-stacked wiring structure armor provided by the present invention not only improve production efficiency and product quality, but also meet environmental protection requirements, and promote the development and widespread application of high-tech products such as YBCO superconducting cables.

[0021] 2. For the first time, the present invention successfully prepared YBCO superconducting wire with tight interface, excellent superconducting performance and enhanced mechanical properties by mixing 3D printing slurry and designing and optimizing traditional 3D printing needles, and designed a densely packed wiring structure armored YBCO superconducting cable. At the same time, it serves as a key technology for efficient energy transmission and storage.

[0022] 3. The multi-material synchronous 3D printing method for preparing metal-core YBCO superconducting wires disclosed in the present invention realizes the preparation of metal-core YBCO superconducting wires with tightly bonded interfaces, excellent superconducting properties, and enhanced mechanical properties through a feeding method that combines pneumatic control and an external micro-thruster, and connects to the mechanical motion platform of the 3D printing platform. At the same time, an armored superconducting cable with a closely packed wiring structure is designed to simultaneously improve the superconducting performance and the mechanical properties of the cable, realizing high-efficiency and low-loss power transmission. A new type of multi-material synchronous 3D printing needle is also developed through CFD simulation to optimize the problems that may be caused by the traditional feeding method. By more precisely designing and adjusting the position and angle of the outer-channel feeding port, the uniformity of the flow is optimized; the key scientific problem of "weak connection" at grain boundaries is also solved: the present invention overcomes the extreme brittleness and high anisotropy of YBCO superconducting materials, improves the "weak connection" phenomenon at grain boundaries caused by its polycrystalline structure, and successfully prepares metal-core YBCO superconducting wires with excellent superconducting properties.

[0023] 4. The present invention prepares a metal-core YBCO armored superconducting cable through a dual-material direct writing synchronous 3D printing technology and designs a multi-tube closely packed wiring structure. Using this technology can not only greatly shorten the preparation time, streamline the preparation process, improve the controllability and consistency of products, but also enable customized design, print wire units with cross-sectional shapes and component configurations, and perform closely packed armor with metal tubes of different sizes to meet the requirements of different application environments. Brief Description of the Drawings

[0024] Figure 1 are the model of the dual-material synchronous 3D printing needle and the stereolithography 3D printing needle;

[0025] Figure 2 is the preparation flow chart of the YBCO armored superconducting cable;

[0026] Figure 3 is the preparation flow chart of the metal-core YBCO superconducting wire;

[0027] Figure 4 is the schematic diagram of the structure of the YBCO armored superconducting cable;

[0028] Figure 5 (A) is the morphology and crystallization performance diagram of the metal-core YBCO superconducting wire, and (B) is the enlarged view of the red box in (A);

[0029] Figure 6 is the superconducting performance characterization of the metal-core YBCO superconducting wire. Detailed Description of the Invention

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0031] Unless otherwise specified, the technical means used in the implementation examples are conventional means well known to those skilled in the art.

[0032] The feeding method of the needle of traditional direct writing dual-material synchronous 3D printing is vertical feeding at the inner channel feeding port and horizontal feeding at the outer channel feeding port. Since laminar flow unevenness occurs in the cavity in the middle of the needle after feeding at the outer channel feeding port, squeezing the cavity part causes the blank at the discharge port to curl and warp to one side, which is very unfavorable for the printing of superconducting wires. Therefore, the present invention also develops a new type of multi-material synchronous 3D printing needle through CFD simulation, optimizes the problems that may be caused by the traditional feeding method, and adjusts the position and angle of the outer channel feeding port through more precise design to optimize the flow uniformity. Specifically, as Figure 1 shown, the material tube is inclined with respect to the outer channel feeding port of the 3D printing needle, that is, inclined downward, to optimize the flow uniformity.

[0033] As Figure 2 、 Figure 3 shown, the present invention discloses the preparation process of YBCO sheathed superconducting cable, and the specific preparation process is as follows:

[0034] (1) Prepare YBCO precursor powder

[0035] Use Y with a purity of 99.99% 2 O 3 、CuO, and BaCO with a purity of 99.95% 3 , mix them in a stoichiometric molar ratio of Y:Ba:Cu = 1:2:3, add absolute ethanol with a mass ratio to the mixed powder (the total mass of Y 2 O 3 、CuO、BaCO 3 ) of 25-30%, and use a planetary ball mill for ball milling. The rotation speed range of the planetary ball mill is 350-400 rpm, the ball milling time is 1-3 h, the ball-powder ratio is about 3:1, add zirconia balls, and the number ratio of balls with diameters of 10 mm, 8 mm, 6 mm, and 4 mm is 1:2:4:8. After ball milling, place it in a drying oven and dry it at a drying temperature of 85-90 °C for 12-16 h to obtain YBCO precursor powder.

[0036] (2) Prepare YBCO precursor printing slurry

[0037] Preparation of water-based slurry: Use sodium carboxymethyl cellulose (CMC) as a binder and deionized water as a solvent to prepare the water-based slurry. Weigh CMC and dissolve it in deionized water, and stir it mechanically for 2 to 3 hours; the mass fraction of sodium carboxymethyl cellulose in deionized water is 6 to 6.5wt%.

[0038] Prepare YBCO precursor printing slurry: weigh 50-55g of yttrium barium copper oxide precursor powder and place it in a crucible, measure 25-30ml of water-based slurry and mix it with YBCO precursor powder, weigh 4-5g of epoxidized soybean oil (ESO) and add it and continue stirring. After stirring evenly, put it in a roller mill and roll it 2-3 times to obtain a uniformly mixed and finely particled yttrium barium copper oxide 3D printing slurry.

[0039] (3) Using CFD simulation and light-curing printing to prepare dual-material simultaneous 3D printing needles

[0040] The needle was modeled using UGNX (Siemens NX software). Based on the traditional dual-material synchronous 3D printing needle, the feeding angle and position of the external channel feed port were changed. In order to optimize the simulation speed and simplify the model, the pipeline of the external channel was used as the simulation model. Then, light-curing 3D printing was used to realize the molding of the new needle. The model and printed needle are as follows Figure 1 POLYFLOW software was used for CFD simulation, and the fluid model adopted the Herschel-Bulkley model, as shown in formula (1):

[0041] ;

[0042] in, is the shear stress, is the initial shear stress, is the consistency coefficient, is the shear rate, n is the rheological index, and m is the blending index, which is generally 1.

[0043] (4) Dual-material collaborative 3D printing of YBCO superconducting precursor filaments

[0044] The conductive silver paste is poured into the printing barrel, and the discharge port of the barrel is connected to the inner channel feed port of the multi-material synchronous 3D printing needle, and the other end is connected to the pneumatic control device of the 3D printing platform, and the air pressure is controlled at 0.1-0.3MPa; the YBCO precursor printing slurry is poured into the printing barrel, and one end of the outer channel feed pipe is connected to the constant flow pump, and the flow rate is controlled at 1-1.5ml / min, and the other end is connected to the outer channel feed port of the multi-material synchronous 3D printing needle. The printing needle is connected to the mechanical motion platform of the 3D printing platform, and the silk thread can be printed along a straight line, a bow shape, a Z shape, and a circle shape. The moving speed along the X-axis and the Y-axis is controlled to be 2mm / s.

[0045] (5)Post-treatment of YBCO superconducting precursor wires

[0046] Freeze-drying: Place the printed YBCO superconducting precursor wires in a freeze-dryer, and remove the excess solvent from inside the YBCO superconducting precursor wires at -30 to -65 °C for 30 to 50 h, and form a complete support structure by means of freeze-drying technology.

[0047] Debinding and phase-forming annealing: Place the freeze-dried YBCO superconducting precursor wires in a box furnace and heat them at a heating rate of 40 to 60 °C / h to 450 to 500 °C, then hold for 5 to 6 h to fully oxidize, decompose, and volatilize the organic matter. Then introduce oxygen with a flow rate controlled at 100 to 200 sccm, and at the same time heat at a heating rate of 50 to 60 °C / h to 920 to 930 °C and hold for 32 to 36 h to allow the powder to fully react and completely form the Y123 superconducting phase. Cool at a cooling rate of 60 °C / h to 450 to 500 °C, introduce high-purity oxygen and maintain it at a pressure of 2 to 4 MPa for 12 to 15 h to fully oxygenate the YBCO crystal structure and achieve good superconductivity, thus obtaining the YBCO superconducting wire with a metal core.

[0048] (6)Loading the single-tube wiring structure

[0049] As Figure 4 shown, take a ring-shaped hollow aluminum tube with an outer diameter of 5 mm, an inner diameter of 4 mm, a length of 150 mm, and a sealed bottom, tightly arrange and load the YBCO superconducting wire with a metal core, and fill the gaps with aluminum powder to obtain a single-tube wiring structure with an outer diameter of 5 mm.

[0050] Take a ring-shaped hollow aluminum tube with an outer diameter of 4 mm, an inner diameter of 3 mm, a length of 150 mm, and a sealed bottom, tightly arrange and load the YBCO superconducting wire with a metal core, and fill the gaps with aluminum powder to obtain a single-tube wiring structure with an outer diameter of 4 mm.

[0051] Take a ring-shaped hollow aluminum tube with an outer diameter of 3 mm, an inner diameter of 2 mm, a length of 150 mm, and a sealed bottom, tightly arrange and load the YBCO superconducting wire with a metal core, and fill the gaps with aluminum powder to obtain a single-tube wiring structure with an outer diameter of 3 mm.

[0052] Take a ring-shaped hollow aluminum tube with an outer diameter of 2 mm, an inner diameter of 1 mm, a length of 150 mm, and a sealed bottom, tightly arrange and load the YBCO superconducting wire with a metal core, and fill the gaps with aluminum powder to obtain a single-tube wiring structure with an outer diameter of 2 mm.

[0053] Take a hollow aluminum tube with a diameter of 1 mm, a length of 150 mm, and a sealed bottom, load the single YBCO wire one by one, and fill the gaps with aluminum powder to obtain a single-tube wiring structure with an outer diameter of 1 mm.

[0054] (7) Sheathed multi-tube dense packing structure, hot press sintering

[0055] Sheathe the single-tube wiring structures of 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm in sequence, and use a high-temperature welding torch to weld and seal the openings of the aluminum tubes. Place the sealed aluminum tubes into a hot press. Under the set pressure condition (80 MPa), control the sintering temperature between 550 and 600 °C, keep the sintering time at 10 - 12 h, and finally cool it to room temperature. After wrapping with an insulating layer, a YBCO sheathed superconducting cable is obtained.

[0056] After testing, the diameter of the yttrium barium copper oxide superconducting wire obtained in this example is 600 μm, and its superconducting performance parameters include: Tc = 89 - 90 K; Jc = 2.3 - 2.4×10 4 A / cm 2 , where Tc is the critical transition temperature and Jc is the critical current density. As Figure 6 shown, Figure 6 the left figure is the critical transition temperature diagram and the right figure is the critical current density diagram; the obtained yttrium barium copper oxide superconducting wire has characteristics such as a high critical current and a tightly bonded YBCO-Ag interface. Figure 5 (A) is the morphology and crystallization performance diagram of the metal-core YBCO superconducting wire, Figure 5 (B) is Figure 5 the enlarged view of the red box in (A).

[0057] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables, characterized in that: The dual-material collaborative 3D printing technology is adopted. The inner channel feed port controls the conductive silver paste, the air pressure is controlled at 0.1-0.3MPa, and the outer channel feed port controls the YBCO precursor printing paste, and the flow rate is controlled at 1-1.5ml / min. The printing needle is connected to the mechanical motion platform of the 3D printing platform to print the YBCO superconducting precursor wire, and then freeze-dried and plasticized and phase annealed to obtain the metal core YBCO superconducting wire. After hot pressing and sintering according to the wiring structure, the YBCO armored superconducting cable is obtained. The preparation process of the YBCO precursor printing slurry is as follows: after Y2O3, CuO and BaCO3 are mixed, anhydrous ethanol is added, ball milling is performed, and drying is performed to obtain YBCO precursor powder; after YBCO precursor powder and aqueous slurry are mixed in a weight ratio of 3:2 to 2:1, epoxy soybean oil is added, stirred evenly, and roller milling is performed for 2 to 3 times to obtain YBCO precursor printing slurry.

2. The method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables according to claim 1, characterized in that: Y2O3, CuO and BaCO3 are in a stoichiometric molar ratio of Y:Ba:Cu=1:2:

3.

3. The method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables according to claim 1, characterized in that: The ball milling speed range is 350-400 rpm, the ball milling time is 1-3 h, and the ball-to-powder ratio is 3:1; zirconia balls with diameters of 10 mm, 8 mm, 6 mm, and 4 mm are added in a ratio of 1:2:4:

8.

4. The method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables according to claim 1, characterized in that: Drying temperature is 85-90℃ and drying time is 12-16h.

5. The method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables according to claim 1, characterized in that: Sodium carboxymethyl cellulose is dissolved in deionized water and mechanically stirred for 2 to 3 hours to obtain an aqueous slurry; the mass fraction of sodium carboxymethyl cellulose in deionized water is 6 to 6.5 wt %.

6. The method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables according to claim 1, characterized in that: The process of plastic removal and phase annealing is as follows: heat up to 450-500°C at a heating rate of 40-60°C / h, keep warm for 5-6h, then introduce oxygen with a flow rate controlled at 100-200 sccm, and heat to 920-930°C at a heating rate of 50-60°C / h and keep warm for 32-36h; then cool to 450-500°C at a cooling rate of 60°C / h, introduce high-purity oxygen and maintain at a pressure of 2-4 MPa for 12-15h.

7. The method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables according to claim 1, characterized in that: The metal core YBCO superconducting filaments are closely arranged and loaded into annular hollow aluminum tubes of different sizes, and the gaps are filled with aluminum powder to obtain single-tube wiring structures of different sizes.

8. The method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables according to claim 7, characterized in that: Single-tube wiring structures of different sizes are sequentially sheathed, the openings are sealed, and then hot-pressed and sintered. After sintering, an insulating layer is wrapped to obtain a YBCO armored superconducting cable.

9. The method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables according to claim 8, characterized in that: The hot pressing sintering temperature is 550-600°C, the time is 10-12h, and the pressure is 80MPa.

Images