Method for 3D printing of yttrium barium copper oxide superconducting cable through bi-material cooperation

Abstract

The invention relates to the technical field of materials, in particular to a method for 3D printing of an yttrium barium copper oxide superconducting cable through bi-material cooperation. According to the specific technical scheme, the method for bi-material collaborative 3D printing of the yttrium barium copper oxide superconducting cable adopts a bi-material collaborative 3D printing technology, an inner channel feeding port controls conductive silver paste, the air pressure is controlled to be 0.1-0.3 MPa, an outer channel feeding port controls YBCO precursor printing paste, and the flow is controlled to be 1-1.5 ml / min; the printing needle head is connected with a mechanical motion platform of the 3D printing platform, printing of YBCO superconducting precursor wires is carried out, plastic removal and phase annealing are carried out after freeze drying, metal core YBCO superconducting wires are obtained, and after hot pressing sintering is carried out according to a certain wiring structure, the YBCO armored superconducting cable is obtained. According to the invention, extreme brittleness and high anisotropy of a YBCO superconducting material are overcome, a crystal boundary weak connection phenomenon caused by a polycrystalline structure of the YBCO superconducting material is improved, the metal core YBCO superconducting wire with excellent superconducting performance is successfully prepared, and the metal core YBCO superconducting wire is armored to obtain the YBCO armored superconducting cable.

Description

Technical Field

[0001] The present invention relates to the field of material technology, and in particular 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 working hard to create practical superconductors that meet industrial needs and reduce costs through technological advances and large-scale production. Superconducting cables formed from high-temperature superconducting (HTS) materials YBCO can achieve high energy 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 strips. Through multi-level or multi-layer winding, superconducting round wires or strips can form a compact and uniform cable structure, thereby improving its current carrying capacity and reducing current loss in the conductor. However, due to the complex crystal structure and chemical properties of YBCO, when preparing YBCO superconducting wires, it is necessary not only to overcome its extreme brittleness and high anisotropy, but also to suppress the "weak connection" phenomenon of grain boundaries caused by its polycrystalline structure. Therefore, it is very difficult to prepare YBCO superconducting wires using traditional methods.

[0004] Surface coating (silver, copper) technologies generally include mechanical coating, physical vapor deposition (PVD), chemical vapor deposition (CVD) and other methods. Mechanical coating requires a rolling process and is therefore not suitable for YBCO brittle ceramics. For PVD or CVD methods, during the deposition of metal films, metal ions (Ag + , Cu 2+ ) At the beginning of deposition on the YBCO surface, it is easy to combine with the O on the YBCO surface to form metal oxides, which seriously reduces the mechanical, thermal and electrical properties of the metal. On the other hand, since the metal ions combine with YBa2Cu3O 7-x The O on the surface leads to an increase in the oxidation state x, an increase in oxygen vacancies in the lattice structure, and a decrease in the superconducting performance of YBCO. This is because the number of oxygen defects affects the electronic conduction performance between the Cu-O layers, thereby affecting the superconducting performance of the material.

[0005] Therefore, it is necessary to develop a dual-material simultaneous 3D printing technology and a dense-stacked wiring structure design to construct complex and customized structures at the meso and micro scales with good precision, while meeting the requirements of tight bonding and no cracking of the YBCO-metal interface, and solving the key scientific problem of severe attenuation of the critical current density Jc when passing through large-angle grain boundaries due to cold processing by traditional methods. Summary of the invention

[0006] In view of the shortcomings 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 implemented through the following technical solutions: The invention discloses a method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables. The dual-material collaborative 3D printing technology is adopted, the conductive silver paste is controlled by an inner feed port, the air pressure is controlled at 0.1-0.3 MPa, the YBCO printing paste is controlled by an outer feed port, 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, and then freeze-drying and plastic removal and phase annealing are performed to obtain a metal core YBCO superconducting wire, and hot pressing and sintering are performed according to the wiring structure to obtain a YBCO armored superconducting cable.

[0008] Preferably, the preparation process of the YBCO precursor printing slurry is: after mixing Y2O3, CuO and BaCO3, adding anhydrous ethanol, ball milling, and drying to obtain YBCO precursor powder; after mixing the YBCO precursor powder and aqueous slurry in a weight ratio of 3:2 to 2:1, adding epoxy soybean oil and stirring evenly, and roller milling 2 to 3 times to obtain YBCO printing slurry.

[0009] Preferably, Y2O3, CuO and BaCO3 are in a stoichiometric molar ratio of Y:Ba:Cu=1:2:3.

[0010] Preferably, the ball milling speed ranges from 350 to 400 rpm, the ball milling time is 1 to 3 hours, and the ball-to-powder ratio is 3:1; zirconium oxide balls with diameters of 10 mm, 8 mm, 6 mm, and 4 mm are added in a ratio of 1:2:4:8.

[0011] Preferably, the drying temperature is 85-90° C. and the drying time is 12-16 hours.

[0012] Preferably, 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 %.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] Preferably, the hot pressing sintering temperature is 550-600° C., the time is 10-12 hours, and the pressure is 80 MPa.

[0017] The present invention has the following beneficial effects: 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.

[0018] 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.

[0019] 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.

[0020] 3. The multi-material synchronous 3D printing method for the preparation of metal core YBCO superconducting filaments disclosed in the present invention realizes the preparation of metal core YBCO superconducting filaments with tight interface bonding, excellent superconducting performance and enhanced mechanical properties through the discharging method combined with pneumatic control and external micro-thruster, and the mechanical motion platform of the 3D printing platform. At the same time, the armored superconducting cable with a dense stack wiring structure is designed, and the superconducting performance and the mechanical properties of the cable are improved simultaneously, so as to realize high energy efficiency and low loss power transmission. A new type of multi-material synchronous 3D printing needle is also developed through CFD simulation, and the problems that may be caused by the traditional feeding method are optimized. The position and angle of the external channel feed port are adjusted through more precise design to optimize the uniformity of the flow; it also solves the key scientific problem of "weak connection" of grain boundaries: the present invention overcomes the extreme brittleness and high anisotropy of YBCO superconducting materials, improves the "weak connection" phenomenon of grain boundaries caused by its polycrystalline structure, and successfully prepares metal core YBCO superconducting filaments with excellent superconducting properties.

[0021] 4. The present invention prepares metal core YBCO armored superconducting cable through dual-material direct writing synchronous 3D printing technology and designs a multi-tube dense stacking wiring structure. The use of this technology can not only greatly shorten the preparation time, streamline the preparation process, and improve the controllability and consistency of the product, but also can perform customized design, print out wire units with cross-sectional shapes and component configurations, and use metal tubes of different sizes for dense stacking armor to meet the requirements of different application environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Models for dual-material simultaneous 3D printing needles and light-curing 3D printing needles; Figure 2 The preparation flow chart of YBCO armored superconducting cable; Figure 3 The preparation flow chart of metal core YBCO superconducting wire; Figure 4 This is a schematic diagram of the structure of the YBCO armored superconducting cable; Figure 5 (A) is the morphology and crystallization performance diagram of the metal core YBCO superconducting wire, and (B) is the enlarged image of the red box in (A); Figure 6 Characterization of the superconducting properties of metal core YBCO superconducting wire. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only 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.

[0024] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0025] The feeding method of the traditional straight-writing dual-material synchronous 3D printing needle is that the inner channel feed port feeds vertically, and the outer channel feed port feeds horizontally. After feeding from the outer channel feed port, uneven laminar flow occurs in the cavity in the middle of the needle, which squeezes the cavity and causes the blank at the outlet to curl to one side, which is very unfavorable for the printing of superconducting filaments. 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 traditional feeding methods, and adjusts the position and angle of the outer channel feed port through more precise design to optimize the uniformity of the flow. Specifically, Figure 1 As shown, the material tube and the outer channel feed port of the 3D printing needle are tilted, that is, tilted downward to optimize the uniformity of the flow.

[0026] like Figure 2 , Figure 3 As shown, the present invention discloses a preparation process of a YBCO armored superconducting cable, and the specific preparation process is as follows: (1) Preparation of YBCO precursor powder Y2O3 and CuO with a purity of 99.99%, and BaCO3 with a purity of 99.95%, are mixed in a stoichiometric molar ratio of Y:Ba:Cu=1:2:3, and anhydrous ethanol is added with a mass ratio of 25-30% to the mixed powder (the total mass of Y2O3, CuO, and BaCO3), and ball milling is performed using a planetary ball mill. The speed range of the planetary ball mill is 350-400 rpm, the ball milling time is 1-3h, the ball-to-powder ratio is about 3:1, and zirconium oxide balls are added, with a diameter of 10mm, 8mm, 6mm, and 4mm in a ratio of 1:2:4:8. After ball milling, it is placed in a drying oven and dried at a drying temperature of 85-90°C for a drying time of 12-16h to obtain a YBCO precursor powder.

[0027] (2) Preparation of YBCO precursor printing slurry 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%.

[0028] 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.

[0029] (3) Using CFD simulation and light-curing printing to prepare dual-material simultaneous 3D printing needles 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): ; 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.

[0030] (4) Dual-material collaborative 3D printing of YBCO superconducting precursor filaments 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.

[0031] (5) Post-processing of YBCO superconducting precursor wire Freeze drying: Place the printed YBCO superconducting precursor wire in a freeze dryer and remove excess solvent from the inside of the YBCO superconducting precursor wire at -30 to -65°C for 30 to 50 hours, using freeze drying technology to form a complete support structure.

[0032] Plastic removal and phase annealing: Place the freeze-dried YBCO superconducting precursor wire in a box furnace and heat it to 450-500℃ at a heating rate of 40-60℃ / h, then keep it warm for 5-6h to fully oxidize, decompose and volatilize the organic matter. Then introduce oxygen with a flow rate of 100-200 sccm, and heat it to 920-930℃ at a heating rate of 50-60℃ / h and keep it warm for 32-36h to make the powder fully react and completely form the Y123 superconducting phase. Cool it down to 450-500℃ at a cooling rate of 60℃ / h, introduce high-purity oxygen and keep it at a pressure of 2-4MPa for 12-15h to fully supplement the YBCO crystal structure with oxygen and achieve good superconductivity, thus obtaining a metal core YBCO superconducting wire.

[0033] (6) Installing single-tube wiring structure like Figure 4 As shown, 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 is taken, and the metal core YBCO superconducting wires are tightly arranged and loaded into it, and the gaps are filled with aluminum powder to obtain a single-tube wiring structure with an outer diameter of 5 mm.

[0034] 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, and tightly arrange the metal core YBCO superconducting wires into it, fill the gaps with aluminum powder, and obtain a single-tube wiring structure with an outer diameter of 4 mm.

[0035] 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, and tightly arrange the metal core YBCO superconducting wires into it, fill the gaps with aluminum powder, and obtain a single-tube wiring structure with an outer diameter of 3 mm.

[0036] 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, and tightly arrange the metal core YBCO superconducting wires into it, fill the gaps with aluminum powder, and obtain a single-tube wiring structure with an outer diameter of 2 mm.

[0037] Take a hollow aluminum tube with a diameter of 1 mm, a length of 150 mm and a sealed bottom, put the YBCO monofilament into it, fill the gap with aluminum powder, and obtain a single tube wiring structure with an outer diameter of 1 mm.

[0038] (7) Jacketed multi-tube dense stack structure, hot pressing sintering The 1 mm, 2 mm, 3 mm, 4 mm, and 5 mm single-tube wiring structures are sequentially sleeved, and the opening of the aluminum tube is welded and sealed using a high-temperature welding gun. The sealed aluminum tube is placed in a hot press. Under the set pressure conditions (80 MPa), the sintering temperature is controlled between 550 and 600 ° C, the sintering time is maintained at 10 to 12 hours, and finally cooled to room temperature. After wrapping the insulation layer, the YBCO armored superconducting cable is obtained.

[0039] After testing, the diameter of the YBCO 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 , Tc: critical transition temperature, Jc: critical current density, such as Figure 6 As shown, Figure 6 The left picture is the critical transition temperature diagram, and the right picture is the critical current density diagram; the obtained yttrium barium copper oxide superconducting wire has the characteristics of high critical current and tight YBCO-Ag interface bonding. Figure 5 (A) is the morphology and crystallization performance diagram of the metal core YBCO superconducting wire. Figure 5 (B) Figure 5 Magnified image of the red box in (A).

[0040] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all 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: Dual-material collaborative 3D printing technology is adopted. The inner channel feed port controls the conductive silver paste and the air pressure is controlled at 0.1-0.3MPa. The outer channel feed port controls the YBCO precursor printing slurry 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, which is then freeze-dried and subjected to plastic discharge and phase annealing 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.

2. The method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables according to claim 1, characterized in that: 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.

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

3.

4. The method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables according to claim 2, 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.

5. The method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables according to claim 2, characterized in that: Drying temperature is 85-90℃ and drying time is 12-16h.

6. The method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables according to claim 2, 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 %.

7. 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.

8. 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.

9. The method for dual-material collaborative 3D printing of yttrium barium copper oxide superconducting cables according to claim 8, 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.

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

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