Magnesium boride superconducting cable for magnet device and preparation method of magnesium boride superconducting cable
The multi-stage cabling of MgB2 superconducting wires with copper and stainless steel insulation addresses the limitations of existing superconductors, enabling stable and high-performance superconducting cables for magnets at 39K.
Patent Information
- Application Number
- CN202510182485.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-19
- Publication Date
- 2025-06-06
AI Technical Summary
Existing low-temperature superconductors like NbTi and Nb3Sn are limited to 4.2K liquid helium environments, while high-temperature superconductors like REBCO and Bi-2223 have complex and costly fabrication processes, hindering their widespread application. MgB2 superconductors offer a promising alternative with a higher critical transition temperature and other advantages, but their integration into practical superconducting cables and magnets is not fully realized.
A multi-stage cabling process involving four-strand composite cables with boron carbide (MgB2) superconducting wires and copper strands, wrapped with stainless steel and high-temperature glass insulation, ensuring stability and protection against electromagnetic forces.
The resulting superconducting cables maintain straightness during winding, achieving high critical current density and magnetic field generation capabilities, suitable for superconducting magnets at 39K, with improved durability and performance.
Smart Images
Figure CN120108843A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of superconducting cables, and in particular relates to a magnesium boride superconducting cable for a magnet device and a preparation method thereof. Background Art
[0002] The zero resistance and complete anti-magnetism of superconducting materials make them ideal materials for transmission cables and superconducting magnets. However, traditional practical low-temperature superconducting materials (LTS) such as NbTi and Nb3Sn can only work in the liquid helium temperature zone of 4.2K. Although oxide high-temperature superconducting materials (OHTS) such as rare earth barium copper oxide (ReBCO) and bismuth strontium calcium copper oxide (Bi~2223) can operate in the liquid nitrogen temperature zone of 77K, the preparation process of such materials is complex, the preparation process is long, and the raw material cost is high, so large-scale application and promotion cannot be achieved in the short term. Magnesium diboride (MgB2) is a non-metallic compound with a simple binary structure, and its superconducting critical transition temperature is about 39K. It is precisely because MgB2 material has many advantages such as higher superconducting critical transition temperature tc, larger coherence length ξ, high critical current density jc, simple crystal structure, higher upper critical magnetic field hc2, and the ability of grain boundaries to transmit current that cables and magnets based on MgB2 material have become the new hope for the next generation of superconducting applications and are a strong competitor to traditional NbTi and Nb3Sn superconducting materials.
[0003] In recent years, relevant domestic scientific research institutions and universities have also carried out a lot of work on the development of MgB2 superconducting materials, including practical long-wire strips. Summary of the invention
[0004] The object of the present invention is to provide a magnesium boride superconducting cable for a magnet device and a preparation method thereof, so as to solve the problems raised in the above background technology.
[0005] In order to achieve the above object, the technical solution adopted by the present invention is:
[0006] A magnesium boride superconducting cable for a magnet device comprises a tertiary cable formed by composite twisting of four secondary cables. The tertiary cable is coated with a stainless steel tape layer, and the stainless steel tape layer is coated with a high-temperature resistant glass fiber insulation layer.
[0007] The secondary cable is formed by composite twisting of four primary cables.
[0008] The primary cable is formed by twisting two magnesium boride superconducting single wires and an annealed soft copper wire.
[0009] The magnesium boride superconducting single wire and the annealed soft copper wire have the same diameter, and a Ni layer is plated on the surfaces of the magnesium boride superconducting single wire and the annealed soft copper wire.
[0010] A method for preparing a magnesium boride superconducting cable for a magnet device comprises the following steps:
[0011] S1: Primary cable stranding: 2 magnesium boride superconducting single wires + 1 1.0 mm annealed soft copper wire are stranded on a CLY500 cage stranding machine. The pay-off tension is controlled at 18-20 N. The stranding die is a tungsten steel die with an aperture of 2.25 mm. The length of the die sizing zone is 1.1 mm. The stranding pitch is 32-34 mm. The take-up tension is 45-55 N.
[0012] S2: Secondary cable stranding: 4 primary cables are stranded on a CLY500 cage stranding machine, the pay-off tension is controlled at 30-35N, the stranding is done with a tungsten steel die, the die aperture is 4.2mm, the die sizing zone length is 2.1mm, the stranding pitch is 55-59mm, and the take-up tension is 55-65N;
[0013] S3: Three-level cable stranding: 4 two-level cables are stranded on a CLY12500 cage stranding machine, the pay-off tension is controlled at 35-40N, the stranding die is a tungsten steel die, the die aperture is 10.0mm, the die sizing zone length is 5.3mm, the stranding pitch is 120-130mm, and the take-up tension is 65-70N;
[0014] S4: Coated stainless steel strip: Concentric wrapping equipment is used for wrapping, the wrapping tension is controlled at 45-50N, the front and rear molds of wrapping are nylon molds, the mold apertures are 10.2 and 10.4 respectively, the steel strip thickness is 0.05±0.01mm, the belt width is 18-20mm, and the overlap rate is 35%-40%;
[0015] S5: Wrapped glass fiber insulating tape: Use concentric wrapping equipment for wrapping, the wrapping tension control range is 40~45N, the front and rear molds of wrapping are nylon molds, the mold apertures are 10.4 and 11.0mm respectively, the mold wire bearing lengths are 5.5 and 6.0mm respectively, the wrapping thickness is 0.18±0.01mm, the high temperature resistant glass silk ribbon is used as the insulating layer, the overlap rate is 45%~50%, and the width of the wrapping tape is 18~20mm.
[0016] In step S4, the steel strips are overlap-welded by resistance welding, and the thickness of the weld is less than twice the thickness of the steel strips.
[0017] In step S5, the glass fiber insulation tape is jointed by overlapping and sewing glass fibers.
[0018] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:
[0019] The magnesium boride superconducting cable produced by the above structure and method is used for winding magnet coils. During the winding process, the cable is straight without any undesirable phenomena such as bending and snaking. The wound coil is cast with epoxy resin. After casting and curing, the voltage resistance of the coil reaches more than 15kv. It realizes the superconducting state at a temperature of 39K, has a high critical current density, generates a higher magnetic field, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 Schematic diagram of the product structure of an embodiment of the present invention.
[0021] Serial numbers and names of the accompanying drawings: 1. Annealed soft copper wire, 2. Magnesium boride superconducting single wire, 3. Stainless steel tape layer, 4. High-temperature resistant glass fiber insulation layer; A. Twisted primary cable, B. Twisted secondary cable, C. Twisted tertiary cable, E. Finished cable coated with stainless steel tape and high-temperature resistant glass fiber insulation tape. DETAILED DESCRIPTION
[0022] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions 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. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.
[0023] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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] Example
[0025] like Figure 1 As shown, the present invention provides a magnesium boride superconducting cable for a magnet device. Since the operating current of the superconducting magnet is relatively large, MgB 2The superconducting single wire is processed into a high-current cable through a multi-stage twisting method to meet the current-carrying application under a strong magnetic field. In order to meet the needs of conductor stability and quench protection, two magnesium boride superconducting single wires 2 and an annealed soft copper wire 1 are twisted together to form a primary cable. The diameter of the magnesium boride superconducting single wire 2 and the annealed soft copper wire 1 are the same; in order to control the size of the transverse resistance between the magnesium boride superconducting single wire 2 and the annealed soft copper wire 1 and meet the requirements of small cable coupling loss, the surface of the magnesium boride superconducting single wire 2 and the annealed soft copper wire 1 are plated with a Ni layer; the secondary cable is made of four primary cables, and the tertiary cable is made of four secondary cables. After the tertiary cable is twisted, a layer of 316L stainless steel belt is overlapped and wrapped for enhanced protection to enhance the cable's ability to resist electromagnetic force and stable operation. The outermost layer is overlapped and wrapped with a layer of high-temperature resistant glass ribbon as an insulation layer.
[0026] A method for preparing a magnesium boride superconducting cable for a magnet device, specifically comprising the following contents:
[0027] 1. Superconducting cable twisting:
[0028] Production equipment: Since magnesium boride is hard and brittle, a fully detwisted cage stranding machine should be used to strand the three cable levels. The first and second level cables are stranded using a 500 / 1+6 cage stranding machine, and the third level cable is stranded using a 1250 / 1+6 cage stranding machine. During stranding, the tension of the pay-off and take-up wires should be precisely adjusted and controlled to prevent tension from damaging the superconducting single wire or the stranded single wire (strand). After being paid out from the pay-off reel of the twisting cage, the superconducting single wire or the stranded single wire (strand) should pass through a guide wheel with a diameter of not less than 120mm and no other guide wheels. Instead, it should pass through the distribution reel and directly enter the stranding mold for stranding to prevent the superconducting single wire from breaking due to the small curvature radius of the guide wheel and the superconducting single wire (strand) from being unable to completely detwist due to passing through too many guide wheels, resulting in stress in the superconducting single wire (strand) after stranding.
[0029] Twisting tension control: The tension of the first, second and third level cables during twisting should be less than or equal to 20N, 35N and 40N respectively. After twisting, the winding tension of the first, second and third level cables should be less than or equal to 60N, 70N and 75N respectively.
[0030] Twisting process parameters: The control range of the twisting pitch ratio (ratio of twisting pitch to twisting diameter) of the first, second and third level cables is: first level cable: 15~16, second level cable: 13~14, third level cable: 12~13.
[0031] Twisting mold: The twisting mold should be made of tungsten steel mold, and the aperture of the mold is: 2.154*wire diameter of superconducting single wire + 0.1mm for the first-level cable; 2.414*(2.154*wire diameter of superconducting single wire)~1mm for the second-level cable, and 2.414*(2.154*wire diameter of superconducting single wire)~2.5mm for the third-level cable.
[0032] The length of the die sizing zone is 0.5 to 0.4 times the hole diameter
[0033] 2. Coated stainless steel belt
[0034] After the superconducting cable is twisted, it is immediately coated with a stainless steel tape to prevent the superconducting cable from loosening and to provide enhanced protection for the cable.
[0035] Wrapping equipment: Use concentric wrapping equipment for wrapping. The wrapping tension should be able to achieve precise control within the control range of 40 to 50 N. The wrapping thickness is 0.05 ± 0.01 mm 316L stainless steel strip, and the overlap rate is 30% to 40%. The width of the wrapping tape is selected according to the wire diameter before wrapping, see Table 1 for details:
[0036]
[0037] Wrapping mold: A mold is set before and after wrapping to fix the twisted wire core during wrapping and minimize the shaking of the wire core during wrapping. The mold should be made of nylon or tungsten steel. The wire-bearing length of the mold is 0.5 to 0.6 times the mold aperture. The mold aperture before and after wrapping is the wire diameter before and after the twisting + (0.2 to 0.3) mm.
[0038] The steel strip is overlapped by resistance welding, and the thickness of the weld should not be greater than 2 times the thickness of the steel strip.
[0039] 3. Glass fiber coated insulation tape
[0040] Wrapping equipment: Use concentric wrapping equipment for wrapping. The wrapping tension should be able to achieve precise control. The tension control range is 35~45N. The wrapping thickness is 0.18±0.01mm. High-temperature resistant glass ribbon is used as the insulation layer. The overlap rate is 45%~50%. The width of the wrapping tape is selected according to the wrapping wire diameter. Please refer to Table 1 for details.
[0041] Wrapping mold: A mold is set before and after wrapping to fix the twisted wire core during wrapping and minimize the shaking of the wire core during wrapping. The mold should be made of nylon or tungsten steel. The wire-bearing length of the mold is 0.5 to 0.6 times the mold aperture. The mold aperture before and after wrapping is the wire diameter before and after wrapping + (0.2 to 0.3) mm.
[0042] Glass fiber insulation tape is jointed by overlapping and sewing glass fibers.
[0043] Taking the 1.0mm superconducting single wire twisted as an example, the product structure is (2 magnesium boride superconducting single wires + 1 1.0mm annealed soft copper wire)*4*4.
[0044] Primary cable stranding: 2 magnesium boride superconducting single wires + 1 1.0mm annealed soft copper wire are stranded on a CLY500 cage stranding machine. The pay-off tension is controlled at 18-20N. The stranding die is a tungsten steel die with an aperture of 2.25mm. The length of the die sizing zone is 1.1mm. The stranding pitch is 32-34mm. The take-up tension is 45-55N.
[0045] Secondary cable stranding: 4 primary cables are stranded on a CLY500 cage stranding machine, the pay-off tension is controlled at 30-35N, the stranding is done with a tungsten steel die, the die aperture is 4.2mm, the die sizing zone length is 2.1mm, the stranding pitch is 55-59mm, and the take-up tension is 55-65N;
[0046] Three-level cable stranding: 4 two-level cables are stranded on a CLY12500 cage stranding machine, the pay-off tension is controlled at 35-40N, the stranding die is a tungsten steel die, the die aperture is 10.0mm, the die sizing zone length is 5.3mm, the stranding pitch is 120-130mm, and the take-up tension is 65-70N;
[0047] Coated stainless steel strip: concentric wrapping equipment is used for wrapping, the wrapping tension is controlled at 45-50N, the front and rear molds are nylon molds, and the mold apertures are 10.2 and 10.4 respectively. The thickness of the steel strip is 0.05±0.01mm, the width is 18-20mm, and the overlap rate is 35%-40%;
[0048] Coated glass fiber insulating tape: Concentric wrapping equipment is used for wrapping, the wrapping tension control range is 40-45N, the front and rear molds of wrapping are nylon molds, the mold apertures are 10.4 and 11.0mm respectively, the mold wire lengths are 5.5 and 6.0mm respectively, the wrapping thickness is 0.18±0.01mm, the high temperature resistant glass ribbon is used as the insulating layer, the overlap rate is 45%-50%, and the width of the wrapping tape is 18-20mm.
[0049] The magnesium boride superconducting cable produced by the above structure and method is used for winding the magnet coil. During the winding process, the cable is straight without any undesirable phenomena such as bending and serpentine. The wound coil is cast with epoxy resin. After casting and curing, the voltage resistance of the coil reaches more than 15kv. It realizes the superconducting state at a temperature of 39K, has a high critical current density, and generates a higher magnetic field.
Claims
1. A magnesium boride superconducting cable for a magnet device, characterized in that: The invention comprises a third-level cable formed by composite twisting of four second-level cables, the third-level cable is coated with a stainless steel tape layer (3), and the stainless steel tape layer (3) is coated with a high-temperature resistant glass fiber insulation layer (4).
2. The magnesium boride superconducting cable for a magnet device according to claim 1, characterized in that: The secondary cable is formed by composite twisting of four primary cables.
3. The magnesium boride superconducting cable for a magnet device according to claim 2, characterized in that: The primary cable is formed by twisting two magnesium boride superconducting single wires (2) and an annealed soft copper wire (1).
4. The magnesium boride superconducting cable for a magnet device according to claim 3, characterized in that: The magnesium boride superconducting single wire (2) and the annealed soft copper wire (1) have the same diameter, and the surfaces of the magnesium boride superconducting single wire (2) and the annealed soft copper wire (1) are both plated with a Ni layer.
5. A method for preparing the magnesium boride superconducting cable for the magnet device according to claim 1, characterized in that: The steps include: S1: Primary cable stranding: 2 magnesium boride superconducting single wires + 1 1.0 mm annealed soft copper wire are stranded on a CLY500 cage stranding machine. The pay-off tension is controlled at 18-20 N. The stranding die is a tungsten steel die with an aperture of 2.25 mm. The length of the die sizing zone is 1.1 mm. The stranding pitch is 32-34 mm. The take-up tension is 45-55 N. S2: Secondary cable stranding: 4 primary cables are stranded on a CLY500 cage stranding machine, the pay-off tension is controlled at 30-35N, the stranding is done with a tungsten steel die, the die aperture is 4.2mm, the die sizing zone length is 2.1mm, the stranding pitch is 55-59mm, and the take-up tension is 55-65N; S3: Three-level cable stranding: 4 two-level cables are stranded on a CLY12500 cage stranding machine, the pay-off tension is controlled at 35-40N, the stranding die is a tungsten steel die, the die aperture is 10.0mm, the die sizing zone length is 5.3mm, the stranding pitch is 120-130mm, and the take-up tension is 65-70N; S4: Coated stainless steel strip: Concentric wrapping equipment is used for wrapping, the wrapping tension is controlled at 45-50N, the front and rear molds of wrapping are nylon molds, the mold apertures are 10.2 and 10.4 respectively, the steel strip thickness is 0.05±0.01mm, the width is 18-20mm, and the overlap rate is 35-40%; S5: Wrapped glass fiber insulating tape: Use concentric wrapping equipment for wrapping, the wrapping tension control range is 40~45N, the front and rear molds of wrapping are nylon molds, the mold apertures are 10.4 and 11.0mm respectively, the mold wire bearing lengths are 5.5 and 6.0mm respectively, the wrapping thickness is 0.18±0.01mm, the high temperature resistant glass silk ribbon is used as the insulating layer, the overlap rate is 45%~50%, and the width of the wrapping tape is 18~20mm.
6. The method for preparing a magnesium boride superconducting cable for a magnet device according to claim 5, characterized in that: In step S4, the steel strips are overlap-welded by resistance welding, and the thickness of the weld is less than twice the thickness of the steel strips.
7. The method for preparing a magnesium boride superconducting cable for a magnet device according to claim 5, characterized in that: In step S5, the glass fiber insulation tape is jointed by overlapping and sewing glass fibers.