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CN-121983384-A - Insulation enhanced superconducting cable and preparation method thereof

CN121983384ACN 121983384 ACN121983384 ACN 121983384ACN-121983384-A

Abstract

The invention belongs to the technical field of superconduction, and relates to an insulation reinforced superconducting cable and a preparation method thereof. According to the invention, a NiCoCr/Cu composite matrix is used for reinforcing the superconducting wire, and BN modified polyimide paint is used for carrying out multi-pass coating and on-line monitoring to form a uniform insulating layer. And then wrapping and hot-pressing by using the B-stage epoxy impregnated polyaramid tape to construct the insulation reinforced structure. And (3) performing stranded cable forming through tension control and a numerical control positioning die, and combining the core wires and the multi-layer insulation reinforced wires to form the composite cable. Finally, the superconducting cable with the coverage area more than or equal to 99.9 percent and the void ratio less than 1 percent is obtained through secondary wrapping and pretension braiding protection, the inter-strand pressure resistance is more than 5000V, the inter-cable pressure resistance is more than 7000V, the mechanical stability and the thermal management performance are obviously improved, and the superconducting cable is suitable for high-field magnets and fast pulse applications.

Inventors

  • Qi Mingyin
  • FANG YUANKUN
  • YAN GUO
  • LIU XIANGHONG
  • FENG YONG
  • LI JIANFENG
  • ZHANG PINGXIANG
  • GUO QIANG
  • WANG RUILONG
  • WANG SHUAI
  • CHEN TONG
  • YANG YIWEN
  • LIU XIANG
  • JIA WENBING
  • HU JINLONG

Assignees

  • 西安聚能超导线材科技有限公司

Dates

Publication Date
20260505
Application Date
20260407

Claims (10)

  1. 1. A preparation method of an insulation reinforced superconducting cable is characterized by comprising the steps of filling a NiCoCr/Cu composite tube with an NbTi alloy rod, preparing a superconducting single core rod through vacuum encapsulation, hot extrusion and drawing, putting the single core rod as a component into an oxygen-free copper sheath, performing secondary assembly and drawing to prepare a superconducting wire, coating insulating paint on the surface of the superconducting wire, solidifying to obtain the insulation superconducting wire, wrapping the insulation superconducting wire by using a polyaramid fiber belt impregnated with B-stage epoxy resin, and performing hot pressing treatment to obtain the insulation reinforced superconducting wire, twisting the insulation reinforced superconducting wire and a core wire to form a composite cable with a concentric n-layer structure taking the core wire as a center, and performing fiber braiding on the surface of the composite cable after wrapping the insulation superconducting wire by adopting a polyaramid fiber belt impregnated with B-stage epoxy resin to obtain the superconducting cable; Wherein n is a positive integer not greater than 5; for the nth layer (n is more than or equal to 2), the number of the insulated reinforced superconducting wires contained in the nth layer is at most (n-1) multiplied by 6; the total number of the insulation reinforced superconducting wire and the core wire is 1+3n× (n-1).
  2. 2. The preparation method of the insulation enhanced superconducting cable according to claim 1, characterized in that the preparation of the insulating varnish comprises the steps of treating boron nitride with a silane coupling agent to obtain aminated boron nitride, coating polydopamine with the aminated boron nitride to obtain modified boron nitride, dispersing the modified boron nitride in N-methylpyrrolidone to obtain boron nitride dispersion liquid, adding the boron nitride dispersion liquid into polyamide acid, and stirring in vacuum to obtain the insulating varnish; The solid content of the boron nitride in the polyamic acid is 1% -5% by weight; The dispersing speed is 5000rpm, and the dispersing time is 1h; and the time of vacuum stirring is 2-4 hours.
  3. 3. The method of manufacturing an insulated enhanced superconducting cable according to claim 1, wherein the NiCoCr/Cu composite tube is composed of NiCoCr alloy layer and oxygen-free copper layer, and the thickness of NiCoCr alloy layer is consistent with that of the oxygen-free copper layer; The temperature of the hot extrusion is 600-800 ℃, and the extrusion ratio is 5:1-15:1.
  4. 4. The method for preparing an insulation reinforced superconducting cable according to claim 1, wherein the curing comprises a residence time of 2-4 hours at 100-150 ℃ and a residence time of 1-5 hours at 300-400 ℃.
  5. 5. The method for manufacturing the insulated reinforced superconducting cable according to claim 1, wherein the wrapping mode is half-wrapping, the angle is 30-60 degrees, and the tension is 5-20N.
  6. 6. The method for preparing an insulation reinforced superconducting cable according to claim 1, wherein the speed of the hot pressing treatment is 0.5-2 m/min, the temperature is 160-200 ℃, and the residence time is 30-120 s; the contact pressure between the aramid fiber tape impregnated with the B-stage epoxy resin and the surface of the insulating superconducting wire is 0.5-2 MPa.
  7. 7. The method of producing an insulation-enhanced superconducting cable according to claim 1, characterized in that the core wire is a copper core wire or an insulation-enhanced superconducting wire; the preparation method of the copper core wire comprises the steps of stretching an oxygen-free copper rod into an oxygen-free copper wire, coating the insulating paint of claim 2 on the surface of the oxygen-free copper wire, staying for 2-4 h at 100-150 ℃ and staying for 1-5 h at 300-400 ℃ to obtain the copper core wire; The residual resistance ratio of the oxygen-free copper rod is >1000.
  8. 8. The method of producing an insulated enhanced superconducting cable according to claim 1, characterized in that the composite cable has an overall void fraction of not more than ±1%, and a concentricity error of not more than ±0.02mm; in the process of the twisting, the tension of the core wire is 10-25N, and the tension of the insulation reinforced superconducting wire is 5-15N.
  9. 9. The method for manufacturing an insulation reinforced superconducting cable according to claim 1, wherein the braiding angle is 45 ° ± 1 °, and the pretightening force is 0.1-0.3 n.
  10. 10. An insulation-enhanced superconducting cable, characterized by being produced by the production method of the insulation-enhanced superconducting cable according to any one of claims 1 to 9; the inter-strand withstand voltage of the superconducting cable is >5000V, and the inter-strand withstand voltage is >7000V.

Description

Insulation enhanced superconducting cable and preparation method thereof Technical Field The invention belongs to the technical field of superconduction, and relates to an insulation reinforced superconducting cable and a preparation method thereof. Background The superconducting magnet can generate a magnetic field with high strength and high stability, and becomes a key component in important scientific devices such as nuclear magnetic resonance imaging, particle accelerators, nuclear fusion experiments and the like and high-end medical equipment. The low-temperature superconducting materials represented by NbTi, nb 3 Sn and the like have stable superconducting property, excellent electromagnetic performance and mature engineering processing capability in a low-temperature environment, and are core materials for constructing a large-scale strong magnetic field system at present. The performance of a superconducting cable directly affects the field strength, safety, and cost of the magnet. The fast pulse magnet is used as an important component and is widely applied to high-energy physical research, controllable nuclear fusion devices, pulse power systems and advanced medical equipment. The working characteristics of the superconducting cable are that rapidly increased current is carried in extremely short time to generate an instantaneous strong magnetic field, so that a high-voltage transient electric field is formed among turns of windings, between layers and between the windings and the ground, partial discharge breakdown is easy to cause, and the development of the high-insulation superconducting cable is severely challenged. Taking a typical 1+6 type primary cable as an example, the structure is 1 strand in the center and6 strands are surrounded on the periphery. The existing superconducting cable preparation technology is applied to a higher-performance magnet, and still faces the technical bottlenecks that the inter-strand insulation performance is insufficient and unstable, the main reasons include limited insulation performance of wires, easiness in damaging an insulation layer in the process of twisting, insufficient insulation to the ground of a cable body, poor consistency, mainly caused by non-uniform insulation layers and air gaps in the cable body, limited current carrying capacity, easiness in damaging the wires to a core wire layer surface during twisting, core breakage caused by the fact that an oxygen-free copper matrix is softer, and low yield, and the quality problems often cause scrapping of the insulation cable and quench of the magnet, so that the manufacturing cost is too high, and large-scale preparation of the high-strand insulated superconducting cable is difficult to realize. Therefore, the art needs to develop a novel preparation method of the superconducting cable, which can effectively improve the insulation performance and stability while maintaining the high critical current density, and optimize the preparation process flow so as to meet the higher requirements of the high-end magnet device on the reliability of the superconducting cable in the future. Disclosure of Invention Aiming at the problems and defects in the prior art, the invention provides an insulation reinforced superconducting cable and a preparation method thereof. The invention provides a preparation method of an insulation reinforced superconducting cable, which comprises the steps of filling a NbTi alloy rod into a NiCoCr/Cu composite tube, preparing a superconducting single core rod through vacuum encapsulation, hot extrusion and drawing, putting the single core rod into an oxygen-free copper sheath as a component, preparing a superconducting wire through secondary assembly and drawing, coating insulating paint on the surface of the superconducting wire, solidifying to obtain the insulation superconducting wire, wrapping the insulation superconducting wire by using a polyaramid fiber belt impregnated with B-stage epoxy resin, and carrying out hot pressing treatment to obtain the insulation reinforced superconducting wire, twisting the insulation reinforced superconducting wire and a core wire to form a composite cable with a concentric n-layer structure with the core wire as a center, and carrying out fiber braiding on the surface of the composite cable after wrapping the insulation superconducting wire by adopting a polyaramid fiber belt impregnated with B-stage epoxy resin to obtain the superconducting cable; Wherein n is a positive integer not greater than 5; for the nth layer (n is more than or equal to 2), the number of the insulated reinforced superconducting wires contained in the nth layer is at most (n-1) multiplied by 6; the total number of the insulation reinforced superconducting wire and the core wire is 1+3n× (n-1). Further, in the preparation method of the insulation enhanced superconducting cable, the preparation of the insulating paint comprises the steps of treating boron nitride by a