CN110828059A - Hectometer-grade 37-core MgB2Magnesium diffusion preparation method of superconducting wire - Google Patents

Hectometer-grade 37-core MgB2Magnesium diffusion preparation method of superconducting wire Download PDF

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CN110828059A
CN110828059A CN201911188599.5A CN201911188599A CN110828059A CN 110828059 A CN110828059 A CN 110828059A CN 201911188599 A CN201911188599 A CN 201911188599A CN 110828059 A CN110828059 A CN 110828059A
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core
mgb
wire
superconducting wire
rod
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杨芳
王庆阳
熊晓梅
冯建情
梁明
李成山
闫果
冯勇
张平祥
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Northwest Institute for Non Ferrous Metal Research
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    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B12/00—Superconductive or hyperconductive conductors, cables, or transmission lines
    • H01B12/02—Superconductive or hyperconductive conductors, cables, or transmission lines characterised by their form
    • H01B12/06—Films or wires on bases or cores
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B12/00—Superconductive or hyperconductive conductors, cables, or transmission lines
    • H01B12/02—Superconductive or hyperconductive conductors, cables, or transmission lines characterised by their form
    • H01B12/10—Multi-filaments embedded in normal conductors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
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    • Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment

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Abstract

The invention discloses a hectometer-grade 37-core MgB2A method for preparing a superconducting wire by magnesium diffusion, the method comprising: firstly, uniformly mixing amorphous boron powder and nano carbon powder and then grinding to obtain mixed powder; secondly, filling the mixed powder into a gap between the magnesium rod and the niobium tube to obtain a first tube-filling composite body; thirdly, performing rotary swaging on the first tubulation complex to obtain a single-core wire; fourthly, assembling 30 single-core wires and 7 CuNb rods into the Monel alloy pipe to obtain a second pipe-loading composite body; fifthly, carrying out rotary swaging and drawing on the second tubulation composite body to obtain a 37-core wire; sixthly, sintering to obtain 37-core MgB2A superconducting wire. The invention adopts a central magnesium diffusion method to combine nano carbon powder and a 7-core CuNb rod to strengthen and generate compact MgB2Layer of MgB is improved2The critical current density of the superconducting wire in a magnetic field improves the mechanical property of the wire, thereby leading the 37-core MgB2The length of the superconducting wire is increased to hundred meters, and MgB is enlarged2The application range of the superconducting wire.

Description

Hectometer-grade 37-core MgB2Magnesium diffusion preparation method of superconducting wire
Technical Field
The invention belongs to the technical field of superconducting material preparation, and particularly relates to a hectometer-grade 37-core MgB2A method for preparing superconducting wire by magnesium diffusion.
Background
MgB2Since the discovery of superconductors in 2001, the superconductors have the advantages of large coherence length, no weak connection of crystal boundaries and the like due to the fact that the critical temperature of the superconductors is 39K, and are attracted by domestic and foreign scientists, and high-performance MgB2The superconducting material is widely applied to medical MRI magnets, low-speed and high-torque wind power motors, superconducting transmission cables and the like.
MgB prepared by the conventional PIT (powder In tube) method2A large number of holes exist in the wire and strip material, so that MgB is reduced2The effective current carrying area of (a) is more pronounced, particularly in multi-core wire structures. To develop MgB with high critical current density2The density of the superconducting core wire is inevitably improved. In recent years, many researchers have started to produce MgB by Internal Magnesium Diffusion (IMD)2Wire and strip material, the wire produced by this method is internationally referred to as second generation wire. In the IMD method, a magnesium rod is placed in the center of the barrier layer and boron powder is filled around the magnesium rod, and the molten magnesium rod permeates into the boron powder during heat treatment to generate dense MgB2The method reduces a large number of holes left after the magnesium powder permeates into the boron powder to react by an in-situ method, and the obtained wire has excellent critical current density.
The multi-core wire can reduce current loss compared to a single-core wire. Central magnesium diffusion (IMD) is well suited for multi-core wire, where magnesium diffuses rapidly into the boron powder even at temperatures below the melting point of magnesium (650℃.) because of MgThe reaction with B is exothermic, which can raise the temperature around the magnesium core, and the low temperature heat treatment can inhibit the growth of crystal grains, improve the superconductive performance such as critical current density, etc., and obtain dense MgB2The layer greatly improves the mechanical property of the wire rod, and is more suitable for large-scale production.
Currently, MgB2The main direction of the research of the second generation wire preparation technology is to obtain the long wire processing technology and the multi-core wire processing technology with practical value, and the multi-core MgB is prepared by the magnesium diffusion method in the prior art2Superconducting wire, but only 37-core MgB2In the report of the superconducting wire, the superconducting performance of a sample is very low, and the wire can only be prepared by about one meter, so that the market requirement cannot be met.
Disclosure of Invention
The technical problem to be solved by the invention is to provide a hectometer-grade 37-core MgB aiming at the defects of the prior art2A method for preparing superconducting wire by magnesium diffusion. The method adopts a central magnesium diffusion method combined with the reinforcement of nano carbon powder and a 7-core CuNb rod, and utilizes the penetration of a molten magnesium rod into boron powder in the heat treatment process of preparation to generate compact MgB2Layer of MgB is improved2The critical current density of the superconducting wire in a magnetic field improves the mechanical property of the wire, thereby leading the 37-core MgB2The length of the superconducting wire is increased to hundred meters, and MgB is enlarged2The application range of the superconducting wire.
In order to solve the technical problems, the invention adopts the technical scheme that: hectometer-grade 37-core MgB2A method for preparing a superconducting wire by magnesium diffusion, comprising the steps of:
step one, uniformly mixing amorphous boron powder and nano carbon powder in an argon-protected glove box, and then putting the mixture into an agate mortar for grinding to obtain mixed powder; the molar ratio of the amorphous boron powder to the nano carbon powder is (2-x): x, and the value range of x is 0.02-0.08;
step two, sequentially polishing the magnesium rod with abrasive paper, scrubbing with ethanol and drying in the air, then filling the magnesium rod into the center of the niobium pipe after acid cleaning, and filling the mixed powder obtained in the step one into the gap between the magnesium rod and the niobium pipe to obtain a first pipe-filling composite body; the diameter of the magnesium rod is 3.0 mm-5.0 mm;
step three, sealing two ends of the first tubulation complex obtained in the step two, then performing rotary swaging to obtain a single-core wire, and then sequentially performing straightening, sizing, cutting, acid washing and drying on the single-core wire; the pass processing rate of the rotary swaging is 10-30%;
step four, assembling the single-core wire rods which are dried in the step three and 7 pickled CuNb rods into the pickled Monel alloy tube to obtain a second tube-loading composite; 7 pickled CuNb rods are placed in the center of the Monel alloy pipe in the assembling process, and 30 dried single-core wires are arranged into a 2-layer annular structure around the CuNb rods along the circumferential direction and are placed in the Monel alloy pipe; the lengths of the dried single-core wire, the pickled CuNb rod and the Monel alloy pipe are the same;
fifthly, performing rotary swaging and drawing on the second pipe-filling composite body obtained in the fourth step to obtain a 37-core wire; the pass processing rate of the rotary swaging drawing is 10-20%;
step six, sealing two ends of the 37-core wire rod obtained in the step five, and then putting the wire rod into flowing argon for sintering to obtain 37-core MgB2A superconducting wire; the 37-core MgB2The superconductive wire has a superconductive phase filling rate of 8.5% or more, and the 37-core MgB2The critical current density of the superconducting wire at 4.2K and 4T is 5 × 105A/cm2The above.
The invention adopts a central magnesium diffusion method to prepare 37-core MgB2The superconducting wire is reinforced by a 7-core CuNb rod, and a fused magnesium rod permeates into boron powder to generate compact MgB in the prepared heat treatment process2The layer reduces a large number of holes left after the magnesium powder permeates into the boron powder to react by an in-situ method, and effectively improves MgB2The density of the superconducting core wire is improved, and then the MgB is improved2Critical current density of superconducting wire in magnetic field, dense MgB2The strengthening effect of the layer combined reinforcing rod greatly improves the mechanical property of the wire, thereby leading the 37-core MgB2The length of the superconducting wire is increased toHundred meter grade, enlarged MgB2The range of use of the wire; simultaneously, the nano carbon powder mixed in the boron powder is doped in MgB2In the layer, MgB is strengthened2The connectivity of the crystal grains effectively refines the crystal grains, more crystal boundaries formed by the refined crystal grains can form pinning centers, and the MgB content is improved2Critical current density of the superconducting wire in a magnetic field.
The hectometer-grade 37-core MgB2The preparation method of the superconducting wire by magnesium diffusion is characterized in that the mass purity of the amorphous boron powder in the step one is not less than 99%, and the particle size is 0.1-10 μm; the mass purity of the nano carbon powder is not less than 99%. The quality purity and the particle size of the raw materials can ensure that the reaction is smoothly carried out during heat treatment.
The hectometer-grade 37-core MgB2The preparation method of the superconducting wire by magnesium diffusion is characterized in that the mass purity of the magnesium rod in the step two is 99.9-99.99%. The high-quality and high-purity magnesium rod can ensure that thicker MgB is generated2The superconducting reaction layer is beneficial to improving the mechanical property of the wire rod.
The hectometer-grade 37-core MgB2The magnesium diffusion preparation method of the superconducting wire is characterized in that the specific processes of acid washing of the niobium tube in the step two and acid washing of the Monel alloy tube in the step four are as follows: acid cleaning is carried out by adopting mixed acid liquor consisting of nitric acid solution, hydrofluoric acid solution and water, then dehydration is carried out by absolute ethyl alcohol, and then drying is carried out at 50-60 ℃; the mass concentration of the nitric acid in the mixed acid liquid is 12-15%, and the mass concentration of the hydrofluoric acid is 5-8%. The acid washing process effectively removes oxides and impurities on the surfaces of the niobium tube and the Monel alloy tube, and ensures that the core wires and the outer sheath are tightly combined.
The hectometer-grade 37-core MgB2The preparation method of the superconducting wire by magnesium diffusion is characterized in that the outer diameter of the niobium tube in the step two is 10-12 mm, and the wall thickness of the niobium tube is 1-2 mm; in the fourth step, the Monel alloy pipe has an outer diameter of 22 mm-37 mm and a wall thickness of 1.5 mm-3 mm. The adoption of the outer sheath with larger size is beneficial to improving the length of the wire.
The hectometer-grade 37-core MgB2The magnesium diffusion preparation method of the superconducting wire rod is characterized in that the diameter of the 37-core wire rod in the fifth step is 0.4-1.4 mm. The preferred diameter is the diameter range commonly used in practical application, and the practical value of the preparation method is improved.
The hectometer-grade 37-core MgB2The magnesium diffusion preparation method of the superconducting wire is characterized in that the sintering process in the sixth step is as follows: heating to 600-680 ℃ at the speed of 10-20 ℃/min, preserving the heat for 1-5 h, and then cooling to room temperature along with the furnace. The sintering process parameters can ensure complete reaction of the superconducting layer to generate compact MgB2And (3) a layer.
Compared with the prior art, the invention has the following advantages:
1. the invention adopts a central magnesium diffusion method and combines the reinforcement of a 7-core CuNb rod to prepare 37-core MgB2The superconducting wire is prepared by penetrating molten magnesium rod into boron powder during heat treatment to generate dense MgB2The layer reduces a large number of holes left after the magnesium powder permeates into the boron powder to react by an in-situ method, and effectively improves MgB2The density of the superconducting core wire is improved, and then the MgB is improved2Critical current density of superconducting wire in magnetic field, dense MgB2The layers improve the mechanical properties of the wire, thereby MgB 37 cores2The length of the superconducting wire is increased to hundred meters, and MgB is enlarged2The application range of the superconducting wire.
2. The nano carbon powder added into the boron powder of the invention is doped in MgB2In the layer, MgB is strengthened2The connectivity of the crystal grains effectively refines the crystal grains, more crystal boundaries formed by the refined crystal grains can form pinning centers, and the MgB is further improved2The critical current density of the superconducting wire in a magnetic field obviously reduces the current loss in practical application.
3. The invention uses 37-core MgB2The length of the superconducting wire is increased to a hundred meter level, a long wire processing technology and a multi-core wire processing technology with practical value are obtained, and the obtained MgB2The critical current density of the superconducting wire can reach 5 multiplied by 10 under 4.2K and 4T5A/cm2The above; MgB prepared by the invention2The density of the superconducting core of the superconducting wire is high, the filling rate of the superconducting phase is more than 8.5%, and the requirement of practical application is met.
4. The invention adopts the Monel alloy tube as the outer sheath material, adopts the 7-core CuNb rod for reinforcement, reduces the cost compared with the conventional oxygen-free copper tube, and obviously improves the MgB2Mechanical strength and processability of the superconducting wire.
The technical solution of the present invention is further described in detail by the accompanying drawings and examples.
Drawings
Fig. 1 is a gold phase diagram of a 37-core wire rod prepared in example 1 of the present invention.
FIG. 2 is a 37-core MgB prepared in example 1 of the invention2Gold phase diagram of superconducting wire.
FIG. 3 is a 37-core MgB prepared in example 1 of the invention2Critical current density curve of superconducting wire at 4.2K.
Detailed Description
Example 1
The embodiment comprises the following steps:
step one, uniformly mixing amorphous boron powder and nano carbon powder in an argon-protected glove box, and then putting the mixture into an agate mortar for grinding to obtain mixed powder; the molar ratio of the amorphous boron powder to the nano carbon powder is 1.95: 0.05; the amorphous boron powder has the mass purity of 99.8% and the particle size of 0.3 mu m; the mass purity of the nano carbon powder is 99.5 percent;
step two, sequentially polishing the magnesium rod with abrasive paper, scrubbing with ethanol and drying in the air, then filling the magnesium rod into the center of the niobium pipe after acid cleaning, and filling the mixed powder obtained in the step one into the gap between the magnesium rod and the niobium pipe to obtain a first pipe-filling composite body; the diameter of the magnesium rod is 4.0mm, and the mass purity is 99.95%; the outer diameter of the niobium pipe is 10mm, and the wall thickness of the niobium pipe is 1 mm; the acid pickling process of the niobium pipe is as follows: acid cleaning is carried out by adopting mixed acid liquor consisting of nitric acid solution, hydrofluoric acid solution and water, then dehydration is carried out by absolute ethyl alcohol, and drying is carried out at 55 ℃; the mass concentration of nitric acid in the mixed acid liquid is 12%, and the mass concentration of hydrofluoric acid is 5%;
step three, sealing two ends of the first tubulation complex obtained in the step two, then performing rotary swaging to obtain a single-core wire, and then sequentially performing straightening, sizing, cutting, acid washing and drying on the single-core wire; the pass processing rate of the rotary swaging is 15%;
step four, assembling the single-core wire rods which are dried in the step three and 7 pickled CuNb rods into the pickled Monel alloy tube to obtain a second tube-loading composite; 7 pickled CuNb rods are placed in the center of the Monel alloy pipe in the assembling process, and 30 dried single-core wires are arranged into a 2-layer annular structure around the CuNb rods along the circumferential direction and are placed in the Monel alloy pipe; the lengths of the dried single-core wire, the pickled CuNb rod and the Monel alloy pipe are the same; the Monel alloy pipe has an outer diameter of 25mm and a wall thickness of 3 mm; the specific pickling process of the Monel alloy pipe is as follows: acid cleaning is carried out by adopting mixed acid liquor consisting of nitric acid solution, hydrofluoric acid solution and water, then dehydration is carried out by absolute ethyl alcohol, and drying is carried out at 55 ℃; the mass concentration of nitric acid in the mixed acid liquid is 12%, and the mass concentration of hydrofluoric acid is 5%;
fifthly, performing rotary swaging and drawing on the second pipe-filling composite body obtained in the fourth step to obtain a 37-core wire; the pass processing rate of the rotary swaging drawing is 10 percent; the diameter of the 37-core wire rod is 1.4 mm;
step six, sealing two ends of the 37-core wire rod obtained in the step five, and then putting the wire rod into flowing argon for sintering to obtain 37-core MgB2A superconducting wire; the sintering process comprises the following steps: heating to 650 ℃ at the speed of 15 ℃/min, preserving heat for 2h, and then cooling to room temperature along with the furnace; the 37-core MgB2The superconducting phase filling rate of the superconducting wire is 8.5 percent, and the 37-core MgB2Critical current density J of superconducting wire at 4.2K and 4TcIs 5.0X 105A/cm2。
37-core MgB prepared in this example2The length of the superconducting wire can reach more than 100 meters.
Fig. 1 is a gold phase diagram of the 37-core wire rod prepared in this example, and it can be seen from fig. 1 that the core wire is uniformly distributed in the 37-core wire rod prepared in this example, and the magnesium rod is located at the center of the wire rod.
FIG. 2 is a 37-core MgB prepared in this example2Gold phase diagram of superconducting wire, as can be seen from FIG. 2, 37-core MgB prepared in this example2The central magnesium rod of the superconducting wire reacts with the boron powder completely to generate compact MgB2And (3) a layer.
FIG. 3 is a 37-core MgB prepared in this example2The critical current density curve of the superconducting wire at 4.2K is shown in FIG. 3, and the 37-core MgB prepared in this example2Critical current density J of superconducting wire at 4.2K and 4TcIs 5.0X 105A/cm2Has excellent superconductivity under medium and high magnetic fields.
Example 2
The embodiment comprises the following steps:
step one, uniformly mixing amorphous boron powder and nano carbon powder in an argon-protected glove box, and then putting the mixture into an agate mortar for grinding to obtain mixed powder; the molar ratio of the amorphous boron powder to the nano carbon powder is 1.92: 0.08; the amorphous boron powder has the mass purity of 99% and the particle size of 0.1 mu m; the mass purity of the nano carbon powder is 99 percent;
step two, sequentially polishing the magnesium rod with abrasive paper, scrubbing with ethanol and drying in the air, then filling the magnesium rod into the center of the niobium pipe after acid cleaning, and filling the mixed powder obtained in the step one into the gap between the magnesium rod and the niobium pipe to obtain a first pipe-filling composite body; the diameter of the magnesium rod is 4.0mm, and the mass purity is 99.99%; the outer diameter of the niobium pipe is 12mm, and the wall thickness of the niobium pipe is 2 mm; the acid pickling process of the niobium pipe is as follows: acid washing with mixed acid solution comprising nitric acid solution, hydrofluoric acid solution and water, dewatering with anhydrous alcohol, and oven drying at 50 deg.C; the mass concentration of nitric acid in the mixed acid liquid is 15%, and the mass concentration of hydrofluoric acid is 8%;
step three, sealing two ends of the first tubulation complex obtained in the step two, then performing rotary swaging to obtain a single-core wire, and then sequentially performing straightening, sizing, cutting, acid washing and drying on the single-core wire; the pass processing rate of the rotary swaging is 20%;
step four, assembling the single-core wire rods which are dried in the step three and 7 pickled CuNb rods into the pickled Monel alloy tube to obtain a second tube-loading composite; 7 pickled CuNb rods are placed in the center of the Monel alloy pipe in the assembling process, and 30 dried single-core wires are arranged into a 2-layer annular structure around the CuNb rods along the circumferential direction and are placed in the Monel alloy pipe; the lengths of the dried single-core wire, the pickled CuNb rod and the Monel alloy pipe are the same; the Monel alloy pipe has an outer diameter of 37mm and a wall thickness of 3 mm; the specific pickling process of the Monel alloy pipe is as follows: acid washing with mixed acid solution comprising nitric acid solution, hydrofluoric acid solution and water, dewatering with anhydrous alcohol, and oven drying at 50 deg.C; the mass concentration of nitric acid in the mixed acid liquid is 15%, and the mass concentration of hydrofluoric acid is 8%;
fifthly, performing rotary swaging and drawing on the second pipe-filling composite body obtained in the fourth step to obtain a 37-core wire; the pass processing rate of the rotary swaging drawing is 15%; the diameter of the 37-core wire rod is 0.4 mm;
step six, sealing two ends of the 37-core wire rod obtained in the step five, and then putting the wire rod into flowing argon for sintering to obtain 37-core MgB2A superconducting wire; the sintering process comprises the following steps: heating to 600 ℃ at the speed of 20 ℃/min, preserving the heat for 5 hours, and then cooling to room temperature along with the furnace; the 37-core MgB2The superconducting phase filling rate of the superconducting wire is 8.60%, and the 37-core MgB2Critical current density J of superconducting wire at 4.2K and 4TcIs 5.1X 105A/cm2。
37-core MgB prepared in this example2The length of the superconducting wire can reach more than 100 meters.
Example 3
The embodiment comprises the following steps:
step one, uniformly mixing amorphous boron powder and nano carbon powder in an argon-protected glove box, and then putting the mixture into an agate mortar for grinding to obtain mixed powder; the molar ratio of the amorphous boron powder to the nano carbon powder is 1.98: 0.02; the amorphous boron powder has the mass purity of 99.9% and the particle size of 10 mu m; the mass purity of the nano carbon powder is 99.5 percent;
step two, sequentially polishing the magnesium rod with abrasive paper, scrubbing with ethanol and drying in the air, then filling the magnesium rod into the center of the niobium pipe after acid cleaning, and filling the mixed powder obtained in the step one into the gap between the magnesium rod and the niobium pipe to obtain a first pipe-filling composite body; the diameter of the magnesium rod is 3.5mm, and the mass purity is 99.9%; the outer diameter of the niobium pipe is 10mm, and the wall thickness of the niobium pipe is 1.5 mm; the acid pickling process of the niobium pipe is as follows: acid cleaning is carried out by adopting mixed acid liquor consisting of nitric acid solution, hydrofluoric acid solution and water, then dehydration is carried out by absolute ethyl alcohol, and drying is carried out at the temperature of 60 ℃; the mass concentration of nitric acid in the mixed acid liquid is 13%, and the mass concentration of hydrofluoric acid is 7%;
step three, sealing two ends of the first tubulation complex obtained in the step two, then performing rotary swaging to obtain a single-core wire, and then sequentially performing straightening, sizing, cutting, acid washing and drying on the single-core wire; the pass processing rate of the rotary swaging is 30 percent;
step four, assembling the single-core wire rods which are dried in the step three and 7 pickled CuNb rods into the pickled Monel alloy tube to obtain a second tube-loading composite; 7 pickled CuNb rods are placed in the center of the Monel alloy pipe in the assembling process, and 30 dried single-core wires are arranged into a 2-layer annular structure around the CuNb rods along the circumferential direction and are placed in the Monel alloy pipe; the lengths of the dried single-core wire, the pickled CuNb rod and the Monel alloy pipe are the same; the Monel alloy pipe has an outer diameter of 30mm and a wall thickness of 2 mm; the specific pickling process of the Monel alloy pipe is as follows: acid cleaning is carried out by adopting mixed acid liquor consisting of nitric acid solution, hydrofluoric acid solution and water, then dehydration is carried out by absolute ethyl alcohol, and drying is carried out at the temperature of 60 ℃; the mass concentration of nitric acid in the mixed acid liquid is 13%, and the mass concentration of hydrofluoric acid is 7%;
fifthly, performing rotary swaging and drawing on the second pipe-filling composite body obtained in the fourth step to obtain a 37-core wire; the pass processing rate of the rotary swaging drawing is 20%; the diameter of the multi-core wire rod is 0.6 mm;
step six, sealing two ends of the 37-core wire rod obtained in the step five, and then putting the wire rod into flowing argon for sintering to obtain 37-core MgB2A superconducting wire; the sintering process comprises the following steps: heating to 680 ℃ at the speed of 20 ℃/min, preserving heat for 1h, and then cooling to room temperature along with the furnace; the 37-core MgB2The superconducting phase filling rate of the superconducting wire is 8.58%, and the 37-core MgB2Critical current density J of superconducting wire at 4.2K and 4TcIs 5.1X 105A/cm2。
37-core MgB prepared in this example2The length of the superconducting wire can reach more than 100 meters.
Example 4
The embodiment comprises the following steps:
step one, uniformly mixing amorphous boron powder and nano carbon powder in an argon-protected glove box, and then putting the mixture into an agate mortar for grinding to obtain mixed powder; the molar ratio of the amorphous boron powder to the nano carbon powder is 1.96: 0.04; the amorphous boron powder has the mass purity of 99.9% and the particle size of 10 mu m; the mass purity of the nano carbon powder is 99.5 percent;
step two, sequentially polishing the magnesium rod with abrasive paper, scrubbing with ethanol and drying in the air, then filling the magnesium rod into the center of the niobium pipe after acid cleaning, and filling the mixed powder obtained in the step one into the gap between the magnesium rod and the niobium pipe to obtain a first pipe-filling composite body; the diameter of the magnesium rod is 3.0mm, and the mass purity is 99.9%; the outer diameter of the niobium pipe is 11mm, and the wall thickness of the niobium pipe is 2 mm; the acid pickling process of the niobium pipe is as follows: acid cleaning is carried out by adopting mixed acid liquor consisting of nitric acid solution, hydrofluoric acid solution and water, then dehydration is carried out by absolute ethyl alcohol, and drying is carried out at the temperature of 60 ℃; the mass concentration of nitric acid in the mixed acid liquid is 13%, and the mass concentration of hydrofluoric acid is 7%;
step three, sealing two ends of the first tubulation complex obtained in the step two, then performing rotary swaging to obtain a single-core wire, and then sequentially performing straightening, sizing, cutting, acid washing and drying on the single-core wire; the pass processing rate of the rotary swaging is 10 percent;
step four, assembling the single-core wire rods which are dried in the step three and 7 pickled CuNb rods into the pickled Monel alloy tube to obtain a second tube-loading composite; 7 pickled CuNb rods are placed in the center of the Monel alloy pipe in the assembling process, and 30 dried single-core wires are arranged into a 2-layer annular structure around the CuNb rods along the circumferential direction and are placed in the Monel alloy pipe; the lengths of the dried single-core wire, the pickled CuNb rod and the Monel alloy pipe are the same; the Monel alloy pipe has the outer diameter of 22mm and the wall thickness of 1.5 mm; the specific pickling process of the Monel alloy pipe is as follows: acid cleaning is carried out by adopting mixed acid liquor consisting of nitric acid solution, hydrofluoric acid solution and water, then dehydration is carried out by absolute ethyl alcohol, and drying is carried out at the temperature of 60 ℃; the mass concentration of nitric acid in the mixed acid liquid is 13%, and the mass concentration of hydrofluoric acid is 7%;
fifthly, performing rotary swaging and drawing on the second pipe-filling composite body obtained in the fourth step to obtain a 37-core wire; the pass processing rate of the rotary swaging drawing is 20%; the diameter of the multi-core wire rod is 0.8 mm;
step six, sealing two ends of the 37-core wire rod obtained in the step five, and then putting the wire rod into flowing argon for sintering to obtain 37-core MgB2A superconducting wire; the sintering process comprises the following steps: heating to 650 ℃ at the speed of 20 ℃/min, preserving heat for 2h, and then cooling to room temperature along with the furnace; the 37-core MgB2The superconducting phase filling rate of the superconducting wire is 8.55 percent, and the 37-core MgB2Critical current density J of superconducting wire at 4.2K and 4TcIs 5.2X 105A/cm2。
37-core MgB prepared in this example2The length of the superconducting wire can reach more than 100 meters.
Example 5
The embodiment comprises the following steps:
step one, uniformly mixing amorphous boron powder and nano carbon powder in an argon-protected glove box, and then putting the mixture into an agate mortar for grinding to obtain mixed powder; the molar ratio of the amorphous boron powder to the nano carbon powder is 1.94: 0.06; the amorphous boron powder has the mass purity of 99.9% and the particle size of 1 micron; the mass purity of the nano carbon powder is 99.9%;
step two, sequentially polishing the magnesium rod with abrasive paper, scrubbing with ethanol and drying in the air, then filling the magnesium rod into the center of the niobium pipe after acid cleaning, and filling the mixed powder obtained in the step one into the gap between the magnesium rod and the niobium pipe to obtain a first pipe-filling composite body; the diameter of the magnesium rod is 3.5mm, and the mass purity is 99.9%; the outer diameter of the niobium pipe is 10mm, and the wall thickness of the niobium pipe is 1.5 mm; the acid pickling process of the niobium pipe is as follows: acid cleaning is carried out by adopting mixed acid liquor consisting of nitric acid solution, hydrofluoric acid solution and water, then dehydration is carried out by absolute ethyl alcohol, and drying is carried out at the temperature of 60 ℃; the mass concentration of nitric acid in the mixed acid liquid is 13%, and the mass concentration of hydrofluoric acid is 7%;
step three, sealing two ends of the first tubulation complex obtained in the step two, then performing rotary swaging to obtain a single-core wire, and then sequentially performing straightening, sizing, cutting, acid washing and drying on the single-core wire; the pass processing rate of the rotary swaging is 30 percent;
step four, assembling the single-core wire rods which are dried in the step three and 7 pickled CuNb rods into the pickled Monel alloy tube to obtain a second tube-loading composite; 7 pickled CuNb rods are placed in the center of the Monel alloy pipe in the assembling process, and 30 dried single-core wires are arranged into a 2-layer annular structure around the CuNb rods along the circumferential direction and are placed in the Monel alloy pipe; the lengths of the dried single-core wire, the pickled CuNb rod and the Monel alloy pipe are the same; the Monel alloy pipe has an outer diameter of 30mm and a wall thickness of 2 mm; the specific pickling process of the Monel alloy pipe is as follows: acid cleaning is carried out by adopting mixed acid liquor consisting of nitric acid solution, hydrofluoric acid solution and water, then dehydration is carried out by absolute ethyl alcohol, and drying is carried out at the temperature of 60 ℃; the mass concentration of nitric acid in the mixed acid liquid is 13%, and the mass concentration of hydrofluoric acid is 7%;
fifthly, performing rotary swaging and drawing on the second pipe-filling composite body obtained in the fourth step to obtain a 37-core wire; the pass processing rate of the rotary swaging drawing is 20%; the diameter of the multi-core wire rod is 1.0 mm;
step six, sealing two ends of the 37-core wire rod obtained in the step five, and then putting the wire rod into flowing argon for sintering to obtain 37-core MgB2A superconducting wire; the sintering process comprises the following steps: heating to 630 ℃ at the speed of 20 ℃/min, preserving heat for 3h, and then cooling to room temperature along with the furnace; the 37-core MgB2The superconducting phase filling rate of the superconducting wire is 8.62 percent, and the 37-core MgB2Critical current density J of superconducting wire at 4.2K and 4TcIs 5.3X 105A/cm2。
37-core MgB prepared in this example2The length of the superconducting wire can reach more than 100 meters.
Example 6
The embodiment comprises the following steps:
step one, uniformly mixing amorphous boron powder and nano carbon powder in an argon-protected glove box, and then putting the mixture into an agate mortar for grinding to obtain mixed powder; the molar ratio of the amorphous boron powder to the nano carbon powder is 1.95: 0.05; the amorphous boron powder has the mass purity of 99.9% and the particle size of 0.4 mu m; the mass purity of the nano carbon powder is 99.5 percent;
step two, sequentially polishing the magnesium rod with abrasive paper, scrubbing with ethanol and drying in the air, then filling the magnesium rod into the center of the niobium pipe after acid cleaning, and filling the mixed powder obtained in the step one into the gap between the magnesium rod and the niobium pipe to obtain a first pipe-filling composite body; the diameter of the magnesium rod is 5.0mm, and the mass purity is 99.95%; the outer diameter of the niobium pipe is 11mm, and the wall thickness of the niobium pipe is 1 mm; the acid pickling process of the niobium pipe is as follows: acid cleaning is carried out by adopting mixed acid liquor consisting of nitric acid solution, hydrofluoric acid solution and water, then dehydration is carried out by absolute ethyl alcohol, and drying is carried out at 55 ℃; the mass concentration of nitric acid in the mixed acid liquid is 14%, and the mass concentration of hydrofluoric acid is 6%;
step three, sealing two ends of the first tubulation complex obtained in the step two, then performing rotary swaging to obtain a single-core wire, and then sequentially performing straightening, sizing, cutting, acid washing and drying on the single-core wire; the pass processing rate of the rotary swaging is 15%;
step four, assembling the single-core wire rods which are dried in the step three and 7 pickled CuNb rods into the pickled Monel alloy tube to obtain a second tube-loading composite; 7 pickled CuNb rods are placed in the center of the Monel alloy pipe in the assembling process, and 30 dried single-core wires are arranged into a 2-layer annular structure around the CuNb rods along the circumferential direction and are placed in the Monel alloy pipe; the lengths of the dried single-core wire, the pickled CuNb rod and the Monel alloy pipe are the same; the Monel alloy pipe has an outer diameter of 25mm and a wall thickness of 3 mm; the specific pickling process of the Monel alloy pipe is as follows: acid cleaning is carried out by adopting mixed acid liquor consisting of nitric acid solution, hydrofluoric acid solution and water, then dehydration is carried out by absolute ethyl alcohol, and drying is carried out at 55 ℃; the mass concentration of nitric acid in the mixed acid liquid is 14%, and the mass concentration of hydrofluoric acid is 6%;
fifthly, performing rotary swaging and drawing on the second pipe-filling composite body obtained in the fourth step to obtain a 37-core wire; the pass processing rate of the rotary swaging drawing is 10 percent; the diameter of the 37-core wire rod is 1.0 mm;
step six, sealing two ends of the 37-core wire rod obtained in the step five, and then putting the wire rod into flowing argon for sintering to obtain 37-core MgB2A superconducting wire; the sintering process comprises the following steps: heating to 650 ℃ at the speed of 10 ℃/min, preserving heat for 3h, and then cooling to room temperature along with the furnace; the 37-core MgB2The superconducting phase filling rate of the superconducting wire is 8.65%, and the 37-core MgB2Critical current density J of superconducting wire at 4.2K and 4TcIs 5.25X 105A/cm2。
37-core MgB prepared in this example2The length of the superconducting wire can reach more than 100 meters.
The above description is only for the preferred embodiment of the present invention, and is not intended to limit the present invention in any way. Any simple modification, change and equivalent changes of the above embodiments according to the technical essence of the invention are still within the protection scope of the technical solution of the invention.

Claims (7)

1. Hectometer-grade 37-core MgB2A method for producing a superconducting wire by magnesium diffusion, characterized in thatThe method comprises the following steps:
step one, uniformly mixing amorphous boron powder and nano carbon powder in an argon-protected glove box, and then putting the mixture into an agate mortar for grinding to obtain mixed powder; the molar ratio of the amorphous boron powder to the nano carbon powder is (2-x): x, and the value range of x is 0.02-0.08;
step two, sequentially polishing the magnesium rod with abrasive paper, scrubbing with ethanol and drying in the air, then filling the magnesium rod into the center of the niobium pipe after acid cleaning, and filling the mixed powder obtained in the step one into the gap between the magnesium rod and the niobium pipe to obtain a first pipe-filling composite body; the diameter of the magnesium rod is 3.0 mm-5.0 mm;
step three, sealing two ends of the first tubulation complex obtained in the step two, then performing rotary swaging to obtain a single-core wire, and then sequentially performing straightening, sizing, cutting, acid washing and drying on the single-core wire; the pass processing rate of the rotary swaging is 10-30%;
step four, assembling the single-core wire rods which are dried in the step three and 7 pickled CuNb rods into the pickled Monel alloy tube to obtain a second tube-loading composite; 7 pickled CuNb rods are placed in the center of the Monel alloy pipe in the assembling process, and 30 dried single-core wires are arranged into a 2-layer annular structure around the CuNb rods along the circumferential direction and are placed in the Monel alloy pipe; the lengths of the dried single-core wire, the pickled CuNb rod and the Monel alloy pipe are the same;
fifthly, performing rotary swaging and drawing on the second pipe-filling composite body obtained in the fourth step to obtain a 37-core wire; the pass processing rate of the rotary swaging drawing is 10-20%;
step six, sealing two ends of the 37-core wire rod obtained in the step five, and then putting the wire rod into flowing argon for sintering to obtain 37-core MgB2A superconducting wire; the 37-core MgB2The superconductive wire has a superconductive phase filling rate of 8.5% or more, and the 37-core MgB2The critical current density of the superconducting wire at 4.2K and 4T is 5 × 105A/cm2The above.
2. A method as claimed in claim 1Hundred meter grade 37 core MgB2The preparation method of the superconducting wire by magnesium diffusion is characterized in that the mass purity of the amorphous boron powder in the step one is not less than 99%, and the particle size is 0.1-10 μm; the mass purity of the nano carbon powder is not less than 99%.
3. Hectometer-grade 37-core MgB according to claim 12The preparation method of the superconducting wire by magnesium diffusion is characterized in that the mass purity of the magnesium rod in the step two is 99.9-99.99%.
4. Hectometer-grade 37-core MgB according to claim 12The magnesium diffusion preparation method of the superconducting wire is characterized in that the specific processes of acid washing of the niobium tube in the step two and acid washing of the Monel alloy tube in the step four are as follows: acid cleaning is carried out by adopting mixed acid liquor consisting of nitric acid solution, hydrofluoric acid solution and water, then dehydration is carried out by absolute ethyl alcohol, and then drying is carried out at 50-60 ℃; the mass concentration of the nitric acid in the mixed acid liquid is 12-15%, and the mass concentration of the hydrofluoric acid is 5-8%.
5. Hectometer-grade 37-core MgB according to claim 12The preparation method of the superconducting wire by magnesium diffusion is characterized in that the outer diameter of the niobium tube in the step two is 10-12 mm, and the wall thickness of the niobium tube is 1-2 mm; in the fourth step, the Monel alloy pipe has an outer diameter of 22 mm-37 mm and a wall thickness of 1.5 mm-3 mm.
6. Hectometer-grade 37-core MgB according to claim 12The magnesium diffusion preparation method of the superconducting wire rod is characterized in that the diameter of the 37-core wire rod in the fifth step is 0.4-1.4 mm.
7. Hectometer-grade 37-core MgB according to claim 12The magnesium diffusion preparation method of the superconducting wire is characterized in that the sintering process in the sixth step is as follows: heating to 600-680 ℃ at the speed of 10-20 ℃/min, preserving the heat for 1-5 h, and then cooling to room temperature along with the furnace。
CN201911188599.5A 2019-11-28 2019-11-28 Hectometer-grade 37-core MgB2Magnesium diffusion preparation method of superconducting wire Pending CN110828059A (en)

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CN106128632A (en) * 2016-06-16 2016-11-16 中国科学院电工研究所 Based on MgB4the magnesium scattering preparation of the MgB 2 superconductor wire material of precursor powder
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CN104916373A (en) * 2015-05-18 2015-09-16 中国科学院电工研究所 Preparation method of magnesium diboride wire rod or strip
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