CN117831854A - Bronze Nb method 3 Preparation method of Sn superconducting wire - Google Patents
Bronze Nb method 3 Preparation method of Sn superconducting wire Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 85
- 238000002360 preparation method Methods 0.000 title claims abstract description 36
- 238000010438 heat treatment Methods 0.000 claims abstract description 79
- 238000012545 processing Methods 0.000 claims abstract description 64
- 239000002131 composite material Substances 0.000 claims abstract description 60
- 230000008569 process Effects 0.000 claims abstract description 41
- 238000010622 cold drawing Methods 0.000 claims abstract description 18
- 238000000137 annealing Methods 0.000 claims description 40
- 238000001816 cooling Methods 0.000 claims description 18
- 238000004519 manufacturing process Methods 0.000 claims description 4
- 238000004321 preservation Methods 0.000 claims description 4
- 229910000906 Bronze Inorganic materials 0.000 abstract description 90
- 239000010974 bronze Substances 0.000 abstract description 90
- KUNSUQLRTQLHQQ-UHFFFAOYSA-N copper tin Chemical compound [Cu].[Sn] KUNSUQLRTQLHQQ-UHFFFAOYSA-N 0.000 abstract description 90
- 239000000463 material Substances 0.000 abstract description 57
- 238000006243 chemical reaction Methods 0.000 abstract description 7
- 238000013461 design Methods 0.000 abstract description 4
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- 239000011159 matrix material Substances 0.000 description 13
- 238000007599 discharging Methods 0.000 description 10
- 230000006698 induction Effects 0.000 description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 7
- 239000010949 copper Substances 0.000 description 7
- 229910052802 copper Inorganic materials 0.000 description 7
- 229910045601 alloy Inorganic materials 0.000 description 6
- 239000000956 alloy Substances 0.000 description 6
- 238000003466 welding Methods 0.000 description 6
- 230000004888 barrier function Effects 0.000 description 5
- 238000012360 testing method Methods 0.000 description 5
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 4
- 238000001125 extrusion Methods 0.000 description 4
- 238000005755 formation reaction Methods 0.000 description 4
- 238000003672 processing method Methods 0.000 description 4
- 230000001360 synchronised effect Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000009826 distribution Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
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- 230000000694 effects Effects 0.000 description 2
- 238000010894 electron beam technology Methods 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 238000007789 sealing Methods 0.000 description 2
- 241001391944 Commicarpus scandens Species 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 239000003153 chemical reaction reagent Substances 0.000 description 1
- 238000005253 cladding Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000002500 effect on skin Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
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- 238000012986 modification Methods 0.000 description 1
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- 238000001556 precipitation Methods 0.000 description 1
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
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- 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
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/60—Superconducting electric elements or equipment; Power systems integrating superconducting elements or equipment
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Abstract
The invention belongs to the technical field of superconducting material preparation, and discloses a bronze Nb method 3 A method for preparing Sn superconducting wire. The method comprises the following steps: s1: nb is processed by adopting a mode of changing the processing rate step by step 3 Carrying out cold drawing processing on the Sn composite rod for a plurality of times until the total processing rate is less than or equal to 65%; s2: by adding the Nb to 3 Heating the Sn composite rod to 180-320 ℃ and preserving heat for 5-30 min; s3: by adding the Nb to 3 And carrying out short-time surface heat treatment for a plurality of times on the Sn composite rod until the surface is completely heated. The invention adopts the design of gradient processing rate, low-temperature preheating and short timeThe surface heat treatment process can greatly shorten the Nb bronze process 3 The processing time of the Sn superconducting wire material promotes the material to form residual stress gradient and temperature gradient to be superposed to induce the CuSnTi phase to be dispersed and evenly separated out, so as to increase Nb after reaction 3 And the Sn superconducting phase pinning center is used for improving the critical current of the wire rod.
Description
Technical Field
The invention belongs to the technical field of superconducting material preparation, and discloses a bronze Nb method 3 A method for preparing Sn superconducting wire.
Background
Bronze process Nb 3 Sn superconducting wire is an important low-temperature superconducting material for manufacturing high-field magnets, and is widely used for manufacturing magnets with a temperature of 10T or more, and is mainly prepared by embedding Nb in a tin bronze matrix to obtain a composite, then repeatedly drawing and annealing to obtain a wire, and finally performing phase-forming heat treatment to generate Nb 3 The Sn superconducting phase obtains superconducting performance. At present, bronze Nb 3 The preparation and application of Sn superconducting wires is limited by two bottlenecks: on the one hand, limited by the solubility limit of Sn in tin bronze (about 16 wt.%) Nb is constrained 3 The content of Sn superconducting phase further limits the improvement of the superconducting performance (critical current) of the wire rod, and brittle Nb is easy to generate on the surface of the Nb core wire in the process of intermediate annealing 3 The Sn phase is easy to break the core and the wire in the processing process, so that the critical current of the wire is reduced; on the other hand, the increase of the Sn content sharply improves the work hardening effect of the tin bronze, repeated intermediate annealing is needed in the drawing process, and the preparation efficiency is low.
Disclosure of Invention
For bronze Nb 3 The invention provides an improvement requirement of Sn superconducting wire on performance and preparation efficiencyFor synchronously lifting bronze Nb 3 The processing method of Sn superconducting wire performance and preparation efficiency designs a novel processing technology of gradient processing rate design, low-temperature preheating and short-time surface heat treatment by utilizing alloy plastic deformation behavior, tissue structure evolution mechanism and induction heating skin effect, can greatly shorten processing time, promote the superposition of residual stress gradient and temperature gradient between the surface and the center of a material in the processing process, effectively release residual stress and induce grain refinement and CuSnTi second phase to be dispersed and evenly separated out in a large amount so as to increase Nb after reaction 3 The Sn superconducting phase contains Ti pinning center, and the critical current of the wire is improved. The invention not only can synchronously promote the bronze Nb process 3 The performance and the preparation efficiency of the Sn superconducting wire keep the advantages of high surface quality and low realization difficulty of cold working deformation.
In one aspect, the present invention relates to a bronze process Nb 3 The preparation method of the Sn superconducting wire comprises the following steps: s1: nb is processed by adopting a mode of changing the processing rate step by step 3 Carrying out cold drawing processing on the Sn composite rod for a plurality of times until the total processing rate of the step is less than or equal to 65%;
s2: by adding the Nb to 3 Heating the Sn composite rod to 180-320 ℃ and preserving heat for 5-30 min;
s3: by adding the Nb to 3 Carrying out short-time surface heat treatment for a plurality of times on the Sn composite rod until the surface reaches 550-800 ℃ all, and cooling to room temperature to obtain Nb 3 Sn superconducting wire. The method of cooling to room temperature is not particularly limited in the present invention, and air cooling or water cooling may be used for cooling to room temperature, for example. If the Nb is 3 And if the target specification size of the Sn superconducting wire is more than or equal to 4mm, finishing processing without subsequent steps.
Further, the bronze Nb method provided by the invention 3 In the preparation method of the Sn superconducting wire, the Nb 3 The target specification size of the Sn superconducting wire is smaller than 4mm, and the method further comprises the following steps: s4: sequentially repeating the steps S1, S2 and S3 until the Nb 3 The diameter of the Sn composite rod is smaller than 4mm;
s5: by pass-by-pass variation of working rateMode of operation Nb 3 Carrying out cold drawing processing on the Sn composite rod for a plurality of times until the total processing rate of the step is less than or equal to 65%;
s6: for the Nb 3 Carrying out intermediate annealing on the Sn superconducting wire;
s7: sequentially repeating the steps S5 and S6 until the Nb 3 And processing the Sn composite rod to a target specification.
Further, the bronze Nb method provided by the invention 3 In the method for producing a Sn superconducting wire, the intermediate annealing includes: vacuum heating treatment and heat preservation for 90 min+/-10 min;
the vacuum degree of the vacuum is less than 1 multiplied by 10 -2 Pa；
The heating is to 350-700 ℃.
Further, the bronze Nb method provided by the invention 3 In the preparation method of the Sn superconducting wire, any one of the methods adopts a mode that the processing rate changes gradually and gradually 3 In the process of cold drawing the Sn composite rod for many times, the processing rate of each pass is 10-25%, and the processing rate variation value between each pass is 3-8%.
Further, the bronze Nb method provided by the invention 3 In the preparation method of the Sn superconducting wire, the heating rate of the short-time surface heat treatment is 10 ℃/s-200 ℃/s, and the length of a heating area is 100 mm-500 mm. The method for short-time surface heat treatment is not particularly limited, and an infrared temperature measuring device is used for monitoring Nb 3 Sn composite rod surface temperature, when the material surface temperature in the heating area reaches the target temperature, changing Nb 3 And the relative position relationship between the Sn composite rod and the coil is used for replacing the heating area until the surface of the material is completely heated.
Further, the bronze Nb method provided by the invention 3 In the preparation method of the Sn superconducting wire, the Nb 3 The Sn composite rod is a straight rod or a wire rod after coiling. For straight bars, heating may be accomplished by moving the material horizontally or by heating coils, for example; for the wire rod after coiling, the heating coil can be fixed, and the wire rod is moved by adopting auxiliary devices such as a steel wheel and the like to finish heating through paying-off and winding operationThe wire is rewound.
Further, the bronze Nb method provided by the invention 3 In the preparation method of the Sn superconducting wire, the Nb 3 In the Sn composite rod, the Sn content is 12-16 wt%, and the Ti content is more than or equal to 0.1 and less than or equal to 2 wt%. Nb of the invention 3 The Sn composite rod has a diameter ranging from 4mm to 70mm and comprises a bronze Nb method obtained by extruding or stretching a blank formed by a bronze/Nb composite body, bronze, a barrier layer and a copper cladding 3 Sn composite rod and bronze Nb method 3 Sn composite wires, bronze/Nb composite rods, bronze/Nb composite wires, bronze rods, bronze wires.
In another aspect, the present invention relates to a bronze Nb 3 And a Sn superconducting wire which is prepared by the preparation method.
In another aspect, the present invention relates to the above preparation method for increasing Nb 3 The application of the Sn superconducting wire performance.
Compared with the prior art, the technical scheme provided by the invention has at least the following beneficial effects or advantages:
the invention provides a synchronous lifting bronze Nb method 3 The processing method of Sn superconducting wire performance and preparation efficiency provides a novel processing technology of gradient processing rate design, low-temperature preheating and short-time surface heat treatment, which can be applied to bronze Nb 3 Materials of high tin bronze matrix (i.e. Nb) involved in Sn wire preparation 3 Sn composite rod), the time for eliminating the processing residual stress can be greatly shortened. Fewer vacuum intermediate annealers are required compared to conventional "cold drawing + intermediate annealing" processes; the temperature required by low-temperature preheating is lower, the time is shorter, and the energy consumption is lower; the preheating temperature is low, the short-time surface heat treatment time is short, the surface of the material can be prevented from being seriously oxidized, a vacuum environment is not needed, the material can be treated in an atmospheric environment, and the method has the advantages of efficiency and cost; and the conventional cold working deformation mode is adopted, and compared with the online hot stretching mode, the method has the advantages of high surface quality and low realization difficulty.
In addition, the process provided by the invention is realized by the method that the surface and the middle of the material areThe superposition of the gradient residual stress field and the gradient temperature field between the cores promotes the rapid release of the residual stress and simultaneously induces the grain refinement and the massive and uniform dispersion and precipitation of the CuSnTi second phase so as to increase the Nb after the reaction 3 The Sn superconducting phase contains Ti pinning center, which is favorable for increasing critical current of the wire rod, thereby realizing synchronous increase of bronze Nb 3 The purpose of the performance and the preparation efficiency of the Sn superconducting wire is to provide a high-performance Sn superconducting wire.
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In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a diagram of bronze Nb 3 The processing technology principle of the Sn superconducting wire preparation method.
FIG. 2 is a schematic diagram of a bronze Nb process according to the present invention 3 A processing flow chart of a preparation method of the Sn superconducting wire.
FIG. 3 is a bronze process Nb provided by the present invention 3 The morphology distribution diagram of the alloy matrix CuSnTi second phase of the Sn superconducting wire preparation method. The white light spot area is a cusniti second phase.
Fig. 4 is a morphology profile of the second phase of cusnpi of the alloy matrix prepared by the "cold drawing + intermediate annealing" method. The white light spot area is a cusniti second phase.
Detailed Description
The following describes the technical aspects of the present invention with reference to examples, but the present invention is not limited to the following examples.
The experimental methods and the detection methods described in the following examples are all conventional methods unless otherwise specified; the reagents and materials are commercially available unless otherwise specified.
Example 1
This example provides a bronze Nb process using the present invention 3 Sn superconducting wireThe specific implementation process of the material preparation method.
Step 1: referring to FIG. 1, 1 piece of bronze Nb with specification of phi 35mm by 2500mm is selected 3 The Sn composite rod (bronze matrix, with Sn content of 12.5wt.%, and Ti content of 0.2 wt.%) is subjected to continuous 3-pass room-temperature drawing with processing rates of 23%, 20% and 17% respectively;
step 2: referring to fig. 1, the material processed in step 1 is heated to 185 ℃ in an atmospheric resistance furnace, and is preserved for 20min for preheating.
Step 3: referring to fig. 1, one end of the material preheated in the step 2 is placed in an induction coil with the width of 120mm for surface heating, after the surface temperature of the material reaches 690 ℃, the material is continuously moved horizontally for 120mm for heating until the whole surface is treated, and then air cooling is carried out to room temperature.
Step 4: repeating steps 1-3, processing the materials to phi 3.08mm, placing in a vacuum heat treatment furnace for annealing, and vacuum degree is 7.1×10 -3 Pa, heating to 470 ℃, preserving heat for 90min, cooling, discharging, and carrying out continuous 3-pass drawing processing with the processing rates of 23%, 20% and 17% respectively.
Step 5: the same intermediate annealing and stretching process in step 4 is repeated until bronze Nb with the specification of phi 0.75mm is obtained 3 Sn superconducting wire.
Step 6: testing critical current (4.2K, 12T) after 700 ℃ x 85h of phase formation reaction heat treatment, and preparing bronze Nb by the steps 3 The critical current of the Sn superconducting wire is 303.9A.
Comparative example 1
This comparative example is identical to example 1, except that bronze Nb is prepared by the conventional "cold drawing+intermediate annealing" method 3 Sn superconducting wires.
Step 1: 1 piece of bronze Nb with phi 35mm by 2500mm, which is the same as in example 1, was selected 3 The Sn composite rod (bronze matrix, with Sn content of 12.5wt.%, and Ti content of 0.2 wt.%) is subjected to continuous 3-pass room-temperature drawing with processing rates of 23%, 20% and 17% respectively;
step 2: the materials processed in the step 1 are placed in a vacuum heat treatment furnace for intermediate annealingVacuum degree 7.1X10 -3 Pa, heating to 700 ℃, preserving heat for 2 hours, and cooling and discharging. Each intermediate anneal is used for 12 hours in total.
Step 3: repeating steps 1-2, processing the materials to phi 3.08mm, placing in a vacuum heat treatment furnace for annealing, and vacuum degree is 7.1×10 -3 Pa, heating to 470 ℃, preserving heat for 90min, cooling, discharging, and carrying out continuous 3-pass drawing processing with the processing rates of 23%, 20% and 17% respectively.
Step 4: the same intermediate annealing and stretching process in step 3 is repeated until bronze Nb with the specification of phi 0.75mm is obtained 3 Sn superconducting wire.
Step 5: testing critical current (4.2K, 12T) after 700 ℃ x 85h of phase formation reaction heat treatment, and preparing bronze Nb by the steps 3 The critical current of the Sn superconducting wire is 270.8A.
Example 1: stretching time is 12h, low-temperature annealing time is 2.6h (7 times), short-time surface heat treatment is 4.3h (7 times), vacuum heat treatment annealing is 60h (12 h/furnace, 5 furnaces are all used), and total time is 78.6h; comparative example 1 of example 1 employed a conventional cold drawing + intermediate annealing process: the stretching time was 12 hours, and the vacuum heat treatment annealed for 144 hours (12 hours/oven, total 12 ovens) for 156 hours.
Compared with the cold drawing and intermediate annealing process of comparative example 1, the processing time of example 1 is reduced by 49.6%, the critical current is increased by 12.2%, the time for intermediate heat treatment is greatly reduced, and the performance is improved.
Example 2
This example provides a bronze Nb process using the present invention 3 The specific implementation process of the Sn superconducting wire preparation method.
Step 1: referring to FIG. 1, 1 piece of bronze Nb with the specification of phi 50mm by 3500mm is adopted 3 The Sn composite rod (the Sn content of the bronze matrix is 16wt percent, the Ti content is 2wt percent) is subjected to continuous 3-pass drawing processing with the processing rates of 24%, 20% and 16% respectively;
step 2: referring to fig. 1, the material processed in the step 1 is placed into a resistance furnace to be heated to 200 ℃, and the temperature is kept for 15min for preheating.
Step 3: referring to fig. 1, one end of the material preheated in the step 2 is horizontally placed in an induction coil with the heating width of 200mm to perform surface heating treatment, after the surface temperature of the material reaches 650 ℃, the induction coil with the heating width of 200mm is horizontally moved to the other end of the material to continue heating the material until the surface of the material is completely treated, and then air cooling is performed to room temperature.
Step 4: repeating the steps 1-3, processing the material to the specification of phi 3.10mm, then placing the material into a vacuum heat treatment furnace for annealing, and vacuumizing to the vacuum degree of 5.0 multiplied by 10 -3 Pa, heating to 430 ℃, preserving heat for 105min, cooling and discharging, and carrying out continuous 3-pass drawing processing with the processing rates of 24%, 20% and 16% respectively.
Step 5: the same annealing and stretching process in step 4 is repeated until bronze Nb with the specification of phi 0.77mm is obtained 3 Sn superconducting wires.
Step 6: the wire is subjected to a phase reaction heat treatment at 630 ℃ for 120 hours, and is tested for critical current (4.2K, 12T), and the bronze Nb prepared by the steps is prepared 3 The critical current of the Sn superconducting wire is 319.9a.
Comparative example 2
This comparative example is identical to example 2, except that bronze Nb is prepared by the conventional "cold drawing + intermediate annealing" method 3 Sn superconducting wires.
Step 1: 1 piece of bronze Nb with phi 50mm multiplied by 3500mm, which is the same as that of example 2, was selected 3 The Sn composite rod (the Sn content of the bronze matrix is 16wt percent, the Ti content is 2wt percent) is subjected to continuous 3-pass room-temperature drawing processing with the processing rates of 24%, 20% and 16% respectively;
step 2: the materials processed in the step 1 are placed in a vacuum heat treatment furnace for intermediate annealing, and the vacuum degree is 7.1 multiplied by 10 -3 Pa, heating to 730 ℃, preserving heat for 1.5h, and cooling and discharging. Each intermediate anneal is used for 12 hours in total.
Step 3: repeating the steps 1-2, processing the material to the specification of phi 3.10mm, placing the material in a vacuum heat treatment furnace for annealing, and vacuumizing to the vacuum degree of 5.0 multiplied by 10 -3 Pa, heating to 430 ℃, preserving heat for 105min, cooling and discharging, and carrying out continuous 3-pass drawing processing with the processing rates of 24%, 20% and 16% respectively.
Step 4: the same intermediate annealing and stretching process in step 3 is repeated until bronze Nb with the specification of phi 0.77mm is obtained 3 Sn superconducting wire.
Step 5: testing critical current (4.2K, 12T) after 630 ℃ x 120h of phase formation reaction heat treatment, and preparing the bronze Nb by the steps 3 The critical current of the Sn superconducting wire is 290.5A.
Example 2 process of the invention: the stretching time is 13.5 hours, the low-temperature annealing time is 2 hours (8 times), the short-time surface heat treatment is 6.9 hours (8 times), the vacuum heat treatment annealing is 60 hours (12 hours/furnace, 5 furnaces are all used), and the total time is 82.4 hours; the comparative example of example 2 uses a conventional cold drawing-intermediate annealing process: the stretching time was 13.5 hours, and the vacuum heat treatment was annealed for 156 hours (12 hours/oven, 13 ovens total), for 169.5 hours.
Compared with the conventional cold drawing and intermediate annealing process of comparative example 2, the processing time of the invention is reduced by 51%, the critical current is improved by 10.1%, the time for intermediate heat treatment is greatly reduced, and the performance is improved.
In addition, FIG. 3 shows the synchronous lifting bronze Nb method provided by the invention in this embodiment 3 Bronze Nb prepared by processing method of Sn superconducting wire performance and preparation efficiency 3 Fig. 4 shows a photograph of the morphology distribution of the second phase of cusniti (white bright spot region is cusniti second phase) of the alloy matrix of Sn wires, and fig. 4 shows a bronze Nb prepared by the conventional "cold drawing+intermediate annealing" method in comparative example 2 3 Morphology distribution photographs of the alloy matrix CuSnTi second phase of the Sn wire rod. Fig. 3 and fig. 4 are both the same specifications and have no final phase formation heat treatment process, and comparison between fig. 3 and fig. 4 shows that the synchronous lifting bronze Nb method provided by the invention 3 Bronze Nb prepared by processing method of Sn superconducting wire performance and preparation efficiency 3 The alloy matrix CuSnTi second phase of the Sn wire is more uniformly dispersed, uniform and fine, which is favorable for increasing Nb after reaction 3 The Sn superconducting phase contains Ti pinning centers, so that the critical current performance of the wire is improved.
Example 3
This example provides a bronze Nb process using the present invention 3 Specific implementation of Sn superconducting wire preparation methodAnd (3) a process.
Step 1: referring to fig. 1, 1 piece of bronze/Nb composite rod (bronze matrix Sn content 13.5wt.%, ti content 0.6 wt.%) with a gauge Φ58×3000mm was selected for continuous 3-pass drawing at processing rates of 22%, 18%, 14%, respectively;
step 2: referring to fig. 1, the material processed in the step 1 is placed into a resistance furnace to be heated to 220 ℃, and the temperature is kept for 25min for preheating.
Step 3: referring to fig. 1, one end of the material preheated in the step 2 is placed in an induction coil with the heating width of 300mm for surface heating treatment, after the surface temperature of the material reaches 700 ℃, the induction coil with the surface temperature of 300mm is moved to the other end of the material for continuously heating the material after about 7 seconds until the surface of the material is completely treated, and the material is cooled to room temperature by air.
Step 4: repeating the steps 1-3, and straightening and cutting the materials into the hexagonal bronze/Nb composite rod with the specification of H4.27mm multiplied by 350mm after the materials are processed to the specification of H4.27 mm.
Step 5: selecting 1056 pieces of bronze/Nb composite bars with the thickness of 3mm and the thickness of H4.27mm multiplied by 350mm, which are prepared in the step 4, closely arranging the Nb barrier layers, putting the Nb barrier layers into an oxygen-free copper tube with the outer diameter phi 208mm and the inner diameter phi 148.8mm, adding copper covers on two sides of the oxygen-free copper tube, and sealing and welding by adopting a vacuum electron beam to obtain a composite wire blank (the vacuum degree is 2 multiplied by 10) -2 Pa, welding current 80 mA), and performing heat preservation at 700 ℃ for 3.5h to obtain bronze Nb with phi 56mm multiplied by 3000mm 3 And 1 branch of Sn composite rod.
Step 6: referring to FIG. 1, 56mm×3000mm bronze Nb is prepared in step 5 3 The Sn composite rod was subjected to continuous 3-pass drawing at a working ratio of 23%, 20% and 17%, respectively.
Step 7: referring to fig. 1, the material processed in the step 6 is placed into a resistance furnace to be heated to 200 ℃, and the temperature is kept for 20min for preheating.
Step 8: referring to fig. 1, one end of the material preheated in the step 7 is placed in an induction coil with a heating width of 300mm for surface heating treatment, after the surface temperature of the material reaches 650 ℃, the induction coil with the surface temperature of 300mm is moved to the other end of the material for continuing to heat the material after about 5 seconds until the surface of the material is completely treated, and the material is cooled to room temperature by air.
Step 9: repeating the steps 6-8, processing the material to the specification of phi 3.22mm, then placing the material into a vacuum heat treatment furnace for annealing, and vacuumizing to the vacuum degree of 3.0 multiplied by 10 -3 Pa, heating to 480 ℃, maintaining the temperature for 50min, cooling and discharging, and carrying out continuous 3-pass drawing processing with the processing rates of 23%, 20% and 17% respectively.
Step 10: the same annealing and stretching process in step 9 is repeated until a rectangular bronze Nb of 1.10X1.64 mm specification is obtained 3 Sn superconducting wires.
Step 11: carrying out phase reaction heat treatment at 700 ℃ for 85h on the wire rod prepared in the step 10, testing critical current (4.2K, 12T), and carrying out bronze Nb preparation by the steps 3 The critical current of the Sn superconducting wire is 788.5a.
Comparative example 3
This comparative example is identical to example 3, except that bronze Nb is prepared by the conventional "cold drawing + intermediate annealing" method 3 Sn superconducting wire.
Step 1: 1 composite bronze/Nb bar with phi 58 multiplied by 3000mm (bronze matrix, sn content 13.5wt.%, ti content 0.6 wt.%) which is the same as that of the example 3 is selected, and continuous 3-pass room-temperature drawing processing with processing rates of 22%, 18% and 14% is carried out;
step 2: the materials processed in the step 1 are placed in a vacuum heat treatment furnace for intermediate annealing, and the vacuum degree is 7.1 multiplied by 10 -3 Pa, heating to 700 ℃, preserving heat for 2 hours, and cooling and discharging. Each intermediate anneal is used for 12 hours in total.
Step 3: repeating the steps 1-2, and straightening and cutting the materials into the hexagonal bronze/Nb composite rod with the specification of H4.27mm multiplied by 350mm after the materials are processed to the specification of H4.27 mm.
Step 4: selecting 1056 pieces of bronze/Nb composite bars with the thickness of 3mm and the thickness of H4.27mm multiplied by 350mm, which are prepared in the step 4, closely arranging the Nb barrier layers, putting the Nb barrier layers into an oxygen-free copper tube with the outer diameter phi 208mm and the inner diameter phi 148.8mm, adding copper covers on two sides of the oxygen-free copper tube, and sealing and welding by adopting a vacuum electron beam to obtain a composite wire blank (the vacuum degree is 2 multiplied by 10) -2 Pa, welding current 80 mA), and performing heat preservation at 700 ℃ for 3.5h to obtain bronze Nb with phi 56mm multiplied by 3000mm 3 And 1 branch of Sn composite rod.
Step 5: bronze Nb with diameter of 56mm multiplied by 3000mm prepared in step 4 3 The Sn composite rod was subjected to continuous 3-pass room temperature drawing at a working ratio of 23%, 20% and 17%, respectively.
Step 6: and 5, placing the material processed in the step 5 into a vacuum heat treatment furnace for intermediate annealing, heating to 730 ℃ at the vacuum degree of 7.1 multiplied by 10 < -3 > Pa, preserving heat for 1.5 hours, and then cooling and discharging. Each intermediate anneal is used for 12 hours in total.
Step 7: repeating the steps 5-6, processing the material to the specification of phi 3.22mm, then placing the material into a vacuum heat treatment furnace for annealing, and vacuumizing to the vacuum degree of 3.0 multiplied by 10 -3 Pa, heating to 480 ℃, maintaining the temperature for 50min, cooling and discharging, and carrying out continuous 3-pass drawing processing with the processing rates of 23%, 20% and 17% respectively.
Step 8: the same annealing and stretching process in step 7 is repeated until a rectangular bronze Nb of 1.10X1.64 mm specification is obtained 3 Sn superconducting wires.
Step 9: carrying out phase reaction heat treatment at 700 ℃ for 85h on the wire rod prepared in the step 10, testing critical current (4.2K, 12T), and carrying out bronze Nb preparation by the steps 3 The critical current of the Sn superconducting wire is 671.2a.
Example 3 process of the invention: the drawing time is 22h (the drawing time of the bronze/Nb composite rod is 9h, and the bronze method is Nb) 3 Sn superconducting wire stretching time 13 h), bronze Nb 3 Preparation time of Sn composite rod extrusion rod is 15h (comprising assembly, welding and extrusion), low-temperature annealing time is 6.3h (preparation of bronze/Nb composite rod: 8 times, bronze Nb method) 3 Preparing a Sn composite wire: 9 times), short-time surface heat treatment for 8.2 hours (bronze/Nb composite rod preparation: 8 times; bronze process Nb 3 Preparing a Sn composite wire: 9 times) and vacuum heat treatment annealing for 36h (bronze Nb method) 3 Preparing a Sn composite wire: 12 h/oven, total 3 ovens) for a total of 87.5h.
Comparative example 3 process using conventional cold drawing + intermediate annealing: the drawing time is 22h (the drawing time of the bronze/Nb composite rod is 9h, and the bronze method is Nb) 3 Sn superconducting wire stretching time 13 h), bronze Nb 3 Extrusion time of Sn composite rod is 15h (comprising assembly, welding and extrusion), vacuum heat treatment and annealing252h (preparation of bronze/Nb composite rod: 12 h/furnace, 9 furnaces total; bronze Nb method) 3 Preparing a Sn composite wire: 12 h/oven, 12 ovens total), for a total of 289h.
Compared with the comparative example 3 of the conventional cold drawing and intermediate annealing process, the processing time of the embodiment 3 of the invention is reduced by 69.7%, the critical current is improved by 17.5%, the time for intermediate heat treatment is greatly reduced, and the performance is improved. Because of the bronze/Nb composite rod and the bronze method Nb 3 The novel process of the invention is adopted in the preparation process of the Sn composite wire, and compared with each comparative example, the efficiency and performance improvement effect of the invention in the embodiment are more obvious.
As described above, the basic principles, main features and advantages of the present invention are better described. The above examples and description are merely illustrative of preferred embodiments of the present invention, and the present invention is not limited to the above examples, and various changes and modifications to the technical solution of the present invention by those skilled in the art should fall within the scope of protection defined by the present invention without departing from the spirit and scope of the present invention.
Claims (9)
1. Bronze Nb method 3 The preparation method of the Sn superconducting wire is characterized by comprising the following steps of: s1: nb is processed by adopting a mode of changing the processing rate step by step 3 Carrying out cold drawing processing on the Sn composite rod for a plurality of times until the total processing rate of the step is less than or equal to 65%;
s2: by adding the Nb to 3 Heating the Sn composite rod to 180-320 ℃ and preserving heat for 5-30 min;
s3: by adding the Nb to 3 Carrying out short-time surface heat treatment for a plurality of times on the Sn composite rod until the surface reaches 550-800 ℃ all, and cooling to room temperature to obtain Nb 3 Sn superconducting wire.
2. The method of claim 1, wherein the Nb 3 The target specification size of the Sn superconducting wire is smaller than 4mm, and the method further comprises the following steps: s4: sequentially repeating the steps S1, S2 and S3 until the Nb 3 The diameter of the Sn composite rod is smaller than 4mm;
s5: nb is processed by adopting a mode of changing the processing rate step by step 3 Carrying out cold drawing processing on the Sn composite rod for a plurality of times until the total processing rate of the step is less than or equal to 65%;
s6: for the Nb 3 Carrying out intermediate annealing on the Sn superconducting wire;
s7: sequentially repeating the steps S5 and S6 until the Nb 3 And processing the Sn composite rod to a target specification.
3. The method of manufacturing according to claim 2, wherein the intermediate annealing comprises:
vacuum heating treatment and heat preservation for 90 min+/-10 min;
the vacuum degree of the vacuum is less than 1 multiplied by 10 -2 Pa；
The heating is to 350-700 ℃.
4. The method according to any one of claims 1 and 2, wherein Nb is processed in a pass-by-pass manner using any one of the above-mentioned process rates 3 In the process of cold drawing the Sn composite rod for many times, the processing rate of each pass is 10-25%, and the processing rate variation value between each pass is 3-8%.
5. The method according to claim 1, wherein the heating rate of the short-time surface heat treatment is 10 ℃/s to 200 ℃/s, and the heating area length is 100mm to 500mm.
6. The method of claim 1, wherein the Nb 3 The Sn composite rod is a straight rod or a wire rod after coiling.
7. The method of claim 1, wherein the Nb 3 In the Sn composite rod, the Sn content is 12-16 wt%, and the Ti content is more than or equal to 0.1 and less than or equal to 2 wt%.
8. Bronze Nb method 3 An Sn superconducting wire, characterized in thatA process according to any one of claims 1 to 7.
9. The process according to any one of claims 1 to 7 for increasing Nb 3 The application of the Sn superconducting wire performance.
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