CN103633529A - Nb3Al superconductive connector preparation method - Google Patents
Nb3Al superconductive connector preparation method Download PDFInfo
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- CN103633529A CN103633529A CN201310613098.3A CN201310613098A CN103633529A CN 103633529 A CN103633529 A CN 103633529A CN 201310613098 A CN201310613098 A CN 201310613098A CN 103633529 A CN103633529 A CN 103633529A
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Abstract
The invention discloses a Nb3Al superconductive connector preparation method, which comprises the steps: selecting raw material powder of which components comprise pure Nb and pure Al, or Nb-Al alloy and pure Al; preparing Nb-Al supersaturated solid solution alloy powder with the selected raw material powder in a high energy ball-milling method; loading the Nb-Al supersaturated solid solution alloy powder and the end part of supersaturated solid solution Nb3Al superconductive wire precursor to be connected into a connector tube, and pre-pressing the powder; then performing heat treatment on the whole connector tube and the Nb3Al superconductive wire precursor together. The Nb3Al superconductive connector is prepared after the heat treatment is finished.
Description
Technical field
The present invention relates to a kind of superconducting line method of attachment, be particularly a kind ofly applicable to the Nb that rapid heating and cooling quenching transformation method makes
3the superconducting joint preparation method of Al superconducting line.
Background technology
High field super magnet plays in technical fields such as nulcear magnetic resonance (NMR), ITER thermonuclear fusion, high-energy physics accelerator the important application can not be substituted.In existing superconducting magnet technology of preparing, 10T and adopt the NbTi alloy superconducting line coiling of mechanical ductility excellence to form with lower magnet.Because the critical magnetic field of NbTi alloy is lower, more highfield more than 10T needs use to possess the more A-15 type intermetallic compound superconductor construction magnet of upper critical magnetic field characteristic.Existing 10-20T magnet NbTi alloy and the Nb that adopt by cryogenic superconductor more
3the nested formation of hybrid coil of Sn superconductor.A-15 type intermetallic compound Nb
3sn superconductor has good economy and higher technology maturity, but its shortcoming is that critical performance is limited, and mechanical performance is especially fragile.High field magnet coil requires can to maintain higher current density bearing larger stress simultaneously, belongs to the Nb of the intermetallic compound of A-15 type crystal structure together
3al compares Nb
3sn possesses the technological merits such as the critical performance of superconduction is high, stress sensitivity is low, radiation-resistant property is good, is expected to become the important materials of high-field nuclear magnetic resonance spectrometer superconducting magnet and following commercial thermonuclear fusion device high field super magnet.Nb
3the technology of preparing of Al superconductor strand mainly comprises: solid-state diffusion method, laser/electron beam heating and quench method etc.Wherein, rapid heating and cooling quenching transformation method is that Nb/Al mixing multifibres wire is heated rapidly to the Nb that Quenching Treatment after approximately 1800 ℃ obtains over-saturation solid solution state
3al superconducting line presoma, and then carry out about 800-900 ℃ diffusion heat treatments and obtain Nb
3al superconducting line.Because over-saturation solid solution state material has good room temperature ductility, be convenient to very much coil winding, be therefore current a kind of main Nb
3al superconducting line preparation method.
At Nb
3in the actual building course of Al magnet, need that coil is carried out to joint and connect processing, the connection of superconducting line is one of key technology in magnet building course.These joint location comprise: the interlayer of superconducting coil connects, the connection between multi-coil and magnet coil and being connected of current feed etc.For Nb
3the requirement of Al superconducting joint performance, on the one hand joint must possess good mechanical strength, to tackle the prestressing force, bending stress, electromagnetic stress, shrinkage stress etc. of magnet.On the other hand, joint also must have lower resistance, the superconducting magnet of operation with closed ring especially, and connection resistance will cause the decay in magnetic field.For example, in nuclear magnetic resonance spectrometer (NMR) magnet, require magnetic field on particular space size distribution, to keep keeping superregulated property in high uniformity and time scale, with this, improve signal to noise ratio and the scanning resolution of system.Wherein, the uniformity of space scale mainly relies on Electromagnetic Design and accurately technique for coiling guarantee; Stability in time scale is to rely on superconducting switch to connect magnet the two poles of the earth by superconducting joint, makes magnet under closed loop state, be able to the operation of constant current state, and the stability that decays to maintain magnetic field by minimizing magnet current ensures.When connection resistance is constant, the magnetic field intensity of closed loop magnet is exponential damping.Connection resistance is larger, and field decay is faster.Usually, when NMR magnet connection resistance is less than 10
-11during Ω, just can make system loss rate be less than 0.02ppm/hour, guarantee NMR system stable operation.Therefore controlling magnetic field decay need to achieve the goal by reduce connection resistance as far as possible.
Nb
3the prior art aspect of Al joint, existing only have the T.Fukuzaki of Japanese RIKEN to propose to adopt solder method to prepare Nb
3al superconducting line joint, but be limited by its superconduction solder compositions and process conditions, the critical back surface field of joint can only reach 0.4T, and actual available back surface field can only reach 0.1T, and harsh to actual joint instructions for use.Nb prepared by existing employing solder method
3in Al superconducting joint, the current path in superconducting joint is two: the radial propagation direction along conductor side is: Nb
3nb in Al superconducting line
3al core → Nb
3nb matrix → the Nb of Al superconducting line
3the Nb on Al superconducting line surface
3sn layer → SnPbBi scolder → Nb
3the Nb on Al superconducting line surface
3sn layer → Nb
3nb matrix → the Nb of Al superconducting line
3nb in Al superconducting line
3al core; Current spread direction along wire termination is: Nb
3nb in Al superconducting line
3al core → SnPbBi scolder → Nb
3nb in Al superconducting line
3al core.In above-mentioned two paths, all need the solder material through SnPbBi, although SnPbBi scolder also has certain superconductivity at low temperatures, the critical poor-performing of its superconduction, especially its critical back surface field is lower, under High-Field, will lose superconductivity, thereby has influence on Nb
3the performance of Al superconducting coil.And electric current is along needing through twice Nb in the radial propagation direction of conductor side
3sn layer, Nb
3although Sn superconductor possesses good superconductivity, than Nb
3the critical performance of Al superconductor is slightly poor, and critical magnetic field and critical current are all than Nb
3al superconductor is low, and stress sensitivity is higher, easily produces the critical performance degradation that stress causes.
Summary of the invention
The object of the invention is to overcome prior art Nb
3in Al superconducting line superconducting joint technology of preparing, the problem such as unstable, complicated harshness of process conditions of quality, proposes a kind of new Nb
3al superconducting line joint preparation method.The inventive method is easy, and steady quality can reduce connection resistance.The present invention can be applicable to the manufacture process of high-field nuclear magnetic resonance spectrometer superconducting magnet and following commercial thermonuclear fusion device high field super magnet.
Technical program of the present invention lies in:
A kind of Nb
3al superconducting joint preparation method, its preparation process is: choose the material powder that particle diameter is 20-200 micron, the component of material powder comprises pure Nb and pure Al, or Nb-Al alloy and pure Al, and the atomic quantity proportioning of the Al in material powder and Nb is 3:1; Material powder is put into the grinding jar of agate or corundum ball material, put into the abrading-ball identical with grinding jar material simultaneously, and put into odium stearate powder as dispersant, by high-energy ball milling mode, be prepared into Nb-Al over-saturation solid solution alloy powder; Remove Nb
3the sheathing material of Al presoma superconducting line.By the Nb of Nb-Al over-saturation solid solution alloy powder and over-saturation solid solution state to be connected
3the end of Al superconducting line presoma is packed in junction block together, and powder is carried out to pre-compacted, and pressure limit is 5-20MPa; Subsequently by junction block together with Nb
3al superconducting line presoma is together heat-treated, and system of heat treatment process is: be first heated to 180 ℃ of insulations 2 hours, the insulation of this temperature is for the odium stearate dispersant of powder surface can be volatilized totally, is beneficial to the sinter bonded of powder; Be warming up to again 800-900 ℃, insulation 10-80 hour, the insulation of this temperature is in order to make the diffusion of Nb-Al atom and Nb
3the formation of Al superconduction phase transformation, Nb in this temperature
3al superconducting phase will generate; Control subsequently heat-treatment furnace temperature Slow cooling to room temperature, Slow cooling is in order to make the Nb of preparation
3al superconducting joint and Nb
3the Stress-strain concentration that variations in temperature causes is reduced in Al superconducting line inside as far as possible, causes the damage of superconductivity; 3 ℃ of heat treatment temperature errors, are convenient to accurately control superconduction phase transformation process; The powder docking in heat treatment process in head tube can give lasting external pressure, also can not apply external pressure.After completing, heat treatment makes Nb
3al superconducting joint.
Wherein, high-energy ball milling comprises planetary type ball-milling, stirring-type ball milling, oscillatory type ball milling.
Wherein, heat treatment atmosphere is vacuum, and vacuum degree is better than 1 * 10
-2pa, or slumpability gas, as argon gas atmosphere.
Wherein, whole Nb
3al superconducting joint preparation process can be carried out in vacuum environment, and vacuum degree is better than 1 * 10
-2pa.
Wherein, the Nb of over-saturation solid solution state
3al superconducting line presoma refers to that adopting at present conventional rapid heating and cooling to quench changes the standby Nb of legal system
3a kind of intermediateness of Al superconducting line.Be Nb/Al mixing multifibres wire to be heated rapidly to the material of a kind of Nb-Al supersaturated solid solution state that after approximately 1800 ℃, Quenching Treatment obtains specifically, the over-saturation solid solution in Nb crystal of Al atom exists.Nb subsequently
3al superconducting line presoma also needs to carry out 800 ℃ of diffusion heat treatments, makes Al atom and the diffusion of Nb atom in Nb-Al supersaturated solid solution generate Nb
3al Compound Phase, finally obtains possessing the Nb of superconducting characteristic
3al superconducting line.Nb
3the Nb of Al superconducting line presoma and end-state
3al superconducting line is compared, and its advantage is that it has good room temperature ductility, is convenient to coil winding, Nb very much
3al superconducting coil is all generally at Nb
3under Al superconducting line presoma state, first turn to after type, then carry out diffusion heat treatments and finally obtain Nb
3al superconducting coil.In general Nb
3al superconducting line producer is at Nb
3can be first to Nb before Al superconducting line product export
3al superconducting line is processed the Nb that makes described over-saturation solid solution state
3al superconducting line presoma.During use, by the Nb of above-mentioned over-saturation solid solution state
3al superconducting line presoma turns to after coil, then carries out about 800-900 ℃ diffusion heat treatments and obtain containing A-15 type Nb
3the Nb of Al superconducting phase
3al superconducting coil.
The Nb that adopts the present invention to prepare
3al superconducting joint is column construction, and it is respectively from the inside to the outside: Nb to be connected
3al superconducting line and be wrapped in Nb
3the Nb of Al superconducting line exterior circumferential
3al sintering block, Nb
3the outside of Al sintering block is junction block, holds Nb in junction block
3al superconducting line and Nb
3al sintering block.Junction block one end closure, the other end is uncovered; The tube wall of junction block is double-decker, and internal layer material is Ta, and skin is Cu.
Wherein, Nb
3al sintering block is prepared through powder sintering process, inner flawless, and Nb
3al sintering block and Nb to be connected
3the contact interface place bonding state of Al superconducting line end is metallurgical binding.
Wherein, the purity 99.99% of the tube wall internal layer Ta of junction block, thickness 1mm.The purity 99.999% of the outer Cu of tube wall of junction block, thickness 1mm.The effect of Cu layer is shunting, once in superconducting joint quench, can prevent that instantaneous temperature is excessive by excessive current distributing at Cu layer, burns superconducting joint or superconducting line.Ta layer is diffusion barrier layer, and effect is that superconducting joint is when vacuum diffusion heat treatments, prevents that the alloying element in the dusty material in junction block from entering in Cu layer by solid-state diffusion effect, reduces the purity of Cu, causes the shunting ability of Cu layer to decline.
Wherein, the length of junction block is not less than 40mm, the Nb in junction block
3al sintering block and Nb to be connected
3the connecting length of Al superconducting line is not less than 30mm.
Wherein, Nb
3the end of Al superconducting line is inclined-plane, Nb to be connected
3al superconducting line tries one's best, and the inclined-plane of these ends is face-to-face placement, or approximately places face-to-face.
Feature of the present invention is:
By Nb
3al superconducting joint preparation process and Nb
3the heat treatment process of Al superconducting line combines, and synchronously completes, and has very strong operability and practicality.Nb
3al superconducting joint must can be prepared after superconducting coil coiling and assembling, and preparation process is subject to the Nb in actual field condition Suo Xian,Yu factory
3al superconducting line preparation process is different.From Nb-Al equilbrium phase diagram, the Nb of stable stoichiometric proportion
3al superconducting phase can only more than 1600 ℃ could obtain.So wire Nb
3the acquisition of Al superconducting phase generally need adopt non-equilibrium technology of preparing, from supersaturated solid solution, by atomic heat diffusion, generates.Adopt high-energy ball-milling process can obtain the nonequilibrium state Nb-Al supersaturated solid solution alloy powder away from thermodynamical equilibrium.Again that Nb-Al supersaturated solid solution alloy powder is compacted together superconducting line parcel to be connected subsequently, adopt powder metallurgy technology at Nb
3in the diffusion heat treatments process of Al superconducting line presoma, by Nb to be connected
3al superconducting line is sintered to one, and generates in the lump Nb by atom diffusion
3al superconducting phase, thus realize Nb
3the superconduction of Al superconducting line connects, and makes superconducting joint.
Compared to existing technology, the structure of superconducting joint of the present invention plays the effect that reduces connection resistance.
The standby Nb of soldering legal system of prior art
3in Al superconducting joint, the current path in superconducting joint is two: the radial propagation direction along conductor side is: Nb
3nb in Al superconducting line
3al core → Nb
3nb matrix → the Nb of Al superconducting line
3the Nb on Al superconducting line surface
3sn layer → SnPbBi scolder → Nb
3the Nb on Al superconducting line surface
3sn layer → Nb
3nb matrix → the Nb of Al superconducting line
3nb in Al superconducting line
3al core; Current spread direction along wire termination is: Nb
3nb in Al superconducting line
3al core → SnPbBi scolder → Nb
3nb in Al superconducting line
3al core.In above-mentioned two paths, all need the solder material through SnPbBi, although SnPbBi scolder also has certain superconductivity at low temperatures, the critical poor-performing of its superconduction, especially its critical back surface field is lower, under High-Field, will lose superconductivity, thereby has influence on Nb
3the performance of Al superconducting coil.And electric current is along needing through twice Nb in the radial propagation direction of conductor side
3sn layer, Nb
3although Sn superconductor possesses good superconductivity, than Nb
3the critical performance of Al superconductor is slightly poor, and critical magnetic field and critical current are all than Nb
3al superconductor is low, and stress sensitivity is higher, easily produces the critical performance degradation that stress causes.
Superconducting joint technology of the present invention will generate the Nb of superconduction after Nb-Al supersaturated solid solution sintering alloy powder
3al sintered body, the current path in superconducting joint is two: the radial propagation direction along conductor side is: Nb
3nb in Al superconducting line
3al core → Nb
3nb matrix → the Nb of Al superconducting line
3al sintering block → Nb
3nb matrix → the Nb of Al superconducting line
3nb in Al superconducting line
3al core; Current spread direction along wire termination is: Nb
3nb in Al superconducting line
3al core → Nb
3al sintering block → Nb
3nb in Al superconducting line
3al core.In the present invention, in current path, use Nb
3al sintering block has replaced Nb
3sn layer and SnPbBi scolder, obviously Nb
3the superconduction critical electric current of Al material and critical back surface field are all than Nb
3sn and SnPbBi material are high, with Nb to be connected
3the critical performance of Al superconducting line is basically identical, has improved joint current carrying capacity and critical back surface field.And, the Nb that adopts sintering process to prepare
3al sintered material is and rapid heating and cooling quenching transformation method Nb
3the heat treatment process of Al superconducting line completes simultaneously, Nb
3al sintered material and Nb
3al superconducting line surface will produce metallurgical binding in heat treatment process, greatly reduce connection resistance.
And preparation process and other processing steps of the supersaturated solid solution powder in the present invention are relatively independent, can complete in advance in other experiment place, with Nb
3the preparation of Al superconducting coil and heat treatment process are not conflicted.And the preparation of supersaturated solid solution powder stores after can once preparing, use in batches.Can guarantee like this unified of supersaturated solid solution powder properties to control.
Accompanying drawing explanation
Fig. 1 Nb
3al superconducting joint preparation flow block diagram,
Wherein, the block diagram content of dotted line is Nb
3the standard work flow (part) of Al superconducting line factory, the block diagram content of solid line is content flow of the present invention;
The standby Nb of soldering legal system of Fig. 2 prior art
3the longitudinal cross-section of Al superconducting joint and the electric current path schematic diagram of flowing through;
Fig. 3 Nb of the present invention
3the composition schematic diagram of Al superconducting joint before diffusion heat treatments;
Fig. 4 Nb of the present invention
3the composition schematic diagram of Al superconducting joint after diffusion heat treatments;
Fig. 5 Nb of the present invention
3the longitudinal cross-section of Al superconducting joint and the electric current path schematic diagram of flowing through;
Fig. 6 prepares high-energy ball milling Nb by planetary type ball-milling mode
3the principle schematic of Al supersaturated solid solution powder;
Fig. 7 prepares high-energy ball milling Nb by stirring-type ball milling method
3the principle schematic of Al supersaturated solid solution powder;
Fig. 8 prepares high-energy ball milling Nb by oscillatory type ball milling method
3the principle schematic of Al supersaturated solid solution powder.
Embodiment
Below in conjunction with the drawings and specific embodiments, further illustrate the present invention.
Nb of the present invention
3flow process prepared by Al superconducting joint is: choose the material powder that particle diameter is 20-200 micron, the composition of material powder comprises pure Nb and pure Al, or Nb-Al alloy and pure Al, and the atom number proportioning of the Al in material powder and Nb is 3:1; Add odium stearate dispersant, material powder is carried out to high-energy ball milling preparation, make Nb-Al supersaturated solid solution powder.Remove Nb
3the sheathing material of Al presoma superconducting line; By the Nb of Nb-Al supersaturated solid solution powder and over-saturation solid solution state to be connected
3the end of Al presoma superconducting line is together packed in junction block, and powder is carried out to pre-compacted, and pressure limit is 5-20MPa.Subsequently by junction block integral body together with Nb
3al superconducting line presoma is together put into vacuum furnace and is carried out vacuum heat, is first heated to 180 ℃ of insulations 2 hours, then is increased to heat treatment temperature point, temperature range 800-900 ℃, 3 ℃ of temperature errors, temperature retention time 10-80 hour.After insulation finishes, Slow cooling arrives room temperature again.The powder docking in heat treatment process in head tube can give lasting external pressure, also can not apply external pressure.Finally make Nb
3al superconducting joint.Fig. 1 is Nb
3al superconducting joint preparation flow block diagram.Wherein, the block diagram content of dotted line is the standard work flow (part) of superconducting line factory, and the block diagram content of solid line is content flow of the present invention.
Adopt the standby Nb of soldering legal system of prior art
3al superconducting joint, the Nb that its joint design is wrapped up by SnPbBi scolder and Nb
3the Nb of Al
3al superconducting line and Nb
3the formations such as Sn layer.Current path in superconducting joint is two: the radial propagation direction along conductor side is: Nb
3nb in Al superconducting line
3al core → Nb
3nb matrix → the Nb of Al superconducting line
3the Nb on Al superconducting line surface
3sn layer → SnPbBi scolder → Nb
3the Nb on Al superconducting line surface
3sn layer → Nb
3nb matrix → the Nb of Al superconducting line
3nb in Al superconducting line
3al core; Current spread direction along wire termination is: Nb
3nb in Al superconducting line
3al core → SnPbBi scolder → Nb
3nb in Al superconducting line
3al core, as shown in Figure 2.
Adopt Nb of the present invention
3al superconducting joint, the composition before diffusion heat treatments is from the inside to the outside: the Nb that comprises Nb matrix and Nb-Al supersaturated solid solution
3al superconducting line presoma, Nb-Al supersaturated solid solution powder and the junction block being formed by Ta layer and Cu layer, as shown in Figure 3.The Nb that adopts the inventive method to prepare
3the composition of Al superconducting joint after diffusion heat treatments is from the inside to the outside: comprise Nb matrix and Nb
3the Nb of Al core
3al superconducting line, Nb
3al sintered body and the junction block being formed by Ta layer and Cu layer, as shown in Figure 4.
Superconducting joint of the present invention and preparation method will generate the Nb of superconduction after Nb-Al supersaturated solid solution sintering alloy powder
3al sintered body, the current path in superconducting joint is two: the radial propagation direction along conductor side is: Nb
3nb in Al superconducting line
3al core → Nb
3nb matrix → the Nb of Al superconducting line
3al sintering block → Nb
3nb matrix → the Nb of Al superconducting line
3nb in Al superconducting line
3al core; Current spread direction along wire termination is: Nb
3nb in Al superconducting line
3al core → Nb
3al sintering block → Nb
3nb in Al superconducting line
3al core, as shown in Figure 5.In the present invention, in current path, use Nb
3al sintering block has replaced Nb of the prior art
3sn layer and SnPbBi scolder, obviously Nb
3the superconduction critical electric current of Al material and critical back surface field are all than Nb
3sn and SnPbBi material are high, with Nb to be connected
3the critical performance of Al superconducting line is basically identical, has improved joint current carrying capacity and critical back surface field.And, the Nb that adopts sintering process to prepare
3al sintered material is and rapid heating and cooling quenching transformation method Nb
3the heat treatment process of Al superconducting line completes simultaneously, Nb
3al sintered material and Nb
3al superconducting line surface will produce metallurgical binding in heat treatment process, greatly reduce connection resistance.In Fig. 5, also show Nb of the present invention
3junction block one end closure in Al superconducting joint, the other end is uncovered, and tube wall is double-decker, and internal layer material is Ta, and skin is Cu; Nb
3the end of Al superconducting line is inclined-plane, Nb to be connected
3al superconducting line tries one's best, and the inclined-plane of these ends is face-to-face placement, or approximately places face-to-face.
Embodiment mono-:
Preparation Nb
3al superconducting joint.First pure Nb powder and pure Al powder are mixed according to the atomic quantity proportioning of 3:1, powder diameter is 20 microns, and mixed powder quality amounts to 200 grams; Pure Nb powder, pure Al powder and 5 grams, odium stearate powder and 3000 grams of agate material ball grinders of together putting into planetary ball mill of agate material abrading-ball are carried out to high-energy ball milling.Process During High Energy Ball Milling carries out in vacuum environment, and vacuum degree is better than 1 * 10-
2pa.Fig. 6 is for to prepare high-energy ball milling Nb by planetary type ball-milling mode
3the principle schematic of Al supersaturated solid solution powder.After ball milling, ball grinder is put into vacuum glove box, under vacuum environment, take out the Nb-Al over-saturation solid solution powder after ball milling, stored dry after Vacuum Package.Remove Nb
3the sheathing material of Al presoma superconducting line.In vacuum glove box, get the Nb of Nb-Al over-saturation solid solution powder and over-saturation solid solution state to be connected
3the end of Al presoma superconducting line is together packed in junction block, and the pre-compacted that powder is carried out, and pressure is 5MPa; Junction block is the tubing string shape of an end closure, and tube wall is double-decker, and internal layer material is pure Ta, and skin is pure Cu; By Nb
3the coil of Al presoma superconducting line coiling and junction block integral body are put into fast vacuum heat treatment furnace and are carried out vacuum heat, vacuum degree 1 * 10-
2pa, is first heated to 180 ℃ of insulations 2 hours, then is warmed up to 800 ℃ of heat treatment temperature points, 3 ℃ of temperature errors, and temperature retention time 80 hours, the powder docking in heat treatment process in head tube gives lasting external pressure; After heat treatment, control heat-treatment furnace temperature, with the cooling rate Slow coolings of 25 ℃/h, arrive room temperature, then open heat-treatment furnace; Prepare Nb
3al superconducting coil and Nb
3al superconducting joint.Whole Nb
3al superconducting joint preparation process is carried out in vacuum environment, and vacuum degree is better than 1 * 10-
2pa.
Superconducting joint in the present embodiment is column construction, and it is respectively from the inside to the outside: Nb to be connected
3al superconducting line, be wrapped in Nb
3the Nb of Al superconducting line exterior circumferential
3al sintering block, most external are to hold Nb
3al superconducting line and Nb
3the junction block of Al sintering block; Junction block one end closure, the other end is uncovered, and tube wall is double-decker, and internal layer material is Ta, and skin is Cu.Nb
3al sintering block is whole block material, and Nb
3al sintering block and Nb to be connected
3the interface cleaning of Al superconducting line end is pollution-free, and bonding state is metallurgical binding.The purity 99.99% of the tube wall internal layer Ta of junction block, thickness 1mm.The purity 99.999% of the outer Cu of tube wall of junction block, thickness 1mm.The length 40mm of junction block, the Nb in junction block
3al sintering block and Nb to be connected
3the connecting length 30mm of Al superconducting line.Nb
3the end of Al superconducting line is inclined-plane.
Embodiment bis-:
Preparation Nb
3al superconducting joint.First Nb-20at%Al alloy powder and pure Al powder are mixed, make the atomic quantity proportioning of Nb and Al in two kinds of powder reach 3:1.The particle diameter of two kinds of powder is 200 microns, and quality amounts to 200 grams; By Nb-20at%Al alloy powder with pure Al powder, carry out high-energy ball milling together with 5 grams, dispersant odium stearate powder and 3000 grams of agate material ball grinders of putting into stirring ball mill of agate material abrading-ball.Fig. 7 is for to prepare high-energy ball milling Nb by stirring-type ball milling method
3the principle schematic of Al supersaturated solid solution powder.After ball milling, ball grinder is put into vacuum glove box, take out the Nb-Al over-saturation solid solution powder after ball milling, stored dry after Vacuum Package.Remove Nb
3the sheathing material of Al presoma superconducting line.In vacuum glove box, get the Nb of Nb-Al over-saturation solid solution powder and over-saturation solid solution state to be connected
3the end of Al presoma superconducting line is together packed in junction block, and the pre-compacted that powder is carried out, and pressure is 20MPa; Junction block is the tubing string shape of an end closure, and tube wall is double-decker, and internal layer material is pure Ta, and skin is pure Cu; By Nb
3the coil of Al presoma superconducting line coiling and junction block integral body are put into fast vacuum heat treatment furnace and are carried out vacuum heat, vacuum degree 2 * 10-
3pa.First be heated to 180 ℃ of insulations 2 hours, then be warming up to 900 ℃, 3 ℃ of temperature errors, temperature retention time 10 hours, the powder docking in heat treatment process in head tube does not give external pressure; After heat treatment, slow cooling is opened heat-treatment furnace to room temperature; Prepare Nb
3al superconducting coil and Nb
3al superconducting joint.
Superconducting joint in the present embodiment is column construction, and it is respectively from the inside to the outside: Nb to be connected
3al superconducting line, be wrapped in Nb
3the Nb of Al superconducting line exterior circumferential
3al sintering block, most external are to hold Nb
3al superconducting line and Nb
3the junction block of Al sintering block; Junction block one end closure, the other end is uncovered, and tube wall is double-decker, and internal layer material is Ta, and skin is Cu.Nb
3al sintering block is whole block material, and Nb
3al sintering block and Nb to be connected
3the interface cleaning of Al superconducting line end is pollution-free, and bonding state is metallurgical binding.The purity 99.995% of the tube wall internal layer Ta of junction block, thickness 1mm.The purity 99.9995% of the outer Cu of tube wall of junction block, thickness 1mm.The length 50mm of junction block, the Nb in junction block
3al sintering block and Nb to be connected
3the connecting length 40mm of Al superconducting line.Nb
3the end of Al superconducting line is inclined-plane.
Embodiment tri-:
Preparation Nb
3al superconducting joint.First pure Nb powder and pure Al powder are mixed according to the atomic quantity proportioning of 3:1, powder diameter is 100 microns, and quality amounts to 200 grams; Pure Nb powder, pure Al powder and 5 grams, dispersant odium stearate powder and 3000 grams of corundum material ball grinders of together putting into oscillatory type ball mill of corundum material abrading-ball are carried out to high-energy ball milling.Fig. 8 is for to prepare high-energy ball milling Nb by oscillatory type ball milling method
3the principle schematic of Al supersaturated solid solution powder.After ball milling, ball grinder is put into vacuum glove box, take out the Nb-Al over-saturation solid solution powder after ball milling, stored dry after Vacuum Package.Remove Nb
3the sheathing material of Al presoma superconducting line.In vacuum glove box, get the Nb of Nb-Al over-saturation solid solution powder and over-saturation solid solution state to be connected
3the end of Al presoma superconducting line is together packed in junction block, and the pre-compacted that powder is carried out, and pressure is 10MPa; Junction block is the tubing string shape of an end closure, and tube wall is double-decker, and internal layer material is pure Ta, and skin is pure Cu; By Nb
3the coil of Al presoma superconducting line coiling and junction block integral body are put into fast heat-treatment furnace and are heat-treated, and heat-treating atmosphere is the argon gas that flows.First be heated to 180 ℃ of insulations 2 hours, then be warming up to 850 ℃, 3 ℃ of temperature errors, temperature retention time 50 hours, the powder docking in heat treatment process in head tube does not give external pressure; After heat treatment, slow cooling is opened heat-treatment furnace to room temperature; Prepare Nb
3al superconducting coil and Nb
3al superconducting joint.
Superconducting joint in the present embodiment is column construction, and it is respectively from the inside to the outside: Nb to be connected
3al superconducting line, be wrapped in Nb
3the Nb of Al superconducting line exterior circumferential
3al sintering block, most external are to hold Nb
3al superconducting line and Nb
3the junction block of Al sintering block; Junction block one end closure, the other end is uncovered, and tube wall is double-decker, and internal layer material is Ta, and skin is Cu.Nb
3al sintering block is whole block material, and Nb
3al sintering block and Nb to be connected
3the interface cleaning of Al superconducting line end is pollution-free, and bonding state is metallurgical binding.The purity 99.99% of the tube wall internal layer Ta of junction block, thickness 1mm.The purity 99.999% of the outer Cu of tube wall of junction block, thickness 1mm.The length 40mm of junction block, the Nb in junction block
3al sintering block and Nb to be connected
3the connecting length 30mm of Al superconducting line.Nb
3the end of Al superconducting line is inclined-plane.
Claims (9)
1. a Nb
3al superconducting joint preparation method, is characterized in that described preparation method's step is: choose the material powder that particle diameter is 20-200 micron, the component of described material powder comprises pure Nb and pure Al, and the atomic quantity proportioning of the Al in material powder and Nb is 3:1; Material powder is put into the grinding jar of agate or corundum ball material, put into the abrading-ball with the identical material of grinding jar simultaneously, and put into odium stearate powder as dispersant, carry out high-energy ball milling and be prepared into Nb-Al over-saturation solid solution alloy powder; Remove Nb
3the sheathing material of Al presoma superconducting line, then by the Nb of described Nb-Al over-saturation solid solution alloy powder and over-saturation solid solution state to be connected
3the end of Al superconducting line presoma is packed in junction block together, and powder is carried out to pre-compacted, and pressure limit is 5-20MPa; Subsequently by junction block together with Nb
3al superconducting line presoma is together heat-treated, and system of heat treatment process is: be first heated to 180 ℃ of insulations 2 hours, then be warming up to 800-900 ℃, insulation 10-80 hour, 3 ℃ of heat treatment temperature errors, control heat-treatment furnace temperature Slow cooling subsequently to room temperature, after heat treatment completes, make Nb
3al superconducting joint.
2. Nb according to claim 1
3al superconducting joint preparation method, is characterized in that in the component of described material powder, with Nb-Al alloy and the pure Nb of combination replacement of pure Al and the combination of pure Al.
3. Nb according to claim 1
3al superconducting joint preparation method, is characterized in that described high-energy ball milling is: planetary type ball-milling, stirring-type ball milling or oscillatory type ball milling.
4. Nb according to claim 1
3al superconducting joint preparation method, is characterized in that described heat treatment atmosphere is vacuum, and vacuum degree is better than 1 * 10
-2pa.
5. Nb according to claim 1
3al superconducting joint preparation method, is characterized in that described heat treatment atmosphere is slumpability gas.
6. Nb according to claim 5
3al superconducting joint preparation method, is characterized in that described slumpability gas is the argon gas that flows.
7. Nb according to claim 1
3al superconducting joint preparation method, is characterized in that the powder docking in head tube in described heat treatment process gives lasting external pressure.
8. Nb according to claim 1
3al superconducting joint preparation method, is characterized in that the powder docking in head tube in described heat treatment process does not apply external pressure.
9. Nb according to claim 1
3al superconducting joint preparation method, is characterized in that whole Nb
3al superconducting joint preparation process need to be carried out in vacuum environment, and vacuum degree is better than 1 * 10
-2pa.
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CN111262051A (en) * | 2020-03-13 | 2020-06-09 | 中国科学院电工研究所 | Nb of internal tin process3Sn superconducting wire joint and preparation method thereof |
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