JP2016164846A - Method for manufacturing oxide superconducting wire rod - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a superconducting wire rod that can suitably produce a superconducting wire rod having a configuration of a superconducting layer covered with a copper protective layer without deteriorating superconducting characteristics while achieving reduction in cost.SOLUTION: The method for manufacturing an oxide superconducting wire rod comprises a step of forming a superconducting layer on an intermediate layer formed on a tape-like substrate, a step of forming a silver stabilization layer on the superconducting layer and a step of forming a copper protective layer on the silver stabilization layer by impregnating a wire rod body 16 having the superconducting layer and the silver stabilization layer formed on a metal substrate in an aqueous solution 25 of copper sulfate in a state where the wire rod body is tensioned between a feed reel 31 and a taking-up reel by using a reel system of feeding from the feed reel 31 and taking up by the taking-up reel 32. The tension of the wire rod body 16 in the aqueous solution 25 during forming the copper protective layer is adjusted so that the tensile strain of the body is 0.6% or less.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for manufacturing an oxide superconducting wire, and in particular, an oxide superconducting wire is manufactured by covering a tape-shaped oxide superconducting wire body having a stabilization layer formed on the superconducting layer with a copper protective film. The present invention relates to a method for manufacturing an oxide superconducting wire.

Oxide superconductors are expected to be applied to superconducting magnets, superconducting cables, power equipment and devices because their critical temperature (Tc) exceeds liquid nitrogen temperature (77K), and many research results have been reported. ing. In order to apply the oxide superconductor to the above-mentioned field, a long wire having a high critical current density (Jc) and a high critical current (indicated by Ic, which means superconducting properties together with Jc) is manufactured. There is a need. On the other hand, in order to obtain a long wire, it is necessary to form an oxide superconductor on a metal tape from the viewpoint of strength and flexibility. Further, in order to be usable at a practical level equivalent to metal superconductors such as Nb ₃ Sn and Nb ₃ Al, a value of Ic of about 500 A / cm (77 K, in a self magnetic field) is required.

As a wire comprising an oxide superconductor satisfying these conditions, the REBa _y Cu ₃ O _z system (RE represents one or more elements selected from Y, Nd, Sm, Eu, Gd and Ho, and y ≦ 2 And z = 6.2 to 7 (hereinafter, also referred to as “RE system”).

  In this oxide superconducting wire (hereinafter also referred to as “superconducting wire”), since the superconductor crystal is biaxially oriented, the critical current (Ic) is higher than that of a well-known bismuth-based silver sheath wire. Excellent magnetic field characteristics at nitrogen temperature. As a result, the RE-based superconducting wire has an advantage that it can be used in a high temperature state by being applied to a superconducting device currently used at a low temperature near the liquid helium temperature.

  In the RE-based superconducting wire, an intermediate layer and a superconducting layer are sequentially formed on a substrate, and a stabilizing layer is formed on the superconducting layer using silver having high conductivity. In this configuration, in order to secure higher superconducting characteristics (critical current) Ic, it is known to increase the thickness of the stabilizing layer. However, since the material of the stabilizing layer is silver, Increasing the thickness of the chemical layer increases costs.

  Therefore, in the superconducting wire, in order to reduce the cost of the silver stabilization layer, the layer is formed by copper plating using copper, which is cheaper than silver, on the substrate laminated up to the silver stabilization layer. Thus, it is known to reduce the cost of the stabilization layer (see, for example, Patent Document 1).

  When a copper layer is formed by applying a copper plating process to a tape material having a superconducting layer, as shown in Patent Document 2, it is arranged in a copper plating tank between a reel for feeding out the tape material and a reel for winding, A copper layer is formed by using a so-called reel-to-reel method in which a tape material is passed through the copper plating tank.

Japanese Patent No. 4934155 Japanese Patent No. 5085931

  Thus, in the conventional manufacturing method of a superconducting wire having a copper layer, when forming a copper protective layer by a copper plating layer on a tape material to be a superconducting wire by a reel-to-reel method, a tape material spanned between reels If the tension (tensile stress) is too high, the tape material is stretched and damage such as cracks in the superconducting layer is derived, and the superconducting property Ic of the manufactured superconducting wire may be deteriorated.

  On the other hand, when the copper plating layer is formed, if the tension of the tape material spanned between the reels is too low, the tape material is loosened, the tape material transport speed is not constant, and the formed copper plating layer is unsatisfactory. It becomes uniform and the superconducting characteristic Ic of the superconducting wire to be manufactured deteriorates.

  Therefore, it is desired to produce a superconducting wire having excellent superconducting characteristics as a superconducting wire having a copper protective layer.

  The present invention has been made in view of the above points, and has a configuration in which a superconducting layer is coated with a copper protective layer, and can produce a superconducting wire that can be suitably manufactured without degrading superconducting characteristics while reducing costs. It aims to provide a method.

  One aspect of the method for producing an oxide superconducting wire of the present invention includes a step of forming a superconducting layer on an intermediate layer formed on a tape-like substrate, and a step of forming a silver stabilizing layer on the superconducting layer. And using a reel system in which the substrate on which the superconducting layer and the silver stabilizing layer are formed is supplied from a supply reel and taken up by a take-up reel, between the supply reel and the take-up reel Dipping in an aqueous solution for forming a copper protective layer in a stretched state and forming a copper protective layer on the silver stabilizing layer, and in the aqueous solution when forming the copper protective layer The tension of the substrate was such that the tensile strain of the substrate was 0.6% or less.

  ADVANTAGE OF THE INVENTION According to this invention, the oxide superconducting wire which has the structure which coat | covered the superconducting layer with the copper protective layer can be manufactured suitably, without reducing superconducting property, aiming at cost reduction.

Schematic which shows the cross section perpendicular | vertical to the axial direction of the tape of the oxide superconducting wire manufactured with the manufacturing method of the oxide superconducting wire of one embodiment which concerns on this invention The flowchart with which it uses for description of the manufacturing method of the superconducting wire which concerns on one embodiment of this invention The figure which shows the process of copper protective layer formation typically Diagram for explaining copper plating formation process The figure which shows the relationship between the tensile strain of a superconducting wire main body, and the change of the superconducting characteristic of an oxide superconducting wire using this superconducting wire main body The figure which shows an example of the characteristic of a wire

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  First, an example of an oxide superconducting wire manufactured by the method for manufacturing an oxide superconducting wire according to the present embodiment will be described.

<Oxide superconducting wire>
FIG. 1 is a schematic view showing a cross section perpendicular to the axial direction of a tape of an oxide superconducting wire manufactured by the method of manufacturing an oxide superconducting wire according to one embodiment of the present invention.

  An oxide superconducting wire (hereinafter referred to as “superconducting wire”) 10 includes, for example, an intermediate layer 12, an oxide superconducting layer (hereinafter referred to as “superconducting layer”) 13, and silver stabilization on a tape-like metal substrate 11. The wire body 16 formed by sequentially laminating the layers 14 is covered with a copper protective layer 15. Thereby, the superconducting wire 10 has a tape shape and is flexible. The wire body 16 is a substrate 11 on which the superconducting layer 13 and the silver stabilizing layer 14 are formed, and corresponds to the substrate in an aqueous solution when the copper protective layer 15 is formed.

  For the metal substrate 11, metals such as Cu, Ni, Ti, Mo, Nb, Ta, W, Mn, Fe, and Ag, which are excellent in strength and heat resistance, or alloys thereof can be used. For example, as the metal substrate 11, Ni or Ni-based alloy containing one or more kinds of additive elements selected from W, Mo, Cr, Fe, Co, V, and Mn is used. Further, when the metal substrate 11 is a metal substrate after a strong rolling process, any one kind of refractory metal selected from Ni-based alloy and stainless steel, Hastelloy (registered trademark), Inconel (registered trademark), and nichrome is laminated. It is also possible to use a composite substrate. Specifically, the metal substrate 11 is made of Ni—Cr (specifically, Ni—Cr—Fe—Mo based Hastelloy (registered trademark) B, C, X, etc.), W—Mo, Fe—Cr. A low magnetic crystal grain non-oriented heat-resistant high-strength metal substrate typified by a material such as an austenitic stainless steel (for example, austenitic stainless steel) or a Fe-Ni based material (for example, a nonmagnetic composition-based material). desirable. The thickness of the metal substrate 11 is 0.1 mm or less, for example.

For example, the intermediate layer 12 has a first intermediate layer (diffusion prevention layer) for preventing diffusion of elements from the metal substrate 11 to reach the superconducting layer 13, and orients crystals of the superconducting layer 13 in a certain direction. A plurality of intermediate layers, such as a second intermediate layer (alignment layer). The intermediate layer 12 may be composed of any number of layers including one or more layers. For example, the intermediate layer 12 is formed on the metal substrate 11 by an aluminum oxide (Al ₂ O ₃ ) layer, a gallium-doped zinc oxide layer (Gd ₂ Zr ₂ O ₇ : GZO), a yttrium-stabilized zirconia (YSZ), or the like. One layer, a _second layer that is a layer such as Y ₂ O ₃ or LaMnO _{3, a third} layer that is composed of magnesium oxide (MgO), a fourth layer that is a layer such as lanthanum manganese oxide (LaMnO ₃ ), cerium oxide ( The fifth layer, which is a CeO ₂ ) layer, is laminated in order. The first layer and the second layer are formed by a sputtering method. Further, a MgO layer (third layer) is formed by ion beam assisted deposition (IBAD), a LaMnO ₃ layer (fourth layer) thereon is formed by sputtering, A CeO ₂ layer (fifth layer) thereon may be formed by sputtering (or PLD). In addition, the thickness of each layer (1-5 layers) which comprises the intermediate | middle layer 12 is about 1000 [nm], for example.

Superconducting layer 13 is, for example REBa _y Cu ₃ O _z based superconductor (RE is, Y, Nd, Sm, Eu , Gd, Tb, Dy, Ho, Er, 1 or 2 or more selected from Tm and Yb It is a rare earth element and is composed of an oxide superconductor such as y ≦ 2 and z = 6.2 to 7). The RE superconductor is typically an yttrium superconductor represented by YBa ₂ Cu ₃ O ₇ . The superconducting layer 13 is formed by metal-organic deposition (MOD), pulsed laser deposition (PLD), sputtering, or metal organic chemical vapor deposition (MOCVD). Vapor Deposition) can be applied.

  Here, the superconducting layer 13 is formed by using the MOD method. In the MOD method, an amorphous active precursor is formed on a substrate surface using an organometallic compound as a raw material, and this is heat-treated and crystallized to form a superconducting layer. In this MOD method, an oxide superconducting layer can be continuously formed on a long substrate even in a non-vacuum state, so that the process is simpler and lower in cost than a vapor phase method such as a PLD method or a CVD method. .

In the superconducting layer 13, it is preferable that 50 [nm] or less oxide particles containing at least one of Zr, Sn, Ce, Ti, Hf, and Nb are dispersed as magnetic flux pinning points. In this case, as a method for forming the superconducting layer 13, a TFA-MOD method using trifluoroacetate (TFA) is suitable. For example, a zirconium (Zr) -containing naphthenate having a high affinity with Ba is mixed in a barium (Ba) solution containing TFA, whereby an oxide containing Zr is added to the superconducting layer 13 made of an RE-based superconductor. Particles (BaZrO ₃ ) can be dispersed as magnetic flux pinning points. A known technique can be applied to the method of dispersing the magnetic flux pinning points in the superconducting layer 13 (for example, JP 2012-059468 A). By dispersing the magnetic flux pinning points in the superconducting layer 13, even if the superconducting wire 10 is used in a curved state, it is hardly affected by the magnetic field and exhibits stable superconducting characteristics.

  The silver stabilizing layer 14 is formed immediately above the superconducting layer 13 and mainly protects the superconducting layer 13 from moisture and the like. In addition, when the superconducting state is partially broken and a resistance is generated (normal conducting transition), a current is supplied. Detour. The silver stabilizing layer 14 is preferably made of a material having low electrical resistivity and high thermal conductivity, and is made of silver (Ag) or a silver alloy. For the film formation of the silver stabilizing layer 14, for example, a sputtering method can be applied. The thickness of the silver stabilization layer 14 is 1-30 [micrometers] here.

  The copper protective layer 15 is formed on the silver stabilizing layer 14, and the cost can be reduced compared to using silver for forming the silver stabilizing layer 14. Here, the copper protective layer 15 is provided on the silver stabilizing layer 14 by covering the periphery of the wire main body 16. The copper protective layer 15 is formed on the wire body 16 using, for example, an electroplating method such as a plating method. The thickness of the wire main body 16, that is, the thickness from the bottom surface of the metal substrate 11 to the surface of the silver stabilizing layer 14 when forming the copper protective layer 15 is set to 50 to 130 μm.

<Outline of manufacturing method of superconducting wire according to this embodiment>
FIG. 2 is a flowchart for explaining a method of manufacturing a superconducting wire according to an embodiment of the present invention.

As shown in FIG. 2, in the method of manufacturing the superconducting wire 10 (see FIG. 1), the intermediate layer 12 is formed on the metal substrate 11 in step S1. Here, the intermediate layer 12 is formed of a plurality of layers. For example, an Al ₂ O ₃ layer and a LaMnO ₃ film are formed on the metal substrate 11 by a sputtering method, and an IBAD (Ion Beam Assisted Deposition) is formed on the LaMnO ₃ layer. ) Method to form an MgO layer. Next, a LaMnO ₃ layer is formed on the MgO layer by a sputtering method, and a CeO ₂ layer is formed on the LaMnO ₃ layer by a sputtering method. The intermediate layer 12 is formed by sequentially forming these layers.

  In step S2, the superconducting layer 13 is formed by the MOD method on the intermediate layer 12 formed on the tape-shaped metal substrate 11, here on the tape-shaped base material formed by forming the intermediate layer 12 on the metal substrate 11. To do. In the MOD method, first, a tape-like base material formed by forming an intermediate layer 12 on a metal substrate 11 is immersed in a superconducting raw material solution (a solution in which an organic metal salt is dissolved in an organic solvent) and pulled up ( The superconducting raw material solution is attached to the surface of the base material, that is, the surface of the intermediate layer 12 by a so-called dip coating method, and pre-baked in a pre-baking furnace. And a superconducting precursor is formed by repeating these processes (dip coating and temporary baking) as appropriate. Next, in the main baking furnace, main baking is performed on the superconducting precursor on the substrate to form an oxide superconducting layer (superconducting layer 13). In addition, each process such as dip coating, pre-baking, and main baking is performed in a device that performs each process (for example, a container storing a superconducting raw material solution, a pre-baking furnace, and a main baking furnace) from a delivery reel to a take-up reel. It is desirable to carry out by passing the base material sent to.

  In step S3, the silver stabilizing layer 14 is formed on the superconducting layer 13 by sputtering. As a result, a wire main body (a substrate on which the superconducting layer 13 and the silver stabilizing layer 14 are formed) 16 (which is formed by sequentially laminating the intermediate layer 12, the superconducting layer 13, and the silver stabilizing layer 14 on the metal substrate 11) ( 1) is formed.

In step S <b> 4, the copper protective layer 15 is formed on the silver stabilizing layer 14 in the wire body 16. Thereby, the superconducting wire 10 is manufactured.
Here, the process of forming the copper protective layer in step S4 of FIG. 2 will be described in detail.

  FIG. 3 is a diagram schematically showing a process of forming a copper protective layer.

  The copper protective layer 15 (see FIG. 1) is formed on the wire body 16 (specifically, the silver stabilizing layer 14 in detail) in Step S4 after the wire body 16 is formed through Step S3. Here, the copper protective layer 15 is formed on the silver stabilizing layer 14 by forming the copper protective layer 15 around the wire body 16 (see FIG. 1).

  The copper protective layer forming step (corresponding to the step S4 in FIG. 2) is performed on the silver stabilizing layer 14 of the wire body 16 using the water washing part 21 and the plating part 22 as shown in FIG. 15 and a finishing step of cleaning and drying using the water washing part 23 and the drying part 24 after the copper protective layer 15 is formed.

  The copper plating process and the finishing process are performed by the copper protective layer forming apparatus 20 having the water washing part 21, the plating part 22, the water washing part 23, and the drying part 24. In addition, this copper protective layer forming apparatus 20 is included in a manufacturing system for manufacturing an oxide superconducting wire.

  The wire body 16 is wound around a supply reel 31, supplied from the supply reel 31 to the copper protective layer forming apparatus 20, and after the copper protective layer is formed by the copper protective layer forming apparatus 20, the take-up reel 32. It is wound up by.

  Specifically, in the copper protective layer forming step, the wire main body 16 delivered from the supply reel 31 is passed through the washing unit 21, the plating unit 22, the washing unit 23, and the drying unit 24, and taken up by the take-up reel 32. Reel method is used. That is, the wire main body 16 that passes through the plating unit 22, the water washing unit 23, and the drying unit 24 is taken up by the take-up reel 32 and is conveyed into the units 21 to 24.

  The washing unit 21 cleans the wire main body 16 (the metal substrate 11 after the superconducting layer 13 and the silver stabilizing layer 14 are formed) supplied from the supply reel 31.

  Here, the rinsing section 21 has a rinsing tank for storing washing water (ion exchange water), and the wire main body 16 is introduced into and passed through the rinsing tank, thereby washing the silver main body 16 and silver. The foreign matter adhering to the surface of the stabilization layer 14 is washed away.

  The plating part 22 forms the copper protective layer 15 by adhering copper to the wire main body 16 supplied from the water washing part 21, and the wire main body 16 on which the copper protective layer 15 is formed has the turn guide part 33. Then, the direction of conveyance is folded back and supplied to the washing unit 23.

  The washing section 23 has a washing tank for storing washing water (ion exchange water), and the wire protection body 15 formed with the copper protection layer 15 is introduced into and passed through the washing tank. The outer surface of 15 is washed, and the foreign matter adhering to the outer surface is washed away.

  The drying unit 24 dries and dries moisture adhering to the wire main body 16 with the copper protective layer conveyed from the washing tank of the washing unit 23. The drying unit 24 removes and removes moisture, for example, by blowing air to the wire main body 16 with the copper protective layer. The air is preferably either dry air or clean dry air. Moreover, you may make it dry the wire main body 16 with a copper protective layer by heating with a heater. Specifically, it dries by passing the wire main body 16 with a copper protective layer through a drying chamber in which a heater is disposed. The superconducting wire formed by drying is taken up by the take-up reel 32.

  FIG. 4 is a diagram for explaining the copper plating process, and is a diagram showing an outline of the plating tank of the plating unit 22.

  In the plating part 22, the copper protective layer 15 is formed by using an electroplating method. The plating unit 22 includes a plating tank 221 that stores an aqueous solution 25 for forming a copper protective layer, and a tension adjusting unit 26 that adjusts the tension of the wire body 16 immersed in the plating tank 221.

  In the plating tank 221, the wire main body 16 conveyed from the water washing tank (not shown) of the water washing section 21 is carried in from one side surface by the operation of the winding reel 32 rotating and winding the wire main body 16, and the copper layer It is immersed in the aqueous solution 25 for formation and carried out from the other side. The aqueous solution 25 for forming the copper layer is, for example, a copper sulfate solution containing copper sulfate and sulfuric acid.

  A copper anode 28 is immersed in the plating tank 221 together with the wire main body 16, and current can be supplied to these from an external power source. The wire main body 16 functions as a cathode in the aqueous solution (copper sulfate solution) 25 in the plating tank 221.

  Thus, in the plating part 22, in the plating tank in which the aqueous solution 25 is stored, the wire body 16 introduced from the water washing part 21 is used as a cathode, soaked in the aqueous solution 25 together with the copper anode 28, and direct current is supplied from the external DC power source. Apply. As a result, the copper protective layer 15 is formed on the surface of the wire body 16 by the cathode reaction. The aqueous solution 25 in the plating tank 221 overflows (see the flow portion 25a) into the liquid receiver 224 provided around the plating tank 221 (for example, front and rear). The aqueous solution 25 recovered in the liquid receiver 224 by overflowing is returned again to the aqueous solution 25 in the plating tank 221 by the pump 27 connected to the liquid receiver 224.

  The tension adjusting unit 26 adjusts the tension of the wire main body 16 immersed in the aqueous solution 25 when the copper protective layer 15 is formed, that is, in a state of being stretched between the supply reel 31 and the take-up reel 32. To do. Here, the tension adjusting unit 26 restricts the movement of the wire main body 16 conveyed to the plating tank 221 by pressing the tape-shaped wire main body 16 in front of the plating tank 221 and being wound by the take-up reel 32. As a result, the stretched state when the wire body 16 stretched between the supply reel 31 and the take-up reel 32 (ie, stretched in a tensioned state) moves in the plating tank 221 is adjusted. To do.

  For example, the tension adjusting unit 26 is disposed on the upstream side of the plating tank 221 and includes a pair of rollers 261 (rollers 261a and 261b) that sandwich the wire body 16 and the rotation direction of one roller 261a of the pair of rollers 261. When the load is applied to the wire body 16, the moving speed of the wire main body 16 sent to the plating tank 221 via the roller pair 261 is regulated. One roller 261a of the roller pair 261 is configured to be rotatable by a motor (not shown), and the movement of the wire main body 16 in the conveying direction is regulated by the motor via a drive unit 264 that controls the rotation of the motor. So that the current is supplied. As a result, the wire main body 16 in the plating tank 221 is fixed on one end side by the tension adjusting unit 26 and pulled in the transport direction on the other end side, that is, pulled in the directions of arrows T1 and T2 at both ends. In this state, a tensile load is applied and tension is generated. Since the other end side of the wire main body 16 is pulled in the transport direction with a constant force by the take-up reel 32, the tension adjusting unit 26 adjusts the movement of the wire main body 16 in the transport direction to perform plating. The tension | tensile_strength of the wire main body 16 in the tank 221 can be adjusted.

  In the plating unit 22, the tension adjusting unit 26 sets the tension of the wire main body 16 when forming the copper protective layer, that is, a predetermined tension applied to the wire main body 16 when the wire main body 16 is immersed in the plating tank 221. adjust.

  In other words, in the plated portion 22, the copper protective layer 15 is formed in a state where the wire main body 16 is tensioned with a predetermined tension.

  The predetermined tension of the wire main body 16 during the formation of the copper protective layer (in the plating tank) is set based on the change in the superconducting property Ic due to the tensile strain of the wire main body 16. Tensile strain is the percentage of the wire body that is stretched and distorted when pulled in the longitudinal direction, (total length when stretched and distorted-total length before being pulled) / total length before being pulled × 100. Indicated by

  FIG. 5 shows the relationship between the tensile strain% of the wire body 16 and the change in the superconducting characteristics of the superconducting wire using this wire body 16. In FIG. 5, two types of wire rods having different superconducting characteristics Ic (wire rod A is indicated by a “◯” graph and wire rod B is indicated by a “■” graph) are used as the wire rod main body. Wires A and B are different from each other only in the thickness of the superconducting layer, and the other configurations are similarly configured. For example, Ic = 130A of the wire A and Ic = 125A of the wire B are set. Further, the horizontal axis in FIG. 5 indicates the tensile strain% of the wire body, and the vertical axis indicates the Ic maintenance rate. Here, the Ic maintenance rate is determined by releasing the tensile tension after the occurrence of each strain due to the tensile force. Is the value (Ic / Ic0) divided by Ic (≡Ic0) before applying the tensile force. That is, the Ic retention rate is a critical current at 0 T in a superconducting wire (critical current under a self magnetic field): Ic0 (= Ic @ 0T), and a critical current at an applied magnetic field (here, a parallel magnetic field) in the superconducting wire Ratio with Ic: Ic / Ic0.

  As indicated by each of the wire A “◯” and the wire B “■” in FIG. 5, when the tension of each wire body 16 exceeds the tensile strain 0.7% of the wire body 16, the superconducting characteristics (Ic) The maintenance rate deteriorates. If the tensile strain is 0.6% or less, the superconducting characteristics (Ic retention rate) are hardly deteriorated. The tension applied to the wire body 16 is preferably such that the tensile strain of the wire body 16 is 0.5% or less.

In addition, when the tension of the wire body 16 is too small, for example, when the tension is less than the lower limit value 0.02 kN, the reel-to-reel method cannot transfer the wire body 16 at a uniform speed as described above, and the wire body 16 The variation in film thickness in the longitudinal direction and the width direction of the copper protective layer 15 formed on the substrate increases. In addition, since the wire main body 16 is loosened in the plating tank, the wire main body 16 is liable to be displaced from an electrode (copper anode 28 shown in FIG. 4) for applying a direct current to the wire main body 16 or to be kinked.
Therefore, the predetermined tension (the tension of the substrate 11 in the aqueous solution when forming the copper protective layer 15) generated in the wire main body 16 by receiving the tensile load from the tension adjusting unit 26 is uniform in the wire main body 16. The tension is 0.02 kN or more, which corresponds to the lower limit value conveyed at the speed, and the tensile strain of the wire body 16 is 0.6% or less. In addition, the relationship between the tension including the lower limit 0.02 kN of the tension with respect to the wire main body 16 and the tensile strain% of the wire main body 16 will be described in an example described later.

  Thus, the wire main body 16 in which the copper protective layer is formed in the plating tank of the plating part 22 is taken up by the take-up reel 32 via the turn guide part 33, the water washing part 23, and the drying part 24.

Thereby, the copper protective layer 15 with a more uniform thickness can be suitably formed on the wire body 16. Further, the superconducting wire 10 is formed by covering the wire body 16 with the copper protective layer 15. Thus, a stabilization layer having a predetermined thickness (for example, a film thickness of several tens of μm) necessary for manufacturing a superconducting wire having a high superconducting characteristic Ic is not entirely silver but partly made of copper instead of silver. Thus, it is possible to form a highly conductive stabilization layer in which the material cost is reduced.
Therefore, the oxide superconducting wire 10 having a configuration in which the superconducting layer 13 is covered with the copper protective layer 15 can be suitably manufactured without deteriorating the superconducting characteristics while reducing the cost.

Using wire rods A and B that become wire rod main bodies (substrates on which a superconducting layer and a silver stabilizing layer are formed) 16 having an SS curve shown in FIG. 6, the manufacturing method shown in FIG. The superconducting wire 10 having the configuration was manufactured. FIG. 6 is a diagram showing an example of the characteristics of the wire rods, showing the SS curves of the wire rods A and B used in FIG. The relationship of tensile strain (%) of the main body is shown.
Wires A and B are wires having a length of 10 m, a width of 5 mm, and a thickness of 100 μm, respectively, and the superconducting characteristics Ic are different due to the different thicknesses of the superconducting layer 13. The superconducting property Ic of the wire A is 130A, and the superconducting property Ic of the wire B is 125A. Moreover, the aqueous solution of the plating tank 221 is made into a copper sulfate solution, and the plating part 22 performs the plating process (copper protective layer formation) by moving the wire body 16 within the plating tank 221 at 20 A, 0.5 m / min. A copper protective layer 15 having a thickness of 20 μm was formed on the wire body. Thus, when manufacturing the superconducting wire 10, as shown in Examples 1-5 and Comparative Example 1, the superconducting wire 10 is manufactured by changing the tension of the wire body 16 (that is, changing the tension to the wire). did.

In Examples 1 to 3, the wire A was used, and tensions of 0.48 kN, 0.06 kN, and 0.3 kN were applied thereto to form a copper protective layer under the above conditions. In Examples 4 and 5, the wire B was used, and tensions of 0.38 kN and 0.06 kN were applied thereto to form a copper protective layer under the above conditions.
In Comparative Examples 1 and 2, a wire A is used, and a copper protective layer is formed under the above conditions by applying tensions of 0.6 kN and 0.01 kN. In Comparative Example 3, a wire B is used and tension is applied thereto. A copper protective layer was formed under the above conditions by applying 0.5 kN. In Comparative Example 4, the wire B was used, a tension of 0.01 kN was applied thereto, and a copper protective layer was formed under the above conditions.

  Table 1 shows the copper plating thickness (thickness of the copper protective layer) of the superconducting wires manufactured in Examples 1 to 5 and Comparative Examples 1 to 4, and the superconducting characteristics Ic of the wire main body measured after applying the tension. “Strain” in Table 1 is the tensile strain of the wires A and B as the wire body, and “Ic” is after applying tension (corresponding to the tensile load on the wire) to the wires A and B as the wire body. The superconducting properties of are shown. In addition, regarding the determination of the change in the film thickness of the copper protective layer in the examples, it was determined that the target film thickness was within the range of ± 1 μm, which was an acceptable range, and was determined to be a uniform film thickness (shown as “uniform” in Table 1). .

  As shown in FIG. 6 and the results of Examples 1 to 5 and Comparative Examples 1 to 4, when the tensile strain of the wires A and B is 0.75 (that is, 0.75 or more), the elastic deformation is changed to plastic deformation. The superconducting property Ic decreases rapidly.

  In addition, the tension applied to the wire main body (the substrate in the aqueous solution when forming the copper protective layer and the substrate on which the superconducting layer and the silver stabilizing layer are formed) 16 during the formation of the copper protective layer is 0.01 kN. (That is, 0.01 kN or less), although the superconducting characteristics to be manufactured are not deteriorated, the thickness of the copper protective layer is not uniform. At this time, the wire main body 16 is likely to be displaced from the electrode (copper anode 28 shown in FIG. 4) for applying a direct current to the wire main body 16, and kinks are likely to occur. This is a value of less than 0.02 kN, where 0.01 kN corresponds to the lower limit value of a predetermined tension generated in the wire body 16 (a substrate on which a superconducting layer and a silver stabilizing layer are formed, mainly a tension of a metal substrate). Because. It corresponds to the lower limit 0.02 kN of the tension (the tension of the wire body) to the wire body 16 where the kink does not occur without the wire body 16 being displaced from the electrode to which direct current is applied (copper anode 28 shown in FIG. 4). The tensile strain% is 0.05%.

  In consideration of these, the tension of the wire main body 16 (mainly the metal substrate on which the superconducting layer and the silver stabilizing layer are formed, mainly the metal substrate) when forming the copper protective layer is the wire main body (mainly the metal substrate 11). ) It is preferable that the tensile strain of 16 is 0.05% or more and 0.6% or less, preferably 0.5% or less.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The embodiment of the present invention has been described above. The above description is an illustration of a preferred embodiment of the present invention, and the scope of the present invention is not limited to this. That is, the description of the configuration of the apparatus and the shape of each part is an example, and it is obvious that various modifications and additions to these examples are possible within the scope of the present invention.

  The method for producing an oxide superconducting wire according to the present invention includes an oxide having a structure in which a superconducting layer is covered with a copper protective layer by suitably forming a copper protective layer on a silver stabilizing layer formed on the superconducting layer. It has the effect of being able to manufacture a superconducting wire material suitably without deteriorating superconducting properties while reducing costs, and is useful for the production of a long tape-shaped oxide superconducting wire.

10 Superconducting wire 11 Metal substrate (substrate)
DESCRIPTION OF SYMBOLS 12 Intermediate | middle layer 13 Superconducting layer 14 Silver stabilization layer 15 Copper protective layer 16 Wire body 20 Copper protective layer formation apparatus 21, 23 Flushing part 22 Plating part 24 Drying part 25 Aqueous solution 26 Tension adjustment part 27 Pump 31 Supply reel 32 Take-up reel 33 Turn guide part 221 Plating tank 224 Liquid receiver 261 Roller pair 264 Drive part

Claims (5)

Forming a superconducting layer on an intermediate layer formed on a tape-shaped substrate;
Forming a silver stabilizing layer on the superconducting layer;
The substrate on which the superconducting layer and the silver stabilizing layer are formed is stretched between the supply reel and the take-up reel using a reel method in which the substrate is supplied from a supply reel and taken up by a take-up reel. And a step of immersing in an aqueous solution for forming a copper protective layer to form a copper protective layer on the silver stabilizing layer,
The tension of the substrate in the aqueous solution when forming the copper protective layer is a tension at which the tensile strain of the substrate is 0.6% or less.
The manufacturing method of the oxide superconducting wire characterized by the above-mentioned. The tension of the substrate in the aqueous solution when forming the copper stabilization layer is a tension that makes the tensile strain of the substrate 0.05% or more.
The method for producing an oxide superconducting wire according to claim 1. Nickel or nickel alloy is used for the substrate.
The method for producing an oxide superconducting wire according to claim 1 or 2. For the substrate, a metal material of Hastelloy (registered trademark), Inconel (registered trademark) or stainless steel is used.
The method for producing an oxide superconducting wire according to claim 1 or 2. The thickness from the bottom surface of the substrate to the surface of the silver stabilizing layer when forming the copper protective layer is 50 to 130 μm.
The manufacturing method of the oxide superconducting wire as described in any one of Claim 1 to 4 characterized by the above-mentioned.

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