JP5695431B2 - Manufacturing method of oxide superconducting wire - Google Patents

Description

The present invention relates to the production how of the oxide superconducting wire of a laminated structure having an intermediate layer and the oxide superconducting layer and a stabilizing layer on a metal substrate.

The RE-123 oxide superconductor (REBa ₂ Cu ₃ O _7-X : RE is a rare earth element including Y) exhibits superconductivity at a liquid nitrogen temperature and has low current loss. Application development has been made as a conductor for coils. As an example of a method for processing this oxide superconductor into a wire, a metal having a high strength, heat resistance, and easy to process into a wire is processed into a long tape, and this metal base tape A technique for forming an oxide superconducting layer thereon is provided.

  In addition, since the oxide superconductor crystals have electrical anisotropy, it is necessary to control the crystal orientation when forming the oxide superconducting layer on the base tape. A technique for laminating an oxide superconducting layer on a base material via an intermediate layer has been implemented. As an example of a technique using this intermediate layer, an ion beam assisted film formation method (IBAD method: Ion Beam Assisted Deposition) is known, and an intermediate layer exhibiting high biaxial orientation by this IBAD method is formed on a substrate. An oxide superconducting conductor having excellent superconducting properties can be obtained by forming an oxide superconducting layer on the intermediate layer.

  In order to obtain the target line width in this kind of oxide superconductor, prepare a base tape of the target line width from the start of production, and then form an intermediate layer and an oxide superconducting layer thereon, An oxide superconducting conductor is manufactured by forming a stabilizing layer, or a base tape having a certain line width is prepared in advance, and an intermediate layer and an oxide superconducting layer are formed thereon, and the stabilizing layer is formed. Research has been made on a method of forming a superconducting oxide to form an oxide superconducting conductor and then cutting it to have a desired line width. In addition, considering the ease of manufacturing and the ability to handle various line widths among these manufacturing methods, an oxide superconducting conductor is prepared in advance with a constant line width, and then cut to the target line width. It is considered that the method of using an oxide superconducting wire is advantageous in terms of production efficiency.

Conventionally, as an example of a method for cutting an oxide superconductor, using a cutter bit having a plurality of sets of two cutting portions, the tape-shaped oxide superconducting conductor is mechanically sandwiched by the cutting edge of the cutting portion of the cutter bit, A method of cutting a plurality of oxide superconducting wires along the width direction of the oxide superconducting conductor has been proposed. (See Patent Document 1)
In addition, in the tape-shaped oxide superconducting conductor provided with the metal substrate, the intermediate layer, the oxide superconducting layer, and the first silver stabilizing layer, after slitting the superconducting conductor on which the first silver stabilizing layer is formed, A method for producing an oxide superconducting wire by forming a second silver stabilizing layer by electroplating to protect the oxide superconducting layer is disclosed. (See Patent Document 2)

JP 2007-287629 A JP 2010-176892 A

In the conventional method for manufacturing an oxide superconducting wire, when the oxide superconducting conductor is mechanically cut using a cutter tool having a cutting portion as described in Patent Document 1, the oxide superconducting conductor has a laminated structure. Therefore, there is a problem that there is a high possibility that the oxide superconducting layer is peeled or deformed in the vicinity of the cut surface and the superconducting property is deteriorated. Thus, the part where peeling has occurred in the oxide superconducting layer becomes a part that is easily peeled off after cutting, and there is a problem that the peeling strength is lowered.
Further, in the method of forming a second silver stabilizing layer by electroplating after slitting an oxide superconductor as described in Patent Document 2, it is necessary to form the second silver stabilizing layer after slitting And the process of forming the second silver stabilizing layer is increased, which increases the cost.
Furthermore, some of the RE-123 type oxide superconducting layer compositions tend to deteriorate the superconducting characteristics when exposed to an atmosphere containing moisture for a long time. Protecting the layer from moisture is also an important issue.

  The present invention has been made in view of the above-described conventional situation. The oxide superconducting conductor is melted by a laser beam to obtain a plurality of oxide superconducting wires, and the oxide superconducting layer is covered at the time of the melting. An object of the present invention is to provide a method for producing an oxide superconducting wire capable of forming a protective layer at the same time, and an oxide superconducting wire obtained.

In order to solve the above problems, the present invention provides an oxide superconducting conductor comprising a tape-shaped substrate, an intermediate layer provided on the substrate, an oxide superconducting layer, and a silver stabilizing layer. The laser beam is irradiated from the outside on the stabilization layer forming side along the length direction of the base material, and the stabilization layer, the oxide superconducting layer, the intermediate layer, and the base material are blown out to thereby oxidize the oxidation layer. When manufacturing a plurality of oxide superconducting wires by dividing an object superconducting conductor in its width direction, by blowing the shielding gas to the fusing point, fusing the stabilizing layer, the oxide superconducting layer, the intermediate layer, and the base material In the step of forming the protective layer by extending the melted solidified body of the stabilization layer in the direction of jetting the shield gas so as to cover the melted portion of the oxide superconducting layer edge and the melted portion of the intermediate layer edge Before the laser beam through the injection nozzle Irradiating the oxide superconductor and blowing the shield gas from the injection nozzle in the thickness direction of the oxide superconductor, and fusing the oxide superconductor while covering the laser beam fusing position with the shield gas In this case, the spray pressure of the shield gas is adjusted to extend the melted portion of the stabilization layer in the flow direction of the shield gas, and is deposited on the melt cross-sectional portion of the intermediate layer and the oxide superconducting layer. The protective layer is formed on the edge portion of the stabilization layer over the entire length of the oxide superconducting wire .
According to the present invention, a plurality of oxide superconducting conductors having a desired width and having a structure in which the melted portion of the oxide superconducting layer and the melted portion of the intermediate layer are covered with the molten solidified body of the silver stabilizing layer. The oxide superconducting wire can be manufactured. In the case of an oxide superconducting wire having this structure, the melted portion of the oxide superconducting layer is covered with a protective layer made of a molten solidified body of the silver stabilizing layer, so that moisture can penetrate into the inside of the oxide superconducting wire. Can be prevented. Therefore, even when the oxide superconducting wire is used for a long time in an atmosphere with a lot of moisture, it is possible to provide an oxide superconducting wire in which the superconducting characteristics are not deteriorated by the ingress of moisture. In addition, since the oxide superconductor is blown while spraying the shielding gas, the oxide superconductor can be cut while preventing the melted portion from being oxidized, and an oxide superconducting wire in a state where the melted portion is not oxidized is obtained. be able to.

  ADVANTAGE OF THE INVENTION According to this invention, the oxide superconducting wire which does not have a possibility of moisture permeation of the structure which covered the fusing part of the base material by the laser beam with the protective layer which consists of a molten solidified body of a silver stabilization layer can be provided.

FIG. 1 is an explanatory diagram showing an example of a state in which an oxide superconducting conductor is melted by a continuous wave laser using a fiber laser device. Schematic which shows the whole structure of the fiber laser apparatus shown in FIG. FIG. 3 shows an oxide superconducting conductor fused by the fiber laser device shown in FIG. 1, FIG. 3 (a) is a perspective view showing an example structure of the oxide superconducting conductor before fusing, and FIG. 3 (b) is after fusing. The perspective view which shows an example structure of an oxide superconducting wire. FIG. 4A is a perspective view showing a state in which an insulating coating with an insulating tape is formed on the oxide superconducting wire after fusing, and FIG. 4B is a partial cross-sectional view of the superconducting wire. FIG. 5 is an explanatory view showing an example of an uneven portion formed on the base material of the oxide superconducting wire after fusing. FIG. 6 is an explanatory diagram of a peel test of the oxide superconducting wire manufactured in the example. FIG. 7 is a perspective view showing an example of a state in which an insulating tape is wound around a conventional oxide superconducting wire. The photograph which shows the cross-section structure | tissue structure of the fusing part of the oxide superconducting wire obtained by fusing an oxide superconducting conductor in an Example.

Hereinafter, an embodiment of a method for producing an oxide superconducting wire according to the present invention will be described with reference to the drawings.
FIG. 1 is an explanatory view showing a state where a tape-shaped oxide superconductor is cut by a continuous wave laser based on the method according to the present invention, and FIG. 2 is a diagram of a fiber laser device used for generating the continuous wave laser. FIG. 3 is a perspective view showing an oxide superconducting conductor to be cut and an oxide superconducting wire after cutting, and FIG. 4 is a diagram showing a state where the obtained oxide superconducting wire is covered and a partially enlarged state. It is.

The oxide superconducting conductor 1 to be cut in the present invention has an intermediate layer 5, an oxide superconducting layer 6 and a stabilizing layer 7 on a metal tape-like substrate 3 as shown in FIG. The oxide superconducting conductor 1 is laminated and cut by a laser beam of a continuous wave laser as will be described later, so that a plurality of oxide superconducting conductors 1 having a width narrower than that of the oxide superconducting conductor 1 (FIG. 3) are obtained. In (b), four oxide superconducting wires 10 can be obtained.
Since this oxide superconducting wire 10 is formed by cutting the oxide superconducting conductor 1 in its width direction, the oxide superconducting wire 10 has exactly the same structure except for its narrow width. The intermediate layer 5a, the oxide superconducting layer 6a, and the stabilizing layer 7a are laminated on the tape-like base material 3a made of the product.

More specifically, the oxide superconducting wire 10 has an intermediate layer 5 composed of a diffusion prevention layer 11, a bed layer 12, an orientation layer 15 and a cap layer 16 on the upper surface of a base material 3a as shown in FIG. The oxide superconducting layer 6a and the stabilizing layer 7a are laminated thereon, and in FIG. 3, the intermediate layer 5 is drawn as one layer for the sake of simplicity. Note that the diffusion preventing layer 11, the bed layer 12, and the cap layer 16 are not essential and may be omitted in some cases.
The oxide superconducting wire 10 shown in FIG. 4 (a) shows a state in which a thicker stabilizing layer 8 is laminated on the stabilizing layer 7a, and is a laminate comprising the oxide superconducting wire 10 and the stabilizing layer 8. An insulating layer 18 is formed by wrapping the resin tape 17 around the entire circumference.
The stabilization layer 8 is formed by pasting or plating after obtaining the superconducting wire 10 as shown in FIG. 3B by cutting with a laser beam.
The oxide superconducting wire 10 insulated with the insulating layer 18 as a structure shown in FIG. 4A can be used for applications such as a superconducting coil by coil processing, and the oxide superconducting wire 10 insulated with the insulating layer 18. Can be used for applications such as superconducting cables for power transmission.

  As shown in detail in FIG. 4 (b), the fusing portion of the oxide superconducting wire 10 is fused to the side surface of the intermediate layer 5a and the oxide superconducting layer 6a with respect to the fusing surface 3b of the side surface of the substrate 3a. A step portion 3c is formed at a position where the surface position of the intermediate layer 5a and the side surface of the oxide superconducting layer 6a is slightly set back. The protective layer 7b is formed by extending the molten solidified body. FIG. 4B shows the thickness of the base material 3a and the thickness of the intermediate layer 5a, the oxide superconducting layer 6a, and the stabilizing layer 7a in a ratio corresponding to the actual thickness. In FIG. Is shown in a simplified manner for easy viewing of the drawings. As shown in FIGS. 3 (b) and 4 (c), in the melted portion of the oxide superconducting wire 10, the edge of the oxide superconducting layer 5a extends from the edge of the stabilizing layer 7a. Covered and covered by. In FIG. 4A, the protective layer 7b is not shown in order to show an exploded perspective view centering on the laminated structure of the oxide superconducting wire 10.

Hereinafter, each element of the oxide superconducting wire 10 will be described.
The base material 3 (3a) can be used as a base material for a normal superconducting wire, has only to be high strength, is in the form of a tape to make a long cable, and is made of a heat-resistant metal. Is preferred. For example, various high-strength, high-heat-resistant metal materials such as nickel alloys such as stainless steel and hastelloy, or ceramics disposed on these various metal materials, and the like can be given. Among various heat resistant metals, nickel alloys are preferable. Especially, if it is a commercial item, Hastelloy (trade name made by US Haynes Co., Ltd.) is suitable, and Hastelloy B, C, G, N, W, which have different amounts of components such as molybdenum, chromium, iron, cobalt, etc. Any type can be used. What is necessary is just to adjust the thickness of the base material 3 suitably according to the objective, Usually, it can be set as the range of 10-500 micrometers.

The diffusion prevention layer 11 is formed for the purpose of preventing the diffusion of the constituent elements of the base material 3 (3a), and silicon nitride (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₃ , also referred to as “alumina”). Alternatively, it is made of GZO (Gd ₂ Zr ₂ O ₇ ) or the like, and is formed by a film forming method such as a sputtering method, and the thickness thereof is, for example, 10 to 400 nm.
The bed layer 12 has high heat resistance and is intended to reduce interfacial reactivity, and is used to obtain the orientation of a film disposed thereon. Such a bed layer 12 is, for example, a rare earth oxide such as yttria (Y ₂ O ₃ ), and is represented by a composition formula (α ₁ O ₂ ) _2x (β ₂ O ₃ ) _(1-x). It can be illustrated. More _{specifically, Er 2 O 3, CeO 2} , Dy 2 O 3, Er 2 O 3, Eu 2 O 3, Ho 2 O 3, can be exemplified _La 2 _{O 3} and the like. The bed layer 12 is formed by a film forming method such as a sputtering method, and has a thickness of 10 to 100 nm, for example.

The alignment layer 15 may have either a single layer structure or a multi-layer structure, and is selected from materials that are biaxially aligned in order to control the crystal orientation of the cap layer 16 laminated thereon. Specifically, preferred materials for the alignment layer 15 are Gd ₂ Zr ₂ O ₇ , MgO, ZrO ₂ —Y ₂ O ₃ (YSZ), SrTiO ₃ , CeO ₂ , Y ₂ O ₃ , Al ₂ O ₃ , Gd _2. Examples thereof include metal oxides such as O ₃ , Zr ₂ O ₃ , Ho ₂ O ₃ , and Nd ₂ O ₃ .
If the orientation layer 15 is formed with a good crystal orientation (for example, a crystal orientation degree of 15 ° or less) by an IBAD (Ion-Beam-Assisted Deposition) method, the crystal orientation of the cap layer 16 formed thereon is increased. A good value (for example, a degree of crystal orientation of about 5 °) can be obtained, and thereby the superconducting characteristics can be exhibited with good crystal orientation of the oxide superconducting layer 6 formed on the cap layer 16. The oxide superconducting layer 6 can be obtained.
For example, the alignment layer 15 made of Gd ₂ Zr ₂ O ₇ , MgO, or ZrO ₂ —Y ₂ O ₃ (YSZ) has a small value of Δφ (FWHM: full width at half maximum) that is an index indicating the degree of crystal orientation in the IBAD method. This is particularly preferable because it can be performed.

The cap layer 16 is epitaxially grown by being formed on the surface of the orientation layer 15 in which the in-plane crystal axes are oriented as described above, and then grows laterally, so that the crystal grains are self-oriented in the in-plane direction. may material, a is not particularly limited as long as it, specifically as _{preferred, CeO 2, Y 2 O 3} , Al 2 O 3, Gd 2 O 3, ZrO 2, Ho 2 O 3, Nd 2 O 3 Etc. can be illustrated. When the material of the cap layer is CeO ₂ , the cap layer may contain a Ce—M—O-based oxide in which part of Ce is substituted with another metal atom or metal ion.
For example, the cap layer 16 made of CeO ₂ is self-orientated as described above, so that a higher in-plane orientation degree than the orientation layer 15, for example, Δφ = about 4 to 6 ° can be obtained.
For example, the CeO ₂ layer can be formed by a PLD method (pulse laser deposition method), a sputtering method, or the like. The thickness of the CeO ₂ layer is preferably 100 nm or more in order to obtain sufficient orientation, but if it is too thick, the crystal orientation deteriorates, so it can be in the range of 50 to 5000 nm.

The oxide superconducting layer 6 (6a) may be a known one, and specifically, is a material made of REBa ₂ Cu ₃ O _y (RE represents a rare earth element such as Y, La, Nd, Sm, Er, Gd). The thing can be illustrated. Examples of the oxide superconducting layer 6 include Y123 (YBa ₂ Cu ₃ O _7-X ) or Gd123 (GdBa ₂ Cu ₃ O _7-X ).
The oxide superconducting layer 6 is laminated by a physical vapor deposition method such as sputtering, vacuum vapor deposition, laser vapor deposition, electron beam vapor deposition, chemical vapor deposition (CVD), or thermal coating decomposition (MOD). In particular, from the viewpoint of productivity, the PLD (pulse laser deposition) method, the TFA-MOD method (organic metal deposition method using trifluoroacetate, coating pyrolysis method) or the CVD method may be used. it can.

The first stabilizing layer 7a laminated on the oxide superconducting layer 6 is formed as a layer made of a metal material having good conductivity, such as Ag, and a low contact resistance with the oxide superconducting layer 6, which is compatible. The In order to form the Ag stabilizing layer 7, a film forming method such as a sputtering method is employed, and the thickness thereof can be formed to about 1 to 30 μm.
The second stabilization layer 8 is provided for stabilizing the oxide superconducting layer 6a, and is provided for bypassing the current to prevent the oxide superconducting layer 6a from transitioning to the normal conducting state. Therefore, it is formed from a highly conductive metal material such as Cu, Al, or an alloy thereof. When the oxide superconducting wire 10 is applied for the purpose of a current limiting device or the like, it is preferable to use a high resistance material as the stabilization layer 8, and thus a metal material having a high resistance to Cu, Ag, Al, such as NiCr It can consist of
The stabilization layer 8 is formed thicker than the stabilization layer 7 and has a thickness of about 100 to 300 μm in order to ensure a sufficient capacity as a current bypass path. In that case, it can be formed on the stabilization layer 7 by using a soldering or conductive adhesive bonding method or a plating method.

In this embodiment, before the thick stabilization layer 8 is provided, this is cut from the state of the oxide superconducting conductor 1 shown in FIG. 3A in which the Ag stabilizing layer 7 is formed on the oxide superconducting layer 6. Then, when the oxide superconducting wire 10 having a narrow width is manufactured, it is cut using a laser beam of a continuous wave laser.
FIG. 1 shows a schematic configuration of a cutting device 20 used for generating a continuous wave laser to cut the oxide superconductor 1, and the cutting device 20 of this example includes a plurality of (three in the example of FIG. 1). A light source 21 for excitation laser, a coupler 22 as a beam combiner for coupling excitation lasers from the plurality of light sources 21, and a double clad fiber connected to the coupler 22 for amplification. The fiber 23, a transmission fiber 24 connected to the amplification fiber 23, and an output unit 25 connected to the tip of the transmission fiber 24 are mainly configured.

  As an example, the amplifying fiber 23 may be a rare earth-doped fiber that is an optical amplifying medium. As a rare earth-doped fiber, a rare-earth element, for example, a core to which rare-earth elements such as Yb (ytterbium), Er (erbium), Tm (thulium), Nd (neodymium), Pr (praseodymium) are added, and the outer periphery of the core are surrounded. A rare earth-doped double clad fiber composed of a first clad and a second clad surrounding the first clad can be used.

The output unit 25 is connected to a cylindrical guide unit 26 for introducing a laser output from the transmission fiber 24, an optical device 27 accommodated on the upper side of the guide unit 26, and a lower side of the guide unit 26. The injection nozzle 28 and the gas supply source 29 connected to the lower side of the injection nozzle 28 are mainly configured.
The optical device 27 includes a plurality of optical lenses, and by adjusting the mutual position of these optical lenses, the diameter of the laser light incident from the transmission fiber 24 is reduced to the outside of the tip of the injection nozzle 28. The laser beam can be focused and irradiated so as to obtain an appropriate beam diameter. A gas introduction part 30 is formed on the upper side wall of the injection nozzle 28, and a gas supply source 29 such as an inert gas is connected to the gas introduction part 30. By sending a shielding gas such as an inert gas from the gas supply source 29 to the inside of the injection nozzle 28, the shielding gas can be ejected from the opening of the tip of the injection nozzle 28.

In order to cut the oxide superconductor 1 using the cutting device 20, the tip of the injection nozzle 28 is positioned, for example, at the center in the width direction of the oxide superconductor 1 installed horizontally as shown in FIG. Then, the central portion of the oxide superconductor 1 is irradiated with a laser beam of a continuous wave laser, and the oxide superconductor 1 is moved in the length direction at a predetermined speed.
The multimode excitation light input from the excitation light emitting device 21 to the coupler 22 via the connection fiber 21 a in the cutting device 20 is optically coupled in the coupler 22 and input to the amplification fiber 23. The wavelength is amplified and the output is amplified at 1, converted into a single mode, and output as a continuous wave laser through the transmission fiber 24.
As an example of a continuous wave laser applied in the present embodiment, a continuous wave laser having a center wavelength of 1080 nm can be used, and the beam front side in the case of converging and irradiating a laser beam to the outside of the tip of the injection nozzle 8 with a beam output of 300 W The beam diameter can be about 10 μm to 100 μm, for example, 20 μm. The center wavelength of the continuous wave laser can be about 1050 to 1100 nm.

With respect to the laser beam reaching the output unit 25 from the transmission fiber 24, the optical device 27 is adjusted so that the laser beam diameter of the continuous wave laser having a center wavelength of 1080 nm is reduced to about 20 μm, and is oxidized from the tip of the injection nozzle 28 as described above. When the central portion of the object superconducting conductor 1 is irradiated, the stabilization layer 7, the oxide superconducting layer 6, the intermediate layer 5, and the base material 3 in the central portion of the oxide superconducting conductor 1 can be fused by a laser beam.
Further, since the laser beam is irradiated from the outside of the stabilization layer 7, the laser beam irradiation portion is sequentially formed in the order of the stabilization layer 7, the oxide superconducting layer 6, the intermediate layer 5, and the substrate 3 in the oxide superconductor 1. Although it can be melted sequentially, the shield gas ejected from the tip of the spray nozzle 28 blows away the melted melt of the stabilization layer 7, oxide superconducting layer 6, intermediate layer 5, and substrate 3. In addition, the shield gas ejected from the tip of the ejection nozzle 28 in a state where the laser beam penetrates the substrate 3 oxidizes the melted stabilization layer 7, oxide superconducting layer 6, intermediate layer 5, and substrate 3. The rear surface side of the object superconducting conductor 1 is also blown away and removed. By these actions, adhesion of molten dross caused by the melt of the stabilization layer 7, the oxide superconducting layer 6, the intermediate layer 5, and the base material 3 can be prevented in the portion melted by the laser beam. The irradiation angle of the laser beam to the oxide superconducting conductor 1 may be 90 °, but may be inclined by about 1 to 2 °. This is to prevent the return light from returning to the optical fibers 24 and 23 side because the light reflectance of the Ag stabilizing layer 7 is high.

From the melting start state by this laser beam, the oxide superconducting conductor 1 is moved in the length direction sequentially at a predetermined speed, for example, 150 mm / s, so that the oxide superconducting conductor 1 is centered over the entire length in the length direction. And can be divided into two oxide superconducting wires.
If the above operation is repeated a plurality of times at predetermined intervals in the width direction of the oxide superconductor 1, the oxide superconductor 1 can be divided into four as shown in FIG. . When the oxide superconducting conductor 1 is long, it takes time to scan the laser beam over its entire length, so four output units 25 are provided in parallel and four laser beams are provided. By adopting a configuration capable of simultaneous irradiation, the entire length of the oxide superconductor 1 may be divided into four by one laser beam scanning.

As described above, when the oxide superconductor 1 is blown by the laser beam of the continuous wave laser, the shield gas is blown from the tip of the injection nozzle 28 while being blown in the thickness direction of the oxide superconductor 1, so that the laser beam is heated. The melted portions of the melted base material 3a, intermediate layer 5a, oxide superconducting layer 6a, and stabilizing layer 7a are blown away by the pressure of the shielding gas, and fusing progresses. Here, when the injection pressure of the shield gas is adjusted, the melted portion of the stabilization layer 7a located at the uppermost layer is extended in the flow direction of the shield gas so that the melt cross-section portion of the intermediate layer 5a and the oxide superconducting layer 6a is covered. Can be blown to wear. By this fusing treatment, the protective layer 7b can be formed on the edge portion of the stabilization layer 7a as shown in FIG. 3B or FIG. 4B over the entire length of the oxide superconducting wire 10.
Thus, it can be set as the structure which shielded the side surface of the oxide superconducting layer 6a with the protective layer 7b over the full length of the oxide superconducting wire 10. FIG. Therefore, it is possible to obtain the oxide superconducting wire 10 having a structure capable of preventing moisture from entering the oxide superconducting layer 6a from the outside.

On the other hand, when the oxide superconductor 1 is blown by the laser beam of the continuous wave laser as described above, the melted portion of the oxide superconductor 1 is formed more smoothly than the conventional method using the pulse laser. it can. FIG. 5 is a partial enlarged view showing an example of a plan view of a fused portion of the oxide superconducting wire 10 obtained by fusing with a laser beam of a continuous wave laser.
As described above, the melted portion of the oxide superconducting wire 10 has a large number of concave and convex portions 10c formed in the length direction of the oxide superconducting wire 10 (in the left-right direction in FIG. 5) in an enlarged plan view. In this way, when the beam diameter is set to 20 μm using a continuous wave laser beam and blown under the above-described conditions, the maximum height Rz of the uneven portion 10 c can be formed to 5 μm or less.

The laser beam of the pulse laser used in the prior art melts the object by repeatedly outputting a laser beam having a peak output with a very high peak output. In the laser beam of this pulse laser, when the oxide superconductor 1 is melted, the maximum height Rz of the concavo-convex portion is larger than 10 μm. For example, when fusing with a YAG laser, the concavo-convex with a maximum height of 10-20 μm Generated. This is because the laser-processed portion is vaporized and sublimated, so that it is difficult to deform the end portion.
In addition, the short wavelength laser lacks the output for fusing the oxide superconductor 1 and the oxide superconductor 1 cannot be melted itself. In addition, the CO ₂ laser having a long wavelength or the like does not emit light from the Ag stabilizing layer 7. Since the reflectivity is high, even if the CO ₂ laser is irradiated, the light reflection of the stabilization layer 7 increases and the oxide superconducting conductor 1 cannot be fused at high speed.
On the other hand, with the laser beam of the continuous wave laser used in the present embodiment, the melted surface can be processed more smoothly than the conventional technique so as to have an uneven portion with a maximum height of 5 μm or less.

  When the oxide superconducting conductor 1 is long, the oxide superconducting conductor 1 is wound around a reel or the like, and the oxide superconducting is performed by irradiating a laser beam while the reel is sequentially drawn out and wound around another reel. The conductor 1 is preferably divided into oxide superconducting wires 10 over its entire length.

"Example 1"
A tape-like base material having a width of 10 mm, a thickness of 0.1 mm, and a length of 100 m made of Hastelloy C276 (trade name of Haynes, USA) is prepared, and a thickness of 100 nm made of Al ₂ O ₃ is formed on the surface of the tape-like base material. Then, a 30 nm thick bed layer made of Y ₂ O ₃ was formed thereon by ion beam sputtering. In carrying out the ion beam sputtering method, the tape-like base material is wound around a reel inside the sputtering apparatus, and can be formed while being fed from one reel to the other reel, over the entire length of the tape-like base material, A diffusion prevention layer and a bed layer were formed. Next, an alignment layer of MgO having a thickness of 10 nm was formed on the bed layer by ion beam assisted vapor deposition. In this case, the incident angle of the assist ion beam was set to 45 ° with respect to the normal line of the tape-shaped substrate film forming surface.

Subsequently, a cap layer of CeO _{2 having} a thickness of 500 nm was formed on the MgO alignment layer using a pulsed laser deposition method (PLD method). Further, an oxide superconducting layer having a thickness of 1 μm of GdBa ₂ Cu ₃ O _7-x was formed on the cap layer by a pulse laser deposition method.
Next, an Ag stabilizing base layer having a thickness of 10 μm was formed on the oxide superconducting layer by sputtering, and oxygen annealing was performed at 500 ° C. Through the above steps, an oxide superconducting conductor having a structure including a diffusion preventing layer, a bed layer, an alignment layer, a cap layer, an oxide superconducting layer, and a stabilizing layer was formed on a long tape-like substrate.

The oxide superconducting conductor is irradiated with a laser beam of a continuous wave laser having a central wavelength of 1080 nm, using a cutting apparatus having a schematic configuration shown in FIG. 1, and the output is 200 W, the beam diameter is 20 μm, and the processing speed is 500 mm / s. A cutting process was performed to divide the oxide superconducting conductor having a width into two oxide superconducting wires having a width of 5 mm. In the cutting process, the nitrogen gas pressure applied to the injection nozzle is set to 0.9 MPa, and nitrogen gas is jetted from the tip of the injection nozzle (inner diameter 2 mm) to the upper surface of the oxide superconductor to cause molten dross on the cutting process surface. It processed so that it might not adhere. Moreover, the oxidation of the molten surface was prevented by injecting nitrogen gas.
By this operation, an uneven portion having a maximum height Rz of 3 μm was generated on the cut surface of the Hastelloy tape base material, but a large uneven portion was not seen by naked eye observation, and the surface was smooth.

The obtained oxide superconducting wire with a width of 0.5 mm was insulated by winding an insulation tape made of polyimide resin with a width of 4 mm and a thickness of 12.5 μm with a tension of 150 g. Insulation treatment was possible.
Further, an aluminum alloy pin member 37 having a disk portion 35 and a rod portion 36 having an outer diameter of 2.6 mm on the upper surface of the stabilization layer 7 of the oxide superconducting wire 10 cut as shown in FIG. 6 is bonded to an epoxy resin adhesive. Then, a peel test was performed in which the rod portion 36 was pulled in a direction perpendicular to the oxide superconducting wire 10. When a similar peel test was performed on five samples of the oxide superconducting wire cut with the laser beam of the continuous wave laser, the average value of the peel force was about 30 kgf.
FIG. 8 shows an enlarged photograph of the melted portion of the oxide superconducting wire of this example. As shown by the white arrow in FIG. 8, a protective layer could be formed on the melted portion of the stabilization layer. This protective layer completely covered and covered the oxide superconducting layer located below the stabilizing layer and the side surface of the intermediate layer, and reached and adhered to the thick substrate located below them. With this structure, it was possible to obtain an oxide superconducting wire capable of preventing moisture from entering.

"Comparative Example 1"
An oxide superconductor having the same configuration as that of the oxide superconductor used in the examples was prepared. Using a fiber laser with a central wavelength of 1080 nm, cutting was performed to divide the 10 mm wide oxide superconductor into 5 mm widths under the conditions of frequency 60 KHz, output 300 W, beam diameter 20 nm, and processing speed 500 mm / s. . The jet pressure applied to the nitrogen gas jet nozzle is 0.9 MPa.
With the fiber laser under this condition, the oxide superconducting conductor could be melted, but a protective layer could not be formed on the edge of the silver stabilizing layer. In the edge part of the silver stabilization layer, the edge part of the silver stabilization layer was blown away with nitrogen gas without deformation. In this example, since the melted cross sections of both end portions of the oxide superconducting layer are exposed, it is necessary to form some protective layer again.
When a resin tape equivalent to that used in the examples was wound around the oxide superconducting wire with the same tension, it could be wound without cutting the resin tape.
When a similar peel test was performed on five oxide superconducting wire samples obtained by cutting with the fiber laser, the average peel force was about 29 kgf.

"Comparative Example 2"
An oxide superconductor having the same configuration as that of the oxide superconductor used in the examples was prepared. Using a YAG laser with a center wavelength of 355 nm, cutting processing to divide the 10 mm wide oxide superconductor into 5 mm widths under the conditions of frequency 30 KHz, output 2.4 W, beam diameter 20 nm, processing speed 5 mm / s. went. During the fusing process, nitrogen gas was blown from the tip of the injection nozzle.
The YAG laser is a pulsed laser that sublimates the material of the blown part in an instant. Therefore, the silver stabilization layer in the blown part instantly sublimates and evaporates, so a protective layer is formed in the melted part of the stabilization layer. It wasn't.
Further, in the YAG laser, when the processing speed was increased from the above-mentioned value, a portion that could not be cut in the oxide superconductor was generated. Alternatively, when the processing speed is increased from the above values, large uneven portions are generated on the cut surface of the base material of the oxide superconducting conductor. Therefore, cutting is performed so that the uneven portions are not generated by setting the above processing speed, and oxidation is performed. A superconducting wire was obtained. Note that, on the cut surface by the YAG laser, an uneven portion having a maximum height Rz of 10 to 20 μm was generated on the cut surface even at the above processing speed.
When a resin tape equivalent to that used in the examples was wound around the oxide superconducting wire with the same tension, it could be wound without cutting the resin tape.
A peel test using the pin member 37 was performed on the obtained oxide superconducting wire under the same conditions as in the example.
When a similar peel test was performed on five oxide superconducting wire samples obtained by cutting with the YAG laser, the average value of the peel force was about 28 kgf.

  The present invention can be used for oxide superconducting wires used in various superconducting devices such as superconducting coils, superconducting cables for power transmission, superconducting motors, and current limiters.

  DESCRIPTION OF SYMBOLS 1 ... Oxide superconductor, 3, 3a ... Base material, 5, 5a ... Intermediate layer, 6, 6a ... Oxide superconductor layer, 7, 7a ... Stabilization layer, 7b ... Protective layer, 8 ... Stabilization layer, 10 DESCRIPTION OF SYMBOLS ... Oxide superconducting wire, 11 ... Diffusion prevention layer, 12 ... Bed layer, 15 ... Orientation layer, 16 ... Cap layer, 17 ... Insulating tape, 18 ... Insulating layer, 20 ... Cutting device, 21 ... Light emitting device of excitation laser , 22 ... coupler, 23 ... amplification fiber, 24 ... transmission fiber, 25 ... output section, 27 ... optical system, 28 ... injection nozzle, 29 ... gas supply source.

Claims (1)

Stabilization of the laser beam of a continuous wave laser on an oxide superconducting conductor comprising a tape-shaped substrate, an intermediate layer provided on the substrate, an oxide superconducting layer, and a silver stabilizing layer By irradiating along the length direction of the base material from the outside of the layer forming side and fusing the stabilizing layer, the oxide superconducting layer, the intermediate layer, and the base material, the oxide superconducting conductor is moved in the width direction. When manufacturing multiple oxide superconducting wires by dividing,
Covering the melted portion of the oxide superconducting layer edge and the melted portion of the intermediate layer edge by blowing the stabilizing layer, the oxide superconducting layer, the intermediate layer, and the base material while spraying a shielding gas to the melted portion. In the process of forming a protective layer by extending the melt-solidified body of the stabilization layer in the direction of jetting shield gas ,
The laser beam is applied to the oxide superconductor through an injection nozzle, and the shield gas is injected from the injection nozzle in the thickness direction of the oxide superconductor to determine the position where the laser beam is fused. When fusing the oxide superconductor while covering with,
Adjusting the injection pressure of the shielding gas to extend the molten portion of the stabilization layer in the flow direction of the shielding gas, and depositing it on the molten cross-sectional portion of the intermediate layer and the oxide superconducting layer, A method for producing an oxide superconducting wire , comprising forming the protective layer on an edge portion of the stabilizing layer over the entire length of the oxide superconducting wire.