JP2010123448A - Oxide superconducting wire rod and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oxide superconducting wire rod having a metal substrate superior in handling characteristics and mechanical strength. <P>SOLUTION: In the oxide superconducting wire rod, as for the tape-form metal substrate T composed of a traveling Ni base alloy of non orientation and nonmagnetism, by passing through a washing device 23 equipped with an ultrasonic supersonic washing tank 23a and a scrub washing roller 23b, and a texturing treatment device 24, texturing treatment is applied on a surface of the metal substrate T, and a fine streak is formed on the surface of the substrate. One layer or two layers or more of intermediate layers, and ReBa<SB>x</SB>Cu<SB>3</SB>O<SB>y</SB>superconductor are formed on the surface of a texturing treatment layer by MOD method. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an oxide superconducting wire suitable for a superconducting application device such as a power transmission cable, a transformer, a motor, and a power storage system, and a manufacturing method thereof, and more particularly to an oxide superconducting wire suitable for a MOD method and a manufacturing method thereof. Regarding improvement.

Oxide superconductor, as compared to the alloy-based superconductors, such as a conventional _Nb 3 Sn based critical temperature (Tc) is high, has the advantage of operating at liquid nitrogen temperature, among others ReBa ₂ Cu ₃ O _y ( Re represents at least one element selected from Y, Yb, Tm, Er, Ho, Dy, Gd, Eu, Sm, Nd, or La. Hereinafter referred to as ReBCO.) A superconductor is a high magnetic field region. Since the decrease in energization current is small, that is, the magnetic field characteristics at liquid nitrogen temperature are superior to those of Bi-based superconductors, it is possible to maintain a practical high critical current density (Jc). In addition to the excellent characteristics in the high temperature range, the manufacturing efficiency without using the noble metal silver is possible and the use of liquid nitrogen as the refrigerant significantly improves the cooling efficiency, making it extremely economically advantageous. It has been known.

  In a ReBCO superconducting wire, at least one or more biaxially oriented oxide layers are generally formed on a metal substrate, an oxide superconducting layer is further formed thereon, and surface protection of the superconducting layer is improved and electrical contact is improved. It has a structure in which a stabilization layer that plays a role as a protection circuit when energized is laminated. In this case, it is known that the critical current characteristic of the ReBCO superconducting wire depends on the in-plane orientation of the superconducting layer, and is greatly influenced by the in-plane orientation and surface smoothness of the intermediate layer and the oriented metal substrate. Yes.

  In other words, the crystal system of the ReBCO superconductor is orthorhombic, the lengths of the three sides of the x-axis, y-axis, and z-axis are different, and the angles between the three sides of the unit cell are slightly different from each other. It is easy to form, and a slight misorientation generates twin grain boundaries and deteriorates current conduction characteristics. Therefore, in order to obtain good current conduction characteristics, it is only necessary to align the biaxial orientation, that is, the CuO plane in the crystal. In addition, since it is required to align the in-plane crystal orientation, it is difficult to make the wire as compared with the Bi-based oxide superconductor.

  In general, ReBCO superconductor (especially YBCO superconductor) wire manufacturing method is based on laser ablation methods such as IBAD (Ion Beam Assisted Deposition) and ISD (Inclined substrate deposition), as well as vacuum deposition. As a non-vacuum process in the category of vapor phase including chemical vapor deposition and chemical vapor deposition (CVD) and its opposite electrode, liquid phase represented by metal organic salt coating pyrolysis method (Metal Organic Deposition Processes: MOD method) It can be classified into two methods, that is, a method of forming a crystallized thin film by applying a liquid to a substrate surface and sintering.

  In these processes, as described above, in order to achieve a high Jc value, it is required to form a superconducting layer having high biaxial orientation on the surface of a polycrystalline tape-like metal substrate. The manufacturing method for increasing the in-plane orientation of the crystal of the ReBCO superconductor and forming the wire while aligning the in-plane orientation is the same as the manufacturing method of the thin film. That is, by forming an intermediate layer having an orientation similar to that of a superconductor on a tape-like metal substrate, and making the crystal lattice of this intermediate layer function as a template, the in-plane orientation degree and orientation of the crystal of the ReBCO superconducting layer Is to improve.

  With the exception of the IBAD method, which can control the in-plane orientation by an assisted ion beam, in other processes, in order to form an intermediate layer with improved in-plane orientation and orientation on a tape-like metal substrate, a tape-like metal It is necessary that the surface of at least the intermediate layer side of the substrate is oriented. For this reason, various biaxially oriented metal substrates are known.

  For example, a metal substrate having a biaxially oriented texture represented by RABiTS (Rolling-Assisted Biaxially Textured-Substrates / trademark) is often used to function as an intermediate layer template.

  On the other hand, as a composite substrate having excellent mechanical strength and excellent orientation, it has a non-oriented non-magnetic first metal layer and a texture that is bonded to the first metal layer and at least the surface layer is oriented. And a second metal layer, and the first metal layer has a higher strength than the second metal layer, and a film-forming alignment substrate having a high strength while maintaining good orientation is known ( For example, see Patent Document 1.)

  Also, a first metal substrate formed by subjecting a metal substrate to be a core material made of non-oriented and non-magnetic metal, and heat treatment or hot rolling after surface activation bonding to both surfaces of the metal substrate, respectively. The first metal layer and the second metal layer are disposed via the bonding layer, the second bonding layer, and at least one surface of the first metal layer or the second metal layer is biaxially oriented. A material using a material having a cubic texture and a mechanical strength greater than the mechanical strength of the first metal layer and the second metal layer is known for the metal substrate (for example, patents). Reference 2).

  On the other hand, with respect to the problem of surface smoothness of the oriented metal substrate, a method of mechanically polishing the surface of a tape obtained by subjecting a Ni alloy after cold working to orientation heat treatment and biaxially orientating, and further electrolysis A rare earth-based tape-shaped oxide superconductor is known in which an oxide superconducting layer is formed on the surface of a polished tape-shaped substrate with an intermediate layer on a polished surface (see, for example, Patent Document 3). .

JP 2006-127847 A JP 2008-210600 A JP 2007-115561 A

  The metal substrate having the biaxially oriented texture by RABiTS is formed by subjecting a face-centered cubic, body-centered cubic or dense hexagonal metal to strong rolling and annealing. Is susceptible to mechanical strain and thermal strain and tends to lose orientation easily.

  As the metal substrate having a biaxially oriented texture by RABiTS, Ni or an alloy based on Ni, which is easy to form a texture and excellent in lattice matching, and contains a small amount of an additive element is used. As a result of strong rolling to form a texture, the thickness is small and the amount of additional elements is small, so that when subjected to orientation heat treatment at high temperature, the mechanical strength decreases to about several tens to 150 MPa, In addition to affecting the handling during subsequent film formation, there were problems such as inability to withstand electromagnetic force when using the wire.

  Further, in the above-mentioned alignment substrate for film formation, the first metal layer and the second metal layer have a configuration in which the first metal layer and the second metal layer are bonded to each other by a method such as rolling. There was a problem that the bonding strength was not sufficient.

  Furthermore, the composite substrate in which the first metal layer and the second metal layer are bonded to both surfaces of the metal substrate by heat treatment after surface activation bonding is excellent in mechanical strength, but surface activation bonding is performed in advance on the surface. Since the material having high surface smoothness obtained by electrolytic polishing is irradiated with an argon ion beam or the like in a high vacuum atmosphere and bonded to the metal substrate by pressure, there is a problem that the manufacturing method becomes complicated.

  On the other hand, in order to obtain the surface smoothness of the oriented metal substrate, if the surface is mechanically polished on the biaxially oriented tape, the temperature of the substrate surface rises and the orientation is easily lost. In the method of improving the surface smoothness of the substrate, problems such as the complexity of the manufacturing method and waste liquid treatment occur.

  The present invention has been made to solve the above problems, and provides an oxide superconducting wire in which a superconducting layer is formed on a metal substrate excellent in orientation and surface smoothness via an intermediate layer, and a method for producing the same. Its purpose is to provide.

  Another object of the present invention is to provide an oxide superconducting wire having a metal substrate that is excellent in handling properties and mechanical strength during film formation and that is easy to manufacture, and excellent in superconducting properties, and the manufacturing thereof. It is to provide a method.

  In order to solve the above problems, the tape-shaped oxide superconducting wire of the present invention has an oxide superconducting layer formed on one or more intermediate layers on a tape-shaped metal substrate having orientation. In the oxide superconducting wire, the tape-like metal substrate is oriented by a texturing process applied to the surface on the intermediate layer side.

  That is, an object of the present invention is to provide an oxide superconducting wire in which an oxide superconducting layer is formed on a tape-like metal substrate via one or more intermediate layers. This is achieved by applying a texturing process to the surface on the side, and sequentially providing an intermediate layer and an oxide superconducting layer on the surface of this processing layer.

  The tape-shaped metal substrate is preferably made of a non-oriented, non-magnetic tape-shaped metal substrate, and in particular, Ni or a Ni-based alloy is preferably used.

  The tape-shaped oxide superconducting wire according to the present invention as described above is a method for producing an oxide superconducting wire in which an oxide superconducting layer is formed on a tape-shaped metal substrate via an intermediate layer, and is non-oriented and non-magnetic. A step of continuously running the tape-shaped metal substrate, a step of cleaning the traveling tape-shaped metal substrate, a step of texturing the one side surface of the tape-shaped metal substrate after the cleaning, and a step after the texturing treatment After sequentially performing the step of cleaning the tape-shaped metal substrate, one or more intermediate layers are formed on one surface of the tape-shaped metal substrate that has been subjected to texturing. It can be easily obtained by forming an oxide superconducting layer on the intermediate layer.

Further, the above-described method for producing a tape-shaped oxide superconducting wire is a method for producing an oxide superconducting wire in which an oxide superconducting layer is formed on a tape-shaped metal substrate via an intermediate layer, and is non-oriented and non-oriented. A step of continuously running a tape-like metal substrate made of magnetic Ni or a Ni-based alloy, a step of cleaning the tape-like metal substrate that runs, and a texturing process on one side surface of the tape-like metal substrate after washing One step or two layers on one side surface of the tape-shaped metal substrate that has been subjected to the texturing process CeO ₂ , Y ₂ O ₃ , YSZ, Gd ₂ O ₃ or REZr ₂ O ₇ (one or more selected from RE = Ce, Gd, Sm, Eu, Dy, Ho, Er and Y) Show elements . Hereinafter the same.) Forming a mid opening layer of oxide, followed ReBa _x Cu ₃ O _y (Re on the intermediate layer is, Y, Yb, Tm, Er , Ho, Dy, Gd, Eu, Sm, And at least one element selected from Nd or La, where x ≦ 2 and y = 6.2 to 7. The same applies hereinafter.) By forming an oxide superconducting layer made of a superconductor by the MOD method It can be obtained most suitably.

  According to the present invention, it is possible to orient the crystal grains of the surface layer of the metal substrate in the in-plane direction of the substrate by performing a texturing process on the surface of the tape-like metal substrate. Since the intermediate layer and the oxide superconducting layer on the metal substrate are also oriented according to the properties, the superconducting properties can be improved.

  In the present invention, the orientation of the tape-shaped metal substrate can be obtained only by the surface layer of the metal substrate by performing the texturing process, so that strong rolling or annealing for obtaining the orientation of the metal substrate is performed. In order to obtain the strength of the metal substrate, it is possible to employ a metal substrate having a sufficient mechanical strength thickness, and most of the metal substrate other than the surface layer remains unoriented and can be employed. It is not necessary to have a composite substrate structure, and it does not affect the electromagnetic force during handling during film formation or when using a wire.

  In addition, since mechanical surface polishing and electropolishing are not required to obtain surface smoothness, there is no need for loss of orientation due to temperature rise on the substrate surface or complicated treatment, which is advantageous in terms of cost. There is an advantage that the intermediate layer can be thinned.

  FIG. 1 shows a cross section perpendicular to the axial direction of a tape-shaped oxide superconducting wire according to the present invention. The tape-shaped oxide superconducting wire 10 has two or more intermediate layers 12 on a tape-shaped metal substrate 11. The oxide superconducting layer 13 and the stabilizing layer 14 are sequentially formed through the structure.

  The tape-shaped metal substrate 11 is a non-oriented, non-magnetic Ni or Ni-based alloy, for example, a Ni-W alloy whose surface is subjected to texturing, and the Ni-W alloy layer 11a and the texturing layer 11b. By subjecting the tape-shaped metal substrate 11 to texturing, it becomes possible to orient the crystal grains of the surface layer of the tape-shaped metal substrate in the in-plane direction of the substrate.

  The texturing process is performed so that the fine streaks on the surface of the tape-shaped metal substrate by the texturing process have a periodic structure parallel to the axial direction of the tape-shaped metal substrate. These fine streaks do not necessarily have to be completely parallel to the axial direction of the tape-shaped metal substrate. By applying a texturing process, the crystal grains of the surface layer of the tape-shaped metal substrate are aligned in the in-plane direction of the substrate. What is necessary is just to be able to orientate. For example, a fine streak has a certain angle in the axial direction of the tape-shaped metal substrate, or a combination of a fine streak parallel to the axial direction of the tape-shaped metal substrate and a fine streak having a certain angle in the axial direction. Thus, the texturing process can be performed.

The intermediate layer 12 is preferably made of CeO ₂ , Y ₂ O ₃ , YSZ, Gd ₂ O ₃ or REZr ₂ O ₇ oxide, and can be formed in one layer or two or more layers. For example, the first intermediate layer 12a on the texturing layer 11b is formed of a CeZr ₂ O ₇ layer or a GdZr ₂ O ₇ layer, and a second intermediate layer 12b made of a CeO ₂ layer is formed on the first intermediate layer. Can be formed. The first intermediate layer 12a and the second intermediate layer 12b take over the crystal orientation of the texturing layer 11b and orient the oxide superconducting layer 13.

  The intermediate layer 12 can be formed by any of the MOD method, the pulse laser deposition method, the sputtering method, and the CVD method.

An oxide superconducting layer 13 is formed on the intermediate layer 12, and this oxide superconducting layer is preferably made of a ReBa _x Cu ₃ O _y superconductor, for example, YBa _1.5 Cu ₃ O _y .

  The oxide superconducting layer 13 can be formed by any film formation process such as MOD, pulsed laser deposition, sputtering, and CVD.

For example, an organic acid salt or an organic metal compound containing Y, Ba, and Cu at a predetermined molar ratio is used as a raw material when forming a YBa _x Cu ₃ O _y superconducting film by the MOD method. As this MOD raw material, for example, octylate, naphthenate, neodecanoate, trifluoroacetate, etc. of each element can be raised, but it is uniformly dissolved in one or more organic solvents, Any material that can be applied to the surface may be used.

  A metallic stabilization layer 14 made of silver or the like is laminated on the oxide superconducting layer 13.

  Examples of the present invention will be described below.

  FIG. 2 shows an outline of an oriented substrate manufacturing apparatus 20 used in the method for manufacturing a tape-shaped oxide superconducting wire of the present invention. The oriented substrate manufacturing apparatus 20 delivers a tape-shaped metal substrate. A device 21 and a winding device 22 are provided, and a cleaning device 23, a texturing processing device 24 and a cleaning device 25 are mainly disposed between the feeding device 21 and the winding device 22.

  In the orientation substrate manufacturing apparatus 20 described above, the tape-shaped metal substrate T made of non-oriented non-magnetic Ni or Ni-based alloy wound on a reel is drawn out from the feeding device 21 and is taken up by a winding device. By being wound up by the belt 22, it continuously travels between the feeding device 21 and the winding device 22.

  The tape-shaped metal substrate T that travels passes through a cleaning device 23 including an ultrasonic cleaning tank 23a and a scrub cleaning roller 23b, whereby the surface of the tape-shaped metal substrate T is cleaned, and then a texturing process is performed. By passing through the device 24, the surface of the tape-shaped metal substrate T is subjected to texturing.

  The texturing processing device 24 includes a delivery reel 24a, a take-up reel 24b, a pressurizing device 24c, and a slurry dropping device 24d, and the texturing tape P is delivered via the pressurizing device 24c. And the take-up reel 24b and the tape-like metal substrate T running on the surface of the tape-like metal substrate T running on the surface of the tape-like metal substrate T running on the slurry dripping device 24d and the pressurizing device 24c. Contact. The texturing tape P can be moved in the opposite direction to the moving tape-shaped metal substrate T, but is not limited to this. The texturing tape P and the tape-shaped metal substrate T are in pressure contact with a relative speed difference. In addition, a reciprocating motion at a certain angle with respect to the running direction within the tape surface of the tape-shaped metal substrate T can be added to the pressurizing device 24c, whereby various fine streaks can be added to the tape-shaped metal substrate T. It can be formed on the surface of the substrate. The form of the fine streak can be determined empirically based on the in-plane orientation of crystal grains in the surface layer of the tape-shaped metal substrate.

  The relative speed difference between the texturing tape P and the tape-shaped metal substrate T is determined empirically as described above. If the relative speed difference is too large or too small, the tape-shaped metal substrate It becomes difficult to orient crystal grains in the surface layer uniformly in the in-plane direction of the substrate.

  In addition, the average surface roughness of the surface of the tape-shaped metal substrate T after texturing is preferably set to Ra of 0.1 nm or more and 10 nm or less. When the average surface roughness Ra is less than 0.1 nm, the orientation of the surface of the tape-shaped metal substrate T becomes insufficient, and when Ra exceeds 10 nm, the intermediate layer formed on the surface of the tape-shaped metal substrate T. Therefore, it becomes difficult to reduce the thickness of the intermediate layer.

  The above-mentioned texturing tape is known as a pressure processing type polishing tool, and a polyester-based ultrafine fiber woven fabric can be used as the texturing tape, while the texturing slurry, ie, the polishing liquid is water-based. The abrasive grains used in the polishing slurry for the diamond slurry include colloidal silica abrasive grains, alumina abrasive grains, or diamond abrasive grains, and abrasive grains having an average particle diameter of 0.03 to 0.5 μm are used.

  The tape-shaped metal substrate T subjected to the texturing process passes through the cleaning device 25, whereby scrubbing (particulate powder substance) such as texturing slurry on the surface of the tape-shaped metal substrate is cleaned. The cleaning device 25 includes an ultrasonic cleaning tank 25a and a scrub cleaning roller 25b. Of course, other cleaning devices such as a brush scrub cleaner may be used instead of the cleaning devices 23 and 25 described above.

Tape-shaped metal substrate texturing process has been applied is wound on the reel of the winding apparatus 22, as described above in a separate step, texturing treatment layer one layer on the surface of or two or more layers of CeO ₂ , Y ₂ O ₃ , YSZ, Gd ₂ O _3, or REZr ₂ O ₇ oxide is formed into an intermediate open layer, and then an oxide superconducting layer made of ReBa _x Cu ₃ O _y superconductor is formed on the intermediate layer by MOD. Formed by law.

  The tape-shaped oxide superconducting wire according to the present invention can be used as an oxide superconductor suitable for use in power equipment such as a power transmission cable and a power storage system and power equipment such as a motor.

It is sectional drawing perpendicular | vertical to the axial direction of the tape-shaped oxide superconducting wire by this invention. It is the outline of the manufacturing apparatus of the orientation board | substrate used for the manufacturing method of the tape-shaped oxide superconducting wire of this invention.

Explanation of symbols

10 Tape-shaped oxide superconducting wire 11 Tape-shaped metal substrate 11a Ni-W alloy layer 11b Texturing layer 12 Intermediate layer 12a First intermediate layer 12b Second intermediate layer 13 Oxide superconducting layer 13
DESCRIPTION OF SYMBOLS 14 Stabilizing layer 20 Oriented substrate manufacturing device 21 Sending device 22 Winding device 23, 25 Cleaning device 23a, 25a Ultrasonic cleaning tank 23b, 25b Scrub cleaning roller 24 Texturing processing device 24c Pressure device 24d Slurry dropping device T Tape-like metal substrate P Texturing tape

Claims (13)

  An oxide superconducting wire in which an oxide superconducting layer is formed on one or more intermediate layers on a tape-shaped metal substrate having orientation, wherein the tape-shaped metal substrate has a surface on the intermediate layer side. A tape-shaped oxide superconducting wire characterized by having an orientation by a texturing process applied to the tape.   In an oxide superconducting wire in which an oxide superconducting layer is formed on one or more intermediate layers on a tape-shaped metal substrate, the tape-shaped metal substrate is subjected to texturing treatment on the surface on the intermediate layer side. A tape-shaped oxide superconducting wire, wherein the intermediate layer and the oxide superconducting layer are sequentially provided on the surface of the treated layer.   3. The tape-shaped oxide superconducting wire according to claim 1, wherein the tape-shaped metal substrate is a non-oriented non-magnetic tape-shaped metal substrate.   The tape-shaped oxide superconducting wire according to claim 3, wherein the tape-shaped metal substrate is made of Ni or a Ni-based alloy.   The texturing process is performed such that fine streaks on the surface of the tape-shaped metal substrate formed by texturing have a periodic structure parallel to the axial direction of the tape-shaped metal substrate. The tape-shaped oxide superconducting wire according to any one of 4 to 4. The oxide superconducting layer is ReBa _x Cu ₃ O _y (Re represents at least one element selected from Y, Yb, Tm, Er, Ho, Dy, Gd, Eu, Sm, Nd, or La, The tape-shaped oxide superconducting wire according to any one of claims 1 to 5, wherein x ≦ 2 and y = 6.2 to 7. The same applies hereinafter. The intermediate layer is CeO ₂ , Y ₂ O ₃ , YSZ, Gd ₂ O ₃ or REZr ₂ O ₇ (RE = Ce, Gd, Sm, Eu, Dy, Ho, Er, and Y or one selected from Y The tape-shaped oxide superconducting wire according to any one of claims 1 to 6, wherein the tape-shaped oxide superconducting wire is composed of an oxide.   A method of manufacturing an oxide superconducting wire in which an oxide superconducting layer is formed on a tape-shaped metal substrate via a middle-open layer, the step of continuously running a non-oriented non-magnetic tape-shaped metal substrate, and running Cleaning the tape-shaped metal substrate, performing a texturing process on one side surface of the tape-shaped metal substrate after cleaning, and cleaning the tape-shaped metal substrate after the texturing process. After the sequential application, one or more intermediate layers are formed on one side surface of the tape-shaped metal substrate that has been subjected to the texturing process, and then the oxide superconducting layer is formed on the intermediate layer A method for producing a tape-shaped oxide superconducting wire, characterized in that   9. The texturing process is performed so that the fine streaks on the surface of the tape-shaped metal substrate by the texturing process have a periodic structure parallel to the axial direction of the tape-shaped metal substrate. Manufacturing method of tape-shaped oxide superconducting wire.   The texturing process is performed by bringing a texturing tape having a relative speed difference against a continuously running tape-like metal substrate into contact with and running with a texturing slurry. A method for producing a tape-shaped oxide superconducting wire according to 8 or 9.   The method for producing a tape-shaped oxide superconducting wire according to claim 8, wherein the cleaning step is performed by ultrasonic cleaning and scrub cleaning.   The method for producing a tape-shaped oxide superconducting wire according to any one of claims 8 to 11, wherein the oxide superconducting layer is formed on the intermediate layer by a MOD method. A method for producing an oxide superconducting wire in which an oxide superconducting layer is formed on a tape-like metal substrate via a middle opening layer, the tape-like metal substrate made of non-oriented non-magnetic Ni or Ni-based alloy A step of continuously running, a step of washing the tape-like metal substrate that is running, a step of texturing the one side surface of the tape-like metal substrate after washing, and the tape-like metal after the texturing treatment After sequentially performing the process of cleaning the metal substrate, one or more layers of CeO ₂ , Y ₂ O ₃ , one side surface on the one-side surface of the tape-shaped metal substrate subjected to the texturing process, YSZ, forming a _Gd 2 _{O 3} or REZr ₂ O ₇ intermediately open layer made of an oxide, and then the oxide superconducting layer consisting of ReBa _x Cu ₃ O _y superconductor on said intermediate layer to form by the MOD method Method for producing a tape-shaped oxide superconducting wire, characterized in that.

Images