JP4921813B2 - Tape-like oxide superconducting wire manufacturing method and intermediate layer heat treatment apparatus - Google Patents

Description

  The present invention relates to a method of manufacturing a superconducting wire and a heat treatment apparatus used therefor, and particularly a tape-like rare earth oxide superconducting wire suitable for use in power equipment such as superconducting cables and superconducting power storage and power equipment such as a motor. The present invention relates to a method for manufacturing an oxide superconducting wire suitable for manufacturing the same and an intermediate layer heat treatment apparatus thereof.

Among oxide superconducting wires, rare earth (RE) 123-based oxide superconductors typified by YBa ₂ Cu ₃ O _7-x (YBCO) superconductors are usually formed in a tape shape. The wire has a structure in which one or more biaxially oriented inorganic material thin films are formed on a metal substrate, and a superconducting film and a stabilizing layer are sequentially formed thereon. Since this wire has biaxial crystal orientation, its critical current (Ic) value is higher than that of bismuth-based silver sheathed wire, and its magnetic field characteristics at liquid nitrogen temperature are superior to those of Bi-based superconductors. Thus, a practically high critical current density (Jc) can be maintained in a high magnetic field.

  If this wire is successfully put into practical use, it will not use silver, which is a noble metal, and the cooling efficiency will improve by several tens to several hundreds of times from the point that liquid nitrogen can be used as a refrigerant. It becomes possible to apply a superconducting wire to a superconducting device used at a low temperature that has not been applied.

  The characteristics of this YBCO superconductor are greatly influenced by the orientation of the crystal, and therefore are greatly influenced by the orientation of the crystals of the substrate and the intermediate layer constituting this lower layer.

  In other words, the crystal system of the YBCO superconductor is orthorhombic. Therefore, in order to bring out the characteristics of the material in terms of current-carrying characteristics, not only align the CuO plane of the crystal but also align the in-plane crystal orientation. Is required. The reason for this is that a slight misalignment generates twin grain boundaries and deteriorates the current-carrying characteristics.

In general, RE123-based superconductors (especially YBCO superconductors) are manufactured by using a vacuum ablation method based on laser ablation methods such as IBAD (Ion Beam Assisted Deposition ) and ISD (Inclined substrate deposition). As a non-vacuum process at the opposite end of the category of vapor phase including vapor deposition and chemical vapor deposition (CVD), the liquid phase represented by the 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 a high in-plane orientation on the surface of a polycrystalline tape-shaped metal substrate. It is necessary to form an intermediate layer film having in-plane orientation similar to a superconductor functioning as a metal substrate on a metal substrate.

Except for the IBAD method in which the in-plane orientation can be controlled by the assisted ion beam, other processes are represented by RABiTS (trademark: Rolling-Assisted Biaxially Textured-Substrates) in order to obtain an intermediate layer having a high in-plane orientation. It is necessary to use a metal substrate having a biaxially oriented texture as a template for the intermediate layer.

  A metal substrate having a 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.

When the MOD method is viewed from the viewpoint of the manufacturing cost of the oxide superconducting wire, it is considered to be very advantageous as a manufacturing method of the low cost wire. That is, the method using the IBAD substrate can obtain high characteristics, but this method has an advantage that a dense and smooth intermediate layer film can be obtained because all layers are formed by a vacuum process by a vapor phase method. On the other hand, there is a problem that the film formation rate is slow, the equipment cost is increased, and the wire price is increased. On the other hand, the CVD method has a higher production speed than other vapor phase processes, but has a high Ic value. There is a problem that it is difficult to increase the film thickness in order to obtain it.
Compared with these methods, the MOD method does not use a vacuum process, and therefore has the advantage of not incurring equipment costs and maintenance costs, and is expected to be able to provide a low-cost superconductor. . In this case, if the intermediate layer can also be formed by the MOD method, the cost can be further reduced.

  On the other hand, since the MOD method is a thermal equilibrium process, there is a disadvantage that the temperature required for crystallization is higher than that in a process for crystallization in a non-equilibrium state in vacuum. This high crystallization temperature is the only major drawback in using the textured metal substrate as described above.

Conventionally, as a heating method of the intermediate layer in the MOD method, a resistance heating method using a batch type electric furnace is generally adopted. In this method, a drum on which a substrate coated with a superconducting precursor is wound in a solenoid shape is placed in a batch type electric furnace and heat treatment is performed. In this resistance heating system using a batch electric furnace, the furnace body is heated by the heat generated by the resistance heating element, and is kept warm by the heat insulating material around the furnace body , and the way heat is transmitted to the wire is a heat source. It is determined by the conduction and radiation from the furnace body, and the convection of the atmospheric gas heated by the furnace body as the heat source. In the case of this method, it is necessary to first heat the furnace body having a large heat capacity. Further, after the heat treatment is completed, the cooling rate of the sample is limited by the cooling rate of the furnace body. Therefore, the sample is retained in the furnace body for a time longer than the heat treatment time originally required.

Therefore, in this case, as the wire becomes longer, the electric furnace becomes larger and the cost increases, and the manufacturing efficiency is lowered. Furthermore, in using the textured metal substrate for forming the intermediate layer, it is not preferable to retain the substrate in a high temperature region for a long time in terms of maintaining the in- plane orientation of the substrate. The disorder of the in-plane orientation of the substrate leads to the disorder of the in-plane orientation of the intermediate layer. As a result, the in- plane orientation of the superconducting film formed on the intermediate layer is deteriorated and the superconducting characteristics are deteriorated.

  On the other hand, a method in which a long wire is continuously heated as compared to the batch heating method has been studied. For example, it has a heating means and a control mechanism for controlling the temperature of the heating means, and runs on one or more strips of a long wire having a superconductor forming portion that becomes an oxide superconductor by heat treatment inside the heating means. There is known a continuous heat treatment apparatus for an oxide superconducting wire in which two or more heat treatment units are provided in the running direction of the long wire by heating the wire to form a long oxide superconducting wire. (For example, refer to Patent Document 1).

  This continuous heat treatment apparatus is not used for forming the intermediate layer, but as a heating means, a tubular heater, a heating tube formed by winding a high-frequency induction heating coil around the outer peripheral surface of a heat-resistant glass tube, or the like is used. It is possible to heat the wire continuously.

JP-A-9-147647

As described above, in the batch-type heating method conventionally employed as a method for heating the intermediate layer, the electric furnace becomes larger and costs increase as the wire becomes longer, and the manufacturing efficiency is lowered. There, furthermore, reduces the plane orientation of the aggregation structure metal substrate has a problem of lowering the superconducting properties by degrading the plane orientation of the intermediate layer and superconducting film, whereas, or tubular heater, In a continuous heat treatment apparatus using a heating tube with a high-frequency induction heating coil wound around the outer peripheral surface of a heat-resistant glass tube, if this is used for the formation of an intermediate layer, the substrate is heated in the same way. of lowering the plane orientation of the tissue metal substrate, resulting in a problem of lowering the superconducting properties by degrading the plane orientation of the intermediate layer and superconducting film.

  The present invention has been made to solve the above problems, and is a tape-shaped oxide superconducting wire capable of efficiently heating the calcined film forming the intermediate layer without affecting the orientation of the substrate. It is an object of the present invention to provide a manufacturing method of the above and an intermediate layer heat treatment apparatus thereof.

  Further, the present invention enables rapid heating and rapid cooling necessary to achieve a high Ic value, and allows heat treatment to be performed in a minimum time necessary for crystallization of an intermediate layer having high in-plane orientation. It is an object of the present invention to provide a method for producing a tape-shaped oxide superconducting wire and an intermediate layer heat treatment apparatus.

In order to achieve the above object, the method for producing a tape-shaped oxide superconducting wire of the present invention comprises heating and cooling a tape-shaped wire formed with a calcined film of an intermediate layer on a metal substrate having orientation. In the method of forming the intermediate layer on the metal substrate and then forming the superconducting layer on the intermediate layer , the calcined film is rapidly heated only by subjecting the calcined film to radiant heating, and then the calcined film The crystallization temperature is maintained, and then rapid cooling is performed to form a highly oriented intermediate layer.

Moreover, the intermediate | middle layer heat processing apparatus of the tape-shaped oxide superconducting wire of this invention heats and cools the tape-shaped wire which formed the calcined film of the intermediate | middle layer on the metal substrate which has orientation, on a metal substrate. A heat treatment apparatus for forming an intermediate layer, the heat treatment apparatus comprising a tape wire feeding device and a winding device, and a heat treatment furnace disposed between the feeding device and the winding device, In addition, the heat treatment furnace is configured to include a rapid heating region in which only the calcined film is rapidly heated by radiation heating and a crystallization temperature region.

  According to the method and apparatus of the present invention, the calcined film can be rapidly heated by radiant heating, then maintained at the crystallization temperature of the calcined film, and then rapidly cooled, so that the orientation of the substrate is maintained. In addition, an intermediate layer and a superconducting layer having high in-plane orientation can be formed, and a tape-shaped oxide superconducting wire having a high Ic value can be produced at low cost.

  In the method for producing a tape-shaped oxide superconducting wire of the present invention, after rapidly heating the calcined film of the intermediate layer on the metal substrate having orientation by radiation heating, the crystallization temperature of the calcined film is maintained, Next, rapid cooling is performed to form a highly oriented intermediate layer. In this case, the calcined film is made of a metal organic acid salt or an organic metal compound containing a metal element constituting the intermediate layer by the MOD method. It is preferable that the mixed solution dissolved in the organic solvent is calcined after coating.

Further, the crystallization temperature after the rapid heating by the radiant heating of the calcined film of the intermediate layer is also maintained by the radiant heating similarly to the rapid heating .

  The rapid heating and the radiant heating for maintaining the crystallization temperature are preferably performed so that the radiant rays are concentrated on the surface of the calcined film. As a result, the thermal effect on the substrate can be reduced and the orientation of the substrate can be maintained.

On the other hand, the intermediate layer a heat treatment apparatus of the tape-shaped oxide superconducting wire of the present invention, said the heat treatment furnace, to constitute a calcined film to consist of rapid heating region and the crystallization temperature region rapidly heated by radiation heating In this case, the calcined film is obtained by applying a mixed solution prepared by dissolving a metal organic acid salt or an organic metal compound containing a metal element constituting an intermediate layer in an organic solvent by MOD method and calcining. It is preferable that

In addition, the crystallization temperature region of the heat treatment furnace is configured by a heating means by radiant heating as in the rapid heating region .

  In this case, the rapid heating region and the crystallization temperature region are preferably constituted by radiation heating means formed so that the radiation rays are concentrated on the surface of the calcined film.

  The tape-shaped wire conveyance path in the heat treatment furnace arranged between the feeding device and the winding device is composed of a transparent core tube, and the feeding device, the winding device and the tape-shaped wire conveyance path are controlled in atmosphere. However, it is preferable to form a sealed structure.

  The above method for producing a tape-shaped oxide superconducting wire and its intermediate layer heat treatment apparatus are suitable when the tape-shaped oxide superconducting wire is a Y-based (123) superconducting wire.

  FIG. 1 shows an outline of an intermediate layer heat treatment apparatus 1 for a tape-shaped oxide superconducting wire, in which 2 is a tape-shaped wire feeding device, 3 is a tape-shaped wire winding device, 4 is a core tube, 5 Is a heat treatment furnace.

  In the above apparatus, the feeding device 2 and the winding device 3 are disposed inside the housings 2a and 3a, respectively, and the housings 2a and 3a form the core tube 4 in the heat treatment furnace 5 that forms a transport path for the tape-shaped wire. And is formed in a sealed structure. As a result, the tape-like wire running between the feeding device 2 and the winding device 3 is heat-treated in a predetermined atmosphere or under reduced pressure by an atmospheric gas supply device or an evacuation device (not shown) connected to the sealed space. be able to.

  The feeding device 2 and the winding device 3 can control the tension by balancing the winding motor and the feeding motor. As an example, tension control by idling of a clutch connected to a delivery motor can be mentioned.

  In the heat treatment furnace 5, radiant heaters 6a, 6b, 6c and 6d are arranged on the upper portion of the furnace core tube 4, the radiant heater 6a is in the rapid heating region A, and the radiant heaters 6b, 6c and 6d are crystallized. A temperature region B is formed. The number of radiant heaters constituting the rapid heating region A and the crystallization temperature region B can be arbitrarily arranged.

  The heat source of the radiant heaters 6a, 6b, 6c and 6d is basically composed of a lamp in which a filament is vacuum-sealed inside a glass tube, and its shape is arbitrary, but the light generated from the lamp is applied to the surface of the calcined film. In consideration of collecting light, it is appropriate to use a linear or circular shape. The wavelength of light emitted from the lamp covers continuously from visible light, near infrared, and far infrared. By combining with the condensing mirror optical system, the irradiation area is specified and only the calcined film surface is concentrated. Heat. The mirror optical system is configured by a pair of parabolic mirrors or a pair of elliptical mirrors.

Since the heating area of the lamp heating source that can be paired is 25 to 600 mm ² , the soaking area is formed in a planar shape by combining the heat sources in the running direction of the tape-shaped wire. By passing the tape-shaped wire through the irradiation area of the lamp at a constant speed, a heat treatment for temperature rising, temperature holding, and cooling is formed in a pattern. Accordingly, since the temperature rise and cooling start from the moment of entering and exiting the irradiation region, rapid heating and rapid cooling are possible. In this case, the heat sources of the radiant heaters 6a, 6b, 6c and 6d do not necessarily have the same shape, and may have different shapes in the rapid heating region A and the crystallization temperature region B.

  In the tape-shaped oxide superconducting wire intermediate layer heat treatment apparatus 1 described above, the tape-shaped wire 7 wound on the drum of the delivery apparatus 2 is drawn out with a predetermined tension, and the inside of the core tube 4 in the heat treatment furnace 5 is drawn. It travels and is wound on the drum of the winding device 3. When the tape-shaped wire 7 traveling in the furnace core tube 4 passes through the rapid heating region A in the heat treatment furnace 5, the calcined film of the intermediate layer on the substrate is rapidly heated by the radiant heater 6a, and the crystallization temperature region When passing through B, the intermediate layer on the substrate is crystallized by the radiation heaters 6b, 6c and 6d. In the rapid heating region A and the crystallization temperature region B, only the calcined film of the intermediate layer on the substrate is held at the rapid heating and crystallization temperature, and the intermediate layer after crystallization is rapidly cooled after passing through the crystallization temperature region B. Is done.

Tape-like wire 7 forms a calcined film of an intermediate layer on the surface of a textured metal substrate formed by a Ni- or Ni-base alloy tape-like base material or a composite base material of Ni or Ni-base alloy and another metal The intermediate layer calcined film is composed of one or two kinds of metal organic acid salt or organic metal compound containing a metal element constituting the intermediate layer, for example, octylate, naphthenate, neodecanoate, etc. What applied and calcined the mixed solution melt | dissolved in the above organic solvent is used.

  Hereinafter, specific examples of the present invention will be described.

  A mixed solution prepared by dissolving a metal organic acid salt of Ce, Nb, and Gd in an organic solvent at a molar ratio of Ce: Nb: Gd = 90: 5: 5 on a Ni substrate having biaxial orientation is calcined after application. Thus, a tape-shaped wire was created. The tape-shaped wire was subjected to continuous heat treatment using the intermediate layer heat treatment apparatus 1 shown in FIG. 1 to form a Ce—Nb—Gd—O intermediate layer film on the Ni substrate. The heat treatment conditions at this time were 1000 ° C. × 1 hour. The half width (Δφ) of this intermediate layer film was measured by X-ray diffraction. The results are shown in FIGS. 2 (A) and 3 (A).

  On the other hand, as a comparative example, the same tape-shaped wire as described above was subjected to heat treatment using a resistance heating batch electric furnace to form a Ce—Nb—Gd—O intermediate layer film on a Ni substrate. The heat treatment conditions at this time were 1000 ° C. × 1 hour. This intermediate layer film was measured by X-ray diffraction. The results are shown in FIG. 2 (B) and FIG. 3 (B).

  From the above results, the half-value width of the Ce—Nb—Gd—O intermediate layer film formed on the Ni substrate using the intermediate layer heat treatment apparatus 1 is Δφ = 7.5 °, whereas the resistance heating method The half-value width of the Ce-Nb-Gd-O intermediate layer film formed on the Ni substrate using a batch-type electric furnace is Δφ = 8.5 °, and the calcined film is rapidly heated by radiant heating and then crystallized. It is clear that a highly oriented intermediate layer can be formed when held at temperature and then subjected to rapid cooling.

  The method for producing a tape-like oxide superconducting wire and the intermediate layer heat treatment apparatus that can be produced according to the present invention can be applied to the production of a rare earth-based tape-like oxide superconducting wire that can be used in cables, power equipment and power equipment. .

It is a schematic sectional drawing which shows one Example of the intermediate | middle layer heat processing apparatus 1 of the tape-shaped oxide superconducting wire of this invention. It is a graph which shows the measurement result by the X-ray diffraction of the intermediate | middle layer film manufactured with the apparatus of this invention, and the conventional apparatus. It is a graph which shows the measurement result by the X-ray diffraction of the intermediate | middle layer film manufactured with the apparatus of this invention, and the conventional apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Intermediate layer heat processing apparatus 2 Tape-shaped wire feeding apparatus 3 Tape-shaped wire winding apparatus 4 Core tube 5 Heat treatment furnace 6a, 6b, 6c, 6d Radiation heater 7 Tape-shaped wire A Rapid heating area B Crystallizing temperature area

Claims (9)

A tape-shaped wire having an intermediate layer calcined film formed on a metal substrate having orientation is heated and cooled to form an intermediate layer on the metal substrate, and then a superconducting layer is formed on the intermediate layer. In the manufacturing method of the tape-shaped oxide superconducting wire to be formed, by rapidly heating only the calcined film by subjecting the calcined film to radiation heating, the calcination film is maintained at the crystallization temperature, and then, A method for producing a tape-like oxide superconducting wire, characterized by forming a highly oriented intermediate layer by rapid cooling. A tape-shaped wire having an intermediate layer calcined film formed on a metal substrate having orientation is heated and cooled to form an intermediate layer on the metal substrate, and then a superconducting layer is formed on the intermediate layer. In the manufacturing method of the tape-shaped oxide superconducting wire to be formed, the calcined film is rapidly heated by subjecting the calcined film to rapid heating by subjecting the surface of the calcined film to radiation so that the radiation is concentrated. A method for producing a tape-shaped oxide superconducting wire, characterized in that a highly oriented intermediate layer is formed by maintaining a crystallization temperature of 2. The calcined film of the intermediate layer is formed by applying a mixed solution in which a metal organic acid salt or an organic metal compound containing a metal element constituting the intermediate layer is dissolved in an organic solvent and calcining. Or the manufacturing method of the tape-shaped oxide superconducting wire of 2 . The method for producing a tape-shaped oxide superconducting wire according to any one of claims 1 to 3 , wherein the tape-shaped oxide superconducting wire is a Y-based (123) superconducting wire. A heat treatment apparatus for forming an intermediate layer on the metal substrate by heating and cooling a tape-shaped wire material on which an intermediate layer calcined film is formed on a metal substrate having orientation, wherein the heat treatment apparatus The tape-shaped wire feeding device and winding device, and a heat treatment furnace disposed between the feeding device and winding device, wherein the heat treatment furnace rapidly radiates only the calcined film. An intermediate layer heat treatment apparatus for a tape-shaped oxide superconducting wire comprising a rapid heating region and a crystallization temperature region for heating. On a metal substrate having a distribution tropism, the intermediate layer tape-shaped wire to form a calcined film of a heat treatment apparatus for heating and cooling to form an intermediate layer on the metal substrate, the heat treatment apparatus Comprises a feeding device and a winding device for the tape-like wire, and a heat treatment furnace disposed between the feeding device and the winding device, and the heat treatment furnace rapidly heats the calcined film. It comprises a heating region and a crystallization temperature region, and the rapid heating region and the crystallization temperature region are configured by radiation heating means formed so that radiation rays are concentrated on the surface of the calcined film. An intermediate layer heat treatment apparatus for a tape-shaped oxide superconducting wire. Calcined film of the intermediate layer, claim, characterized by comprising a mixed solution of a metal organic acid salt or organometallic compound containing a metal element constituting the intermediate layer in an organic solvent calcined after application 5 Or an intermediate layer heat treatment apparatus for a tape-shaped oxide superconducting wire according to 6 . The transport path for the tape-shaped wire rod in the heat treatment furnace disposed between the feeding device and the winding device is constituted by a transparent furnace core tube, and the feeding device, the winding device, and the transport path for the tape-shaped wire rod. The intermediate heat treatment apparatus for a tape-shaped oxide superconducting wire according to any one of claims 5 to 7 , characterized in that is configured in a sealed structure so that the atmosphere can be controlled. 9. The intermediate heat treatment apparatus for a tape-shaped oxide superconducting wire according to any one of claims 5 to 8 , wherein the tape-shaped oxide superconducting wire is a Y-based (123) superconducting wire.

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