JP4728847B2 - Oxide superconductor conducting element - Google Patents

Description

  The present invention relates to an oxide superconductor energization element, for example, a technique suitable for use in an energization element using an oxide superconductor used for a current lead, a current limiter, a permanent current switch, or the like.

  If an oxide superconductor is used, a large current can flow with zero electrical resistance. Therefore, it is used for current-carrying elements such as current leads, current limiters, and permanent current switches. Such an oxide superconductor energization element is composed of an oxide superconductor and an electrode terminal for connection to an external power source or the like.

  Since the electrode terminal member is a current-carrying element that passes a large current, copper, silver, aluminum, or the like, which is a good electrical conductor, is used to reduce Joule heat generation at the electrode terminal. In addition, since the oxide superconductor has low mechanical strength, it may be reinforced with a support.

  Regarding the support, in order to reduce the thermal stress generated in the oxide superconductor during cooling, it has been proposed to use a material having a thermal expansion coefficient close to that of the oxide superconductor. Due to the restriction that it must be a good electrical conductor, a material having a thermal expansion coefficient close to that of an oxide superconductor could not be used. As a result, cracks and the like are likely to occur in the oxide superconductor near the joint surface with the electrode terminal, and there is a problem that the critical current of the oxide superconductor energization element is reduced.

  Therefore, as means for solving this problem, in Patent Document 1, an oxide superconductor energized electron in which an electrode terminal is a composite of a good electrical conductor and a thermal contraction adjusting body having a smaller thermal expansion coefficient than that of the good electrical conductor. Has been proposed.

JP 2004-47259 A

  As described above, by making the electrode terminal a composite of an electrical good conductor and a thermal contraction adjuster having a smaller thermal expansion coefficient than that of the electrical good conductor, the thermal expansion coefficients of the oxide superconductor and the electrode terminal are made closer to each other. The thermal stress generated in the oxide superconductor during cooling can be reduced. As a result, it is possible to prevent the critical current of the oxide superconductor conducting element from decreasing. However, making the electrode terminal a composite of a good electrical conductor and a heat shrinkage adjustment body having a smaller coefficient of thermal expansion than the good electrical conductor has a problem in that the manufacturing process is complicated and the manufacturing cost is high. It was.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an oxide superconductor energization element that is easy in manufacturing process and has a small decrease in critical current.

The oxide superconductor energization element of the present invention includes an oxide superconductor, electrode terminals electrically joined to both ends of the oxide superconductor, and a support that reinforces the oxide superconductor . A superconducting current-carrying element , wherein a taper that continuously narrows toward the tip is provided at a joint side end of the electrode terminal with the oxide superconductor, and the tip of the taper is the tip of the electrode terminal; and the thickness of the tapered tip is Ri der 1/2 or less in the absence of the tapered portion, wherein the support is characterized that you have close contact with the tapered portion.
Other features of the oxide superconductor energizing element of the present invention include an oxide superconductor, electrode terminals electrically joined to both ends of the oxide superconductor, and reinforcing the oxide superconductor. An oxide superconductor energizing element having a support , wherein the electrode terminal is provided with a stepped structure at a joint-side end with the oxide superconductor, and the thickness of the stepped structure portion tip is a stepped structure. der 1/2 or less in the absence of parts is, the support is a Rukoto in close contact with the stepped structure.
Other features of the oxide superconductor energization element of the present invention include an oxide superconductor, electrode terminals electrically joined to both ends of the oxide superconductor, and the oxide superconductor are reinforced. an oxide superconductor current element having a support, the electrode wherein a groove or indentation in the bonding end portions of the oxide superconductor of terminals, Ri least 1mm der depth of the groove or recess the support is a Rukoto in close contact with the groove or recess.

  According to the present invention, it is possible to provide an oxide superconductor energization element that is easy in manufacturing process, can reduce the thermal stress acting on the oxide superconductor during cooling, and has a small decrease in critical current.

Embodiments of the present invention will be described below with reference to the drawings.
Figure 1 is a sectional reference view showing a structure of oxides superconductors energizing element. In FIG. 1, electrode terminals 2 for external connection are electrically joined to both ends of an oxide superconductor 1 with solder or the like (not shown). Further, a taper portion is provided at a joint end portion of the electrode terminal 2 with the oxide superconductor 1.

FIG. 2 shows an example of the present invention in which a support 3 for reinforcement is provided in the structure of FIG. The support 3 is fixed with an adhesive, bolts or the like not shown. On the other hand, FIG. 8 is a sectional view showing the structure of a conventional example of an oxide superconductor energization element. In FIG. 8, the electrode terminal portion in the vicinity of the joint surface between the oxide superconductor 1 and the electrode terminal 2 has no taper portion.

Compared with FIG. 8, in the example of the present invention of FIG. 2, a taper portion is provided outside the electrode terminal 2 in contact with the oxide superconductor 1, and the taper portion has a thin tip. I understand. By providing a tapered portion with a thin tip, thermal stress acting on the oxide superconductor 1 during cooling can be reduced due to the difference in thermal expansion coefficient between the oxide superconductor 1 and the electrode terminal 2. In order to reduce the thermal stress acting on the oxide superconductor 1, it is preferable to reduce the thickness of the tip of the taper portion, but if the thickness of the tip of the taper portion is ½ or less of the case where there is no taper portion, The effect of providing the tapered portion can be obtained.

  By adopting the structure as in the present invention, the same effect as that obtained when the electrode terminal 2 is a composite of a good electrical conductor and a thermal contraction adjusting body having a smaller thermal expansion coefficient than that of the good electrical conductor can be obtained in the production process. Can also be obtained very simply.

  Further, if the electrode terminal portion is provided with a taper portion, there is a concern that Joule heat generation of the electrode terminal portion may increase. However, if the ratio of the taper portion length to the joint portion length (= taper portion length / joint portion length) is 1 or less. For example, the current flowing through the oxide superconductor energization element is likely to flow toward the oxide superconductor 1 in the vicinity of the junction surface between the oxide superconductor 1 and the electrode terminal 2, and is therefore large in Joule heat generation at the electrode terminal 2. There is no change. Accordingly, the ratio of the taper length to the joint length is preferably 1 or less. The taper portion is for reducing thermal stress by narrowing the tip, and if the angle between the taper portion and the joint is large, the effect of narrowing the tip is small. The angle between the tapered portion and the joint portion is preferably 45 degrees or less. Moreover, in the example of FIG.1 and FIG.2, although the taper part is thinning linearly, the same effect is acquired even if it becomes thin curvilinearly.

  FIG. 3 is a schematic structural diagram of another embodiment of the oxide superconductor energizing element of the present invention. In the example of FIG. 3, the structure in the vicinity of the joint surface of the electrode terminal 2 with the oxide superconductor 1 is stepped. By making the structure in the vicinity of the joint surface stepped, the cross-sectional area at the tip of the joint surface of the electrode terminal 2 can be reduced as in the case of the taper structure, and as a result, thermal stress acting on the oxide superconductor 1 during cooling. Can be reduced.

  Although it is preferable to reduce the thickness of the tip of the stepped structure portion, the effect of providing the stepped structure portion is obtained if the thickness of the tip of the stepped structure portion is ½ or less of the case where there is no stepped structure portion. be able to. In FIG. 3, an example of a one-stage step structure is shown, but the same effect can be obtained with a plurality of stages. If the electrode terminal portion is provided with the stepped structure portion, there is a concern that the Joule heat generation of the electrode terminal portion increases, but in order to suppress the Joule heat generation, the ratio of the stepped structure portion length to the joint length is 1 or less. Is preferred.

  By adopting the structure as in the present invention, the same effect as that obtained when the electrode terminal 2 is a composite of a good electrical conductor and a thermal contraction adjusting body having a smaller thermal expansion coefficient than that of the good electrical conductor can be obtained in the production process. Can also be obtained very simply. Furthermore, a stepped structure and a taper structure can be combined, and the same effect can be obtained.

4 to 6 are structural schematic diagrams of other examples of the oxide superconductor energizing element of the present invention. 4 to 6, a groove (or a depression) 4 is provided in the vicinity of the joint surface between the electrode terminal 2 and the oxide superconductor 1. In the example of FIGS. 2 and 3, the cross-sectional area at the tip of the joint surface of the electrode terminal 2 is reduced by making the structure in the vicinity of the joint surface of the electrode terminal 2 with the oxide superconductor 1 tapered or stepped. Although the thermal stress acting on the oxide superconductor 1 during cooling is reduced, a groove (or recess) 4 is provided in the vicinity of the joint surface of the electrode terminal 2 with the oxide superconductor 1 as shown in FIGS. The same effect can be obtained.

  In the case of this structure, thermal stress is relieved by mechanical deformation of the groove (or recess) 4. Furthermore, the groove (or recess) 4 provided in the electrode terminal 2 has an effect of increasing the adhesive strength of the adhesive when fixing the support that reinforces the oxide superconductor conducting element. When the adhesive strength of the adhesive is increased, the support sufficiently functions to suppress thermal strain, so that the resistance to thermal stress is further increased.

  When comparing the groove and the depression, the effect of relieving the stress per piece is larger in the groove, but in the case of the depression, as shown in the plan view of FIG. 7A and the cross-sectional view of FIG. A large number can be provided in an array, and the same effect can be obtained in total. As for the cross-sectional shape of the groove (or recess), a rectangular shape as shown in FIG. 4, a triangular shape as shown in FIG. 5, and a hemispherical shape as shown in FIG. If it is possible, it will not be limited to an Example.

  The groove (or depression) 4 is formed on the surface of the electrode terminal 2 that is in contact with the oxide superconductor 1 as shown in FIG. 4 and the electrode terminal 2 parallel to the joint surface with the oxide superconductor 1 as shown in FIG. It is preferable to provide on the surface. Or you may provide in both surfaces like FIG. Further, when a tapered structure or a stepped structure is provided in the vicinity of the joint surface of the electrode terminal 2 with the oxide superconductor 1, a groove (or a depression) may be provided in the tapered structure or the stepped structure portion.

The oxide superconductor used in the present invention is not particularly limited as long as it is an oxide superconductor, and RE-Ba-Cu-O (RE is at least one element selected from Y or rare earth elements). A system oxide superconductor, a Bi system oxide superconductor bulk body, etc. may be sufficient. Among oxide superconducting bulk bodies, an oxide superconducting bulk body in which a RE ₂ BaCuO ₅ phase (211 phase) is finely dispersed in a single-crystal REBa ₂ CuO _x phase (123 phase) produced by a melting method is critical. It is more preferable because of high current density.

(Example 1)
A Dy-Ba-Cu-O-based oxide superconductor having a diameter of 46 mm, a thickness of 15 mm, and a 25 mol% 211 phase finely dispersed in the 123 phase, produced by a melting method, has a length of 40 mm, a width of 3 mm, and a thickness of 1 mm. A rod-shaped sample was cut out, soldered to the copper electrode terminal 2, and reinforced with glass fiber reinforced plastics (GFRP) to produce an oxide superconductor energization element having a structure as shown in FIG.

  The longitudinal length (depth) of the groove at the center of the electrode terminal into which the oxide superconductor 1 is inserted was 5 mm, and the taper length was 4 mm. The thickness of the electrode terminal 2 at the joint surface with the oxide superconductor 1 was 4 mm on one side at a position where there was no taper, and the thickness of the tip of the tapered portion was 0.5 mm on one side.

  For comparison, an oxide superconductor energization element having a structure without a taper portion as shown in FIG. 8 was produced using the same material. Ten of each were prepared and the critical current at the liquid nitrogen temperature was compared. The average value of the critical current without the taper was 520A, but the average value of the critical current with the taper portion was 615A. From this experiment, it was confirmed that the critical current was improved by about 20% in the oxide superconductor conducting element having the structure of the present invention.

(Example 2)
A Gd—Ba—Cu—O-based oxide superconductor having a diameter of 46 mm, a thickness of 15 mm, and a 20 mol% 211 phase finely dispersed in the 123 phase, having a length of 40 mm, a width of 5 mm, and a thickness of 1 mm. A rod-shaped sample was cut out, soldered to the copper electrode terminal 2, and reinforced with GFRP to produce an oxide superconductor energization element having a structure as shown in FIG.

  The longitudinal length (depth) of the groove at the center of the electrode terminal into which the oxide superconductor 1 is inserted is 6 mm, the stepped structure is one step, and the length of the portion having a small cross-sectional area is 3 mm. The thickness of the electrode terminal 2 at the joint surface with the oxide superconductor 1 is 5 mm on one side at the thick part, and the thickness at the tip of the stepped structure portion is 1 mm on one side.

  For comparison, an oxide superconductor energization element having a structure without a stepped structure as shown in FIG. 8 was produced using the same material. Ten of each were prepared and the critical current at the liquid nitrogen temperature was compared. The average value of the critical current without the stepped structure was 980 A, but the average value of the critical current with the stepped structure was 1200 A. From this experiment, it was confirmed that the critical current was improved by about 20% in the oxide superconductor conducting element having the structure of the present invention.

(Example 3)
The component ratio of the RE site was Gd: Dy = 0.5: 0.5 with a diameter of 60 mm and a thickness of 20 mm produced by the melting method, and 30 mol% of the 211 phase was finely dispersed in the 123 phase (Gd-Dy ) A bar-shaped sample having a length of 50 mm, a width of 4 mm, and a thickness of 2 mm was cut out from a -Ba-Cu-O-based oxide superconductor, soldered to a tin-plated copper electrode terminal 2, and reinforced with GFRP. An oxide superconductor energization element having the structure as described above was produced.

  The longitudinal length (depth) of the groove at the center of the electrode terminal into which the oxide superconductor 1 is inserted is 4 mm, and the longitudinal length (depth) of the groove 4 for stress relaxation provided above and below the groove at the center of the electrode terminal. ) Was 1 mm, and the width of the groove 4 was also 1 mm.

  For comparison, an oxide superconductor energization element having a groove-free structure as shown in FIG. 8 was produced using the same material. Ten of each were prepared and the critical current at the liquid nitrogen temperature was compared. The average critical current without the grooves was 1500 A, but the average critical current with the grooves was 1850 A. From this experiment, it was confirmed that the critical current was improved by about 20% in the oxide superconductor conducting element having the structure of the present invention.

Example 4
40 mm in length, 40 mm in width, 15 mm in thickness, 25 mm% of 211 phase and a Ho-Ba-Cu-O-based oxide superconductor finely dispersed in 123 phase, 40 mm long and 2.5 mm wide A bar-shaped sample having a thickness of 1.5 mm was cut out, soldered to the silver electrode terminal 2, and reinforced with GFRP to produce an oxide superconductor energization element having a structure as shown in FIG.

  The longitudinal length (depth) of the groove at the center of the electrode terminal into which the oxide superconductor 1 is inserted is 5 mm, and the longitudinal length (width) of the groove 4 for stress relaxation provided above and below the groove at the center of the electrode terminal. ) Was 1 mm, and the depth of the groove 4 was 1.5 mm.

  For comparison, an oxide superconductor energization element having a groove-free structure as shown in FIG. 8 was produced using the same material. Ten of each were prepared and the critical current at the liquid nitrogen temperature was compared. The average critical current without grooves was 625 A, but the average critical current with grooves was 750 A. From this experiment, it was confirmed that the critical current was improved by about 20% in the oxide superconductor conducting element having the structure of the present invention.

(Example 5)
A Dy-Ba-Cu-O-based oxide superconductor having a diameter of 46 mm, a thickness of 15 mm, and a 30 mol% 211 phase finely dispersed in the 123 phase, having a length of 40 mm, a width of 3 mm, and a thickness of 1 mm. A rod-shaped sample was cut out, soldered to a tin-plated copper electrode terminal 2, and reinforced with GFRP to produce an oxide superconductor energizing element having a structure as shown in FIG.

  The longitudinal length (depth) of the groove at the center of the electrode terminal into which the oxide superconductor 1 is inserted is 5 mm, and a recess 4 for stress relaxation having a diameter of 1 mm and a depth of 1 mm is provided in the vicinity of the groove. .

  For comparison, an oxide superconducting current-carrying element having a structure having no depression as shown in FIG. 8 was produced using the same material. Ten of each were prepared and the critical current at the liquid nitrogen temperature was compared. The average value of the critical current when there was no depression was 540A, but the average value of the critical current when there was a depression was 720A. From this experiment, it was confirmed that the critical current was improved by about 30% in the oxide superconductor conducting element having the structure of the present invention.

  According to the present invention, it is possible to provide an oxide superconductor energization element that is easy in the manufacturing process and has a small decrease in critical current, so that the industrial application range of the oxide superconductor is expanded.

It is a structural cross-sectional view showing a reference example of oxides superconductors energizing element. 1 is a structural cross-sectional view showing an embodiment of an oxide superconductor energizing element of the present invention. It is structural sectional drawing which shows another Example of the oxide superconductor energization element of this invention. It is structural sectional drawing which shows another Example of the oxide superconductor energization element of this invention. It is structural sectional drawing which shows another Example of the oxide superconductor energization element of this invention. It is structural sectional drawing which shows another Example of the oxide superconductor energization element of this invention. It is a top view which shows the mode of the hollow in the oxide superconductor energization element of this invention. It is sectional drawing which shows the structure of the conventional oxide superconductor energization element.

Explanation of symbols

1 Oxide superconductor 2 Electrode terminal 3 Support 4 Groove (or depression)

Claims (7)

An oxide superconductor energization element having an oxide superconductor, electrode terminals electrically joined to both ends of the oxide superconductor, and a support for reinforcing the oxide superconductor ,
A taper that continuously narrows toward the tip is provided at the joint side end of the electrode terminal with the oxide superconductor, the tip of the taper is the tip of the electrode terminal, and the thickness of the tip of the taper There Ri der 1/2 or less in the case where there is no taper portion,
Oxide superconductor energizing elements the support is characterized that you have close contact with the tapered portion.   2. The oxide superconductor energization element according to claim 1, wherein a ratio of the taper length to the joint length is 1 or less.   3. The oxide superconductor energization element according to claim 1, wherein an angle formed between the tapered portion and the joint portion is 45 degrees or less. 4. An oxide superconductor energization element having an oxide superconductor, electrode terminals electrically joined to both ends of the oxide superconductor, and a support for reinforcing the oxide superconductor ,
Wherein the stepped structure on the bonding end portions of said oxide superconductor electrode terminals provided state, and are half or less of the case where the thickness of the step-like structure tip no stepped structure,
Oxide superconductor energizing elements the support is characterized that you have close contact with the stepped structure.   5. The oxide superconductor energization element according to claim 4, wherein a ratio of the stepped structure portion length to the joint portion length is 1 or less. An oxide superconductor energization element having an oxide superconductor, electrode terminals electrically joined to both ends of the oxide superconductor, and a support for reinforcing the oxide superconductor ,
The electrode wherein a groove or indentation in the bonding end portions of the oxide superconductor of terminals, Ri least 1mm der depth of the groove or recess,
Oxide superconductor energizing elements the support is characterized that you have close contact with the groove or recess. The oxide superconductor is characterized in that a RE ₂ BaCuO ₅ phase is finely dispersed in a single-crystal REBa ₂ CuO _x phase (RE is one or more selected from Y or a rare earth element). The oxide superconductor energizing element according to any one of claims 1 to 6 .

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