JPH01196105A - Superconductive oxide solenoid and manufacture thereof - Google Patents

Abstract

PURPOSE:To obtain a superconductive oxide solenoid, which has a dense structure having no crack and high critical current density and the number of turns of which can be doubled easily, by a method wherein a cylindrical member made of silicon nitride is provided with helical grooves on its inner and outer surfaces and with a through-hole connecting the grooves, and superconductive oxide coils are disposed in the grooves and through-hole by the use of the cylindrical member as a winding core. CONSTITUTION:A superconductive oxide is buried as wire-like into an inner circumferential surface side groove 12, an outer circumferential surface side groove 13 and a through-hole 14, resulting in that an inner circumferential surface side coil 15 and an outer circumferential surface side coil 16 composed of the superconductive oxide and a connecting wire 17 are disposed on the inner circumferential surface and outer circumferential surface of a cylinder member 11. Electric power is supplied through the end sections 18, 19 of the coils 15 and 16, and the cylinder member 11 functions as a solenoid using the superconductive oxide as a conductor at a temperature lower than a fixed critical temperature. Sufficient insulating properties are ensured between the mutual conductors of each coil 15, 16. Since the conductors are insulated by the grooves, the pitches of the coils are made smaller than conventional devices. The coils 15, 16 are connected electrically by the connecting wire 17, and the number of turns can easily be doubled without reducting the pitches of the wire.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a superconducting oxide solenoid that uses superconducting oxide as a conductor and which enables production of a small and powerful electromagnetic magnet 1, and a method for producing the same.

[Prior Art] Conventionally, a superconducting oxide solenoid has been manufactured as follows. FIG. 3 is a schematic diagram showing a conventional manufacturing method. A cylindrical winding core 1 has an insulating layer coated on its outer peripheral surface. Then, a mixture T of oxides having a composition exhibiting superconductivity
h (for example, Y2O3; 1/2 mol, BaO; 2 mol,
CuO (mixed at a blending ratio of 3 moles) is kneaded into a paste, and this paste oxide 3 is charged into the cylinder 2. Next, this oxide 3 is pushed out from the noise 5 at the tip of the cylinder 2 onto the outer peripheral surface of the winding core 1 by the piston 4. Then, by rotating the winding core 1 around its axis and moving the nozzle 5 in the axial direction of the winding core 1,
The oxide 3 extruded from the nozzle 5 is formed into a coil shape on the circumferential surface of the winding core 1.

Next, the oxide 3 wound around the winding core 1 is heated and fired together with the winding core 1 at approximately 900°0 for several hours to several tens of hours in an oxidizing atmosphere to generate a superconducting oxide and forming a superconducting solenoid. Manufacture. A superconducting solenoid manufactured by such a method has a critical current density of approximately 1000 A/
era.

FIG. 4 is a schematic diagram showing another conventional manufacturing method. Superconducting oxide powder 7 is enclosed in a silver vibro, and this powder 7 is knotted with a drawing die 8 together with the silver vibro to make it into a fine wire, and the wire 9 after wire drawing is coated with an insulating layer. The core 1 is wound with: Z oil. Next, this wire 9 is heated together with the winding core 1 at a temperature of about 900° C. for several hours to several tens of hours in an oxidizing atmosphere to sinter the oxide powder 7 in the silver vibro. Thereafter, the silver vibro is dissolved with acid to obtain a superconducting oxide solenoid. A superconducting solenoid manufactured in this way at °C has a critical current density of about 50 OA/cn? It is.

[Problems to be Solved by the Invention] However, all of these conventional methods have the following drawbacks. First, in the case of the method shown in Figure 3, when the cylindrical core 1 is heated to the firing temperature, it tends to thermally expand, whereas the coiled oxide paste 3 densifies during firing. Shrink. Therefore, the coiled oxide paste that is about to shrink is subjected to a tensile force by the winding core 1 that is about to expand, and fine racks are generated locally. When such a rack occurs, the number of superconducting paths decreases significantly, and the superconducting properties deteriorate.

Further, in the case of the method shown in FIG. 4, when the silver pipe 0 is heated to the firing temperature, it tends to thermally expand, whereas the oxide compact 7 inside the silver vibro tends to contract. For this reason, cracks also occur in the powder 7 and the superconducting properties deteriorate. Furthermore, since the powder 7 in the silver vibro is compressed and then wound into a coil, cracks may occur in the powder 7 when it is wound into a coil.

Furthermore, when attempting to double the number of turns using the conventional method, it is necessary to wind the coil twice, and it is necessary to insulate the conductor before winding it. In this case, as shown in FIG. 3, when extruding into a paste form, the first layer is unstable, so special consideration is required when extruding the second layer. On the other hand, as shown in FIG. 4, in the case of a metal seal, the diameter of the conductor increases due to insulation treatment, making it difficult to obtain a small solenoid.

The present invention has been made in view of such problems, and includes:
It is an object of the present invention to provide a superconducting oxide solenoid that has a dense structure without cracks, a high critical current density, and can easily double the number of turns, and a method for manufacturing the same.

[Means for Solving the Problems] A superconducting oxide solenoid according to the present invention includes a spiral groove formed on the inner peripheral surface and the outer peripheral surface of a cylindrical member made of silicon nitride,
a through hole that penetrates the cylindrical member in the thickness direction at one end of the cylindrical member and connects a groove on the inner circumferential surface and a groove on the outer circumferential surface; and a superconducting oxide coil connected through the through hole.

A method for manufacturing a superconducting oxide solenoid according to the present invention includes carving a spiral groove on the inner circumferential surface and outer circumferential surface of the solenoid, and penetrating the spiral groove in the thickness direction at one end thereof to form the inner circumferential groove and the outer circumferential groove. A cylindrical member made of silicon nitride provided with a through hole connecting the two is immersed in a melt having a superconducting oxide composition, and after solidifying the melt in the spiral groove and through hole, The method is characterized in that a superconducting oxide is generated by removing the coagulated material adhering to the outside, and then heat-treating the coagulated material within the spiral groove and through-hole.

[Function] In the superconducting oxide solenoid according to the present invention, a spiral groove is formed on the inner and outer circumferential surfaces of a silicon nitride cylindrical member having excellent electrical insulation and thermal shock resistance, and a A coil of superconducting oxide is placed in each case, and both coils are electrically connected through a through hole provided at one end of the cylindrical member. Therefore, according to the present invention, special insulation treatment is possible.
The number of turns can be doubled without adding = 6-.

In addition, in the method of the present invention, a cylindrical member made of silicon nitride with spiral grooves carved on the inner peripheral surface and outer peripheral surface and a through hole connecting the pair of grooves is fused with a superconducting oxide composition. Immerse in liquid. Then, the melt solidifies in the spiral tube. Therefore, when this cylindrical member is pulled up from the melt and the solidified matter adhering to areas other than the inside of the spiral groove and the through hole is removed, the solidified matter of the melt remains in the spiral groove in the form of a coil. Next, this coiled solidified material is heat-treated to produce a superconducting oxide, thereby producing a superconducting oxide solenoid with double the turn number density. In this way, in the present invention, the solenoid is molded by the melt-solidification method, so that cracks and the like do not occur in the solenoid as in the conventional method, and excellent superconducting properties can be obtained.

[Examples] Examples of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing a superconducting oxide solenoid according to an embodiment of the present invention, and FIG. 2 is a sectional view in the thickness direction of a cylindrical member. An inner circumferential side groove 12 and an outer circumferential side groove 13 are spirally carved on the inner circumferential surface and outer circumferential surface of the cylindrical silicon nitride cylindrical member 11, respectively. And cylindrical member 1
1 has an inner circumferential side groove 12 and an outer circumferential groove 1 at one end in the longitudinal direction.
A through-hole 14 is provided extending through the thickness direction.

Superconducting oxide is linearly embedded in the inner circumferential surface side groove 12, outer circumferential surface side groove 13, and through hole]4, thereby forming an inner circumferential surface coil 15 and an outer circumferential surface coil 1 of superconducting oxide, respectively.
6 and connecting wires 17 are arranged on the inner and outer peripheral surfaces of the cylindrical member 11.

In the superconducting oxide solenoid configured in this way, the inner circumferential surface side coil 15 extending from the other end of the cylindrical member 11 is
By supplying power through the ends 18 and 19 of the outer peripheral surface side coil 16, the coil 16 acts as a solenoid using superconducting oxide as a conductor at a temperature below a predetermined critical temperature. In this case, since the conductors of each coil 15, 16 are embedded in the grooves 12, 13 formed in the electrically insulating silicon nitride cylindrical member 11, sufficient insulation is ensured between them. . Furthermore, since the grooves provide insulation, the pitch of the coils can be made smaller than in the past. Furthermore, the coils 15, 1.6 are connected to the connecting wire 1 embedded in the through hole 14.
7, the number of turns can be easily doubled without reducing the pitch of the wire compared to the conventional case where the superconducting wire is wound on one circumferential surface. be able to.

Next, a melt having a superconducting oxide composition is stored in the six crucibles described above for manufacturing the superconducting oxide solenoid, and heated and maintained at a temperature of, for example, 1300°C. and,
A cylindrical member 11 made of silicon nitride, in which grooves 12, 13 are formed and through holes 14 are provided, is immersed in the melt in this crucible.

Then, the solidified melt adheres in a layer to the inner and outer peripheral surfaces of the cylindrical portion 4 and 11, including the insides of the holes 12 and 13 and the through hole 14. Thereafter, the cylindrical member 11 is pulled up from the melt, and unnecessary solidified matter adhering to the portions of the cylindrical member 11 other than the spiral groove 12.1.3 and the through hole 14 is chemically dissolved or gradually removed using a grindstone. The grooves 12, 1 of the cylindrical member 11 are removed by grinding, as shown in FIG.
．． The solidified oxide is left only in the holes 3 and 14.

As a result, a coil-shaped oxide having a superconducting composition is formed on the inner peripheral surface and outer peripheral surface of the cylindrical member 11.

Thereafter, this oxide is heat-treated together with the cylindrical member 11 at, for example, 930° C. for several hours to several tens of hours in an oxidizing atmosphere, thereby firing the oxide and producing a superconducting oxide coil. As a result, a superconducting oxide solenoid having the electrically insulating silicon nitride cylindrical portion 1'J' 11 as a winding core is manufactured.

In this example, since the cylindrical member 11 is made of silicon nitride, the cylindrical member 11 can be immersed in the melt in the crucible and subjected to rapid temperature changes from room temperature to 1300°C. It will not be damaged by thermal shock. In addition, this silicon nitride reacts with the oxide melt to create a buffer layer at the interface (between the inner surface of the groove of the cylindrical member 1 and the oxide solidified material) that absorbs slight differences in the coefficient of thermal expansion. do. This M layer suppresses the occurrence of cracks in the solidified oxide during the process of solidifying the melt and cooling the solidified material to room temperature. Moreover, this buffer layer suppresses the occurrence of cracks in the oxide even during the heat treatment in the post-process.

Next, the results of actually manufacturing a superconducting oxide solenoid using the method of the present invention will be described.

An oxide containing 1/2 mole of Y2O3, 2 moles of BaO, and 3 moles of CuO was heated and melted in an aluminum crucible up to 1300°C and maintained at this temperature. Then, 20 turns of a semicircular spiral ij^ with a groove cross-sectional area of 1- were carved on the inner and outer circumferential surfaces of a silicon nitride cylindrical member with a length of 60 mm, an outer diameter of 30 mm, and an inner diameter of 24 mm. , furthermore, one end of the cylindrical member has a diameter of 1.6+nm.
A through hole was provided to connect both spiral grooves. Then, after immersing this cylindrical member in the melt in the aluminum crucible and taking it out, the solidified material is gradually dissolved from the surface layer with 5N (regular) nitric acid, and finally the solidified material is only formed in the spiral groove. remained. Thereafter, when heat-treated at 930° C. for 30 hours in an oxygen gas flow for 100 m and 07 minutes, this coiled oxide exhibited a superconducting state even when a current of 50 A was passed through it.

In addition, when an electromagnet is created by insulating the circumferential surface of a mild steel iron core with a diameter of about 20 man, and then inserting this iron core inside the cylindrical member, the 20 man
It had twice the magnetic force compared to the one with superconducting coils arranged in turns.

In addition, a solenoid with similar characteristics was obtained by grinding with an endless belt with abrasive grains moving at a low speed of 1 m/min using methyl alcohol as a coolant, without using chemical dissolution. .

[Effects of the Invention] As explained above, the superconducting oxide coil according to the present invention is a cylinder made of silicon nitride with spiral grooves carved on its inner and outer circumferential surfaces and a through hole connecting both grooves. Since the superconducting oxide coil is placed in the groove and through hole using the member as a winding core, the number of turns can be easily doubled without applying special insulation treatment to the superconducting conductor itself or increasing the external dimensions. can do.

In addition, in the method for manufacturing a superconducting oxide solenoid according to the present invention, a cylindrical member made of silicon nitride in which a spiral groove is carved in advance is used, and a melt having a superconducting oxide composition is solidified in the spiral groove, so that a superconducting oxide solenoid can be obtained. The resulting pores and noids become a dense structure that is not porous like powder, and the critical current density increases. In addition, when the silicon nitride cylindrical member is immersed in the melt, it slightly reacts with the oxide melt, and a buffer layer is generated at the interface that absorbs the slight difference in thermal expansion, so the melt does not solidify. Furthermore, during the process of cooling down to room temperature, cracks do not occur in the oxide solidified product. In addition, the crack prevention effect of the buffer layer is exhibited even in the subsequent heat treatment. As a result, the critical current density of the resulting solenoid increases.

[Brief explanation of the drawing]

FIG. 1 is a side view showing a superconducting oxide coil according to an embodiment of the present invention, FIG. 2 is a sectional view showing the vicinity of a through hole provided in a cylindrical member, and FIGS. 3 and 4 are views showing a conventional method. FIG.

Claims (2)

[Claims] (1) A spiral groove formed on the inner and outer circumferential surfaces of a silicon nitride cylindrical member, and a groove on the inner circumferential surface and an outer circumferential surface that penetrates in the thickness direction of the cylindrical member at one end of the cylindrical member. and a coil of superconducting oxide arranged in the groove on the inner circumferential surface and the groove on the outer circumferential surface and connected through the through hole. solenoid. (2) Nitriding in which a spiral groove is carved on the inner circumferential surface and the outer circumferential surface, and a through hole is provided at one end of the spiral groove to penetrate in the thickness direction and connect the inner circumferential groove and the outer circumferential groove. After immersing a silicon cylindrical member in a melt having a superconducting oxide composition and solidifying the melt in the spiral groove and the through hole, removing the solidified material that has adhered to areas other than the spiral groove and the through hole, A method for manufacturing a superconducting oxide solenoid, characterized in that a superconducting oxide is generated by subsequently heat-treating the solidified material in the spiral groove and the through hole.