JPS63107004A - Manufacture of nb3sn series superconductive disk - Google Patents

Abstract

PURPOSE:To form a superconductive intermetallic compound uniformly in the whole region of a disk, and to manufacture the superconducting disk displaying stable superconductive characteristics by covering a substrate with a thin member containing Sn and executing heat treatment through which a laminated plate is heated at a specific temperature. CONSTITUTION:A first substrate 11 in a laminated plate 14 with the first substrate 11 containing Cu and a second substrate 12 including Nb is covered with a thin member 15 containing Sn, and first heat treatment through which the laminated plate 14 is heated at a temperature higher than the melting point of Sn and lower than 300 deg.C is executed. Second heat treatment through which the laminated plate 14 is heated at a temperature higher than the first heat treatment temperature and lower than a diffusion heat treatment temperature is carried out, and diffusion heat treatment for forming Nb3Sn is executed, thus manufacturing a superconductive disk 20. The thin member 15 such as one consisting of Sn is stuck onto the surface of the laminated plate 14 in which the first substrate 11 such as one composed of Cu, the second sub strate 12 such as one made up of Sn and a stabilized substrate such as one 13 consisting of Cu are laminated. The upper surface of the member 15 is covered with a ceramic board 16 and first heat treatment is carried out, and an intermediate layer 11a composed of Cu and Sn is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a method of manufacturing a Nb3Sn-based superconducting disk used for a magnet for a particle accelerator, a magnet for a nuclear magnetic resonance apparatus, etc.

"Prior Art" Nb3Sn-based superconductors are known as superconductors that have a high critical temperature and can obtain a large critical current density. As an example of a method for manufacturing a superconducting disk constructed using this Nb3Sn-based superconductor, conventional methods shown in FIGS.
A method described below based on the figures is known.

To manufacture the Nb3Sn-based superconducting disk, first, as shown in FIG. 6, a first substrate l made of Cu or a Cu-Sn alloy, a second substrate 2 made of Nb, and a stable substrate made of Cu or Cu alloy A laminated plate 4 is formed by bonding the first substrate 1 and the first substrate 1, and a Sn plating layer 5 is formed on the surface of the first substrate 1 by electroplating.

Next, the laminated plate 4 is heat-treated to diffuse Sn in the Sn plating layer 5 into the first substrate 1, so that the first substrate 1 is
The alloy plate 6 shown in the figure has a high SnQ degree.

Next, circuit forming processing such as groove processing is performed on the surface side of the laminated plate 4, and after processing, a diffusion heat treatment is performed to generate Nb3Sn to diffuse and react Nb and Sn, thereby forming a superconducting circuit made of the Nb3Sn superconducting intermetallic compound. and manufactured superconducting sheet coils.

[Problems to be Solved by the Invention] When manufacturing a large-sized superconducting disk using the above-mentioned manufacturing method, since Sn, which contributes to the formation of Nb3Sn, has conventionally been supplied by electroplating, it is necessary to If the Sn plating layer 5 formed on the surface has a non-uniform thickness, a problem arises in that Sn is not uniformly diffused.

Here, in FIGS. 8 and 9, the thickness of the plating layer formed on the surface of the laminate 4 by the electroplating method is shown by curves B and C.
Indicated by Curve B in FIG. 8 indicates the plating thickness at each portion along the lateral direction of the laminate 4, and curve C in FIG. 9 indicates the plating thickness at each portion along the longitudinal direction of the laminate 4. Figures 8 and 9
As is clear from the figure, there is a tendency for the plating thickness on the outer peripheral side of the laminate 4 to be thicker than the plating thickness on the central part of the laminate, and the thickness of the Sn plating layer 5 It became clear that non-uniformity was occurring.

Then, using the laminated plate 4 having non-uniformity in the thickness of the Sn plating layer 5 as described above, heat treatment is performed for the purpose of diffusing Sn into the laminated plate 4 to form a Cu-Sn alloy plate with a high Snn degree. When this is done, as shown in Fig. 1θ, a portion with an extremely high Sn concentration is generated at the outermost circumference of the laminate 4, a portion E with a high Sn concentration of 1 degree is generated inside the laminate, and only the center portion of the laminate 4 has a portion E with a high Sn concentration. This results in a portion F having a uniform Sn concentration. Then, when the laminate 4 having non-uniform Sn concentration is subjected to diffusion heat treatment to diffuse Sn and generate Nb3Sn,
There is a problem in that not only the amount of N bs S n produced is partially nonuniform, but also discontinuous portions occur in the formed superconducting circuit, resulting in discontinuous superconducting paths. Furthermore, since there is a large amount of 5nffi on the outer peripheral side of the laminate 4, a brittle Cu-Sn compound is generated in the outer peripheral portion where there is a large amount of 5nfi, which has the disadvantage of deteriorating the mechanical properties of the superconducting disk.

The present invention has been made in view of the above-mentioned problems, and can produce superconducting intermetallic compounds uniformly over the entire area of the disk, making it possible to manufacture a superconducting disk that exhibits stable superconducting properties, as well as eliminating the complicated plating process. It is an object of the present invention to provide a method that can improve manufacturing efficiency by omitting this step and can manufacture a superconducting disk having a desired m of superconducting intermetallic compounds.

"Means for Solving the Problems" In order to solve the above-mentioned problems, the present invention provides a laminate including a first substrate containing Cu and a second substrate containing Nb, in which Sn is applied. In the method of manufacturing an Nb3Sn-based superconducting disk by applying diffusion heat treatment to forming a superconducting circuit after supplying the first substrate, a thin member containing Sn is covered with the first substrate, and at a temperature higher than the melting point of Sn, a first step of heating the laminate to a temperature lower than °C;
A heat treatment is performed, and then a second heat treatment is performed to heat the laminate to a temperature higher than the first heat treatment temperature and lower than the diffusion heat treatment temperature, and a diffusion heat treatment for Nb3Sn generation is further performed.

"Operation" A thin-walled member is placed over the first substrate and heated to a temperature higher than the melting temperature of Sn (
Moreover, by heating to a temperature lower than 300° C., Sn in the thin member is uniformly diffused into the first substrate to generate an η phase in the first substrate, and then heated to a temperature higher than the first heat treatment temperature. By heating to a temperature lower than the diffusion heat treatment temperature, the η phase disappears, and by further performing the diffusion heat treatment, Sn reacts with Nb of the second substrate to generate a Nb3Sn superconducting intermetallic compound.

"Example" Figures 1 to 5 show an example of the manufacturing method of the present invention. In order to manufacture an Nb3Sn superconducting sheet coil, first a first substrate 11 made of Cu or a Cu-Sn alloy is prepared. , a foil-like or plate-like second substrate 12 made of Sn.
Then, a stabilizing substrate 13 made of Cu or a Cu alloy is laminated using a joining means such as explosive welding or rolling to create a laminated plate 14 shown in FIG. Next, the first substrate l! of the laminate 14! A foil-like or plate-like thin member 15 made of Sn is pasted on the surface as shown in FIG.

Next, in an inert gas atmosphere or a vacuum atmosphere, the ceramic plate 16 is placed on the top surface of the thin member I5, and while the whole is held, the melting temperature of Sn (232° C.
) A first heat treatment is performed at a higher temperature of 300° C. or less for several tens of hours. During this first heat treatment, the thin member 15 is sandwiched between the ceramic plate 16 and the first substrate 11 in order to suppress the flow of Sn. Here, since there are fine irregularities on the surface of the ceramic plate 6, it is possible to prevent the thin member t5 from flowing due to melting. By this first heat treatment, the Sn of the thin member 15 can be completely and uniformly diffused into the first group [11], and the η phase (
The reason why the upper limit of the heating temperature in the first heat treatment is limited to 300°C is because the upper limit of the heating temperature in the first heat treatment is 300°C. This is because an intermetallic compound phase other than the η phase is generated.

Next, a second heat treatment is performed to heat the laminated plate 4 at 500 to 600° C. for several tens of hours. This second heat treatment transforms the second substrate 12 into a Cu-Sn alloy plate 1 with a high Sn concentration as shown in FIG.
7, and the Sn in the η phase can be diffused and the η phase can also be eliminated. In this second heat treatment,
Since Sn has already been uniformly diffused into the first substrate 11 by the first heat treatment, Cu-S containing Sn uniformly
n alloy plate" 7 can be created. The temperature range in which the second heat treatment is performed is limited to 500 to 600°C because, as is clear from the Cu-5n alloy phase diagram, this is the temperature range in which Sn easily forms a solid solution in Cu.

Next, the laminated plate 4 is processed with a spiral groove, and further,
Diffusion heat treatment for Nb3Sn generation (600-850℃ for 2
The alloy plate 17 is heated for about 0 to 300 hours.
By diffusing Sn into the second substrate 12, a superconducting disk 20 having a spiral Nb3Sn superconducting circuit 18 as shown in FIG. 5 is manufactured.

Note that when manufacturing the superconducting disk 20 from the laminate 4, a spiral superconducting circuit may be created by performing diffusion heat treatment while heating the laminate 4 in a spiral using a laser beam with a defined beam width. can.

The superconducting disk 20 manufactured by the above method is manufactured by diffusing Sn from the Cu-Sn alloy plate I7 in which Sn is uniformly dispersed into the second substrate 12 to generate Nb3Sn. , Nb3Sn is generated uniformly over the entire second substrate 12, and the superconducting properties do not deteriorate.

Further, in the method, using the thin member 15, Sn
Since 5nffi is supplied, the supplied 5nffi can be adjusted by adjusting the thickness of the thin member 15 to a desired value. Therefore, a superconducting disk having a desired amount of Nb3Sn superconducting intermetallic compound can be manufactured.

Furthermore, since m of Sn can be uniformly supplied to the laminated plate 4,
Even when manufacturing large superconducting disks, Nb+
This has the effect of making it possible to manufacture a superconducting disk with stable Sn generation. In addition, since the plating process that was conventionally required to be performed can be omitted, the manufacturing process of the superconducting disk can be simplified.

On the other hand, in the above embodiment, pure Sn was used as the thin member 15 to cover the first substrate 11, but Sn is known as a third element that improves the critical current characteristics of compound superconductors in high magnetic field regions. Tis Ta, In
A thin member made of an Sn alloy containing one or more of Hr, Al, and Si may also be used. A superconducting disk obtained by using this Sn alloy thin member has improved superconducting properties in a high magnetic field region.

"Manufacturing Example" A 4 mm thick bronze plate containing 8% by weight of Sn,
thickness! After joining a IIIIIII Nb plate and a 6 mm thick oxygen-free copper plate by explosive welding, they were rolled to a thickness of 0, 1111111%, width of 400 mm, length of 40 mm.
A 0 mm laminate was created. In this laminate, the thickness of the bronze part is 36 μm, and the thickness of the Nb part is 9 μm.
The thickness of the u portion was 55 μm.

A Sn foil with a thickness of 4 μm is bonded to the laminate, a ceramic plate is placed on top of the Sn foil, and a first heat treatment in which the whole is heated to 250 ° C. for 50 hours and a second heat treatment in which the whole is heated to 550 ° C. for 50 hours are sequentially performed. provided. After removing the ceramic plate, a spiral groove with a width of 2 ma+ was formed by electric discharge machining so that the groove width was 2III11. Thereafter, a diffusion heat treatment of heating at 800° C. for 50 hours was performed to react Nb and Sn to produce a Nb3Sn-based superconducting disk.

When we measured the superconducting characteristics at both ends of the completed Nb3Sn superconducting circuit, we were able to obtain a critical current characteristic value of 80 A at 10T (Tesla), and a current density of 10
It showed an excellent value of 00 A/mm''. When the inside of this superconducting disk was observed, it was found that the Nb1Sn layer had a thickness of about 5 μm in each circuit portion.

"Effects of the Invention" As explained above, the present invention provides a method for manufacturing a superconducting disk, which is manufactured by subjecting a laminate including a first substrate containing Cu and a second substrate containing Sn to diffusion heat treatment. In this step, a thin member containing Sn is placed on the first substrate, and then a first heat treatment is performed in which the thin member containing Sn is heated to a temperature higher than the melting point of Sn and 300° C. or less, and then heated to a temperature lower than the diffusion heat treatment temperature. Since the second heat treatment is performed, Sn can be uniformly diffused into the first substrate by the first heat treatment. Therefore, during the diffusion heat treatment, the metal element can be uniformly diffused into the laminated plate to uniformly generate Nb3Sn, and there is an effect that a superconducting disk without non-uniformity in superconducting properties can be manufactured.

Further, by setting the thickness of the thin member to a desired value, it is possible to set the 5nffl supplied to the laminate to a desired value, and there is an effect that a superconducting disk having a desired amount of N bs S n can be manufactured. By the way, in the conventional method, due to non-uniformity in the thickness of Sn plating, there was a problem in which Nb3Sn was produced non-uniformly when manufacturing large superconducting disks, but the method of the present invention has this problem. In addition, since metal elements can be uniformly supplied to the laminate without plating, it is possible to manufacture large-sized superconducting disks with desired characteristics.

[Brief explanation of the drawing]

Figures 1 to 5 are for explaining one embodiment of the present invention. Figure 1 is a perspective view showing a state in which a ceramic plate is placed over a laminate, and Figure 2 is a perspective view showing a state in which a ceramic plate is placed over a laminate. A side view showing the state in which it is covered, Figure 3 is Figure 3! FIG. 4 is a side view showing the state after the second heat treatment is applied to the laminate, FIG. 5 is a perspective view showing the superconducting disk, and FIGS. 6 and 7 The figures are for explaining the conventional manufacturing method of superconducting wires. Figure 6 is a cross-sectional view of a laminate, Figure 7 is a sectional view of a laminate after heat treatment, and Figure 8 is a cross-sectional view of a laminate in the lateral direction. FIG. 9 is a plan view showing the plating thickness along the longitudinal direction of the laminate, and FIG. 1O is a plan view showing the Sn concentration distribution inside the laminate. ! l...First substrate, 12...Second substrate, 13...Stabilizing substrate, 15...
...Thin-walled member, 20...Superconducting disk.

Claims (1)

[Claims] After supplying Sn to a laminate comprising a first substrate containing Cu and a second substrate containing Nb, a diffusion heat treatment is performed to form an Nb_3Sn superconducting circuit, thereby forming an Nb_3S superconducting circuit.
In the method for manufacturing an n-based superconducting disk, after covering the first substrate with a thin member containing Sn, the laminate is heated to a temperature higher than the melting point of Sn and lower than 300°C. 1 heat treatment, then performs a second heat treatment in which the laminate is heated to a temperature higher than the first heat treatment temperature and lower than the diffusion heat treatment temperature, and then a diffusion heat treatment for Nb_3Sn generation is performed. A method for manufacturing a Nb_3Sn-based superconducting disk.