JPH0453048B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical field of the invention] The present invention relates to a method for producing a compound superconductor,
For example, the present invention relates to a manufacturing method capable of stably and efficiently manufacturing a long A-15 type compound superconductor or a long Siebrel type compound superconductor. [Technical background of the invention and its problems] As is well known, the compound superconductors currently in practical use are Nb ₃ Sn and V ₃ Ga. However, magnets formed using these compound superconductors are limited to generating a magnetic field of up to 20T. On the other hand, Nb ₃ Al, Nb ₃ Ga,
A-15 type compound superconductors such as Nb ₃ Ge and Nb ₃ (Al.Ge) and Siebrel type compound superconductors such as PbMo ₆ S ₈ are known. For example, Nb ₃ Al,
_{PbMo6S8 has} a critical temperature of 18.9K and 14.4K, respectively.
High values of critical magnetic fields of 30T and 50-60T have been reported. By the way, A-15 type compound superconductors and Siebrel type compound superconductors are currently produced by sputtering,
The reality is that they are manufactured on a laboratory scale using vapor phase deposition methods such as CVD. However, in these manufacturing methods, there is a limit to the production speed, and the limit is to obtain a superconductor with a width of 1 cm, a length of several cm, and a thickness of about 2 to 3 μm. Some examples have been reported in which samples of several meters in length were prepared, but they have not been put to practical use because of large variations in superconducting properties along the length. Further, since high superconducting properties can be obtained only with a film thickness of several μm, the critical current Ic is as small as several 100 mA at most. In this way, A-15 type compound superconductors and Siebrel type compound superconductors other than Nb ₃ Sn and V ₃ Ga are
Although it has been found that superconducting properties are superior to conventional compound superconductors, the question of how to produce compound superconductors that can be put to practical use remains unresolved. [Object of the Invention] The present invention has been made in view of the above circumstances, and its purpose is to develop compound superconductors that are long and have a high critical current (for example, A-
The object of the present invention is to provide a manufacturing method that can easily and stably manufacture 15-type compound superconductors and Siebrel-type compound superconductors. [Summary of the Invention] According to the present invention, the first step is to mix a plurality of types of powder materials that serve as a base material for compound superconductor production, and to form a long shaped product by forming the mixture. and irradiating the surface of the molded product obtained through this step with a laser beam at a predetermined relative speed along the longitudinal direction of the molded product,
A second step of sequentially rapidly melting the surface portion of the molded product by this irradiation and then rapidly cooling and solidifying it to generate a compound superconducting layer in the melted and solidified portion. A method of manufacturing a superconductor is provided. More specifically, the laser beam irradiation is performed in vacuum or Ar gas. The power of the laser beam is then set to 100W or more. If the power is less than 100W, the sample will not be sufficiently melted and mixed, and the constituent elements will not react with each other. Therefore, a compound superconductor cannot be formed.
Moreover, preferable results can be obtained if the second step includes a step of performing heat treatment before and after laser beam irradiation. These heat treatment steps contribute to improving superconducting properties. In particular, the heat treatment before laser beam irradiation serves to cause the constituent elements to react with each other in advance and to assist in the formation of a superconductor by subsequent laser beam irradiation. However, it is necessary to limit the heat treatment temperature at this time to 400 to 2000°C. If the heat treatment temperature is less than 400°C, the reaction between the constituent elements will hardly proceed, and if it exceeds 2000°C, compounds other than superconductors will be formed, and favorable results will not be obtained. On the other hand, heat treatment after laser beam irradiation increases the regularity of the crystals of the compound formed by laser beam irradiation and contributes to improving superconducting properties. In this case as well, it is necessary to limit the heat treatment temperature to 300 to 1500°C. When the heat treatment temperature is less than 300°C, almost no movement of elements occurs, so it hardly contributes to improving crystal regularity. If the heat treatment temperature exceeds 1500°C, crystal grains will become coarser, and the superconducting properties will deteriorate. [Effects of the Invention] According to the production method of the present invention, the effect of rapidly melting by laser beam irradiation and then rapidly cooling and solidifying, that is, the rapid melting makes it possible to improve the mixing of the reaction materials. It is possible to accelerate the reaction and to make the reaction uniform, and by rapidly cooling and solidifying, it is possible to make the reaction crystal grains finer. Superconductors or Siebrel-type compound superconductors can be easily produced.
In particular, in the manufacturing method of the present invention, the surface of the molded workpiece obtained in the first step is simply irradiated with a laser beam, so either the laser beam is fixed and the molded workpiece is moved at high speed, or A long superconductor can be easily produced by fixing a molded workpiece and sweeping a laser beam at high speed. Further, since it is possible to form a superconductor layer several 100 μm thick by laser beam irradiation, a superconductor with a sufficiently high critical current Ic can be produced. As described above, according to the manufacturing method of the present invention, the critical temperature is lower than that of Nb ₃ Sn and V ₃ Ga, which are currently in practical use.
Tc, critical magnetic field Bc ₂ , and critical current density Jc are much higher, and long compound superconductors can be easily produced. Therefore, it is possible to contribute to the realization of a superconducting magnet that generates a stronger magnetic field. In addition, conventional Nb ₃ Sn and V ₃ Ga superconductors are manufactured using a composite processing method, which requires many steps such as wire drawing, extrusion, and intermediate annealing, as well as diffusion heat treatment in the final step. number 10 ~ number
It requires 100 hours. However, according to the manufacturing method of the present invention, a superconductor can be manufactured by laser beam irradiation in an extremely short period of time, so that manufacturing costs can be significantly reduced. [Embodiments of the Invention] Examples of the present invention will be described below. Example 1 As sample number 1, Nb powder with a purity of 99% and purity
99.9% Al powder was mixed at a ratio of Nb-25 at% Al, and this was filled into a Cu tube with an outer diameter of 10 mm and an inner diameter of 8 mm as a base material for forming an A-15 type compound superconductor.
Next, both ends of the Cu tube were welded and sealed, and the whole was drawn into a wire and rolled into a tape shape. After that, the outer Cu was removed with nitric acid. Obtained Nb
-The Al powder mixture tape had a thickness of 0.5 mm and a width of 3 mm. The above is the first step. In addition to the above, samples having the compositions of Sample No. 2 to Sample No. 11 shown in Table 1 were prepared in the same manner. The surface of each of the samples No. 1 to No. 11 prepared in this way was irradiated with a laser beam using the laser irradiation device 1 shown in FIG.
process). Here, the configuration of the laser irradiation device 1 will be briefly explained as follows. That is, 2 in the figure is a CO ₂ laser oscillator (maximum output 10KW). This CO ₂ laser oscillator 2
A laser beam 3 emitted from the vacuum chamber 6 is guided into a vacuum vessel 6 via a reflecting mirror 4 made of Cu and a lens 5 made of ZnSe. A feed drum 8 for sending out the sample 7 and a winding drum 9 for winding up the sample 7 are provided in the vacuum container 6.
After being irradiated with the laser beam 3, the sample 7 sent from the sample 7 is wound onto a winding drum 9. In addition, the vacuum container 6 is equipped with an exhaust pump 10.
and is selectively connected to the Ar gas cylinder 11. Then, each sample was irradiated with a laser beam in the following manner. That is, first, sample 7
After setting the feed drum 8 and take-up drum 9, the pressure inside the vacuum container 6 is reduced to 10 _-5 torr, and then
Ar gas was introduced to create a pressure of 1 atmosphere. Next, sample 7
The surface of the sample 7 was irradiated with the laser beam 3 having the power shown in Table 1 while being unwound from the winding drum 8 at a speed of 10 m/min. When we observed the samples that had been irradiated in this way, for example, each sample that had been irradiated with a laser beam with a power of 2.5 KW, we found that the surface of sample 7 had a width of about 0.5 mm and a depth of about 0.1 mm, as shown in Figure 2. A compound superconducting layer 12 was formed.
The surface looked like welding marks. For each sample with a compound superconducting layer formed in this way, the critical temperature Tc and the critical current Ic at 17T
When measured, the results shown in column b of Table 1 were obtained. As can be seen from these results, each sample has Tc
is sufficiently high, and Ic is also over 10A. This is converted to critical current density Jc by 2×
This is a large value of 10 ⁴ A/cm ² or more. The Ic of compound superconductors obtained by conventional vapor phase deposition is several hundred at most.
Considering that it is mA, the adoption of this manufacturing method results in an improvement of about two orders of magnitude or more. Further, when the longitudinal characteristics of each sample were examined, it was confirmed that the characteristics were the same as those in column b of Table 1 over the length range of 30 to 100 m. In other words, by adopting this manufacturing method, a sufficiently high
A long compound superconductor containing Tc and Ic can be easily produced. Therefore, by using the compound superconductor produced by this production method, it is possible to produce a superconducting magnet that generates a strong magnetic field of 20 T or more, which was previously considered impossible. On the other hand, after laser beam irradiation, a portion of each sample was heat-treated at 700°C for 100 hours. As a result, as shown in column c of Table 1, each sample was 1K
An increase in Tc before and after the test was observed, and an increase in Ic at 17T was also observed. In addition, a portion of each sample was heat-treated at 1000°C for 30 minutes before laser beam irradiation. Regarding the above parts of each sample after laser beam irradiation
When Tc and Ic were measured, it was confirmed that each was improved as shown in column d of Table 1. Furthermore, a portion of each sample that obtained the results in column d of Table 1 was subjected to heat treatment at 700° C. for 100 hours after laser beam irradiation. For these parts, Tc
When Tc and Ic were measured, as shown in column e of Table 1, an increase in Tc and Ic was observed in each sample. Therefore, it has been found that it is effective to perform heat treatment before and after laser beam irradiation.

【table】

[Table] Example 2 In the first step explained in Example 1, when producing an Nb group A-15 type compound, the Nb tube was used as a tube to be filled with each powder; A V-tube is used to produce a Siebrel-type compound, and a Mo-tube is used to produce a Siebrel-type compound. After filling with powder in the same manner as in Example 1, sealing and molding are performed to form the above-mentioned tube. The laser beam was irradiated without removing it. When we investigated the characteristics of each sample obtained in this way, we found that b
Almost the same results as shown in the column were obtained. With such a manufacturing method, the step of removing the tube can be omitted, which can further contribute to cost reduction. Example 3 Sample number 8 shown in column a of Table 1 of Example 1
(Nb-17.5at%Al-7.5at%Ge) and 11 samples each having the same composition as sample number 9 (V-25at%Si) were prepared, and a laser power of 10W to 10KW was applied to these samples. Laser beams with different powers were irradiated within the range of . We measured Ic at 17T for these samples and investigated the dependence of Ic on laser power. Figure 3 shows the results. In the figure, A shows the case of a Nb-Ai-Ge sample, and B shows the case of a V-Si sample. As can be seen from Fig. 3, a laser power of 100 W or more is required to obtain a high critical current Ic.
In this experiment, a CO ₂ laser oscillator with a maximum output of 10KW was used. For this reason, it was not possible to irradiate a laser beam with a power exceeding 10 KW, but from the results shown in FIG. 3, it can be judged that sufficiently high characteristics can be obtained even with a power exceeding 10 KW. Example 4 Sample number 6 shown in column a of Table 1 of Example 1
Prepare 15 samples identical to (Nb-25at%Ge),
Before laser beam irradiation, each sample was heat treated for 30 minutes at different temperatures within the range of 100 to 2500℃, and each sample after each heat treatment was irradiated with a laser beam with a power of 3KW to obtain 15 compound superconductors. . For these superconductors, Ic at 17T was measured, and the dependence of Ic on the temperature of heat treatment before laser irradiation was investigated, and the results shown in FIG. 4 were obtained. Note that in FIG. 4, C indicates the value of a superconductor of the same composition that has not been subjected to heat treatment. From FIG. 4, it was found that a heat treatment temperature range of 400 to 2000° C. before laser beam irradiation is effective. Example 5 Eleven samples with the same composition as the sample (Nb-25at%Ge) used in Example 4 were prepared, and 1000 samples of each of these samples were prepared.
After heat treatment at ℃ for 30 minutes, a laser beam with a power of 3KW was irradiated. After irradiation, each sample was heat treated at different temperatures within the range of 100 to 1800°C for 100 hours. obtained in this way
When Ic was measured for 11 superconductors under 17T conditions, the results shown in Figure 5 were obtained. Note that D in the figure is the value of a superconductor of the same composition that was not heat-treated after laser beam irradiation. From this figure 5, the heat treatment temperature after laser beam irradiation is 300
A temperature of ~1500°C was found to be effective. Example 6 Sample number 1 shown in column a of Table 1 of Example 1
We prepared 11 samples with the same composition as (Nb-25at%Al), and after irradiating these samples with a laser beam with a power of 2.5KW, we heat-treated each sample for 100 hours at different temperatures within the range of 100 to 1800℃. Summer. 17T for the 11 superconductors obtained in this way
When Ic was measured under the following conditions, the results shown in FIG. 6 were obtained. Note that E in the figure indicates the value of a superconductor of the same composition that was not heat-treated after laser beam irradiation. From this figure 6, it can be seen that even when heat treatment is performed separately after laser beam irradiation, the
It was found that a heat treatment temperature of °C was effective. In each of the above-mentioned Examples, the composition shown in column a of Table 1 is used as the base material for forming an A-15 type compound superconductor or a Siebrel type compound superconductor, but the composition is not limited to this. None. That is, as a base material, (1) a mixture of one type of powder selected from Nb and V and at least one type of powder selected from Al, Ge, and Si, (2) Nb,
A mixture of alloy or compound powder consisting of two or more elements among Al, Ge, Ga, and Si and Nb powder,
(3) A mixture of powder of an alloy or compound consisting of two or more elements among V, Al, Ge, Ga, and Si and powder of V; (4) One element among Al, Ge, Ga, and Si. At least one powder selected from the alloys or compounds of the above elements and Nb; (5) alloys or compounds of V and one or more elements among Al, Ge, Ga, and Si; At least one selected powder, (6) Al, Ge,
At least one powder selected from alloys or compounds of one or more elements among Ga and Si and Nb, and at least one powder selected from Al, Ge, Ga, and Si. 2 of Al, Ge, Ga, Si
(7) At least one powder selected from alloys or compounds of one or more elements among Al, Ge, Ga, and Si and V and a mixture with powder of an alloy or compound of more than one element. and at least one powder selected from Al, Ge, Ga, and Si, or Al, Ge,
(8) Metal M (M is Pb, Sn,
A mixture of (9) metal M (M is selected from Pb, Sn, Cu, and Ag) powder, Mo powder, and S powder; (10) a mixture of sulfide powder of metal M (M is one element selected from Pb, Sn, Cu, and Ag); A mixture of powder, Mo powder, and at least one powder selected from the above metal M powder and S powder, (11) metal M (M is Pb, Sn, Cu, and Ag); selected 1
a mixture of at least one powder selected from the sulfide powders of the metal M and a sulfide powder of Mo, (12) a metal M (M is Pb,
At least one powder selected from the sulfide powder of the above metal M; a sulfide powder of Mo; powder, a mixture with at least one powder selected from S powder, (13) S powder,
One or more powders selected from sulfide powder of metal M (M is one element selected from Pb, Sn, Cu, and Ag) and sulfide powder of Mo, and the above metals. A mixture of M and Mo alloy or compound powder, (14) S powder, metal M (M is Pb, Sn, Cu,
one or more powders selected from a sulfide powder of one element selected from Ag, a sulfide powder of Mo, and a powder of an alloy or compound of the metal M and Mo. , a mixture of the above metal M powder and at least one powder selected from Mo powder, (15) metal M (M is one element selected from Pb, Sn, Cu, and Ag); ), a powder of a compound consisting of the three elements Mo and S, or a powder of the above powder and the above metal M, a powder of Mo, a powder of S, a powder of the above metal M and
A mixture with at least one powder selected from powders of alloys or compounds with Mo, powders of sulfides of metal M, and powders of sulfides of Mo, (16) (9) to (15) above. The sulfide powder of metal M in
A mixture in which two or more of the metals M having different compositions are substituted with sulfide powder, (17) the above (11) to
The Mo sulfide in (15) has two different compositions.
A mixture in which more than one species of Mo is substituted with sulfide,
(18) The powder of the compound consisting of the three elements of metal M, Mo, and S in (15) above has two different compositions.
A mixture or the like can be used in which the above metal M is substituted with a powder of a compound consisting of three elements of Mo and S.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a laser irradiation device used in an embodiment of the manufacturing method of the present invention, FIG. 2 is a local perspective view of a compound superconductor manufactured by the manufacturing method of the present invention, and FIG. FIGS. 6 to 6 are diagrams showing the results confirmed by each example. 1... Laser irradiation device, 2... CO ₂ laser oscillator, 3... Laser beam, 6... Vacuum container, 7
...Sample, 12...Compound superconducting layer.

Claims (1)

[Scope of Claims] 1. A first step of mixing a plurality of types of powder materials that serve as a base material for compound superconductor production, and forming a long molded product by molding this mixture; and this step. A laser beam is irradiated onto the surface of the molded workpiece obtained by the method at a predetermined relative speed along the longitudinal direction of the molded workpiece, and this irradiation sequentially rapidly melts the surface of the molded workpiece. a second step of forming a compound superconducting layer in the melted and solidified portion by rapidly cooling and solidifying the compound superconductor. 2. The method for manufacturing a compound superconductor according to claim 1, wherein the power of the laser beam is 100 W or more. 3 In the second step, the molded workpiece is treated with the molded workpiece before the molded workpiece is irradiated with the laser beam.
The method for producing a compound superconductor according to claim 1, which comprises a step of heat treatment at 400 to 2000°C. 4 The second step is to irradiate the molded workpiece with the laser beam and then irradiate the molded workpiece with the laser beam.
2. The method for producing a compound superconductor according to claim 1, which comprises a step of heat treatment at 300 to 1500°C. 5. Claim 5, characterized in that the powder material is one kind of powder selected from Nb and V, and at least one kind of powder selected from Al, Ge, and Si. A method for producing a compound superconductor according to item 1. 6. Claim 1, characterized in that the powder material is an alloy powder or compound powder consisting of two or more elements among Nb, Al, Ge, Ga, and Si, and Nb powder. A method for producing a compound superconductor. 7. Claim 1, characterized in that the powder material is an alloy powder or compound powder consisting of two or more elements among V, Al, Ge, Ga, and Si, and a V powder. A method for producing a compound superconductor. 8 The powder material is one of Al, Ge, Ga, and Si.
2. The method for producing a compound superconductor according to claim 1, wherein the method is at least one powder selected from an alloy powder or a compound powder of Nb and one or more elements. 9 The powder material is one of Al, Ge, Ga, and Si.
2. The method for producing a compound superconductor according to claim 1, wherein the powder is at least one kind selected from an alloy powder or a compound powder of at least one element and V. 10 The powder material includes at least one powder selected from alloy powder or compound powder of Nb and one or more elements among Al, Ge, Ga, and Si;
At least one selected from Al, Ge, Ga, and Si
The method for producing a compound superconductor according to claim 1, wherein the method is a seed powder, an alloy powder or a compound powder of two or more elements among Al, Ge, Ga, and Si. 11 The powder material includes at least one powder selected from alloy powder or compound powder of V and one or more elements among Al, Ge, Ga, and Si;
At least one selected from Al, Ge, Ga, and Si
2. The method for producing a compound superconductor according to claim 1, wherein the method is a seed powder or an alloy powder or a compound powder of two or more elements among Al, Ge, Ga, and Si. 12 The powder material is a metal M (M is Pb, Sn,
2. The method for producing a compound superconductor according to claim 1, wherein the powder is a powder of one element selected from among Cu and Ag, a powder of Mo, and a powder of S. 13 The powder material is a metal M (M is Pb, Sn,
The method for producing a compound superconductor according to claim 1, characterized in that the sulfide powder is a sulfide powder of one element selected from Cu and Ag, and a powder of Mo. 14 The powder material is a metal M (M is Pb, Sn,
a sulfide powder of one element selected from Cu, Ag), a Mo powder, and at least one powder selected from the above metal M powder and S powder. A method for producing a compound superconductor according to claim 1, characterized in that: 15 The powder material is a metal M (M is Pb, Sn,
one type of element selected from Cu, Ag) powder,
2. The method for manufacturing a compound superconductor according to claim 1, characterized in that at least one powder selected from the sulfide powders of metal M and sulfide powder of Mo are used. 16 The powder material is a metal M (M is Pb, Sn,
one type of element selected from Cu, Ag) powder,
At least one powder selected from the sulfide powder of metal M, sulfide powder of Mo, powder of Mo, and powder of S. A method for producing a compound superconductor according to claim 1, characterized in that: 17 The powder material is S powder, metal M (M is
One element selected from Pb, Sn, Cu, Ag)
1 or more powders selected from sulfide powder of M and sulfide powder of Mo, and an alloy powder or compound powder of the metal M and Mo. A method for producing the compound superconductor described. 18 The powder material is S powder, metal M (M is
One element selected from Pb, Sn, Cu, Ag)
sulfide powder, one or more powders selected from sulfide powder of Mo, an alloy powder or compound powder of the metal M and Mo, a powder of the metal M,
and at least one kind of powder selected from powders of Mo.
A method for producing a compound superconductor as described in Section 1. 19 The powder material is a metal M (M is Pb, Sn,
A compound powder consisting of three elements (one kind of element selected from Cu, Ag), Mo and S, and the above metal M
powder, Mo powder, S powder, the above metal M and
Alloy powder or compound powder with Mo, the above metal M
2. The method for producing a compound superconductor according to claim 1, wherein at least one powder selected from Mo sulfide powder and Mo sulfide powder are used. 20. Any one of claims 13 to 19, characterized in that the sulfide powder of the metal M is replaced with two or more sulfide powders of the metal M having different compositions. A method for producing a compound superconductor according to. 21 The Mo sulfide powder has a different composition 2
Claims 15 to 19, characterized in that the Mo sulfide powder is substituted with at least one Mo sulfide powder.
A method for producing a compound superconductor according to any one of the above. 22 The compound powder consisting of the three elements of the metal M, Mo and S is replaced with a compound powder consisting of two or more of the metals M, Mo and S, which have different compositions. A method for producing a compound superconductor according to claim 19. 23. The method for manufacturing a compound superconductor according to any one of claims 5 to 11, wherein the powder material is filled into a Nb tube or a V tube. 24. Claims 12 to 22, characterized in that the powder material is filled into a Mo tube.
A method for producing a compound superconductor according to any one of the above.