DE1790062C - Superconductors with an Nb deep 3 Sn layer on the surface and processes for their production - Google Patents

Description

special high-temperature-resistant metals or metal-alloy 60 In the case of the previously known superconductors with from the

Mention, for example the deposited under the trade name gas phase Nb ^ n layers is against it

"Hastelloy" well-known nickel-based alloy. Carbon, if at all, at most as random,

The so-called critical contamination in extremely small quantities is of decisive importance for the unintentional technical use of superconductors as a result of the starting materials, see current density j _c . If this current density exists through 65 in these layers,
In a preferred embodiment of the superconductor according to the invention, the superconductor contains the Nb ₃ Sn layer, the superconductor goes from the superconducting to the electrical 0.25 to 1.3 percent by weight of carbon. Superconductor

790

_ith these carbon contents in the Nb ₃ Sn SChJcIu a second Quarzrohr2, which by means of a Quurz-

"'* wand3 is divided. One part 4 of the pipe 2,

in which during the operation of the device a niobium supply 5 is used as a niobium chloride. 5 The other part 6 of the tube 2, in which the Operation of the device a tin supply 7 is used as a tin chlorinator. The quartz tube 2 is on both Provide ends with pipe sockets 8 and 9 for introducing chlorine gas. Through the quartz wall 3 is a

d Til 4 d pipe 2 in

show // -y, values of over 5 · 10 ¹⁰ A ■ GauB ■ cm ² .

With K-Silenstoff contents of 0.4 to 1.1 weight percent: n the Nb ₃ Sn layer even // - / V values between 7-10 ^ia and about 9 to ^{10-10 10} A-Gc'uu-i -: !! ² can be achieved.

Germ- vn: he invention, the superconductor with a k-. LiLnstoffhaltigen Nb ₃ Sn-Schioht are advantageously produced in such a way that gaseous

Provide chlorine gas. Major Q

Each of niobium and tin mixed and an inflow of gas from part 4 of the tube 2 in

on et \>
hochwa
Metal-
and d; ·.
Cabbage ::

■ 750 to 1000 "C heated carrier made of a m-resistant metal or a highly heat-resistant ■: The mixture of halides is reduced to a gaseous form by means of hydrogen

prevents part 6 and vice versa. The tube I is closed at both ends with graphite bodies 10 and II, each with the narrowest possible opening for the passage of a band-shaped carrier 12

little
material '
ON
included
niobium
geeii:; - pcnl.r
and /
tin

less
Tin'
falN i
given
(Nbi

ff compound is added, which are provided on the er 15. The carrier 12 is taken from the roll 13

i rager with splitting off of carbon is partially decomposed or by the water will.

-shaped halides of nio 'and tin are ^ special niobium tetra'-horid (NbCl ₁ I b / .w.

.! jchloride (NbCl ₅ ) and tin chloride (SnCl,) L: s can also bromides, such as niobium

.mid (NbBrJ or niobium tetrabromide (NbBr ₁ ) iidibromide (SnBr ₂ ), as well as iodides of niobium and rwendet.

r can, as has already been suggested, irachloride together with tin dibromide

which is more easily reducible than .hlorid. In addition, like this

and wound onto the motorized roller 14 after coating. The carrier 12 stands with the graphite bodies 10 and 11 in electrical conductive connection. These are connected to an electrical power source via leads 15 and iu.

The pipe socket 17, which is inserted into an in the coating chamber 1 arranged with zah'-rich Openings provided tube 19 opens. Through this tube 19 a uniform distribution of the Causes hydrogen in the coating chamber To supply the gaseous carbon compound, the tube 20 is used, for example with a

It has already been proposed to avoid 30 storage vessel 21 for liquid carbon tetrachloride

any disturbing niobium trichloride-,! -deprecipitation on the walls of the coating

tung ^ - always, in which the reduction of the halides takes place, the gaseous niobium tetrachloride durci

22 can be connected. The storage vessel 21 is located in a liquid thermostat 23, which is used for Setting the temperature of the carbon tetrachloride supply 22 is used. The at the coating

Admixture of chlorine gas, at least partially in the reaction, are released by the tube niobium pentachloride be transferred. nozzle 24 removed from the coating chamber 1.

_{Carbon tetrachloride (CCl 4} ) and carbon monoxide (CO) are particularly suitable as gaseous carbon compounds. These connections split

The coating chamber 1 is connected to the quartz tube 2 through the quartz tube 25. The quartz tubes 1. 2

_Λ . ,, ......, ^ .....- .. ~ -., - ν - / · _e - .. ~ r ~ and 25 are of suitably shaped, for example

th in the presence of hydrogen at temperature 40 hinged tubular furnaces 26 surrounded by which doors between 750 and 1000 ° C, the individual parts of the device are heated in sufficient quantities Carbon, but decompose at lower temperatures.

temperatures hardly, so that the carbon separation.

takes place only on the carrier and not on the parts of the coating device with a carbon content of 0.4 percent by weight located at the lower temperature of a strip-shaped superconductor with an Nb _{3 temperature.} By appropriate choice of the amount of
Gaseous coals mixed with the halides

material compounds, the carbon content desired in each case in the Nb ₃ Sn layer can be set very precisely.

The invention will be explained in more detail using a few figures and examples.

F i g. I shows schematically an embodiment of a device for producing a tape-shaped Superconductor according to the invention;

F i g. 2 shows schematically in longitudinal section a tape-shaped superconductor according to the invention;

F i g. 3 shows the dependence of the product H · je on the carbon content in the Nb ₃ Sn layer

described in more detail using carbon tetrachloride.

For example, a band made of the high-temperature alloy known under the trade name “Hastelloy Alloy Β” (DIN designation NiMo 30) is used as the carrier 12, which has about 62 ° / ₀ Nicke !, 26 to 30 ° / ₀ molybdenum and the remaining part is small Quantities of elements cobalt, silicon, manganese, iron. Contains carbon and vanadium. This carrier

SS is inserted into the quartz tube 1 in a suitable manner and pulled through the tube at constant speed during coating. Further The starting materials niobium and tin are used in the Niöbchlorinator 4 and the Zinnchlorinator

in a superconductor according to the invention. 60 and a carbon tetrachloride supply 22 in the die in FIG. 1 is suitable storage vessel 21 introduced. Before the start of the disc, for example to produce a band-shaped formation reaction, the air is displaced from the device in the case of superconductors according to the invention, with argon being displaced from gas, for example by introducing inert gas such as helium-shaped niobium tetrachloride and tin dichloride. Via the supply lines 15 and Avird, which by passing chlorine gas 65 16 is generated by the carrier 12 electrical current ge over heated niobium or heated tin, conducts, which is dimensioned so that the carrier on a The device consists essentially of a temperature of about 900 ⁰ C is heated. With the aid of the quartz tube 1 serving as the coating chamber and the tube furnaces 26, the wall of the coating

5 6

chamber 1 are heated to about 700 ° C, the Niobchlorinator 4 and position of superconductors with carbonaceous the Zinnchlorinator 6 to about 800 ⁰ C and the encryption Nb ₃ Sn Scluchten virtually in the same way connecting pipe 25 pass to avoid condensation, as in that of the chlorides described above is heated to about 650 ° C. The carbon embodiment. Only through the pipe 20 is tetrachloride supply 22 with the help of the liquid 5 is then not with gaseous carbon tetrathermostats 23 at a temperature of 5 ° C chloride-laden hydrogen, but directly th. Through the pipe socket 8 chlorine gas is introduced into the gaseous carbon monoxide. In the case of a niobium chlorinator 4 and through the pipe socket 9, 0.1 l / h of carbon monoxide is introduced into the tin chlorinator 6 through the chlorine gas. In the case of tube 20 in the coating chamber, the chlorine gas is passed over the heated niobium device according to FIG. 1 and otherwise unchanged, gaseous niobium tetrachloride is used; when the search conditions were passed, an Nb ₃ Sn layer with 0.22% by weight of tin dichloride was formed on the band of the chlorine gas over the molten tin 7 gaseous carrier 12. The chlorides of the percent carbon deposited. The niobium and tin mixed in this way in the tube 25 and the band-shaped superconductor produced in a flow through this tube into the coating 15 external magnetic field of 50 Oe had an H'je value of chamber 1. At the same time, the coating is about 5 · 10 ¹⁰ A · Gauss · cm- *,
chamber 1 through the pipe socket 17 hydrogen of course, the gaseous halogen

led, to which to avoid Nb ₈ Sn-Nieder- nide of niobium and tin is not necessarily admixed by flashovers on the wall of the coating chamber gas conducts of halogen gas over heated niobium or tin-shaped hydrogen chloride. Furthermore, ao will be generated. Rather, hydrogen as a carrier gas can also be passed directly into the storage vessel 21 from the gaseous compounds, which there with gaseous carbon tetrahedron.

chloride is loaded and this gaseous carbon one by the method described above

Material tetrachloride is transported through the pipe 20 into the coated strip-shaped superconductor in the elongation chamber 1. The chlorides of niobium »5 cut in FIG. 2 shown. The ribbon-shaped and tin and carbon tetrachloride are "Hastelloy-Alloy-B" carrier with 31, which adorns the carbon-containing Nb ^ n layer, which is firmly adhering to the heated 1 rager i2 redu carrier by the hydrogen, with a carbon-containing layer designated by 32. Investigations on metallographic Nb ₃ Sn layer is coated. The coated see sections suggest that the built-in support is led out of the tube 1 and _{wound onto the 30 of the carbon in the Nb 3} Sn base material in the form of a roll 14. ^of finely divided excretions. It can

In the present example, however, the coating had not to be excluded that part of the chamber in the tube 1 a length of about 30 cm. The carbon with the niobium also Niobcarbidaus-Niobchlorinator 4 and the tin chlorinator 6 were divorce forms.

each about 40 cm and the connecting pipe 25 about 20 cm 35 In FIG. 3, the dependence of the # · je value is long. The tubes 1, 2 and 25 also each had the carbon content in the Nb ₃ Sn layer with the same band diameter of about 3.5 cm. The surface of the chlorine gas-shaped superconductor with NbgSn layers on the salt through the niobium chlorinator 4 was approximately shown. The HJ is _0-4 l / h on the ordinate, the chlorine gas throughput due to the tin chlorine value, and the carbon content in gate 6 is about 10 l / h on the abscissa. _{About 40 Nb 3} Sn layers in percent by weight were applied through the nozzle 17. The 15 l / h of hydrogen was introduced, to which about 2.5 l / h of the continuously drawn part of the curve and the measuring hydrogen chloride gas were added. With a carbon tetrachloride stock 22, 3 l / h of hydrogen were passed through a large number of measurements on tape-shaped as carrier gas, which at a temperature of 5 ° C determined superconductors at a temperature of 5 ° C Carbon tetrachloride saturated 45 standing embodiment using were. The tape-shaped support 12, which was made of carbon tetrachloride or carbon monoxide 0.2 cm wide and 50 μm thick, was set at one speed. The dashed part of the curve is from about 20 to 25 cm per minute by the Ro.ir 1 on the basis of the measured values estimated The outer pulled and thereby with an approximately 8 μ thick Nb ₃ Sn magnetic field H in each case was in these measurements coating mi: "", 4 percent by weight carbon content 50 50 kOe. The curve in FIG. 3 clearly shows that coated. The c value material content in the Nb ₃ Sn layer increases rapidly unc from about 7 · 10 ¹⁰ A · Gauss · cm- *. The critical current density drops again after passing through a maximum depending on the cross-section of the Nb _{3 Sn-} The highest H · jV value measured so far related to the layer: 55 9.2 · 10 ¹⁰ A · Gauss · cm *. A maximum of the H -j _e

Nb ₃ Sn layers with different carbon contents value of about 10 · 10 ¹⁰ A · Gauss · cm "* is fü, with otherwise constant conditions, carbon contents of about 0.8 to about 1.0 Ge can be produced by keeping the temperature of the Fig. 3 clearly shows the carbon tetrachloride supply 22 with the aid of the liquid that the addition of carbon changes the fluid thermostat 23. If the temperature is increased by 60 H-per values compared to the previously known values, the carrier gas is used can be increased considerably.
Hydrogen with more carbon tetrachloride, at- The thickness of the carbon-containing Nb ^ n layer.

Lower temperature with less Koblenstofftetra- in the superconductors according to the invention is advantageously loaded with chloride. The carbon tetrachloride is at hait between about 3 and 10 μ. Thinner layers under the specified conditions in the coating 65 are very difficult to deposit evenly from the gas chamber, not completely, but only to about 20 ¹ V ₀ phase; thicker layers tend to be electrically reduced. see instabilities, ie to sudden transition

When using carbon monoxide to restore the normal electrical conductivity before egg

range of the critical current density to be expected.

In addition to the tape or wire shape, the erfindungsge'i Ate superconductors also have other shapes. For example, one-sided with a

carbon-containing NbjSn-layer coated hollow cylinders for shielding magnetic fields. In addition to heat-resistant metals and metal alloys are in such superconducting bodies, for example, quartz or ceramic are also suitable as a carrier.

1 sheet of drawings

Claims (2)

ι 2 Irish noniialleitenden state over, whereby the ohm Pater.t claims: see resistance of the superconductor increases from zero to a relatively high value. The critical one 1. Superconductor, consisting of a carrier with a current density j _c , depends on the external magneteiner due to the deposition of niobium and tin from 5 field H, in which the superconductor is located in each case, gaseous compounds of these elements take up and usually with increasing external generated Nb ₃ Sn layer on the surface, d a magnetic field. The relationship between the fact that the Nb ₃ Sn-rem magnetic field and the critical current density can contain 0.1 to 1.5 percent by weight of carbon, as is known, is represented by so-called // - jc curves. that the various superconductor materials 2. Superconductor according to claim 1, characterized thereby extending differently. draws that the Nb ₃ Sn layer 0.25 to 1.3 Ge superconductors with Nb.Sn layers are known contains weight percent carbon. of particular technical importance as this 3. Superconductor according to claim 2, characterized in that the layers, even in high magnetic fields, are characterized by the fact that the Nb ₃ Sn layer shows 0.4 to 1.1 Ge 15 critical current densities. Contains superconductors with such weight percent carbon. Layers are therefore particularly useful for magnetic coils 4. Expire s for the production of a superconductor suitable for generating very high magnetic fields. Since according to one of claims 1 to 3, characterized in that the // - / - curve of Nb ₃ Sn in the range of // between indicates that gaseous halides of 50 and 80 kOe are almost hyperbolic, it is niobium and tin mixed and on a sensible to about 20, the product H ■ j _c as a measure for the current 750 to 1000 C heated carrier made of a high load-bearing capacity of superconductors with Nb _? Specify Sn layers of heat-resistant metal or a highly heat-resistant. _{In the known superconductors with Nb 3} Sn layers deposited from a metal alloy by means of hydrogen, the gas phase is reduced on the one side and on the surface of the mixture of halides, this product H · per maximum gaseous carbon compound is admixed with 25 values of about 4 · 10 ¹⁰ A Gauss cm ² . A supra becomes, which on the heated carrier with splitting off conductors with this //·./> value has, for example, carbon. a critical current density j _c = 8 · 10 ⁵ A-cm * ² . Ob-S. Method according to claim 4, characterized by the // · y _e values of these known superconductors draws that as gaseous halides of niobium 30 are already relatively high, it is in particular and tin niobium tetrachloride or niobium pentachloride for the generation of very high magnetic fields and tin dichloride can be used. desirable to increase the H- j _c values even further 6. The method according to claim 4 or 5, thereby increasing, since at a higher possible current density characterized in that less than gaseous carbon to generate a certain magnetic field compound carbon tetrachloride uses 35 turns are required and thus becomes superconductor, material saved and the outer diameter of the 7. The method according to claim 4 or 5, thereby solenoid coil can be reduced. Also marked, that as gaseous carbon stands in the manufacture of these known superconductors compound carbon monoxide is used. some difficulty in that they achieved 40 // - y't values are subject to fluctuations and cannot always be set reproducibly. The invention is based on the object Superconductors, consisting of a carrier with a gaseous through deposition of Ν> υο and tin The invention relates to a superconductor, consisting of 45 gene connections the = c elements produced Nb ₃ Sn- from a carrier with a layer deposited on the surface, on the one hand the // - y'e values Niobium and tin from gaseous compounds increase this further _Z u and on the other hand the Hj _c values Elements produced Nb ₃ Sn layer on the surface. to make reproducible. Such superconductors in which, for example, the superconductor is used to solve this problem Nb ₃ Sn layer formed according to the invention by reducing the chlorides of 50 in such a way that the Nb _{3 Sn-} Niobium and tin by means of hydrogen on the heated substrate, layer 0.1 to 1.5 weight percent carbon is deposited on the surface of this carrier are holds. known (article by Hanak, Strater and The Invention is based on the surprising C u 11 e η in "RCA Review", Vol. XXV, September position that the targeted introduction of coal 1964, pp. 342 to 365, and British patent specification 55 material in the Nb ₃ Sn deposited from the gas phase 381). You can especially tape or wire layers the critical current density j _{c of} these layers be shaped and are suitable, for example, for the and thus also for the product Hj _{c in a} readily reproducible manner Windings of superconductive magnet coils to be set and in particular increased significantly generation of high magnetic fields. Can serve as a carrier.