WO1996036484A1

WO1996036484A1 - Methods for producing hts components using porous and expanded metal reinforcement, and components produced

Info

Publication number: WO1996036484A1
Application number: PCT/US1996/006586
Authority: WO
Inventors: Leszek R. Motowidlo
Original assignee: Intermagnetics General Corp.
Priority date: 1995-05-15
Filing date: 1996-05-09
Publication date: 1996-11-21

Abstract

High temperature superconductor components are produced from expanded metal and porous materials (10, 16, 34, 40, 42) that are impregnated with a powder of superconducting material or are dip coated with a slurry of such materials, and are further worked and treated. The figure shows such a component. In modifying powder-in-tube techniques, a sheath that is conventionally made of solid silver or continuous foil, is replaced by a sheath of porous silver having a foam-like construction. As little as five percent by volume of the sheath comprises silver; the remaining volume being void. Additionally, porous silver may be formed into components such as disks and shields (36).

Description

METHODS FOR PRODUCING HTS COMPONENTS USING POROUS AND EXPANDED METAL REINFORCEMENT, AND COMPONENTS PRODUCED

BACKGROUND OF THE INVENTION It is now well known that high temperature superconducting ceramic materials present problems with regard to mechanical strength and also with regard to critical current densities. High temperature superconducting ceramic materials generally need mechanical support if they are to have practical commercial applications. Overheating and melting of superconducting elements when electrical currents unexpectedly exceed critical current densities is another problem. These problems are overcome by using a substrate or other mechanical reinforcement for the superconducting material, which substrate/reinforcement also serves as a low resistance shunt conductor and provides electrical stability in the event a superconducting element suddenly reverts to a normal or non-superconducting state.

Superconducting wires have been made with a superconducting core that is surrounded by a sheath of highly conductive metal such as copper or silver. The sheath provides both the structural strength and also the shunt conductor capability that are needed for a successful superconductor. There is an intimate and continuous bond between the two materials. The superconductor wire may then be cut into lengths that are bundled and enclosed in another sheath of highly conductive material and drawn or extruded to provide a multi-filament conductor.

Processes have been invented with different constructions to improve the critical current density of the conductor and to provide adequate mechanical strength. A manufacturing method which has shown advances in current transport properties of short superconductive tapes, and also exhibits long-length wire manufacturing potential for magnet applications, is the so-called powder-in-tube (PIT) process. In the PIT process, a highly conductive metal tube is filled with superconducting powder. The combination is then drawn or extruded into a superconducting wire from which tapes may be formed by rolling or pressing. Heat treatment is generally part of the process.

Bi₂Sr2Ca2Cu3θ₁₀, hereafter BI(2223) , and Bi₂Sr2Ca₁Cu2θg, hereafter BI(2212), which are high temperature superconducting materials, are particularly suitable for the PIT approach as these compounds can be textured readily and densified by a sequence of thermo-mechanical processes. Moreover, the PIT approach is amenable to producing high temperature superconducting (HTS) materials on an industrial scale, similar to the manufacture of NbTi and NbgSn low temperature superconductors.

Recent efforts in fabrication of BI(2223), superconducting tapes by the PIT process have resulted in significant improvements in the tapes transport current capabilities. For example, critical current densities (Jc) exceeding 6X10⁴ amps per centimeter square at 77K and zero applied magnetic field, have been reported.

After a conductor has been drawn by the PIT method, the drawn conductor is rolled or pressed to form a tape. Pressing provides vastly superior transport characteristics as compared to the rolled tapes. Additionally, solenoids wound from rolled tape conductor require extremely uniform properties along the entire conductor length. Using prior art rolling technology it has been difficult to attain consistently uniform property characteristics.

While results achieved by high temperature superconducting products from the PIT technique are impressive, further improvements in performance and economy could be realized if the critical current density in the HTS tape conductor could be raised to a higher level . The present state of technology and fabrication of HTS conductors and coils has not achieved the performance level for applications to be economically competitive at low temperatures with conventional superconductors and has not provided a cost effective processing for higher temperature operation.

In addition to the electrical characteristics which are important for design of high field coils, the mechanical properties of HTS conductors are also important for successful applications. For example, present mechanical properties of BiSrCaCuO/Ag tapes and wires fabricated by the PIT method are net adequate for future magnet applications where large magnetic fields will be required and large electromagnetic forces will be generated.

For example, the yield strength of such composites including silver is too low after final heat treatments. The problem is further compounded by a need to minimize cost by reducing the fraction of the product represented by the silver sheath. For some applications such as current leads, bearings, and flux trapped magnets, both composite strength and minimum silver are desirable. The required improvements are not easily achievable by the PIT method, dip coating method, or any other conventional approaches, which have been developed for high temperature superconducting technology. In d superconducting technolog superconducting material is prepared. Then, a strip of thin silver foil is dipped into the slurry. The slurry forms a thin coating on either side of the silver tape. The coating is then dried and heat treated, and the composite may be further rolled through to produce a superconductive tape.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to provide improved HTS components with higher transport current capabilities, that is, higher critical current densities, and thereby accelerate the commercialization of HTS materials.

Another object of the invention is to provide HTS components that have improved strength characteristics and use a reduced quantity of silver in combination with the superconductive materials, as compared to the prior art. In accordance with the invention, HTS components are produced from porous materials or expanded metal that are impregnated with a powder of superconducting materials or are dip-coated with a slurry of such materials, and further treated. For example, a superconducting product is produced by dipping a billet of "solid" but porous cylindrical rod or core into a slurry of HTS superconducting materials. The round core is then extruded and/or drawn through a die and' used as a conductor, and may be further rolled or pressed to form a superconducting tape. The resultant product has mechanical strength comparable to that achieved with a solid silver sheath but greatly reduces the amount of silver, which is incorporated. The drawn wire may serve as a conductor or can be pressed into a tape to be used for magnetic coils.

In another product, a Bitter-like plate or disc of porous conductive material may also be dipped into a superconductive slurry and pressed to provide superconductive tape after drying and heat treatment. When superconductive powder or slurry is used to fill the voids in a porous silver substrate, a large surface area for contact between the silver and superconductive materials is provided. This is an interface area far in excess of that provided when a solid sheath of silver is used. Thus, a conductor using porous metal as a substrate has a higher current density capability than the prior art conductors.

Additionally, porous silver may be formed into components such as leads and shields . The components are then filled with powder, dipped in slurry, or otherwise coated and may be further thermo-mechanically treated to become superconducting elements. In place of porous silver, a porous zirconia may be used after dipping the zirconia in silver such that it presents coated silver surfaces similar to those provided by the pure porous silver. After preforms of porous metal have been prepared by addition of superconductive material, a final HTS product can be stamped from the preform and is ready to use. As an alternative in making superconducting tapes, expanded silver strips, that is, silver sheets that have been slitted and pulled apart so as to leave gaps in the surface, may be used to form tapes by dipping the expanded metal into a slurry of superconductive materials, and further treatment of a conventional nature. Techniques for expanding metal sheets are well known. An expanded metal sheet will have far more surface area for contact with superconducting materials than a solid sheet of the same thickness and face dimensions. The invention accordingly comprises the several steps and the relation of one or more of such steps with respect to each of the others, and the articles produced possessing the features, properties and the relation of elements, which are exemplified in the following detailed disclosure, and the scope of the invention will be indicated in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

For a fuller understanding of the invention, reference is had to the following description taken in connection with the accompanying drawings, in which:

Figure 1 is a cross section of a mono-core billet for superconducting components in accordance with the invention;

Figure 2 is a cross section of a multi-filament billet for a superconducting component in accordance with the invention; Figure 3 is the cross section of a superconducting component in accordance with the invention produced from billets of Fig. 2;

Figure 4 is a partial view in perspective, of a superconductive tape or plate in accordance with the invention; Figure 5 is a cross sectional view of a mono-core billet in accordance with the invention;

Figure 6a is a perspective view of a stackable superconductive components in accordance with the invention; Figure 6b is a sectional view of stacked elements of Fig. 6a;

Figures 7 and 8 are cross sections of alternative embodiments of billets in accordance with the invention; and

Figure 9 is a partial front view of a superconducting component fabricated from expanded metal, in accordance with the invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

Methods for manufacture of high temperature superconducting HTS conductors, coils and other components in accordance with the invention provide an alternative approach to the conventional PIT and dip coating methods that are currently used to make HTS conductors and magnets. The new methods use metals, that by mechanical constructions have lower densities than the solid metals which they replace for producing reinforcement and shunt paths in HTS components. These lower density metal materials include both porous metals and also, for some applications expanded metal. (Sheets of metal that have been slit in a regular pattern on the face may be laterally stretched or "expanded" so that the slits become openings and total area for contact is increased.)

Sponge-like metal parts with controlled porosity have dual characteristics that are especially attractive in HTS applications. While providing properties of the parent metal from which they are made, properties such as strength and high electrical and thermal conductivity, the parts also have advantages of low density, high strength-to-weight ratio, large surface area and high porosity. Where expensive materials such as silver are used, a significant cost saving is also effected.

A most important and useful property of porous metal is controlled porosity, which can result in as little as 5% metal and 95% void fractions in highly conductive silver. In addition, the pore size can be controlled such that the number of pores per inch can be optimized to provide a desired fraction of superconductor to silver. Porous silver of suitable quality is commercially available in sheets and in block form.

In the prior art PIT method, silver tubes, having dimensions of approximately one-half to one inch outside diameter, are used in lengths which can be several feet long depending on the required final conducted dimension and length. Because a PIT composite billet relies on the strength of the silver tube to successfully process to final dimensions of a HTS conductor, and because of the low yield strength of silver, it is currently impossible to start with silver tubing that represents less than 10-20% of the total cross sectional area of a mono-core billet. That is, in the prior art, the silver tubing or sheath generally represents more than 20% of the cross sectional area of the original billet, and also represents the same area fraction in a finished drawn product. This is expensive.

However, in accordance with the invention, a core 10 (Fig. 1) of porous metal having only five to ten percent silver by volume may be encased in a thin silver sheath 12 or in foil to form a billet 14. These constructions provides significant reduction in total silver content in the conductor cross section, that is, in the order of 10-20% silver. Then, superconductive materials such as BSCCO 2212 or 2223, for example, in known powder form are shaken into the porous core 10. Subsequently, the billet 14 is extruded and/or drawn through a die (not shown) and further thermo-mechanically processed by known techniques to provide a superconductor element, e.g. a conductor, that has a similar but smaller cross section.

In addition to achieving a higher strength-to-weight ratio, and lower overall silver content, use of the porous silver metal core 10 with an external foil or solid silver sheath 12, enhances the total surface area where the high temperature superconducting material can interact with silver. It is well known, and widely accepted in the art, that the desirable formation and growth of highly aligned grains is significantly promoted by a silver interface with, for example, BSCCO superconducting materials. Also, the highest critical current densities and transport of current occurs adjacent to the silver/HTS interfaces.

Thereby, the large surface area of a porous sponge-like metal surface is expected to enhance the electrical characteristics. Furthermore, use of porous silver metal inside a monocore or multi-filament conductor may help in reduction of cracks or micro-crack propagation in the HTS core, improve strength and sensitivity to bending for coil fabrication, and reduce damage introduced by conductor fabrication processes such as rolling. A conductor produced by drawing/extruding the billet 14 using porous silver as an original core element 10, may be rolled or pressed into superconductive tape.

In addition to enhanced monocore properties by using the above porous metal method, porous metal e.g. silver, may be used in multi-filament development to provide fabrication of superconductors of long length. For an example, a porous silver tube 16 (Fig. 7) , which was 5%-10% silver and the remainder void, was sheathed in a thin walled silver tubing 18, representing 10% of the volume of a small diameter billet 20. The porous silver tube 16 was filled with BSCCO powder 22.

Thirty-seven such tubes 20 of 0.440 inches OD were stacked into a 1.5 inch (OD) non-porous silver tube and drawn (Fig. 2) to approximately 0.5 inch diameter with much extended length. Filaments 22, entirely embedded in a matrix 24 of compressed tubings 16, 18, are the result of drawing through a circular die. The first-drawn conductor 26 was then cut into shorter lengths and restacked into another 1 1/2 inch (OD) non-porous silver billet holding seven drawn elements 26. Nineteen or thirty-sever. elements 26 may also be used in the restacked billet. The second restacked billet was drawn to 0.5 inches outside diameter (Fig. 3) and further processed to final wire diameter. By this method total lengths of one to five kilometers are feasible in a multi- filament conductor 28. As stated, Fig. 2 illustrates a cross section of a superconductor 26 after the first stacking and drawing, and Fig. 3 illustrates the result after a restacking and second draw through a die (not shown) . The resultant conductor 28 provides a plurality of multi-filament clusters 30 embedded in silver that is the result of the restacking in a tube and drawing of the conductors 26.

In a dip coating process of the prior art, wide, thin silver sheets are coated with a slurry of BSCCO 2212, that dries on the sheet surface. The sheets are heat treated and then stacked to form a solenoid coil, for example. Attempting to make larger coils by this method has proven to be a stumbling block because of the weight involved, which results in distortion of the silver at the coil ends. Stronger silver alloys are being investigated by researchers to overcome this difficulty. However, the cost of silver and its alloys may counterbalance any advantages that are achieved after final heat treatments are completed.

In accordance with the invention, dip coated HTS tapes 32 would comprise strips 34 of porous silver metal (Fig. 4) . For example, a rectangularly shaped starting form is dipped in a BSCCO 2212 slurry. After drying, the rectangular form is rolled to final sheet dimensions. Then a coil is fabricated from the sheet. The weight-to-strength ratio in this approach in accordance with the invention is significantly superior and additionally provides considerably more silver surface area. Less silver is used; electrical properties are enhanced, and strength is maintained.

It should be understood that the invention is not limited to use of porous silver in its pure form; silver alloys in porous form may be used, as well as other metals in porous form. Also, porous surroundings that take a silver (or other conductive) coating may be used in instances where the material is not to be drawn or bent. Thus porous zirconia may have pore surfaces, which are silver coated, and be used in producing HTS components.

Annular preformed discs of porous metal, silver or silver alloys, or silver coated porous materials, can be fabricated in large quantities on a regular production basis that makes it cost effective. The preforms are then impregnated with BSCCO 2212 or BSCCO 2213 powder or slurry, or any other HTS material. After impregnation, drying and heat treatment may be required by conventional procedures. Metal discs can be stamped, as required, using industrial stamping machines. The discs may then, for example, be slotted to form a "C" ring disc 36 (Fig. 6a) .

Such BSCCO/Ag discs 36 may be assembled by stacking like "Bitter Plates" to manufacture high field solenoids, wherein insulation layers separate adjacent discs except at the opposite surfaces end 37, 37' adjacent to the gap 39 where the discs are connected electrically in series with adjacent discs 36 (Fig. 6b) . Figure 6b schematically illustrates three discs 36 concentric to an axis 35 and connected in series at opposed exposed surfaces 37, 37' to form a generally continuous helical current path. Insulation (not shown) separates the discs 36 except where they are electrically joined and the gaps 39 are spirally staggered around the external periphery.

Joining techniques for parts using HTS materials have been developed, enabling cost effective formation of continuous paths for current sheets and generation of large HTS magnets for certain applications. Porous silver and HTS powder may be used to manufacture current leads, bearings, and trapped field magnets. In all applications, the goal to minimize silver that is used with HTS components and still provide high strength is desirable. HTS components prepared with porous silver metal or alloys can be extruded/drawn to form dense composites, such as current leads, having as little as 5% silver in an interconnected matrix.

Another advantage in using porous metal in place of solid silver or other highly conductive metal in superconductors and other superconductive elements, lies in an ability to apply known forming processes and techniques to reach a final product after the porous metal has been substituted for solid material in the manufacturing procedures.

Generally speaking, products made from porous metal that has been impregnated with superconducting material whether by dipping or filling with powder, may be compacted by drawing, extrusion, pressing, rolling, etc. A thin external wrap of silver foil is used with the powder fill prior to compacting.

Figure 5 illustrates a solid core 38 of porous material; this could be porous silver, a silver alloy, or porous zirconia that has its surfaces coated with silver or a silver alloy. The core 38 is then dipped in an HTS slurry which is allowed to dry. Then the core 38 may be drawn or extruded through a die to form a round conductor. Further processing by rolling or pressing can convert this round conductor into a flat superconducting tape.

In Fig. 8 a hollow tube 40 of porous silver or silver alloy (or other conductive material) may be dipped into an HTS slurry. After the slurry is dry, the tube 40 may be drawn or extruded through a die so as to be compacted. A hollow porous tube may also be made from other porous materials having their porous surfaces coated with an electrical conductor such as silver. Such known non-metal materials, e.g., zirconia, may not be worked by drawing, extruding, pressing and rolling as is done with porous metal. Thus, the porous non-metal tube is generally produced in the final dimensions for the desired finished product.

Figure 9 illustrates a segment of a flat superconducting tape 42. The tape has openings 44 arranged in a pattern on the face 46. The face 46 as well as the edges 48 of the openings 44 are coated with dried HTS material such that a superconducting tape 42 is provided.

The tape 42 is made from a thin strip of a conductor such as silver, silver alloy or copper, as examples, which has been expanded by conventional techniques to produce an expanded metal. Generally speaking, expanded metal is produced by slitting a flat sheet on its face surface and applying transverse stresses such that the slits are stretched apart at their edges to form the openings 44. The expanded metal is then dipped in an HTS slurry and allowed to dry. After the drying it may be rolled or pressed and then cut to final dimensions.

Although the descriptions above have been limited to the steps of adding superconducting powder to porous metal objects or dipping such porous metal objects in a superconducting slurry, it should be understood that other methods and techniques are available for filling the voids in the porous metal or for coating surfaces with superconducting material. For example, such addition of superconducting material may be effected by chemical vapor deposition, jet spray processes, metallizing, plasma spraying, and the like. These techniques may also be used to add superconducting material onto surfaces of an expanded metal object.

Also, although the superconducting materials Bi2223 and Bi2212 have been specifically mentioned above, it should be understood that other superconducting materials may be used in conjunction with porous and expanded metals or other porous objects having their internal surfaces which are conductive.

These other superconducting materials may include, e.g., niobium and alloys with tin, hafnium, zirconium, aluminum, vanadium, gallium, titanium. Also there are known superconducting compounds based on lanthanum, barium and copper oxides. Also known are yttrium barium, copper oxide compositions, and thalium barium calcium copper oxide compositions.

New superconducting materials, not yet known, may also be useful with porous conducting structures having physical characteristics as described above. The scope of the invention is intended to include such new materials that may be combined with porous structures.

It will thus be seen that the objects set forth above, among those made apparent from the preceding description, are efficiently attained and, since certain changes may be made in carrying out the above method and in the articles set forth without departing from the spirit and scope of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

WHAT IS CLAIMED IS:

1. A superconducting component, said component being the product of at least partially filling voids in a porous object with a superconducting material, said porous object having a surface area interfacing with said superconducting material, at least a portion of said interfacing surface area being electrically conductive.

2. A superconducting component as in claim 1, wherein the material of said porous object is one of a porous electrically conductive metal and a ceramic sponge including pores having a coating of an electrical conductor on surfaces of said pores, said coated surfaces serving as said surface area interfacing with said superconducting material.

3. A superconducting component as in claim 2, wherein said electrically conductive metal and said coating are one of silver and a silver alloy.

4. A superconducting component as in claim 1, wherein said porous object is one of a porous tube, a solid porous core and a porous plate, and said superconducting material that at least partially fills said voids is one of a superconducting powder, a superconducting slurry that has dried, and a film.

5. A superconducting component as in claim 4, wherein said powder is introduced to said voids by a process of shaking or vibration, said slurry being introduced to said voids by wetting said porous object with a superconducting slurry, said thin film being formed by one of chemical vapor deposition, a jet spray process, metallizing and plasma spraying.

6. A superconducting component as in claim 1, wherein said porous object is a prefabricated form of substantially final dimensions for a finished product.

7. A superconducting component as in claim 1, wherein said superconducting component is brought to final dimensions of a finished product after said filling with said superconducting material by at least one of drawing, extruding, pressing, rolling, stamping and heat treating.

8. A superconducting component as in claim 4, wherein said superconducting component is brought to final dimensions of a finished product after said filling with said superconducting material by at least one of drawing, extruding, pressing, rolling, stamping and heat treating.

9. A superconducting component, comprising: a porous object having an interconnected structure defining interconnected spaces within said object, internal surfaces that define said spaces of said porous object being electrically conductive; a superconducting material at least partially filling said interconnected spaces and being in electrical contact with at least a portion of said internal surfaces of said porous object.

10. A superconducting component as in claim 9, wherein said porous object is one of porous metal and a porous ceramic, said internal surfaces of said porous ceramic being covered with a layer of electrically conductive material.

11. A superconducting component as in claim 10, wherein said porous metal object is one of silver and a silver alloy, said ceramic object being zirconia.

12. A method for fabricating a superconducting component, comprising the steps :

(a) providing a porous object having an interconnected structure defining interconnected spaces within said object, internal surfaces of said interconnected spaces being electrically conductive; (b) filling at least a portion of said spaces with a superconducting material;

(c) working said at least partially filled porous object to dimensions of a finished product, said working being performed at least one of before and after step (b) .

13. A method as in claim 12, wherein said working includes at least one of drawing, extruding, pressing, rolling, stamping and heat treating.

14. A method as in claim 12, wherein said porous object is one of a hollow tube, a solid porous core, and a sheet.

15. A method as in claim 12, further comprising the step:

(1) following step (a) , enclosing said porous object with one of a solid sheath and a thin foil of electrically conductive material.

16. A method as in claim 15, wherein in step (b) , said porous object is at least partially filled by one of adding a powder of superconducting material, wetting said porous object with a slurry of superconducting materials, and forming a layer of superconducting material on said interconnected surface by one of chemical vapor deposition, a jet spray process, metallizing and plasma spraying to form a superconductive film on said surface.

17. A component comprising a core including superconducting material enclosed in a sheath of worked electrically conductive porous metal.

18. A superconducting component as in claim 17, wherein said superconducting component is the product of working by one of drawing and extruding through a die a tube of said porous metal, said tube having a hollow center, said hollow center being at least partially filled with superconducting powder prior to said working.

19. A method of fabricating a superconducting component, comprising the steps: (a) providing a cylinder of an electrically conductive porous metal, said cylinder having a cross section with a hollow center;

(b) filling said hollow center with a powder of superconducting materials; (c) one of drawing and extruding said filled cylinder through a die to dimensionally reduce said cross section.

20. A superconducting component as in claim 9, wherein said porous object is one of a porous tube, a "solid" porous core and a porous plate, said superconducting material that at least partially fills said voids is one of a superconducting powder, a superconducting slurry that has dried and a thin layer on said internal surfaces.

21. A component as in claim 20, wherein said powder is introduced to said voids by a process of shaking and vibration, said slurry being introduced to said voids by wetting said porous object with a superconductive slurry, said thin layer being formed by one of chemical vapor deposition, a jet spray process, metallizing and plasma spraying to form a superconductive film on said surface.

22. A component as in claim 1, said component being one of a flat tape, round conductor, shield and portion of a magnetic winding.

23. A superconducting component, comprising: a sheet of electrically conducting and expanded metal; a coating of superconducting material on surfaces of said expanded metal.

24. A superconducting component as in claim 23, wherein said superconducting material on said surfaces is a product of one of wetting said sheet with a slurry of said superconducting material and drying said slurry on said sheet, chemical vapor deposition, a jet spray process, metallizing, and plasma spraying.

25. A method of fabricating a finished superconducting component, comprising the steps:

(a) forming a porous electrically conductive material to one of a preform and a finished shape of said superconducting component;

(b) one of dipping said formed porous material into a slurry of said superconducting material, filling said porous material with a superconducting powder, and forming a thin layer of superconducting material on said porous material by one of chemical vapor deposition, a jet spray process, metallizing and plasma spraying.

26. A method as in claim 24, wherein said forming provides a preform of a finished superconducting component, further comprising the step:

(c) working said preform to said finished shape.

27. A method as in claim 26, wherein said working is by at least one of stamping, rolling and pressing.

28. A method as in claim 12, wherein said porous object is a hollow tube and said filling is accomplished by one of dipping said tube into a slurry of said superconducting material, filling said porous material with a superconducting powder, forming a film on said internal surfaces by one of chemical vapor deposition, a jet spray process, metallizing and plasma spraying.

29. A component as in claim 1, wherein said superconducting material is at least one of Bi₂Sr2Ca2Cu₃0-_LQ, Bi2Sr₂Ca₁Cu2θg; Nb and alloys of Sn, Hf, Zr, Al, V, Ti, a; compounds based on La, Ba and copper oxides; compositions of Y, Ba and copper oxides; and compositions of TI, Ba, Ca and copper oxides.

30. A component as in claim 8, wherein said superconducting material is at least one of Bi2Sr₂Ca2Cu3θ₁₀ and Bi₂Sr₂Ca₁CU2θ₈; Nb and alloys of Sn, Hf, Zr, Al, V, Ti, a; compounds based on La, Ba and copper oxides; compositions of Y, Ba and copper oxides; and compositions of Tl, Ba, Ca and copper oxides.

31. A component as in claim 11, wherein said superconducting material is at least one of Bi₂Sr2Ca2Cu₃O₁₀; Bi₂Sr₂Ca₁Cu2θ₈; Nb and alloys of Sn, Hf, Zr, Al, V, Ti, a; compounds based on La, Ba and copper oxides; compositions of Y, Ba and copper oxides; and compositions of Tl, Ba, Ca and copper oxides.

32. A component as in claim 16, wherein said 5 superconducting material is at least one of Bi2Sr₂Ca₂Cu3θ₁₀ and Bi₂Sr₂Ca₁Cu₂0₈; Nb and alloys of Sn, Hf, Zr, Al, V, Ti, a; compounds based on La, Ba and copper oxides; compositions of Y, Ba and copper oxides; and compositions of Tl, Ba, Ca and copper oxides.

10 33. A component as in claim 22, wherein said superconducting material is at least one of Bi₂Sr₂Ca₂Cu₃O₁₀ and Bi₂Sr₂Ca₁Cu₂0₈; Nb and alloys of Sn, Hf, Zr, Al, V, Ti, a; compounds based on La, Ba and copper oxides; compositions of Y, Ba and copper oxides; and compositions of Tl, Ba, Ca and copper

15 oxides.

34. A component as in claim 24, wherein said superconducting material is at least one of Bi2Sr2Ca₂Cu₃0-_]_o ^and Bi₂Sr₂ ■_ ₂ B^i Sr Ca Cu 0 ; Nb and alloys of Sn, Hf, Zr, Al, V, Ti compounds based on La, Ba and copper oxides; compositions of Y,

20 Ba and copper oxides; and compositions of Tl, Ba, Ca and copper oxides.

35. A superconducting component as in claim 1, wherein said porous object is one of silver and an alloy of silver, the percentage by volume of said porous object being in a range of

25 approximately 5% to 50% solid and 50% to 95% void.

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36. A superconducting component as in claim 4, wherein said porous object is a solid porous core, and further comprising one of a conductive sheath and a conductive foil around said object.

37. A superconducting component as in claim 1, wherein said porous object is one of a preform and final form of said superconducting component, and said superconducting material that least partially fills said voids is one of a superconducting powder, a superconducting slurry that has dried, and a layer of superconducting material that is formed by one of said thin film being formed by one of chemical vapor deposition, a jet spray process, metallizing and plasma spraying.

38. A method as in claim 15, wherein said sheath is of the same material as said porous object.

39. A superconductive component, comprising: a plurality of superconductive plates, each plate being formed of an annular ring of porous conductive material having porous data at least partially filled with superconductive material bonded to said porous conductive material, each said annular ring having a radial gap in its circumference to form a C shape and to provide in opposition across said gap a first end and a second end, each of said plates being stacked concentrically about a central axis of said plates with said gaps staggered to bring a surface at said first end of one said plate into electrical contact with a surface at said second end of the next adjacent plate, whereby said adjacent plates are electrically connected in series; and insulation means positioned between adjacent plates except where said electrical contacts exist thereby providing a continuous generally helical superconductive conductor.