Bi-Layer Barrier Assembly for Iron-Based Superconductor and Associated Methods

Abstract

Bi-layer barrier assemblies for iron-based superconductor (IBS) and associated sheathed wire fabrication methods employ insulating material to prevent interdiffusion between inner silver (Ag) and outer matrix components at heat treatments. A superconductor assembly comprises a core IBS material (e.g., mono-filamentary or multi-filamentary IBS powder) layered, in turn, with an AG barrier material, an insulating barrier material (e.g., niobium (Nb), tantalum (Ta), and/or a NbTa alloy); and a matrix material (e.g., copper (Cu), Cu alloy, and/or monel). Assembly comprises 1) packing the IBS material into the Ag sheath (barrier) material, defining a packed first assembly; 2) layering the insulating barrier material upon the Ag sheath material, defining an insulated second assembly; and 3) layering the matrix material upon the insulating material, defining a matrixed third assembly. Additional steps may comprise respective drawing of the packed first assembly, the insulated second assembly, and/or the matrixed third assembly, and/or stacking for multi-filamentary implementations.

Claims

1. A superconductor assembly comprising: at least one iron-based superconductor (IBS) material [310]; a silver (Ag) barrier material layered upon a respective first outer surface of each of the at least one IBS material [310]; an insulating barrier material layered upon a second outer surface of the Ag barrier material opposite the at least one IBS material [310]; and a matrix material layered upon a third outer surface of the insulating barrier material opposite the Ag barrier material [320].

2. The superconductor assembly according to claim 1, wherein the at least one IBS material is of one of a mono-filamentary type and a multi-filamentary type [200].

3. The superconductor assembly according to claim 1, wherein the insulating barrier material comprises at least one of niobium (Nb), tantalum (Ta), and a NbTa alloy.

4. The superconductor assembly according to claim 1, wherein the matrix material comprises at least one of copper (Cu), Cu alloy, or monel.

5. A method of superconductor fabrication comprising the steps of: applying a silver (Ag) sheath material to a respective first circumference of each of at least one iron-based superconductor (IBS) material [310], to define a packed first assembly [510]; applying an insulating material to a second circumference of the Ag sheath material opposite the at least one IBS material [310], to define an insulated second assembly [514]; and applying a matrix material to a third circumference of the insulating material opposite the Ag sheath material [320], to define a matrixed third assembly [518].

6. The method according to claim 5, wherein the at least one IBS material is of one of a mono-filamentary type and a multi-filamentary type [200].

7. The method according to claim 5, wherein the insulating material comprises one of niobium (Nb) and tantalum (Ta).

8. The method according to claim 5, where the applying the Ag sheath further comprises the step of: packing the at least one iron-based superconductor (IBS) material into the Ag sheath material [320].

9. The method according to claim 5, where the applying the insulating material further comprises the step of: drawing the insulating material onto the second circumference of the Ag sheath material [320].

10. The method according to claim 5, where the applying the matrix material further comprises the step of: drawing the matrix material onto the third circumference of the insulating material [330].

11. A method of superconductor fabrication comprising the steps of: packing at least one iron-based superconductor (IBS) material into a silver (Ag) sheath material [320], to define a packed first assembly [510]; layering an insulating material comprising at least one of niobium (Nb), tantalum (Ta), and NbTa alloy upon the Ag sheath material opposite the at least one IBS material [310], to define an insulated second assembly [514]; and layering a matrix material upon the insulating material opposite the Ag sheath material [320], to define a matrixed third assembly [518].

12. The method according to claim 11, wherein the at least one IBS material is of one of a mono-filamentary type and a multi-filamentary type [200].

13. The method according to claim 12, wherein the at least one IBS material is of a mono-filamentary type and is characterized by a core radius less than one (1) millimeter (mm).

14. The method according to claim 11, wherein the Ag sheath material is characterized by a first-layer thickness less than one (1) millimeter (mm).

15. The method according to claim 11, wherein the insulating material is characterized by a second-layer thickness less than one (1) millimeter (mm).

16. The method according to claim 11, wherein the matrix material is characterized by a third-layer thickness less than one (1) millimeter (mm).

17. The method according to claim 11, further comprising the step of drawing the packed first assembly [510].

18. The method according to claim 11, further comprising the step of drawing the insulated second assembly [514].

19. The method according to claim 11, further comprising the step of drawing the matrixed third assembly [518].

20. The method according to claim 11, further comprising the step of preventing, using the insulating material of the matrixed third assembly at a heat treatment, an interdiffusion between the Ag sheath material and the matrix material [340].

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The preferred embodiments of the invention will hereinafter be described in conjunction with the appended drawings provided to illustrate and not to limit the invention, where like designations denote like elements, and in which:

[0014] FIG. 1 is a cross-section view of an exemplary mono-filamentary IBS assembly according to the prior art;

[0015] FIG. 2 is a cross-section view of an exemplary multi-filamentary IBS assembly according to the prior art;

[0016] FIG. 3 is a cutaway, perspective top view of a bi-layer barrier IBS assembly according to an embodiment of the invention;

[0017] FIG. 4 is a cross-section view of the bi-layer barrier IBS assembly of FIG. 3 taken through line A-A; and

[0018] FIG. 5 is a flow chart of method steps for fabricating a mono-filamentary bi-layer barrier IBS assembly according to an embodiment of the invention.

[0019] Like reference numerals refer to like parts throughout the several views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

[0020] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0021] Although the following detailed description contains many specifics for the purposes of illustration, anyone of ordinary skill in the art will appreciate that many variations and alterations to the following details are within the scope of the invention. Accordingly, the following embodiments of the invention are set forth without any loss of generality to, and without imposing limitations upon, the claimed invention.

[0022] As used herein, the word exemplary or illustrative means serving as an example, instance, or illustration. Any implementation described herein as exemplary or illustrative is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to make or use the embodiments of the disclosure and are not intended to limit the scope of the disclosure, which is defined by the claims.

[0023] Furthermore, in this detailed description, a person skilled in the art should note that quantitative qualifying terms such as generally, substantially, mostly, and other terms are used, in general, to mean that the referred to object, characteristic, or quality constitutes a majority of the subject of the reference. The meaning of any of these terms is dependent upon the context within which it is used, and the meaning may be expressly modified.

[0024] Referring initially to FIGS. 3 and 4, a bi-layer barrier IBS assembly according to an embodiment of the present invention is now described in detail. Throughout this disclosure, the present invention may be referred to as a bi-layer barrier assembly, an IBS assembly, an IBS, a bi-layer superconductor tape, a bi-layer superconductor wire, a bi-layer superconductor, a superconductor, an assembly, a tape, a wire, and/or a method for bi-layer barrier IBS fabrication. Embodiments of the invention may include systems and methods, including mathematical methods differing in specific detail from the ones illustrated in the figures and examples below, but nonetheless delivering the same HTS functionality for high-field magnet applications. Those skilled in the art will appreciate that this terminology is only illustrative and does not affect the scope of the invention.

[0025] Referring more specifically to FIGS. 3 and 4, an embodiment 300, 400 of the present invention may be characterized as an IBS PIT design that may comprise an IBS powder 310 that may be fittedly packed within a substantially cylindrical and/or tubular silver (Ag) sheath 320 (also referred to as a silver reaction barrier or an Ag barrier). Although the illustrated IBS PIT design 300, 400 is characterized by the IBS powder 310 in monofilament form, a person of skill in the art will immediately recognize multi-filamentary IBS wires and/or tapes may be employed without departing from the scope of the invention. Between the Ag barrier 320 and an outermost matrix 340, a barrier 330 may be positioned to act as an insulator (more specifically, a reaction suppressor) between the Ag barrier 320 and the matrix 340. For example, and without limitation, the barrier 330 (also referred to herein as an insulating barrier or insulating layer) may comprise a material such as niobium (Nb), tantalum (Ta), or some NbTa alloy. By separating the Ag barrier 320 and the matrix 340 using the insulating barrier 330 of Nb, Ta, or other metals or alloys that react with neither Ag nor the matrix material (e.g., Cu), the present invention may advantageously prevent Ag/matrix reaction and thereby enable use of the optimal heat treatment to improve IBS performance and also to prevent degradation of thermal conductivity. Embodiments of the present invention may be characterized by working sizes/dimensions similar to those of various IBS PIT designs known in the art, as described hereinabove.

[0026] Referring now to FIG. 5, and continuing to refer to FIGS. 3 and 4, a method of fabrication 500 for a bi-layer barrier IBS assembly 300 according to an embodiment of the present invention is now described in detail. From the start at Block 502, a PIT step may comprise packing (Block 510) a precursor IBS powder 310 in a silver (Ag) sheath 320 to create a packed first assembly that, for example, and without limitation, may be extruded/swaged/rolled/drawn through an extruder/swager/roller/drawing machine (Block 512) to create an object (i.e., first drawn assembly) of fixed and substantially uniform cross-sectional profile (e.g., a sheathed wire). At Block 514, an insulator material (e.g., Nb barrier 330) may be assembled (e.g., layered) about a circumference of the first drawn assembly to insulated second create an assembly that may be drawn/extruded/swaged/rolled (Block 516) to create a second drawn assembly having the insulator layer 330 in the wire under fabrication. At Block 518, a matrix material (e.g., matrix 340) may be assembled (e.g., layered) about a circumference of the second drawn assembly to create a matrixed third assembly that may be drawn/extruded/swaged/rolled (Block 520) to create a bi-layer barrier IBS monofilament 300 according to an embodiment of the present invention, at which point the method 500 may end (Block 599). Although FIG. 5 illustrates steps for fabricating a mono-filamentary bi-layer barrier IBS wire, any of the mentioned assemblies may be stacked to create an assembly that may be drawn/extruded/swaged/rolled to create a multi-filamentary IBS wire. For example, and without limitation, the multi-filamentary wire may be directly wound into coils, rolled to flat tapes, or cold/hot pressed to different shapes, and finally heat treated with or without pressure.

[0027] A person of skill in the art will immediately recognize that the various assembly and drawing/extrusion/swaging/rolling steps described hereinabove may be accomplished in alternative order (e.g., complete assembly steps such as those at Blocks 514 and 518, in turn, followed by a single drawing/extrusion/swaging/rolling step such as Block 520 to make the assembled materials 310, 320, 330, 340 into an IBS wire 300) without departing from the scope of the invention. Furthermore, additional fabrication steps to address specific handling requirements due to respective properties of Nb, Ta, and/or other metals or malleable alloys that react with neither Ag nor the matrix material may complement the method described hereinabove without departing from the scope of the invention.

[0028] Some of the illustrative aspects of the present invention may be advantageous in solving the problems herein described and other problems not discussed which are discoverable by a skilled artisan.

[0029] While the above description contains much specificity, these should not be construed as limitations on the scope of any embodiment, but as exemplifications of the presented embodiments thereof. Many other ramifications and variations are possible within the teachings of the various embodiments. While the invention has been described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best or only mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. Also, in the drawings and the description, there have been disclosed exemplary embodiments of the invention and, although specific terms may have been employed, they are unless otherwise stated used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention therefore not being so limited. Moreover, the use of the terms first, second, etc. do not denote any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another. Furthermore, the use of the terms a, an, etc. do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced items.

[0030] Thus, the scope of the invention should be determined by the appended claims and their legal equivalents, and not by the examples given.