Superconductor technology: apparatus – material – process – High temperature – per se – Free metal containing
Reexamination Certificate
1999-09-29
2001-05-29
Kopec, Mark (Department: 1751)
Superconductor technology: apparatus, material, process
High temperature , per se
Free metal containing
C505S230000, C505S705000, C505S785000, C505S812000
Reexamination Certificate
active
06239079
ABSTRACT:
BACKGROUND OF THE INVENTION
High temperature superconductor (HTS) ceramics discovered in the end of 1980's are very chemically active, brittle and degrade under environmental and magnetic field influences. Until now it was unknown how to avoid these disadvantages for practical use of the HTS ceramics. For example, it was unknown to make continuous and quality assured HTS wires and coils, shaped films and variously shaped products from these very fragile ceramics to produce practical and inexpensive electrical energy and electronics applications. It is believed to be clear that it is very important to develop a high temperature superconductor ceramic composite material with high workability of the raw material composition, which makes possible a cost-effective manufacture of all necessary products for Electrical and Electronics industries, avoiding disadvantages of the prior art.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an innovative high temperature superconductor composite material with significantly improved and increased electrical-magnetic and structural properties, such as strain tolerance and ductility, which has practically acceptable reliability and durability on the air and in working conditions at temperatures more 77 K. It is also an object of the present invention to provide a new material of this type from a workable raw material composition, which allows to make a suspension of the fine powder particles of the high temperature superconductor ceramics and silver dope in silicone rubber or silicone lacquer emulsion in toluene or acetone. An application of the workable and homogeneous suspension provides several advantages in adjusting and creatively combining known forming and thermal treatment methods and physical impacts on the composite material.
In accordance with the invention, chemical composition of raw materials, associated chemical ingredients, additives, aids and susceptors to the HTS ceramics to accommodate invented HTS composite material formulation for all potential needs of the Electrical and Electronics industries. In keeping with these objects and with others, which will become apparent hereinafter, one key feature of present invention resides, briefly stated in a high temperature superconductor composite material which comprises a sintered compound of intermixed components including high temperature superconductor ceramics, a silver dope, and sintering products of interaction of said superconductor ceramics and said silver dope with silicone material.
HTS composite material formulations include a preparation of the suspension of a HTS ceramic powder of the material selected from the group consisting of, for example, YBa
2
Cu
3
O
7−x
(Y—Ba—Cu—O or Y123) and Bi
2
Sr
2
Ca
2
Cu
3
O
10
, a material selected from the group consisting of rubber silicone and lacquer silicone, and an ultra-fine silver powder dope. The formulations include forming a material, treating the formed material chemically, thermally, mechanically, and physically. This results in HTS composite material in a form of the final HTS product. When the material is composed of the above mentioned components and the final HTS material is produced from the above-mentioned high workable material formulation, it eliminates the disadvantages of the prior art and provides for highly advantageous practical results.
We invented a specially effective method of the mix preparation of solid ceramics and metal additive particles in order to form ceramics materials of various types and shapes comprising of the wet method of the preparation and application of the ceramic slurry in polymer emulsion of the silicon rubber in toluene or acetone solvent if applied ceramics degrade in water suspension and/or at open air exposure during forming.
The following methods can be used to make corresponding materials and products:
adhesive coating of the continuous filament substrate core by the invented material suspension to produce continuous HTS filaments for combining wires, coils, and cables;
adhesive coating of the continuous tape substrate by the invented material suspension to produce continuous HTS tapes for combining wires, coils, and cables;
film casting on a silver or quartz glass chip-like substrate to produce some HTS electronics elements and devices;
spraying or spattering of the invented suspension on the large-size substrate surface, producing, for example, HTS radar screens.
Also there can be used:
extrusion or injection molding of the plastic mass from condensed suspension to produce, for example, long-length HTS rods, tubes, rails or beams;
ordinary or hot isostatic pressing of the material from condensed suspension to produce products with complicated or particular shapes, such as tablets, rings, tile, bolls, 3D device details, etc.
Silicone does not interact with copper, barium, and rare earth oxide containing ceramics and moreover silicone prevents degradation of the high temperature superconductor properties of the high temperature superconductor ceramics.
When HTS ceramic powder and silicone polymer and silver dope are heated, silicone components are subjected to destruction and organic radicals are tom out from silicon, which leads to the formation of silicon, silica and carbon crystals. Then, silica reacts with carbon to form silicon carbide and gas: SiO
2
+3C→SiC+2CO↑.
The silicon carbide, silicon, silica and carbon are uniformly distributed in the composite material body. Additionally, during high temperature thermal treatment some components of the composite ceramic material interact with the silica and carbon, so as to form different composites, for example Ba
2
SiO
4
, SiC, etc. It was confirmed by an X-ray phase analysis.
The silicone residuals and products of their reactions with each other and ceramic components together with the silver dope significantly increase electrical conductivity and magnetic field resistance of the superconductor composite. The silicone residuals and products of their reactions are also ceramic sintering aid and microwave susceptors. Additionally, these residuals and products of their reactions together with silver dope prevent degradation of superconductor ceramic products, provide ductility and increase flexibility of the shaped product. This is a physical-chemical phenomenological discovery, which results in this invention.
As the Ginzburg's physical theory explains, the scientific phenomena discovered and employed in this invention is the cause of the superior electrical-magnetic properties of the invented composite material. This theory says that particular micro impurities can improve superconductor properties of high temperature superconductor ceramics. Silicone residuals and products of their high temperature reactions and silver dope play a role of such especially useful impurities, which actually are additives. They pin electrical current vortexes significantly increasing electrical conductivity of the HTS ceramics.
Homogeneous distribution of the solid micro-particles of the ceramic and silver powders in liquid silicone-based carrier emulsion causes a homogeneous suspension, making possible homogeneous and uniform adhesive precipitation cladding of the solid particles on the silver or quartz filament or tape substrate. The same ceramics-silver-silicone suspension can be dried and polymerized, which cause densification or condensation of the above-mentioned suspension into a plastic mass. This mass is suitable for an application of the pressing or extrusion forming methods. Thus, silicone-containing emulsion provides both formability of high temperature superconductor material working as a liquid carrier and as a plastic binder. This silicone binder keeps formed cladding film or a shape of the bulk product in a stable form up to the time period of polymerization and sintering processes that provide final hardening of the products.
Invented raw material composition is highly suitable for industrial conveyer and cost-effective mass production of the superior and
Rokhvarger A. E.
Topchiashvili M. I.
Kopec Mark
Zborovsky I.
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