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AssigneeThe United States of America as represented by the Secretary of the Air Force
InventorsTapan K. Gupta, George J. Bich, William N. Lawless
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The composite insulation coating consists of a mixture of glass and ceramic oxide(s), coated onto a wire by conventional wire enameling techniques followed by heat treatment at 600.degree.-850.degree. C. The enamel when initially applied, the "green" coat slurry, consists of four components: (1) the glass, (2) an inorganic filler (ceramic oxide powder, (3) an organic binder and (4) an organic solvent. The glasses can be selected from several commercial glasses (Corning 7570 and 7050) as well as Westinghouse glasses A-508, M 3072 and M 3073. None of these glasses contain lead or boron, allowing for nuclear applications. Suitable ceramic fillers are alumina, and the CeramPhysics, Inc. ceramics SC1C and SC1A. Organic binder materials and solvents are used. It is preferable that a copper wire to be coated with Ni, Inconel or Cr prior to coating with the subject insulation. For superconductors, the brittle nature of Nb.sub.3 Sn wire and the high reaction temperature (.about.700.degree. C.) required to form it preclude the use of standard organic insulation systems. The inorganic insulation with SC1C and SC1A ceramics, characterized by unusually high specific heats and thermal conductivities at cryogenic temperatures, offers the opportunity of providing increased enthalpy stabilization in a superconducting winding. The glass and ceramic is chosen so that the vitrification temperature of the composite coincides with the reaction temperature of 600.degree.-800 .degree. C. The most successful glasses meeting this criterion are A-508 and M3072.
The method of making an inorganic insulation system for superconducting Nb.sub.3 Sn wire embedded in a copper matrix, for fast pulse superconducting magnets and energy storage devices which require high current, high field, low loss, stable superconductors and associated insulation systems, which can withstand a high formation temperature and yet be electrically satisfactory at low use temperature (4.degree.-8.degree. K.), and which is able to absorb energy dissipated during fast charge and discharge of a magnet, comprising the steps:
The method of making an inorganic insulation system for superconducting Nb.sub.3 Sn wire embedded in a copper matrix, for fast pulse superconducting magnets and energy storage devices which require high current, high field, low loss, stable superconductors and associated insulation systems, which can withstand a high formation temperature and yet be electrically satisfactory at low use temperature (4.degree.-8.degree. K.), and which is able to absorb energy dissipated during fast charge and discharge of a magnet, comprising the steps:
The method according to claim 3, wherein the step of preparing a slurring comprises preparing the slurry with the glass (M3072) of a composition comprising by weight 55% SiO.sub.2 4% Al.sub.2 O.sub.3, 11% Na.sub.2 O, 20% BaO, 6% CaO, and 4% Y.sub.2 O.sub.3.
Dependencies are inferred from the claim text.