The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 06, 1994
Filed:
Apr. 29, 1992
Sophia R Su, Weston, MA (US);
Margaret O'Connor, Worcester, MA (US);
Scott Butler, N. Oxford, MA (US);
GTE Laboratories Incorporated, Waltham, MA (US);
Abstract
A method for producing a superconducting copper oxide based helical resonator coil exhibiting improved quality factor, Q. A copper oxide based superconductor powder is mixed with a binder melt at about 45-65% solids by volume. The binder is an RCOOR' ester wax with R and R' each a long chain hydrocarbon group of at least 6 carbons. The ester wax has a melting point of about 40.degree.-100.degree. C. and a viscosity of about 94-2000 centipoise at its melting point. The binder/powder mixture is extruded and wrapped around a mandrel to form a helical coil. The coil is embedded in a setter powder and heated in an oxidizing atmosphere at up to about 2.degree. C./min to about 450.degree.-650.degree. C., and held for a time sufficient to remove the binder. The coil is then heated in the oxidizing atmosphere at up to about 3.degree. C./min to at least about 920.degree. C., and held at about 920.degree.-990.degree. C. for a time sufficient to achieve a density of at least about 93% of theoretical density. The densified coil is cooled in the oxidizing atmosphere at below about 2.degree. C./min to at or below about 550.degree. C., and annealed at about 450-550.degree. C. in flowing oxygen for a time sufficient to convert the crystal structure of the coil to at least 50 v/o high T.sub.c phase superconducting perovskite crystal. The geometry of the extruded, wrapped helical coil is selected to produce, after subsequent densification, a helical resonator coil about 3-17 mm in inner diameter, of a total length n .lambda./2, wherein n is an integer and .lambda. is the operating wavelength of the helical resonator coil.