Patents

The method relates to an improved joint between tube superconductors, which are formed of oxide superconductors. The oxide superconductors of the superconducting tubes, which are oppositely joined to each other, are clubbed together on a common bush. A method of joining oxide superconducting tubes formed from cold isostatic pressing, which comprises a step of preparing oxide superconducting tubes having end faces to be joined, a step of polishing inner/outer surfaces of both end portions and both end faces of these tubes for exposing a fresh surface, a step of applying superconducting paste on the said polished end faces/inner surfaces, a step of clubbing these tubes together on a common bush, a step of close pressing the said coated end faces together, a step of coating the joined end portions with the superconducting paste to form a joint, a step of wrapping the said coated end portions with a perforated silver sheet followed by a step of sintering the joint portion and the tubes in air for 100 to 150 hours and at temperatures in the range from 830° to 850°C. In the joint obtained according to this method, it is possible to stably carry not less than 91% of the transport current of the high temperature superconducting tubes. A method of joining together oxide superconductors whereby, when joining the oxide superconductors by use of a bush made of a superconducting oxide material, a modified superconducting paste is applied in a region inner surface/outer surface, where a transmission path of electric current flowing between oxide superconductors component tubes as joined together is not obstructed by rendering at least portions of butting surfaces/tube-bush interface of the oxide superconducting tubes to be joined together into polished end faces/surfaces, thereby improving the superconductivity of the joined superconductors.