Process for joining oxide superconducting tubes with a superconducting joint

摘要

The present invention provides a process for joining oxide-superconducting tubes with a superconducting joint. The process involves the preparation of a partially preformed superconducting material, followed by cold isopressing of the powder of partially performed superconducting material into tube shape and further provided with grooves at both ends of the tubes with a subsequent deposition of a silver layer. The process further involves the lapping of one of the end faces of a pair of said tubes to be joined. These lapped end faces of both the tubes clubbed together on a common silver bush are coated with a paste of the same partially preformed superconducting material in organic formulation. Then these coated end faces are closed pressed together to form a joint. This joint portion and the end portions of the tubes are wrapped with a perforated silver foil followed by deposition of another layer of silver. Finally, the assembly of this joint portion and the pair of tubes is heat treated in air for 100 to 150 hours and at temperatures from 830° to 850° C. The joint made according to this process is able to stably carry not less than 80% of the transport current of the high temperature superconducting tubes.