Abstract
Joining processes for Bi-2223 multi-filament tapes in Bi-family superconductor tapes were investigated, in order to develop a technique that can obtain the joint with superior mechanical and superconductive characteristics.
The superconductive characteristics of the diffusion-bonded joints were better than those obtained by soldering, but did not reach the level of the base metal. Critical current of the lap joints was a third of the base superconductor tape. The electric properties of the lap joints were superior to the scarf joints, and the application of the superconductor materials as interlayer to bonding zone did not improve the electric properties of the scarf joint. Although the lap joint had a silver layer with a normal conductive state at the bonding interface, the silver layer was so thin that it had only slight influence on the electric property. The diffusion-bonded joints were broken at the base metal. Though the electric property of the base materials was depressed during the diffusion bonding process by heating and pressing superconductor tape, it had a recovery with bonding temperatures from 700 to 800°C.
