Diffusion Bonding with a Powder Interlayer Between Bi-Sr-Ca-Cu-O Superconducting Tapes

Abstract

A diffusion bonding technology with an uniaxial pressure to the bonding region during the thermalcycle using a superconducting powder interlayer has been applied to join Bi-Sr-Ca-Cu-O 61 multifilamentary superconducting tapes. The precursor powders used for the preparation of Bi-Sr-Ca-Cu-O tapes were adopted as interlayers, which were mainly composed of Bi-2212 phases. The effects of holding time and uniaxial pressure on the superconductivity and microstructures of the joints were investigated preliminarily. The results indicate that appropriate holding time and uniaxial pressure during the diffusion bonding had beneficial effects both on the formation of metallurgical interface between the powder interlayer and superconducting cores and on the superconductivity of the joints. The Bi-2212 phases of the powder bonding interlayer partially decomposed into (Sr,Ca) 2 CuO 3 , CuO and other non-superconducting phases at bonding temperature during the several hours of holding time. The average superconducting critical current of the joints reached up to 38% of that of the original tapes.