Microstructure and superconducting properties of silver clad Bi-2223 tape produced by sequential pressing

It is well known in the processing of silver clad Bi-2223 tapes that tapes whose manufacture route includes a cold pressing step have significantly higher critical current densities than tapes produced by cold rolling only. It has been widely assumed that tapes produced with uniaxial pressing are limited to lengths of a few centimetres, and are consequently of little technical value. In this paper we present data showing that by utilising "sequential pressing" (SP, pressing adjacent sections along a tape) it is possible to produce longer lengths of tape with the characteristics of pressed rather than rolled tape. Central to this novel processing technique are shaped pressing platens designed to deform under load, generating the high local pressures required for high J/sub c/'s. The data shows no significant degradation of the local J/sub c/ in the region of overlap of adjacent pressings. In the light of our results we comment on the implications of the SP process on the economics of tape production.<
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