Textured joints for conductors and complex shaped components using the composite reaction texturing method

摘要

A new technique for forming textured high critical current joints between superconducting ceramic artefacts is presented. The method uses composite reaction texturing (CRT). For the Bi/sub 2/Sr/sub 2/Ca/sub 1/Cu/sub 2/O/sub x/ (Bi-2212) system, a Bi-2212 preform is seeded with specifically aligned MgO whiskers which determine the texture in the joint region during a subsequent reaction treatment that involves partial melting. The technique can be used to join green or previously reacted components and if binders are used polymer joining techniques can be exploited. Samples retain their shape for repeated partial melting. Although it is also possible to join previously reacted components by use of a lower melting point Bi-2212 compound (e.g. Li doped). The quality of joints was assessed by transport measurements on joined bars and magnetisation measurements on cylinders formed from polymer processed sheet. It was found that the joint region carried as large a critical current as non-joint sections. For the rare earth system, RBa/sub 2/Cu/sub 3/O/sub x/ (R-123), a variation of the above technique can be used to form joints.