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Effects of overpressure processing on porosity in Ag-sheathed Bi-2212 multifilamentary tapes with various geometries
| Content Provider | Semantic Scholar |
|---|---|
| Author | Reeves, J. Hellstrom, E. E. Irizarry, V. Lehndorff, Beate |
| Copyright Year | 1999 |
| Abstract | In long lengths of Bi-2212 tapes and wires, gases such as CO/sub 2/ and H/sub 2/O can cause bubbling of the Ag-sheath and porosity in the superconducting core. Applying a pre-processing step, which consists of vacuum annealing and annealing at 835/spl deg/C in 100% O/sub 2/ (VA+835), eliminates H/sub 2/O and reduces CO/sub 2/ that evolves during heating. To also counteract porosity, an overpressure heat treatment was utilized. Air was compressed to 5 atm total pressure (P/sub total/) while keeping pO/sub 2/ fixed at 1 atm. Thickness variations were measured for a number of variables: with and without VA+835; P/sub total/ 1 or 5 atm; and sample geometry such as round wires and rectangular tapes with different silver wall thickness. Light micrographs and SEM images show thin-walled monocore and multifilamentary tapes bubble unless they are pre-processed. The size and shape of pores in thick and thin multifilaments changes with overpressure processing. Microstructures with smaller and more uniformly distributed pores correlate with higher critical current values. |
| Starting Page | 1836 |
| Ending Page | 1839 |
| Page Count | 4 |
| File Format | PDF HTM / HTML |
| DOI | 10.1109/77.784814 |
| Volume Number | 9 |
| Alternate Webpage(s) | https://minds.wisconsin.edu/bitstream/handle/1793/8986/file_1.pdf?sequence=1 |
| Alternate Webpage(s) | https://doi.org/10.1109/77.784814 |
| Journal | IEEE Transactions on Applied Superconductivity |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
