| Autor: |
Scheuerlein, C., Gasser, Ph., Jacob, P., Leroy, D., Oberli, L., Taborelli, M. |
| Předmět: |
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| Zdroj: |
Journal of Applied Physics; 2/1/2005, Vol. 97 Issue 3, p033909, 7p, 6 Black and White Photographs, 1 Diagram, 2 Charts, 1 Graph |
| Abstrakt: |
The large hadron collider superconducting cables are submitted to a 200 °C heat treatment in air in order to increase the resistance between the crossing strands (RC) within the cable. During this treatment the as-applied Sn–Ag alloy strand coating is transformed into a CuSn intermetallic compound layer. The microstructure, the surface topography, and the surface chemistry of the nonreacted and reacted coatings have been characterized by different techniques, notably focused ion beam, transmission electron microscopy, energy dispersive x-ray spectroscopy, and x-ray photoelectron spectroscopy. Based on the results obtained by these techniques the different influences that the intermetallics have on RC are discussed. The desired RC is obtained only when a continuous Cu3Sn layer is formed, i.e., a sufficient wetting of the Cu substrate by the tinning alloy is crucial. Among other effects the formation of the comparatively hard intermetallics roughens the surface and, thus, reduces the true contact area and it strongly affects the oxide growth on the strand surface. The oxide formed on the fully reacted coatings, which may essentially contain Cu oxides, appears to be more stable, both mechanically and thermally, as compared to the oxide formed on the tinning alloy. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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