High temperature YBa2Cu3Ox- (123, YBCO) superconductors have been shown to possess high current carrying capability which is confined to currents flowing along the strongly super-conducting a-b planes within a single oriented domain. Usually, in this material, thermal cycling occurs in the temperature region ranging from -196°C (liquid nitrogen) under actual operation to room temperature under out of operation for maintenance. Micro-cracks are considered to initiate during these thermal cycles which result in the high electric resistance. Therefore, the existence of micro-cracks is considered to be a dominant factor in decreasing J c. In this study, an apparatus for thermal cycling has been designed and built to provide thermal cycles ranging from -196°C to room temperature. To clarify the time sequential deterioration on the mechanical properties of YBCO due to thermal cycles, a sharp notched RCT specimen with 20° of notch tip angle and 0.02 mm of notch tip radius was designed. By using this specimen, the time sequential deterioration of stiffness, dP/dδ and fracture toughness of YBCO for a sharp notched RCT specimen due to thermal cycles were investigated. The results show a correlation between these mechanical properties and previously obtained the super-conducting properties of this material. Thermal cycling causes the deterioration of mechanical properties which results in the deterioration of critical current density.
|Number of pages||9|
|Journal||Strength, Fracture and Complexity|
|Publication status||Published - 2004 Nov 16|
ASJC Scopus subject areas
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering