Evaluation of delamination characteristics in GdBCO CC tapes under transverse load using anvil test methods for various anvil contact configurations at 77 K

Abstract

The performance characteristics of second-generation rare-earth barium copper oxide-coated conductor (CC) tapes are influenced by stress and strain induced during fabrication, cool-down, and operation. Electromechanical characteristics have been improved using several methods such as adding a stabilizer and external lamination. In multilayered structures such as CC tapes, structural delamination or ballooning phenomenon can occur in the interlayers. In particular, when CC tapes are applied to magnets or coils under a high field magnet, delamination is a critical damage. Therefore, it is important to examine the failure behaviors of CC tapes under transverse tension load and to evaluate the delamination characteristics. In this study, anvil test methods were used to mechanically and electromechanically investigate the delamination characteristics of CC tapes processed by reactive co-evaporation by deposition and reaction under transverse tension load at 77 K and a self-field. To check the effectiveness of the anvil test method in evaluating the delamination strength of the CC tapes, various upper anvil/specimen contact configurations were used. As results, damage at the edges of CC tape samples were found to significantly influence both mechanical and electromechanical delamination strength including Ic degradation behaviors. Finally, the fractographic morphologies of CC tape samples delaminated under transverse tension loads were microscopically observed, and these observations were used to explain variations in electromechanical delamination strength depending on the upper anvil/specimen contact configuration.