Delamination Strength of the Soldered Joint in YBCO Coated Conductors and Its Enhancement

We now report the delamination properties of soldered lap joints in YBa₂Cu₃O_7-x coated conductors (YBCO CCs) without removing the metallic stabilizer. The delamination strength, current, and resistance behaviors in the lap joints under transverse tension are investigated at 77 K. It is found that the current shows no degradation (95% of the critical current I_c0 in original YBCO CC sample as a criterion) before a visible delamination, whereas there is no remarkable change in resistance of the lap joints. Moreover, the lap joint shows significant edge effects on the critical anvil strength, which can be raised as high as the original CC samples by adding solder fillets at the edge of the joint. In addition, the delamination of the YBCO layer (including Buffer layer) and Hastelloy in YBCO CC samples presented in literature is successfully simulated by using a 3-D ANSYS, and the enhancement of delamination strength in the lap joint reported in this paper is also interpreted by the simulation.