Mechanical bending property of YBCO coated conductor by IBAD/PLD

We investigated the dependence of critical current, Ic, of YBCO tapes on the mechanical bending strain in order to apply them to solenoid and pancake type magnets. The tensile and compressive bending strains were applied to the YBCO tapes. The thickness of the YBCO layer on the CeO2 and Y2O3 buffer layers was 0.5 and 1.0 μm, respectively. The Ag cap layer has thickness of 10, 20, and 30 μm respectively. In every sample, no degradation of the normalized critical current, Ic/Ic0, was observed up to the first tensile and compressive strains of approximately 0.4% and 0.5%, respectively. The strain property of the YBCO tapes that were deposited with the 20 and 30 μm thick Ag cap layers showed an improvement over the tape that was deposited with the 10 μm thick Ag cap layer in terms of the tensile and compressive strains of approximately 0.5% and 0.6%, respectively. Cracks were observed on the YBCO film surface under a tensile bending strain of over 0.5%. The generation of the crack appears to be the primary reason for the Ic/Ic0 degradation. The heat cycle test was performed 10 times by applying the tensile strains of approximately 0%, 0.3% and 0.5%. The degradation of Ic/Ic0 was not observed in every sample.