Measurement of Shear Delamination Strength of REBCO Coated Conductors

A new test method for the measurement of shear interfacial delamination strength of Rare-earth barium copper oxide (REBCO) coated conductor (CC) tapes was implemented in this study. A novel shear specimen was designed and constructed. The shear specimen of epoxy resin was cured by three-dimensional printing technology and embedded with a short REBCO CC tape. The tape plane is parallel to the longitudinal axis of the specimen to realize pure shear load to REBCO CC tape through the universal uniaxial tensile load. The torque effect, non-interface elastic-plastic mechanical deformation and overflowed solder appearing in the traditional testing method are omitted. The experimental results show that the valid shear delamination strength is from 10.30 MPa to 11.98 MPa with the average value of 11.27 MPa, indicating the serious scattering of the tested data in traditional testing methods is eliminated. Through the analysis of delaminated interfaces morphology and the energy dispersive spectroscopy, it is observed that the interface delamination mainly occurs within the REBCO superconducting film itself, and a small portion of buffer layers are also peeled due to the brittle nature. In addition, based on the analysis of invalid data and the corresponding morphology after delamination, it is shown that the initial defects and failures significantly affect the experimental data, resulting in a lower testing value than the real shear interfacial delamination strength.