Effect of the SS304 coating layer on the electrical and thermal properties of REBCO commercial tape

The effect of the 304 stainless steel (SS)-coated layer on the electrical and thermal properties in the radial direction of REBCO commercial tape was systematically investigated. The single SS-coated layer significantly increased electrical resistivity and decreased thermal conductivity. In contrast, double SS tape demonstrated a lower electrical resistivity than the original commercial REBCO tape due to the clean procedure to remove the possible carbon and oxidation in the Cu layer. We found that the surface microhardness of the SS-coated REBCO tape, a previously neglected factor, could be one of the primary factors determining turn-to-turn electrical resistivity. The other possible factor could be interface heterogeneity. The different materials on both sides of the interface could bring apparent different electrical and thermal resistivity. This study provides a possible method to increase the turn-to-turn electrical resistivity of REBCO tape without increasing tape thickness, sacrificing the critical engineering current density.