Progress in R＆D of coated conductor in M-PACC project

Abstract

The five-year national project in Japan for R&D of coated conductors and applications, named as the Materials and Power Applications of Coated Conductors (M-PACC) project, was finished at the end of FY2013. The project consists of four sub-themes as cable, transformer, SMES and coated conductors. In the theme of coated conductors, the fabrication process had been developed to satisfy the requirements from the applications such as in-field I c performance, low AC loss in the long tapes etc. Through the project, the remarkable progress was achieved as follows; a high in-field minimum I c value over 54A/cm-width under 3T at 77K was realized in a 200m long EuBCO tape with artificial pinning centers of BaHfO 3 by the pulsed laser deposition (PLD) technique on the IBAD template. On the other hand, the AC loss reduction was confirmed in the tapes fabricated by both PLD and the metal organic deposition (MOD) techniques by scribing 100m tapes into 10-filamments. Additionally, the mechanism of the delamination phenomenon was systematically investigated and the strength was improved by eliminating the origins of the weak points in the films. Through the development, all targeted goals were accomplished and the several results were appreciated as a world champion data.

Critical current density above 15 MA cm−2at 30 K, 3 T in 2.2μm thick heavily-doped (Gd,Y)Ba2Cu3Oxsuperconductor tapes

“…The J c value of the 2.2 thick film compares well with the record-high J c value of 20.1 MA cm −2 reported at 30 K, 3 T [19] (in this case in a 0.9 μm thick, 25 mol% Zr-added film). Hence contrary to previous findings with PLD [10,20], our results show that high critical current values in films thicker than 2 μm is possible even with BZO addition just as it has been with BHO addition. Further, our results confirm that high quality thick films can be made even with heavily-doped REBCO.…”

“…These defects could include the Cu-Zr nanoparticles that were found near the BZO nanocolumns in heavily-doped (Gd,Y)BCO tape [19] as well as stacking faults that are abundantly found. The I c,min value at 3 T corresponds to a J c,min value of 12.46 MA cm −2 which compares to a J c value of 7 MA cm −2 reported in a recent work on 3.9 μm thick film of BHO-doped EuBa 2 Cu 3 O x tape that had exhibited a high I c,min value of 141 A cm −1 at 77 K, 3 T [20,28]. Our results reveal that high in-field performance can be achieved in thick films of REBCO coated conductors regardless of the type of dopant and rare earth used.…”

“…The minimum value of critical current (I c,min ) in angular dependence measurements has been viewed as an important parameter since a wide range of field orientations is experienced in superconducting coils. There has been be a substantial effort placed in enhancing the I c,min value especially at 77 K in fields of 1-3 T [10,20,28]. We had previously shown that the I c values at 77 K, 3 T, B||c rather than I c,min values at 77 K correlate well with I c,min values at lower temperatures [18].…”

“…It was discovered that REBCO films with well-aligned nanocolumns of BZO exhibited the highest lift factor in critical current (ratio of critical current at a particular temperature and magnetic field to the critical current at 77 K, zero field) [18]. There have been reports that the alignment of BZO nanocolumns degrade with increasing film thickness resulting in reduced improvement in critical current of BZOdoped REBCO films thicker than 2 μm [20]. Hence, a purpose of this study was to examine the critical current of heavily Zrdoped REBCO tapes made by MOCVD with film thickness over 2 μm.…”

High Performance Coated Conductors Fabricated by UTOC-MOD Process

“…8. We succeeded in improving the withdrawal rate of dip-coating from 5 m/h [18] to 50 m/h. These results suggest that the application of the proposed approach to industrial coating processes is possible.…”