The Role of Buffer Layer on the Performance and Uniformity Improvement of Long-Length HTS YBa2Cu3O7−x Tapes Derived by MOD

Progress in superconducting REBa2Cu3O7 (RE = rare earth) coated conductors derived from fluorinated solutions

“…Understanding the main trends of REBCO nucleation and growth has strongly facilitated to prepare CCs using different metallic substrates (RABiT, IBAD) leading to fairly good superconducting performances, including the reel-to-reel continuous process used at industrial scale [30,58,140,142,[169][170][171][172]. It is also worth to remark that owing to the global complexity of the CSD BaF 2 growth process, several attempts of using experimental fast screening and big data approaches have been made to accelerate the optimization of CCs and to correlate processing, nanostructure and superconducting properties [143,147,173].…”

“…We should mention, for instance, the extension of the CSD growth process to other REBCO compositions which required tuning the growth conditions (figure 23), and they were applied in Y 1−x Gd x BCO conductors on RABiT and IBAD substrates [63,169,171,216]. As it has been described previously (section 3.1), it was necessary to fine tune the temperature and PO 2 conditions for growth to minimize the formation of BCO at the substrate interface and, depending on the quality of the buffer layer of the metallic substrate [58,80,81,142,171,172]. Additional results confirming that the self-field critical currents are indeed decreased when the in-plane boundary angle among grain boundaries of the top buffer layer (cap layer) increases have been recently reported using IBAD substrates with CeO 2 cap layers on top of the CC architecture.…”

“…At industrial scale the preferred solution deposition techniques are slot die coating or dip coating, although IJP has also been demonstrated and several different metallic substrates have been used, i.e. RABiT, IBAD and copper clad [29,30,146,167,172,[309][310][311]. The specific adaptation of composition to reach controlled rheological properties of the solutions have been widely implemented at the industrial scale to minimize the number of depositions.…”

“…The final step in CSD CC manufacturing is the growth of REBCO films through the BaF 2 route, also including the final oxygenation process, two processes which have been widely discussed in previous sections. There exist several industrial producers which have implemented CSD CC manufacturing units producing lengths in the range of hundreds meters to one km [30,63,77,172,309,312,313]. Most of these systems use reel-to-reel units although some have also built batch furnaces adapted to coils of several hundred meters [63].…”

“…In all cases, however, the REBCO growth rate remains quite low thus limiting the throughput of the BaF 2 process because then it requires quite extended high temperature annealing times or long furnaces. Concerning the demonstrated superconducting performance, several producers have already demonstrated I c values at 77 K in the range of 400-500 A cm −1 -w with lengths of 300-1.000 m and a fairly good homogeneity [30,63,172,316]. The CSD CCs are already being considered a competitive industrial product and so they are being implemented in power devices such as cables.…”