The strain effect on critical current in YBCO coated conductors with different stabilizing layers

Abstract

The tensile strain dependences of the critical current (I c ) in YBa 2 Cu 3 O 7−δ (YBCO) coated conductors fabricated by using the rolling-assisted biaxially textured Ni-W substrates (RABiTS)-pulsed laser deposition (PLD) method were examined at 77 K and in self magnetic field. Cu and stainless steel layers were used as stabilizers to the YBCO coated conductor, and the effects of stabilizing layers on the strain tolerance of I c were investigated, compared with the case without a stabilizing layer. The lamination of stabilizer produced an increase in the yield strength and strain tolerance of I c in coated conductors. All YBCO coated conductors tested showed a reversible strain effect and a peak in the relation between I c and applied strain. The peak strain of I c and the irreversible strains for I c degradation were enhanced when the YBCO coated conductor was laminated with a stabilizing layer. For the case laminated with a stainless steel layer, I c recovered reversibly until the applied strain reached to about 0.5% and showed its peak at a strain of 0.42%, comparing to the case without a stabilizing layer, which were 0.21% and 0.18%, respectively. It can be predicted that the lamination of a stabilizing layer produced a significant residual compressive strain to the YBCO film during cooling to 77 K, which influenced the axial strain tolerance of YBCO coated conductors. Therefore, the I c -tensile strain relation in YBCO coated conductors could be explained by a two-stage deformation; stage I is the region where YBCO film behaves elastically and I c recovers when the stress is released. Stage II is the region where I c decreases irreversibly attributable to the cracking induced in the YBCO film due to the significant plastic deformation of the substrate or the stabilizing layer.

Progresses and challenges in the development of high-field solenoidal magnets based on RE123 coated conductors

“…In 2005 Shin et al [62], investigated the effect of stabilizer layer on critical current for a PLD-Y123 CC deposited onto a 50 μm thick NiW substrate. In particular, their results showed that a 70 μm thick laminated SS tape significantly increases the irreversible tensile strain, because SS contracts more than NiW, inducing a large precompression in the superconductor layer.…”

Establishment of strain measurement system for evaluation of strain effect in HTS tapes under magnetic field

“…Under self field at 77 K, electromechanical properties evaluation of the CC tapes under tension was done adopting the test rig reported in [14]. Loading frame was mounted on a universal test machine and load was applied to the sample by moving the pull rod.…”

“…Strain effects in superconducting wires/tapes have been intensively investigated by adopting different testing procedures [14][15][16][17]. Recently, fundamental stress-strain measurements on NbTi/Nb 3 Sn wires were completed as international standards (IEC 61788-6) within the framework of IEC/TC90 and VAMAS/TWA 16 with the key task on assessment of the sensing system resolution, accuracy and precision when measuring the elastic modulus [13].…”

Review of progress in electromechanical properties of REBCO coated conductors for electric device applications

“…Consequently, the ε irr significantly increased with an addition of stabilizer and also the improvement depends on stabilizer material adopted [19,20]. Primarily, substrate holds the whole CC superconductor composite, thus it influences the mechanical behavior of the whole tape especially for Ag-stabilized CC tape samples [21].…”