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Electro-mechanical Property Evaluation of REBCO Coated Conductor Tape with Stainless Steel Substrate
Dedicatoria, M.J.,Shin, H.S.,Ha, H.S.,Oh, S.S.,Moon, S.H. The Korean Society of Superconductivity and Cryoge 2010 한국초전도저온공학회논문지 Vol.12 No.4
In this study, the electromechanical property of REBCO coated conductor (CC) tape adopting a stainless steel substrate has been investigated. Sample was subjected to uniaxial tension and measured its mechanical properties at RT and 77 K. $I_c-{\varepsilon}_t$ relations was also studied in which the strain and stress corresponding to the 95% $I_c$ retention and reversible strain limit were measured. In addition, these results were compared to the case of conventional REBCO CC tape adopting a Hastelloy substrate. As a result, by adopting a stainless steel substrate comparable strength and good electromechanical property to Hastelloy one could be achieved.
Dedicatoria, M. J.,Shin, H. S. IEEE 2013 IEEE transactions on applied superconductivity Vol.23 No.3
<P>Critical current, <I>I</I><SUB>c</SUB>, in REBCO coated conductor (CC) tapes may increase or decrease reversibly within the reversible region with stress/strain but degrade permanently beyond the irreversible limits due to cracking of the superconducting film. Analyzing quantitatively the stress/strain tolerances of <I>I</I><SUB>c</SUB> is of importance on the possibility to suppress the onset of cracking on the REBCO coating film. In this study, the stress/strain tolerance of GdBCO CC tapes was experimentally measured from <I>I</I><SUB>c</SUB> -strain measurement test at 77 K. The improvement in the irreversible strain limit in CC tapes was analyzed by calculating the pre-compression induced by additional layers. The increase of about 0.10%-0.15% in irreversible strain limit with additional Cu and brass laminate is much larger compared with the measured 0.03%-0.06% residual strain due to thermal contraction difference among constituent layers. This result showed that the improvement in the ε<SUB>irr</SUB> cannot be solely explained by the coefficient of thermal expansion difference among constituent layers.</P>
Bending Strain Dependence of the Transport Property in Jointed BSCCO Tapes
Dedicatoria, Marlon J.,Shin, Hyung-Seop The Korean Society of Superconductivity and Cryoge 2010 한국초전도저온공학회논문지 Vol.12 No.2
In this study, the effect of bending strain on the transport property and critical current of lap and butt-jointed (non-laminated) BSCCO tapes has been investigated. The samples were joined using a mechanically controlled jointing procedure. To achieve a uniform thickness at the joint a single point loading contact has been devised. GFRP mandrels with different bending radii which support the sample during bending have been used. $I_c$ have been measured at 77 K and self field. In the case of easy bending test for jointed BSCCO tapes, sudden degradation of $I_c$ is caused by the local strain concentration due to non uniform deformation at the edge parts of the joint. In the case of hard bending test of jointed BSCCO tapes transverse macroscopic crack at specific subsection caused a large $I_c$ degradation. The transport property of jointed BSCCO tapes in each bending mode was discussed with the damage morphology occurred.
Dedicatoria, Marlon J.,Bautista, Zhierwinjay,Shin, Hyung-Seop,Sim, Kideok American Institute of Physics 2015 Review of scientific instruments Vol.86 No.8
<P>In this note, the effectiveness of voltage tap clipping technique was assessed in evaluating the electromechanical properties of high temperature superconductor (HTS) tapes in the aspect of practical device applications. In the four-probe transport I-c measurement, instead of directly soldering the voltage lead wires onto the HTS samples, they were tapped to the sample by either just clipping or soldering them to the clips. This technique facilitated the simultaneous and repeated retained I-c measurement test for multiple samples. Finally, the critical double bending diameter of HTS tapes and the electrical properties of jointed and striated coated conductor tapes could be easily determined. (C) 2015 AIP Publishing LLC.</P>
Delamination Characteristics in Wide REBCO Coated Conductor Tapes Under Transverse Loading
Gorospe, Alking,Dedicatoria, Marlon J.,Hyung-Seop Shin Institute of Electrical and Electronics Engineers 2015 IEEE transactions on applied superconductivity Vol.25 No.3
<P>Superior characteristics and great potential of coated conductor (CC) tapes are some of the promises in pursuit of energy efficient application in electrical field. However, in electric device applications, the coefficient of thermal expansion (CTE) mismatch of each constituent layer, screening current, excessive radial tensile stresses during operation, and other coil fabrication related reasons might cause delamination damage in CC tapes. It was reported that the delamination among its constituent layers resulted to the degradation of its electromechanical properties on coil application. Therefore, the investigation on its delamination behavior is necessary for device application design. In this study, using the anvil test method, the delamination behaviors in 12-mm-wide Cu stabilized and brass laminated GdBa<SUB>2</SUB>Cu<SUB>3</SUB>Oy CC tapes with stainless steel substrate were investigated. The mechanical delamination strength of the CC tapes for differently assembled upper anvil and CC tape configurations about widthwise direction was investigated by using a 4 mm × 8 mm size upper anvil. Mechanical delamination strength of the CC tape was not enhanced by the addition of brass laminate and showed no significant difference depending on the superconducting side or the substrate side. Furthermore, both CC tapes exhibited similar delamination mechanisms and sites but showed different fracture morphologies.</P>