• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.30 no.1
• /
• pp.32-36
• /
• 2017

The Ag thin film of YBCO (yttrium barium copper oxide) CC (coated conductor) protect the YBCO layer and, at the same time, affects the electrical characteristics of the YBCO CC. Therefore, YBCO CC with the commercialization of the Ag thin film layers makes it easy to establish a process, it can lead to a variety of characteristic changes in YBCO CC. In this paper, plasma surface treatment was carried out to facilitate the deposition of the Ag thin film and the deposition process of YBCO CC. Surface roughness from the test results was increased as the time of the plasma surface treatment increased from 5 to 20 minutes. On the other hand, the surface roughness was decreased for the time of the plasma surface treatment over 20 minutes. Furthermore, after depositing, the increasing of deposit amount and reduced lifting phenomenon showed a similar tendency with the rise time of surface roughness.

• Proceedings of the KIEE Conference
• /
• summer
• /
• pp.1010-1012
• /
• 2004

AC loss is an important factor in the development of superconducting tapes and superconducting power applications. In this paper we measured and compared characteristics of BSCCO tape and YBCO Coated Conductor(YBCO CC). BSCCO tape was fabricated by PIT method. We measured critical current density and transport current loss of it. Also, YBCO CC tape consist of substrate. buffer, YBCO and metal layers. We measured critical current density on variations of external magnetic field and transport current loss of these cases. The results of measurement show that normalized critical current of YBCO CC is smaller then that of BSCCO tape in the external magnet field. According to the results. measured loss and calculated of the YBCO CC show the same tendency.

• Progress in Superconductivity and Cryogenics
• /
• v.12 no.1
• /
• pp.17-21
• /
• 2010

In the case of designing superconducting power apparatuses using the second generation high temperature superconducting wire, it is necessary to have a tape-splicing technique to achieve low splice resistance between coated conductor (CC) tapes. In this paper, an experimental splice method between YBCO CC tapes is proposed for a coil application. Splices were performed with a 37Pb-63Sn solder. YBCO samples were fabricated with various pressures and cooling rates. Joint resistances of the spliced samples of jointed YBCO CC tapes were measured and evaluated from V-I curves. In addition, optical micrographs were obtained to analyze the cross sectional microstructure of jointed samples.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.21 no.10
• /
• pp.950-953
• /
• 2008

YBCO coated conductor called the second-generation superconducting tapes have resistance increase significantly more than BSCCO tapes in terms of the speed or amount when quench occurs, they may have different ranges of application. Such characteristics are thought to get different properties by selection of stabilizing materials in manufacturing superconducting tapes. It is important in selecting superconducting tapes which will be applied to power devices in the future. In this study, one kind of BSCCO tapes and two kinds of YBCO CC with different stabilizing materials and one kind of YBCO CC with non stabilizing materials were used to compare and examine transport characteristics in flux-flow state and quench state with each tape joint of HTS tapes.

• Progress in Superconductivity and Cryogenics
• /
• v.12 no.3
• /
• pp.16-20
• /
• 2010

For large scale power applications of HTS conductor, it is getting more important to have a stacked HTS coated conductor with low loss and large current capacity. But it was not easy to measure some electric properties. Stabilizer free YBCO CC for striated/ stacked conductors is easily burned out during the measurement of the critical current density because it has no stabilizer and it is difficult to set-up the current lead and voltage taps because it has many pieces of YBCO CC in a conductor. Instead of direct measuring the critical current of a stacked HTS coated conductor, indirect estimation from measuring a magnetization loss of HTS coated conductor could be useful for practical estimation of the critical current. The magnetization loss of a superconductor is supposed to be affected by a full penetrating magnetic field, and it tends to show an inflection point at the full penetrating magnetic field when we generate the graph of magnetization loss vs. external magnetic field. The full penetrating magnetic field depends on the shape of the conductor and its critical current density, so we can estimate the effective critical current density from measuring the magnetization loss. In this paper, to prove the effectiveness of this indirect estimation of the critical current, we prepared several different kinds of YBCO CC(coated conductor) including a stacked conductor short samples and measured the magnetization losses and the critical currents of each sample by using linked pick up coils and direct voltage measurement with transport current respectively.

• Progress in Superconductivity and Cryogenics
• /
• v.9 no.3
• /
• pp.26-31
• /
• 2007

In recent years. YBCO coated conductor (CC) called as second generation HTS (high temperature superconducting) wire has been developed as a suitable material for resistive superconducting fault current limiter (SFCL). For designing the SFCL. the required length of superconducting wire is inverse proportional to the maximum temperature reached when a fault occurs. Since the required length strongly affects a manufacturing cost, it is the most important parameter to determine the maximum temperature reached. It is necessary to observe the repetitive over-current characteristics of HTS wire. This paper attempts to measure the variation of critical current of YBCO CC after repetitive over-current pulse. No degradation of the critical current of CC sample was observed by applying 100 times over-current pulse which makes temperature above 400 K after 100ms. This study can be useful in designing optimally resistive SFCL employing YBCO CC. The maximum permissible temperature can be set to 400K. so wire length could be reduced by 30% compared in case of 300K-criterion.

• Progress in Superconductivity
• /
• v.11 no.1
• /
• pp.1-7
• /
• 2009

HTS coated conductor was heat treated at high temperatures below the melting points of silver and YBCO at different oxygen partial pressures. Current carrying capacity and microstructure were varied depending on the presence of silver protection layer. Critical current of coated conductor without silver protection layer was not changed when heat treatment was performed at $850^{\circ}C$ for 2 hr in an oxygen atmosphere. However, coated conductor with silver protection layer revealed abrupt drop of $I_c$ from 140A to 8A when heat treatment was performed at $800^{\circ}C$ for 2 hr in an oxygen atmosphere. Coated conductor with silver protection layer retained $70{\sim}80$ percent of its original $I_c$ when heat treatment was performed at $800^{\circ}C$ for 2 hr in an argon atmosphere containing 1000ppm oxygen. SEM and XRD observations showed the presence of interaction between YBCO and silver depending on the atmosphere of heat treatment. The reaction between YBCO superconductor and silver was accelerated at high oxygen partial pressure and resulted in the change in microstructure and decrease of critical current density even by the heat treatment performed at temperature much lower than the melting points of silver and YBCO.

• Progress in Superconductivity and Cryogenics
• /
• v.7 no.3
• /
• pp.34-38
• /
• 2005

Multi-stacked HTS tapes are needed to conduct large current in the power application. In this paper, magnetization losses of the multi-stacked YBCO coated conductor and the BSCCO tape have been measured and compared. Magnetization losses of single tape, 2-stacked, 3-stacked and 4-stacked HTS tapes have been presented in this paper. Multi-stacked tapes have been fabricated using face-to-face type stacking method. Measurements of magnetization loss were performed under various angle of external magnetic field to consider the anisotropic characteristics of HTS tapes. Test results show that loss density per unit volume decreased for both YBCO coated conductors and BSCCO tapes when the stacking number of tapes is increased. The magnetization losses of YBCO CC are larger than those of BSCCO tapes when the external magnetic field is increased.

• Progress in Superconductivity and Cryogenics
• /
• v.11 no.3
• /
• pp.15-19
• /
• 2009

Recently, it is proposed to make striations on the YBCO coated conductor and to transpose each other as one of the solutions to decrease the perpendicular magnetization loss. For large power application using HTS, the stacked conductor packing the YBCO coated conductors should be used because single conductor is limited in flowing of demanded large current. In this paper, we research the affect of the striation and continuously transposed stacking geometry on the magnetization loss in perpendicularly exposed magnetic field. Several short samples having different number of striation and continuously transposed stack are prepared and tested in perpendicularly exposed magnetic field for the magnetization loss characteristics. The magnetization loss of striated sample was lower than sample without striation. The reduction effect on magnetization loss by the striation is obviously appeared in higher field and lower number of stack and decreased as increasing the transposed stacking number. Also, the reduction effect by transposed stack is obviously appeared in lower field at lower number of striation and isn't appeared at higher striation number and higher magnetic field.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.290-291
• /
• 2008

Recently High Temperature Superconductor(HTS) Tape is limelight of the applied superconducting machines. Mainly used superconducting tape are BSCCO tape and YBCO coated tape. These superconducting tape are applied such as SMES, superconducting generator and MAGLEV. Actually superconductor tape's experimental gauge is short. For this reason, experiment was conducted. Firstly length of 50cm BSCCO, YBCO Coated conductor@Cu and YBCO coated conductor@sus are prepared. and flow the over-current. Secondly, BSCCO and Coated conductor connected with lenth of 25cm and flow the over-current. Coupled line of HTS tape was compared with single line of HTS tape and these overcurrent characteristics was investigated.