• Progress in Superconductivity
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• v.10 no.2
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• pp.103-107
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• 2009

$Bi_2Sr_2Ca_1Cu_2O_x$(BSCCO 2212) superconductors for current lead were fabricated by centrifugal melting process(CMP). BSCCO 2212 powder was melted at $1200^{\circ}\C$ in a resistance furnace using a Pt crucible and poured in a rotating cylindrical mold preheated at $550^{\circ}\C$ for 2 hour. The solidified BSCCO-2212 samples were heat-treated by partial melting process in oxygen atmosphere. The current-voltage curves at 77 K of the samples were obtained by transport measurement, and the microstructure was investigated by scanning electron microscope. The $J_c$ values at 77 K of the tubes partially melted at $840^{\circ}C,\;860^{\circ}C\;and\;880^{\circ}C$ were 492, 430 and 398 $A/cm^2$, respectively. It was observed that the plate-like grains in BSCCO 2212 tube was more developed in the sample heat-treated at $840^{\circ}C$. It was found that the critical current of the BSCCO 2212 samples was dependent on the partial melting schedule regarding the grain shape and size of the BSCCO 2212.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.589-590
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• 2005

BSCCO:2212-2223 thin films were fabricated by using the ion beam sputter with a evaporation method at various substrate temperatures, $T_{sub}$, and ozone gas pressures, $pO_3$. The correlation diagrams of the BSCCO phases with Tsub and $pO_3$ are established in the 2212 and 2223 compositional films. In spite of 2212 compositional sputtering, Bi2201 and Bi2223 as well as Bi2212 phases come out as stable phases depending on Tsub and $pO_3$. From these results, the thermodynamic evaluation of ${\Delta}H$ and ${\Delta}S$, which are related with Gibbs' free energy change for single Bi2212 or Bi2223 phase, was performed.

• Progress in Superconductivity
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• v.8 no.1
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• pp.98-103
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• 2006

[$Bi_2Sr_2Ca_1Cu_2O_x$](BSCCO 2212) tubes were fabricated by centrifugal melting process(CMP). BSCCO 2212 powder was melted in a Pt crucible and solidified in a rotating steel mold. The BSCCO 2212 tube samples separated from steel mold were heat-treated at $800^{\circ}C\;and\;810^{\circ}C$ in oxygen flow. The critical current($I_c$) of the samples was measured by transport measurement at 77K, and the microstructure was investigated by scanning electron microscope. The $J_c$ at 77K of the tubes heated treated at $800^{\circ}C\;and\;810^{\circ}C$ were 197 and 240 $A/cm^2$, respectively. It was observed that the plate like grains in BSCCO 2212 tube was more developed in the sample heat treated at $810^{\circ}C\;and\;800^{\circ}C$ heated tube. It is found that the critical current($I_c$) of the BSCCO 2212 sample was dependent on the heating schedule regarding the growth of the BSCCO 2212 grains.

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.285-288
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• 2000

The effect of the initial BSCCO 2212 grain size on the final gain size and the formation of the BSCCO 2223 was studied using a powder precursor synthesized by two-powder method. 2212 and CaCuO$_2$ tapes were prepared by dip coating and joined by pressing and then followed by the repeated thermo mechanical treatment. The samples were characterized by XRD and SEM analysis. The formation and grain size of the BSCCO 2223 depended on the initial BSCCO 2212 grain size.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.06a
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• pp.267-267
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• 2006

전력에 큰 손실을 초래하는 고장전류를 차단하기 위한 한류기(FCL) 소재로서 고온 초전도체인 BSCCO 2212가 사용된다. 고온에서 용융된 BSCCO 2212 분말은 원심성형법에 의해 한류기용 튜브로 제조되었다. BSCCO 튜브의 기계적 특성을 높이고 용융온도를 낮추기 위해 $SrSO_4$(10wt-%)를 첨가하였다. 용탕은 $1200^{\circ}C$에서 완전히 용융되어 금속 몰드로 주입되었고 원심성형에 사용되는 금속 몰드는 $550^{\circ}C$ 온도로 2시간 예열 후 1020 ~ 2520 RPM으로 회전시켰다. 원심력에 의해 성형된 BSCCO 튜브는 약 48시간 동안 로에서 서냉 후 금속 몰드로부터 분리하였다. 튜브의 용이한 분리를 위해 이형제로서 BSCCO 2212 powder를 사용하였고 임계전류측정을 고려하여 Ag tape 단자를 튜브 끝단에 부착하였다. BSCCO 제조 공정에 있어서 몰드의 예열온도, 용융온도, 몰드 회전속도 등의 변수를 조절하여 최적의 조건을 확립하였다. 제조한 BSCCO 튜브의 임계전류($I_c$)와 임계전류밀도($J_c$)는 77K에서 536A와 $205A/cm^2$ 이었다. 본 연구에서는 BSCCO 2212 튜브를 제조하는 공정조건 변화와 각 조건에서 제조된 BSCCO 2212 튜브의 전기적 특성 및 그에 따른 분석에 대해 기술하였다.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2000.11a
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• pp.104-105
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• 2000

High quality BSCCO thin films have been fabricated by means of an ion beam sputtering at various substrate temperatures, T$_{sub}$, and ozone gas pressures, PO$_3$. The correlation diagrams of the BSCCO phases appeared against T$_{sub}$ and PO$_3$are established in the 2212 and 2223 compositional films. In spite of 2212 compositional sputtering, Bi2201 and Bi2223 phases as well as Bi2212 one come out as stable phases depending on T$_{sub}$ and PO$_3$. From these results, the thermodynamic evaluations of ΔH and ΔS which are related with Gibbs'free energy change for single Bi2212 or Bi2223 phase are performed.ormed.i2212 or Bi2223 phase are performed.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.104-107
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• 2000

High quality BSCCO thin films have been fabricated by means of an ion beam sputtering at various substrate temperatures, T$\_$sub/, and ozone gas pressures, PO$_3$. The correlation diagrams of the BSCCO Phases appeared against T$\_$sub/ and PO$_3$ are established in the 2212 and 2223 compositional films. In spite of 2212 compositional sputtering, Bi2201 and Bi2223 phases as well as Bi2212 one come out as stable phases depending on T$\_$sub/ and PO$_3$. From these results, the thermodynamic evaluations of ΔH and ΔS which are related with Gibbs' free energy change for single Bi2212 or Bi2223 phase are performed.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.19 no.6
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• pp.579-585
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• 2006

We fabricated BSCCO-2212 (2212) rod by the melt casting process (MCP) and evaluated the effect of the melt flowing on the critical current ($I_c$) by using vertical and tilt casting. It was observed that the $2212-SrSO_4$ rod processed by the tilt casting method with homogeneous pre-heating temperature of the mold had a higher $I_c$ than that processed by the vertical casting method. We also evaluated the influence of the strontium sulfates ($SrSO_4$) addition on the texture, microstructure, critical current and temperature, and mechanical hardness of the $2212-SrSO_4$ rods. It was observed that the addition of $SrSO_4$ improved the critical current ($I_c$) and mechanical hardness of the 2212. The $I_c$ of the 2212 increased as the $SrSO_4$ content increased and reached a peak value (260 A at 77 K) at an $SrSO_4$ content of 6 wt.%. In addition, the addition of $SrSO_4$ had a beneficial effect on the mechanical hardness of the 2212. We studied the possible cause of the variation in the $I_c$ with the melt flowing and the $SrSO_4$ content based on the XRD, EPMA analysis and the microstructural observation.

• Proceedings of the KWS Conference
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• 2007.11a
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• pp.282-284
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• 2007

The superconductor characteristics of BSCCO spray films by Heat treatment was studied. $Bi_2Sr_2CaCu_2O_x$(Bi-2212) is high-Tc superconductor(HTS) coatings have been prepared by Heat treatment. Where high current carrying capabilities are required and therefore thick film and bulk material are called for, the Bi2Sr2Ca1Cu2O8-d(Bi-2212)compound has evoleved as one of the most promising. and the Bi-2212 HTS coating layer is synthesized through the peritectic reaction between Sr-Ca-Cu oxide coating layer and Bi-Cu oxide coating layer by partial melting process. The superconducting characteristics depends on the spray distance which was related to the spray particle melt. The Bi-2212 HTS layer consists of the whisker growth and secondary phase in 2212 layer were observed.

• Progress in Superconductivity
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• v.9 no.2
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• pp.193-198
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• 2008

We fabricated BSCCO-2212(2212) bulk superconductors by using a casting process and evaluated the superconducting properties. The effects of annealing conditions on microstructure and critical properties were studied. It was found that the homogeneous and uniform microstructure improved the critical properties and the microstructures of ingot and annealed rods were different with the size of 2212 rod and tube. The critical current($I_c$) of rods increased with increasing annealing time, probably due to increased grain size of 2212. Annealing time of the highest $I_c$ for the smaller rod(diameter of 10 mm) was shorter(150 hr) than that of the larger rod(diameter of 16 mm, 400 hr). This size effect seems to be related to different grain sizes of the intermediate phases such as 2201 and secondary phases in the ingot. In addition, we fabricated 2212 tubes from the rod by removing the center region which contained inhomogeneous microstructures. The $I_c$ of 2212 tube with the outer diameter of 16 mm and the thickness of 2 mm was measured to 844 A, which corresponds to the critical current density of $1017\;A/cm^2$ at 77 K.