• 한국초전도학회:학술대회논문집
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• 2007.07a
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• pp.69-69
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• 2007

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.11a
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• pp.182-184
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• 1997

Superconducting thick films were fabricated with various paticle sizes on Allumina substrates by MPMG method. The sample of about 63${\mu}{\textrm}{m}$ in this experimented the size of particles was the best for uniformity and the number of Y211. In this experiment It is observed that powder size is very important to fabricate the superior thick finns.

• Proceedings of the Materials Research Society of Korea Conference
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• 1997.05a
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• pp.44-44
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• 1997

• 한국초전도학회:학술대회논문집
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• v.10
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• pp.276-279
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• 2000

When high temperature superconducting tapes is fabricated using the PIT (Powder In Tube) method, the length of HTS tapes is increased more than 500 ${\sim}$ 1,000 times of initial powder packed billet. On mechanical processing, heterogeneous properties between the ceramic superconducting core and Ag/Ag alloy sheath occur the non-uniformity deformation as like sausaging that deteriorate the critical current properties of HTS tapes. In this study, we investigated the workability of Bi-2223/Ag/Ag alloy sheath tapes fabricated by the PIT method involving a number of different mechanical processes, multi drawing and rolling. In order to obtain the high critical current density and high uniformity of Bi-2223/Ag sheath tapes, the influences of powder packing density, drawing die angle and rolling parameters were studied. We found that the roll diameter is an important variable in the rolling process, as critical current of tapes rolled using 250 mm rolls was higher than that using 150 mm rolls.

• Progress in Superconductivity
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• v.12 no.1
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• pp.1-5
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• 2010

In this work we synthesized both MgB2 and Carbon doped MgB2 superconductor with Ag addition via high energy milling and substituent heat treatment. Heat treatments were performed at $900\;^{\circ}C$ for 30 min in flowing Ar gas. We varied amount of Ag powder. In a range of Ag powder was 0~5wt%. The effect of Ag was correlated with superconducting properties. The results show a slight decrease in critical temperature ($T_c$) and a reduction of critical current density ($J_c$) at high fields for the Ag-doped samples as compared to the un-doped samples. Reduction of $J_c$ may be due to the formation of MgAg compound.

• Progress in Superconductivity
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• v.13 no.2
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• pp.122-126
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• 2011

Superconducting $MgB_2$ thin films were fabricated by using a novel aerosol deposition technique wherein the pre-reacted powder is directly transformed into respective thin film. The formed thin films were characterized by X-ray diffraction technique and FE-SEM to understand its structure and morphology and the superconducting behavior has been characterized with the four probe resistivity measurement. The as-deposited thin films were formed into the frustrated amorphous structure, which were relaxed on the further heat treatment at $900^{\circ}C$ for 3 hrs. The relaxed amorphous $MgB_2$ thin films showed a comparatively high superconducting onset at about 38 K.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.570-574
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• 1999

In this paper, by using the electrophoresis, preparation of YBCO superconducting wire deposited on metal Ag base wire was studied with its Properties. YBCO Powder could be prepared by solid state reactions with calcining and sintering processes. Superconducting wire prepared on metal Ag wire used as cathode of deposition base could be also fabricated in the YBCO/acetone-dispersed solution to obtain several tens of re thick films. And then it could be used as superconducting wire for measurement after calcination, sintering and oxygen absorption processes. In the process of film deposition, a catalyst I$_2$added into the suspension solution was very useful for preparing thick film of YBCO, and BaF$_2$ of additive material was also necessary for preparing crack-free wire of YBCO superconductor. As a result, YBCO superconducting wire added 2~3wt.% of BaF$_2$\ulcorner with catalyst, 12 had better deposition condition for uniform and dense YBCO wires, and critical current density, Jc was calculated at the value of 1,458A/$\textrm{cm}^2$(more than 10$^{3}$A/$\textrm{cm}^2$ ,77K, o[T]) of 30${\mu}{\textrm}{m}$ thick sample by 4 point prove method.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.11 no.12
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• pp.1139-1145
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• 1998

In this paper, to fabricate a superconducting fault current limiter(FCL) of thick film type, $YBa_2Cu_3O_X superconducting thick films were fabricated by surface diffusion process using the screen printing method. Powder mixture of $3BaCuO_2$+2CuO was screen printed on $Y_2BaCuO_5$(d=15mm). And critical current densities of the thick films were observed as the sintering temperature(92$0^{\circ}C$~95$0^{\circ}C$) and holding time(2h~10h). Based on experimental data, the thick films for superconducting FCL were sintered at $940^{\circ}C$ in 2 hours. The superconducting FCL with a current limiting area of 1mm wide and 66mm long was prepared on $Y_2BaCuO_5$ substrate. To measure the characterization of the fabricated FCL, an alternating voltage (60Hz) was applied to the FCL in 77K liquid nitrogen. At an applied voltage of 4V, the FCL was limited from 20A into 0.6A not farther than 0.5ms.

• 한국초전도학회:학술대회논문집
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• v.9
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• pp.388-391
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• 1999

Well oriented Bi2212 superconductor thick films were formed successfully on a copper substrate by liquid reaction between a Cu-free precursor and Cu tape method in which Cu-free BSCO powder mixture was' printed on copper plate and heat-treated. And we examined the effect of heat-treatment atmosphere for the superconducting properties and microstructure of Bi2212. The composition of Cu-free BSCO powder mixture was Bi$_2O_3$ : SrCO$_3$ : CaCO$_3$ = 1.2~2 : 1 : 1 and the heat-treatment for the superconducting formation reaction was performed in air, oxygen, nitrogen and low oxygen pressure. At heat-treatment temperature, the printing layer partially melt by reacting with CuO of the oxidizing copper plate, and the nonsuperconducting phases present in the melt are typically Bi-free phases and Cu-free phases. Among the nonsuperconducting phases, it is known that the (Sr,Ca)CuO$_3$ phase restrain the formation of the Bi2212 superconducting phase. Because a kind of the nonsuperconducting phases is controled by the oxygen partial pressure, the optimum condition in which the remnants of the second phases don't leave in the fully processed conductor was determined by XRD and the critical tempera to re (Tc) analysis.

• Progress in Superconductivity and Cryogenics
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• v.9 no.2
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• pp.15-18
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• 2007

The sub micron sized spherical $MgB_2$ powders were synthesized by spray reaction method. $MgB_2$ tapes with Al addition were fabricated by Powder in Tube (PIT) method. The superconducting property and microstructure of Al doped $MgB_2$ tapes were characterized by X-ray diffraction, optical microscopy and transport measurement under magnetic field. The $J_c$ value of $MgB_2$ tapes was increased with 10 vol. % Al addition. The $J_c$ value of 5,500 A/$cm^2$ and 11,000 A/$cm^2$ at 4.2 K and 5 T were obtained for the $MgB_2$ tape and 10 vol. % of Al added $MgB_2$ tape without heat treatment, respectively. The $J_c$ value of 8,000 A/$cm^2$ and 33,000 A/$cm^2$ at 4.2 K and 5 T were obtained for the $MgB_2$ tape and 10 vol. % of Al added $MgB_2$ tape with heat treatment, respectively. The $J_c$-B curves show enhancement in $J_c$ (B), which suggests that the microstructure and transport properties of $MgB_2$ tapes have been improved with Al addition.