• 한국초전도ㆍ저온공학회논문지
• /
• 제22권2호
• /
• pp.26-31
• /
• 2020

Since 2014, Sam Dong Co., Ltd. has successfully developed high-performance MgB₂ superconducting wires with a kilometer-scale. Herein, we studied performances of various MgB₂ wires fabricated by the Sam Dong with different Cu fractions and diameters for practical applications. Critical current densities of our commercial wire, 18+'1'Cu multifilamentary MgB₂ wire, are estimated to be 270,000 A/㎠ at 3 T and 4.2 K and 100,000 A/㎠ at 2 T and 20 K, respectively. We further discuss research progress of various MgB₂ superconducting wires at Sam Dong Co., Ltd and make an effort to align with customers' requirements.

• 한국세라믹학회지
• /
• 제27권3호
• /
• pp.355-360
• /
• 1990

One of the possible ways to make a flexible wire of high-Tc superconductiong ceramics is the extrusion of a mixture slurry of superconducting powder with an appropriate polymer binder. The fabrication procedure for $YBa_2Cu_3O_{7-{\delta}}$ superconducting coils with this plastic mass is described. The major factors limiting the formation of extruded wire are the binder content, powder size, and entrapped gas in the mixture slurries. The optimum content of binder for both good flexbility and strength of wire was estimated to be 30wt%. The finer the powder size is, the more homogeneous structure the extruded wire has. The vacuum degassing before extrusion was necessary to remove the entrapped gas in as-extruded wire. The formability of wire depends greatly on the wire radius and binder content. After burning out the binder and the successive sintering, the contacts between the superconducting grains could be made. The resistivity vs. temperature behavior measured in the final wire showed the transition temperature of 90K with narrow transition width. However, the critical current densities of these wires are much lower in comparison to those of conventional bulk specimens.

• 한국전기전자재료학회논문지
• /
• 제28권10호
• /
• pp.625-629
• /
• 2015

The second-generation HTS wire its YBCO coated conductor is widely used in the superconducting power apparatus. The YBCO coated conductor uses the normal-superconducting junction to increase the transport capacity of superconducting power apparatus when it is applied. The normal-superconducting junction can be a cause of reducing the stability of the superconducting power apparatus when a fault current is applied. Thus, in this study we have conducted the effect analysing normal-superconducting junction for the fault current using transport current and quench resistance. From the experimental results when a fault current is applied, the effect on the normal-superconducting junction is reduced the larger the amplitude of the fault current and is helpful to maintain the thermal stability of the HTS wire.

• 한국전기전자재료학회논문지
• /
• 제11권11호
• /
• pp.1028-1034
• /
• 1998

Bi-2223 superconductor is known as one of the candidates for practical superconducting wires. Ag-sheathed Bi-2223 superconducting wires were fabricated using the powder-in-tube(PIT) method. When the 19-filaments wire was immersed in liquid nitrogen(77K), maximum critical current density Jc of 62 A/$mm_2$ at 0T was achieved. The critical current density has been shown to depend on the mechanical properties such as tensile stress and bending strain in Ag-sheathed Bi-2223 superconducting wires. The tensile strain for Jc degradation onset was in the range of 0.12~0.3%. In the case of 19-filaments wire, the bending strain is estimated to be smaller than 0.3% for the reasonable Jc value. The observed degradation of the critical current density due to strain effect is inevitable and can be attributed to the formation of microcracks within the superconducting core.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 하계학술대회 논문집 Vol.5 No.1
• /
• pp.97-100
• /
• 2004

In this paper, the preparation of BSCCO superconducting wire by electrophoretic deposition method and the effect of suspension medium used with various solvent solutions of ethanol and buthanol for electrophoretic deposition were studied. The preheating technique in vacuum system for the superconducting powders coated on Ag wire was also investigated. As a result, it was confirmed that the preheating technique was very useful to remove the influence of remains affected to the surface conditions of superconducting wire. And the adsorbed solvent solution which was existed between and on the deposited particle surfaces was almost disappeared at the treating conditions of about $10^{-3}$ Torr and around $200^{\circ}C$ in bell-jar system. By measurement of 4-point prove method, the critical current density($J_c$) of BSCCO superconducting wire was obtained at the value of more than $10^4\;A/cm^2$ in liquid $N_2$(77 K, 0 T).

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 1994년도 춘계학술대회 논문집
• /
• pp.34-37
• /
• 1994

.In this study, we measured Ic depending on a curvature radios of High Tc superconducting tapes which were made of a single wire, two and three WIT(wire in tube). Wires are manufactured by the process of press ins and sintering (150h, at 845$^{\circ}C$ ) for the growth of 2223 high Tc Bi superconducting phase. We know that Ic of a single wire decrease with reduction of a curvature radius. The maximum Ic of 2 WIT wire is 2.54 (A) and have a better characteristic than a single wire (0.89 A) at a curvature radius 75mm.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2000년도 하계학술대회 논문집 B
• /
• pp.775-777
• /
• 2000

Superconducting racetrack coils are used in areas of generators, motors, wiggler magnets and so on. Especially now a days many advanced nations including U.S., Japan are developing high temperature superconducting(HTS) wire which has better performance than low temperature superconducting(LTS) wire. Most of HTS wires such as Bi-2223 are manufactured with PIT(Power In Tube Method) process, so the shape of the wire looks like tape different from LTS wire of round shape as normal conductors. Generally HTS racetrack coils are composed of a few partial double-pancake colis and then the double-pancakes are jointed each other according to their applications.

• 한국전기전자재료학회논문지
• /
• 제28권3호
• /
• pp.191-195
• /
• 2015

Inside the existing superconducting cables, the superconducting wire carries a loss-free current, and the cable former (the stranded copper wire) bypasses the fault current to prevent damage and loss of the superconducting cable when the fault current is applied. The fault-current-limiting-type superconducting cable proposed in this paper usually carries a steady current; but in a fault state, the cable generates self-resistance that makes the fault current lower than a certain width. That is, the superconducting cable that transmitted only a low voltage and a large capacity power repetitively limits the fault current, as does a superconducting current limiter. To complete this structure, it is essential to investigate the mutual resistance relationship between the superconducting wires after applying a fault current. Therefore, in this paper, one kinds of superconducting wires (a wire without a stabilization layer) were connected parallel 4 tapes, respectively; and after applying a fault current, the current, voltage, resistance and thermal stability of the HTS thin-film wires were examined.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2006년도 제37회 하계학술대회 논문집 B
• /
• pp.741-742
• /
• 2006

This paper deals with an efficient superconducting joint method between 2G high superconducting(HTS) wire, YBCO coated conductor(CC). Recently CC is one of the most promising superconducting wire due to high n-value and critical current independency from external magnetic field. It is expected to be used many superconducting application such as fault current limiter, persistent current system and cable etc. In most HTS applications, superconducting magnet is used, and it is necessary to joint between superconducting wire to fabricate superconducting magnet system. A CC tape used in this research consists of copper stabilizer, silver layer, YBCO layer, buffer and substrate. Direct joint using soldering method was inefficient due to resistance of copper, then copper lamination is removed by chemical etching method to reduce resistance between CC tapes. Jointed tapes were fabricated and tested. Transport current through jointed area and induced voltage were measured to characterize the I-V curve. Resistance between CC wire using chemical etching was compared with resistance of direct jointed tapes using soldering method in this paper.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 센서 박막재료 반도체 세라믹
• /
• pp.53-56
• /
• 2003

The properties of YBCO thick film coated on Ag wire with YBCO powder is deeply affected by cracking on its surface which was deposited in organic solution by electrophoretic method. YBCO superconducting thick films were prepared on Ag wire$({\Psi}0.8mm)$ by electrophoresis in acetone with added PEG (Poly-Ethylene Glycol, 3% in Acetone), 1ml for being crack-free. The surface properties of YBCO superconducting wire was evidently improved with adding PEG. Added PEG which molecular weight is 600, 1000, 3400 was affected with variation of deposition voltages to the surface properties of samples. As a result, with adding PEG (its molecular weight is 3400), YBCO superconducting wire was better on its surface properties.