• 한국초전도ㆍ저온공학회논문지
• /
• 제7권2호
• /
• pp.31-34
• /
• 2005

There are many kinds of high temperature superconducting (HTS) application using Bi-2223 tape which is the most commercialized HTS material. Also, resistive superconducting fault current limiters (SFCLs) have been developed using many kinds of superconducting material such as YBCO thin film, Bi-2212 bulk and so on. However, SFCL using Bi-2223 tape has never been developed. This paper deals with the feasibility study on SFCL using Bi-2223 wire. The over-current behaviors of Bi-2223 short-length sample were measured. To make the resistive SFCL, two small-scale bifilar winding modules using 7m Bi-2223 wire were fabricated; i.e. solenoid type bifilar coil and pancake type one. The short-circuit tests of the coils were successfully performed up to 16 V$_{rms}$ From these tests, the current limiting capabilities of Bi-2223 bifilar coils were confirmed and current limiting performances between two winding types were compared. In addition, the feasibility of resistive SFCL using another HTS wire, i.e. YBCO coated conductor, was also investigated.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2009년도 추계학술대회 논문집
• /
• pp.214-214
• /
• 2009

While critical properties of BSCCO wires rely considerably on grid direction upon BSCCO and have very complicated mechanism of generating a superconducting phase, making it difficult to improve properties of wires, YBCO thin-film wires which can be formed in a superconducting phase upon metal board through vapor deposition processing can get excellent direction and reduce manufacturing costs with more flexibility in improving critical properties; thus, they will be suitable for instrument application in the future. Contrary to BSCCO wires for which thick silver alloy covering materials should inevitably be used, moreover, YBCO thin-film wires have an advantage of making thickness and quality of covering materials different by usage. Such a property can be an important element to widen application of wires by presenting possibility of using thin-film wires as superconducting material for fault current limiter as well as for high power current application. In this study we intend to prepare YBCO thin-film wires with different stabilizer layers to analyze current application and current restriction properties by stabilizer layers on the basis of detailed researches on changes in current classification properties below critical value.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2010년도 하계학술대회 논문집
• /
• pp.43-43
• /
• 2010

HTS(High Temperature Superconductor) cable has a high possibility of practical use due to the possibility of low voltage and high capacity transmission caused by its lower power loss than copper cable. On the other hand, when fault current occurred, resistance increase caused by superconductivity loss, the amount of power supplies has diminished, furthermore, it's necessary to take the possible danger of damage to HITS cable into account. Therefore, an effective plan for dealing with the above problem is to link HITS cable to SFCL. In this study, we researched the possibilities of normal transport current as well as the safety of HITS cable by analyzing the properties of transport current in HITS cable connected with SFCL.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
• /
• pp.104-106
• /
• 2003

다층의 산화물 박막으로 이루어진 coated conductor의 제조를 위하여 각층의 증착조건이 최적화되어야 한다. 가공/열처리를 통하여 2축배향성을 가지는 Ni 금속 기판위에 $Y_2O_3$, YSZ, $CeO_2$ 등의 산화물 완충층을 증착한 후 초전도층인 YBCO를 증착하였다. 12도와 8도의 in-plane fwhm (full width at half maximum)과 out-of-plane fwhm을 가지는 Ni 기판을 이용하여 13도와 4.5도의 in-plane 및 out-of-plane fwhm을 가지는 YBCO coated conductor를 제조하였다. 임계온도 (Tc), 임계전류 (Ic), 및 임계전류밀도 (Jc) 는 각각 84K, 3.3A, 및 $310,000\;A/cm^2$ 이었다.

• 한국초전도ㆍ저온공학회논문지
• /
• 제17권2호
• /
• pp.25-30
• /
• 2015

In order to realize economical applications, it is important to reduce the ac loss of 2G high-temperature superconductor coated conductors. It seems to be reasonable that a multi-filamentary wire can decrease the magnetization loss. In this study, we prepared two samples of YBCO coated conductors with striations. We measured local superconducting properties of both samples by using Low Temperature Scanning Laser and Hall Probe Microscopy (LTSLHPM). The distribution of the local critical temperature of samples was analyzed from experimental results of Low Temperature Scanning Laser Microscopy (LTSLM) near the superconducting transition temperature. According to LTSLM results, spatial distributions of the local critical temperature of both samples are homogeneous. The local current density and the local magnetization in samples were explored from measuring stray fields by using Scanning Hall Probe Microscopy (SHPM). From SHPM results, the remanent field pattern of the one bridge sample in an external magnetic field confirms the Bean's critical state model and the three bridge sample has similar remanent field pattern of the one bridge sample. The local magnetization curve in the three bridge sample was measured from external fields from -500 Oe to 500 Oe. We visualized that the distribution of local hysteresis loss are related in the distribution of the remanent field of the three bridge sample. Although the field dependence of the critical current density must be taken into account, the relation of the local hysteresis loss and the remanent field from Bean's model was useful.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2000년도 추계학술대회 논문집
• /
• pp.503-506
• /
• 2000

YBCO superconducting thick films were prepared on Ag wire by electrophoresis in acetone and ethanol with chemically modified suspension. The addition of organic compounds, such as PEG, EG into suspension solution for improving critical current density was investigated. Surface state, deposition condition, pore distribution and cracks were investigated by using SEM photographs. Controlling preparation conditions were studied for reducing these defects. As a results, in acetone solution, the surface crack of samples was decreased with increasing PEG. On the contrary, the surface crack of sample was increasing with increasing the amount of EG. In ethanol solution without I$_2$, which was generally used for an electrolyte, the deposition time was longer than this of acetone. For that reason the sample deposition in ethanol time was needed with enough stirring time for suspending YBCO powder and deposition time.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
• /
• pp.63-66
• /
• 2003

The electrophoretic deposition method has the advantage of relatively few fabrication facilities and simple process procedure as well as the economical and technical merit of allowing various forms of deposition and easy control of deposition thickness and wire length. A study, especially electric field and additive, on the optimization method to increase the density of particles and uniformity of their orientation have been performed to overcome the cracking and the porosity problems in the fabricated superconductor.

• 한국재료학회:학술대회논문집
• /
• 한국재료학회 2003년도 추계학술발표강연 및 논문개요집
• /
• pp.235-235
• /
• 2003

The development of a buffer layer is an important issue for the second -generation wire, YBCO coated metal wire. The buffer layer demands not only on the prohibition of the reaction between YBCO and metal substrate, but also the proper lattice match and conductivity for high critical current density (Jc) of YBCO superconductor, In order to satisfy these demands, we suggested CaRuO3 as a useful candidate having that the lattice mismatches with Ni (200) and with YBCO are 8.2% and 8.0%, respectively. The CaRuO3 thin films were deposited on Ni substrates using various methods, such as e-beam evaporation and DC and RF magnetron sputtering. These films were investigated using SEM, XRD, pole-figure and AES. In e-beam evaporation, the deposition temperature of CaRuO3 was the most important since both hi-axial texturing and NiO formation between Ni and CaRuO3 depended on it. Also, the oxygen flow rate had i[n effect on the growth of CaRuO3 on Ni substrates. The optimal conditions of crystal growth and film uniformity were 400$^{\circ}C$, 50 ㎃ and 7 ㎸ when oxygen flow rate was 70∼100sccm In RF magnetron sputtering, CaRuO3 was deposited on Ni substrates with various conditions and annealing temperatures. As a result, the conductivity of CaRuO3 thin films was dependent on CaRuO3 layer thickness and fabrication temperature. We suggested the multi-step deposition, such as two-step deposition with different temperature, to prohibit the NiO formation and to control the hi-axial texture.

• Progress in Superconductivity
• /
• 제6권1호
• /
• pp.74-78
• /
• 2004

YBCO coated conductor is one of the most promising materials as a new generations wire especially for practical power applications. In this work, $YBa_2$$Cu_3$$O_{7}$ -$\delta$/(YBCO) coated conductors (CC) were deposited by pulsed laser deposition (PLD) from buffer layers to superconducting layer on hi-axially textured metal tape. The oxide multilayer buffered substrate of architectures of $CeO_2$/$YSZ/Y_2$$O_3$ was fabricated by PLD at steady status. Then YBCO layer was deposited on RABiTS substrate by stationary and reel-to-reel (R2R) continuous process and we compared with deposition conditions of both processes. The degree of texture of each layer was investigated using X-ray diffraction including $\theta$-2$\theta$ scans, $\omega$-scans and $\Phi$-scans analysis. Their surface morphology was observed by scanning electron microscopy (SEM). The FWHM of the X-ray $\Phi$-scans and $\Phi$-scans indicated that YBCO and buffer layers closely replicate the in-plane and out-of-plane texture of metal tape. Critical current (Ic) at 77 K, self-field of 75.8 A/cm-width, critical temperature (Tc) of 85 K, and critical current density (Ic) of 3.7 MA/$\textrm{cm}^2$ were measured from coated conductor deposited by stationary process. And coated conductor deposited by R2R continuous process had Ic of 57.5 A/cm-width, Tc of 86.5 K and Jc of 2.0 MA/$\textrm{cm}^2$. The film also exhibits a homogeneous and dense surface morphology.

• 한국산학기술학회논문지
• /
• 제7권5호
• /
• pp.801-804
• /
• 2006

[ $YBa_2Cu_3O_{7-{\delta}}(YBCO)$ ]계 초전도 선재용 $GdAlO_3(GAO)$ 버퍼층을 졸-겔(sol-gel) 공정에 의해 제조하였다. 전구체 용액은 Gd 질산염과 Al 질산염을 1:1 화학양론비로 하여 메탄올에 용해하여 준비하였다. 전구체 용액을 $SrTiO_3(STO)$ (100) 단결정 기판위에 스핀 코팅하고, 수분이 포함된 $N_2-5%\; H_2$ 분위기에서 $1000^{\circ}C$에서 2시간 열처리 하였다. 열처리 후 GAO 층의 표면에 대한 주사전자현미경 관찰에 의해 GAO 층이 에피택셜의 특징인 각면 형상을 갖는 것을 알 수 있었다. X-선 회절분석에 의하면 GAO 버퍼층은 c-축으로 우선 배향된 에피택셜 박막으로써 반가폭이 각각 (002)면에서 $0.29^{\circ}(out-of-plane)$, {112}지면에서 $1.10^{\circ}(in-plane)$의 우수한 배향성을 나타내었다.