• 한국초전도ㆍ저온공학회논문지
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• 제24권2호
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• pp.7-18
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• 2022

European efforts to design superconducting conductors for a future tokamak have involved Nb₃Sn cable-in-conduit conductor (CICC). Nb₃Sn coils which undergo heat treatment to activate the Nb₃Sn material are mostly produced through the wind-then-react route. However, some Nb₃Sn coils have been proposed with CICCs of the react-then-wind route. The latter CICCs are physically constrained due to handling limitations which if not adhered to will result in irrecoverable damage to the Nb₃Sn cable inside, nullifying any performance advantage. A group at the Swiss Plasma Center has proposed such CICC designs, constructing samples and testing them for performance. The characteristics and performance of these react & wind (R&W) CICCs are compared with the more common wind & react (W&R) CICCs, and it is found that the R&W designs show more extreme characteristics than typical W&R Nb₃Sn CICCs for some parameters that are known to influence CICC performance. Where the R&W CICCs extend the range of those parameters, they also continue trends formed by the W&R CICCs with the parameters. The main observation, however, is that although the current sharing temperature performances of the R&W samples are above the average of the W&R samples they were compared to, they are not the highest. A similar observation applies to a cost comparison of the superconducting material where the R&W CICCs are found to be relatively cheap but not the cheapest. Given these results, clear practical advantages to the R&W CICC design is not evident.

• 한국초전도저온공학회:학술대회논문집
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• 한국초전도저온공학회 1999년도 제1회 학술대회논문집(KIASC 1st conference 99)
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• pp.14-17
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• 1999

Four designed $Nb_{3}$Sn superconductors have been fabricated in order to investigate the effect of pre-heat treatment for internal tin process. 3 types of sub-elements and 2 types of Sn reservers were fabricated. Diffusion of Sn is better in the strand divided Sn equally than in the strand had one large Sn reserver during pre heat-treatment.

• 한국전기전자재료학회논문지
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• 제11권11호
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• pp.1022-1026
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• 1998

The mutifilamentary $Nb_3$Sn wire containing 135 Nb filaments was manufactured by the internal tin method. The critical current density ($J_C$) in magnetic fields for the wires heat-treated at $660^{/circ}C$ and $700^{/circ}C$ were investigated. The Non-Cu $J_C$ and n-value of 0.82 mm$\phi$ $Nb_3$Sn wire heat-treated at $700^{/circ}C$ for 240 hours was approximately 450 A/$mm^2$ at 12T, 4.2K and 14, respectively. Also the $B_{C2}$ of $Nb_3$Sn wire extrapolated by Kramer plot was 27.2T. The wire heat-treated at $700^{/circ}C$ for 240 hours showed smaller residual tin concentration in the matrix and the larger area of $Nb_3$Sn layer as comparison with the wire heat-treated at $660^{/circ}C$.

• 한국재료학회지
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• 제9권5호
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• pp.452-459
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• 1999

고연소도 핵연료피복관용 신합금 재료를 개발하기 위한 연구로 Zr-0.8Sn-xNb(x = 0.2,0.4,0.8, 1.0) 계 합금을 제조하여 Nb 첨가량이 Zr 합금의 미세구조 및 부식특성에 미치는 영향을 조사하였다. 미세조직 관찰결과 Nb첨가량이 증가함에 따라 결정립의 크기는 강소하였고 석출물의 량은 증가하였다. $360^{\circ}C$ 물 분위기에서 부식시험 한 결과 Nb 함량이 적을수록 부식저항성이 증가하는 경향을 나타냈으며며, Zr-0.8Sn-0.2Nb 합금이 가장 우수한 부식저항성을 보였다. 동얼 두께의 산화막에 대하여 XRD 분석한 결과, 내식성이 우수한 0.2 wt.% Nb 합금에서는 산화막내 tetra-$ZrO_2$의 분율이 높게 관찰되었다. 합금설계 관점에서 Zr-O.8Sn-xNb 합금계에 Nb올 첨가할때 Nb은 고용도 이하로 첨가되어야 한다고 사료된다.

• 한국초전도ㆍ저온공학회논문지
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• 제5권1호
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• pp.123-127
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• 2003

For disseminating a ney IEC international standard of critical trmperature of NbTi,Nb$_3$Sn and Bi-2223 Composite Suterconductors, we develpted a measuring system and studied standardization of test method. The measuring system consisted of cryogenic reservoir, base plate, thermometer, voltmeter and current source. Various specimens of the Nbti, Nb$_3$Sn and Bi-2223 composite superconductors were tested using this system for measuring their critical temperatures. After measuring the resistance-temperature relation, the data were compensated with thermoelectric voltages for NbTi Nb$_3$Sn specimens. NbTi specimens showed 9.2 K ~ 9.5 K of transition temperature and Nb$_3$Sn specimen showed about 18 K. Bi-2223 specimens showed 104 K ~ 107 K of transition temperature.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 하계학술대회 논문집
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• pp.104-107
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• 2001

In order to investigate the effect of Ge addition to the Cu matrix on the microstructure and the critical current density, four kinds of internal tin processed Nb$_3$Sn strands with pure Cu and Cu 0.2, 0.4, 0.6 wt % Ge alloys were drawn to 0.8 mm diameter. The microstructure and critical current of internal tin processed Nb$_3$Sn wires that were heat treated at temperatures ranging from 68$0^{\circ}C$ to 74$0^{\circ}C$ for 240h were investigated. The Ge addition to the matrix did not make workability worse. A Ge rich layer in the Cu-Ge matrix suppressed the growth of the Nb$_3$Sn layer and promoted grain coarsening. The greater the Ge content in the matrix, the lower the net Jc result after Nb$_3$sn reaction heat treatment. There was no significant variation in Jc observed with heat treatment temperature ranging from 68$0^{\circ}C$ to 74$0^{\circ}C$. The values of AC loss of Ge added wires were decreased to 40 % compare with no addition wire. Low AC loss was due to segregation of Ge rich layer in the Cu-Ge matrix. If Ge added wire with thin Nb filaments were fabricated, slow diffusion rate of Sn would be overcome and decreased AC loss that is weak Point of internal tin method.

• 한국초전도ㆍ저온공학회논문지
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• 제22권4호
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• pp.24-30
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• 2020

The test results of the ITER toroidal field conductors demonstrated a decrease of the current sharing temperature (Tcs) with an increase in the number of electromagnetic cycles in general. This is associating with several factors. One of them is the superconducting Nb3Sn filaments cracking and another one is the redistribution of the relative deformation of the Nb3Sn strands under Lorentz forces. Despite these factors, some conductors have shown the absence or significantly less degradation of Tcs during electromagnetic cycling. This article considers another possible reason for a more stable conductors Tcs behavior, namely, the local compression of Nb3Sn wires in the cross section of a conductor. In this article presents the results of a quantitative analysis Nb3Sn superconducting filaments cracking of strands extracted from a conductor that has passed electromagnetic cycling and the model of a conductor compaction, as well as calculation results based on this model are presented also.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1171-1172
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• 2006

Addition of 2.0wt%$Dy_2O_3$ or 0.3wt%Sn proved to be very effective in improving the permanent magnetic properties of NdFeNbB magnets. $Dy_2O_3$ additions result in the increase in the Hci and temperature dependence due to formation of (NdDy)-rich phase and grain refinement of $\Phi$ phase. This improvement of the coercivity stability of the magnets from the addition of Sn is attributed to the smoothing effect of the Sn addition at the grain boundaries. The magnetic properties, the temperature dependence and Curie temperature of NdFeNbB with $Dy_2O_3$ and Sn combined addition were found to be considerably improved.

• 한국재료학회지
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• 제9권2호
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• pp.188-194
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• 1999

2원계 (Zr-xNb, Zr-xSnl 와 3원계 (Zr-O.8Sn-xNb, Zr-O.4Nb-xSnl Zr합금의 기계적 특성에 미치는 Nb와 Sn의 영향올 조사하기 위하여 인장시험 빛 마세조직 분석을 실시하였다. Nb와 Sn량이 많이 첨가될수록 2원계와 3원계 합금의 강도는 정진적으로 증가하는 경향을 보이는데, Nb와 Sn이 고용도 이상으로 첨가될 때 강도중가는 더욱 두드러진 것으로 냐타났다. 강도 증가현상을 고용강화, 석출강화, 결정립 미세화에 의한 강화, 집합조직에 의한 강화효과 관정에서 분석한 결과, 고용강화 효과가 가장 두드러지며 Nb와 Sn이 고용도 이상에서는 석출강화가 강도에 기여하는 것으로 냐타났다. 합금원소 첨가에 따른 결정립미세화도 강도에 약간은 영향을 미치는 것으로 사료된다. 그러나 집합조직은 합금원소 변화에 따라서 거의 변화가 없는 것으로 냐타났으므로 집합조직은 강도증가에 기여하지 않는 것으로 생각된다.

• 한국주조공학회지
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• 제20권3호
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• pp.208-215
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• 2000

The mechanical properties and corrosion resistance of Ti alloys for medical implants have been investigated. Ti, Ti-15Sn-4Nb and Ti-15Sn-4Nb-2Zr alloys were melted in arc furnace and the corrosion resistance of Ti alloys was evaluated by anodic polarization test. The microstructure and mechanical properties of Ti alloys were analysed by optical microscope, hardness and tensile tester. The tensile strength of the pure-Ti improved by addition of Sn and Nb and Ti-15Sn-4Nb alloy showed better Rockwell hardness compared with pure Ti. However, there was no significant difference in corrosion resistance between thoseTi-alloys made of Pure-Ti and Ti-15Sn-4Nb alloy. The passive films on the Ti-15Sn-4Nb alloy in air atmosphere consisted of $TiO_2$, SnO and NbO as demonstrated by X-ray photoelectron spectroscopy(XPS)