통합 검색 | Korea Science

김은실;김원기;최한철
- Corrosion Science and Technology
- /
- 제12권1호
- /
- pp.34-39
- /
- 2013
In this study, the effect of niobium addition on the passivation behavior of Ti alloys in NaCl solution was investigated using various electrochemical methods. An ${\alpha}$-phase in Ti alloy was transformed into a ${\beta}$-phase and martensite structure decreased as Nb content increased. The corrosion and passivation current density($+300mV_{SCE}$) decreased as Nb content increased, and thereby a stable passive film was formed on the Ti alloy. Potential of Ti-xNb alloy in the passive region increased, whereas, current density decreased with time from results of potentiostatic and galvanostatic tests. Also, the corrosion morphology showed the smaller pits as Nb content increased. Consequently, Ti alloy contained high Nb content showed a good resistance to pitting corrosion in 0.9% NaCl solution.
https://doi.org/10.14773/cst.2013.12.1.034 인용 PDF KSCI

남성진;한종수;김응찬;남효덕
- 한국전기전자재료학회:학술대회논문집
- /
- 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
- /
- pp.253-254
- /
- 2006
초미세립 복합상 영구자석은 연 경자성상의 크기와 분포에 큰 영향을 받는 자성재료이다. 또한, 결정립간 교환상호작용력은 초미세립 복합상 영구자석의 잔류자속밀도에 큰 영향을 미친다. 이에 $Nd_8Fe_{86-x}Nb_xB_6$(x=0, 1, 2, 3) 조성으로 급냉자성 분말을 제조하고, 열처리 후 자기특성을 평가하였다. Nb 첨가에 따른 $Nd_2Fe_{14}B$ 상과 $\alpha$-Fe 상과의 교환상호작용력을 Henkel(${\delta}M$) plot을 통해 평가하고, 각 상의 크기와 분포를 조사하여 자기특성 변화를 합리화하였다. 본 연구에서 얻은 최대 자기특성은 $B_r$ = 9.791 kG, $_iH_c$ = 5.565 kOe, 그리고 $(BH)_{max}$ = 14.61 MGOe였고, Nb를 첨가함으로서 보자력이 증가하였다.
PDF

Lim B.S.;Choi J.Y.;Lee S.I.;Kim D.J.;Park W.W.;Woo I.S.;Song Y.J.;Song N.H.;Kim C.S.;Lee D.G.;Kim K.P.;Park H.T.;Joo J.J.
- 한국초전도ㆍ저온공학회논문지
- /
- 제8권2호
- /
- pp.25-28
- /
- 2006
The magnet system of KSTAR(korean Superconducting Tokamak Advanced Research) is consisted of 16 TF (Toroidal Field) coils and 14 PF (Poroidal Field) coils. Internal cooling CICC(Cable in Conduit Conductor) type conductor is used for both of TF and PF coil systems. The conduit material for $Nb_3Sn$ cable is Incoloy 908 and 316LN stainless-steel was used as conduit material for NbTi cable. $Nb_3Sn$ CICC is used for all TF coils and PF1-5 coils while NbTi CICC is used for PF6 and 7 coils. $Nb_3Sn$ and NbTi strands were made for KSTAR superconducting strand. They are satisfied with KSTAR superconducotr requirements. The $Nb_3Sn$ strands supplied from three companies; MELCO (Mitsubishi Electric Co.), OAS (Outokumpu Advanced Superconductor) and KAT (Kiswire Advanced Technology) were used. A special CICC jacketing system is developed for the KSTAR CICC fabrication which uses the tube-mill process consisted of forming, welding, sizing and squaring procedures. The. procedures for cabling and jacketing of CICC for TF and PF coils and their results including the geometrical specification and characteristics of strands are described.
https://doi.org/10.9714/psac.2006.8.2.025 인용 PDF KSCI

John G. Fisher;Kwi-Hak Lee;Won-Jin Moon
- Journal of Ceramic Processing Research
- /
- 제21권1호
- /
- pp.5-13
- /
- 2020
(K0.5Na0.5)NbO3-based ceramic powders for lead-free piezoelectric applications are usually prepared by solid state synthesis. This generally involves wet ball milling in an organic liquid such as ethanol, which is a drawback for industrial production. In the present work, a method for the preparation of NaNbO3 nanopowders is modified to produce a simple method of preparing (K0.5Na0.5)NbO3 nanopowders by an aqueous route. K2CO3, Na2CO3 and NH4[NbO(C2O4)2].xH2O are mixed in water and dried to form a gel, which is then calcined at temperatures between 400 ~ 650 ℃ for 1 h. The uncalcined gel and calcination products are analysed using Thermogravimetric Analysis/Differential Thermal Analysis, X-ray Diffraction, Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Transmission Electron Microscopy and Raman Scattering. A single phase tetragonal (K0.5Na0.5)NbO3 nanopowder with a particle size of ~ 30 nm can be produced after calcination at 650 ℃ for 1 h.
https://doi.org/10.36410/jcpr.2020.21.1.5 인용