• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1089-1090
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• 2006

Biomimetic apatite deposition behaviors on Zr-1Nb and Ti-6Al-4V plate with various surface conditions were examined. Both alloys were polished with abrasive papers to have different roughness and some of them were treated in NaOH before exposition in simulated body fluid. NaOH treatment was found to enhance the deposition rate of apatite on Ti-6Al-4V significantly. On the other hand, the deposition rate of Zr-1Nb was not influenced by NaOH treatment. Without NaOH treatment, the polished Zr-1Nb with abrasive paper was found to induce more apatite nucleation than the polished Zr-6Al-4V.

• Korean Journal of Materials Research
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• v.11 no.5
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• pp.405-412
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• 2001

Corrosion tests were carried out in $360^{\circ}C$ water and $360^{\circ}C$ 70ppm LiOH solution to investigate the corrosion behavior of new zirconium alloys (Zr-0.4Nb-0.8Sn-xFeCrMn, Zr-0.2Nb-1.1Sn-xFeCrMn, Zr-1.0Nb-xFeCu). Microstructures of tested alloys were analyzed by optical microscope and TEM. The cross-sectional surface and crystalline structure of the oxide layer were analyzed by SEM and XRD. From the results of corrosion test, all the alloys showed higher corrosion rates in $360^{\circ}C$ 70ppm LiOH aqueous solution thats in $360^{\circ}C$ water. Especially, high Nb-containing alloy exhibited the acceleration of corrosion rate in LiOH solution. The low Nb- and Sn-added alloys showed better corrosion resistance than the Sn- free high Nb alloy. from the effect of final annealing on the corrosion, it was observed that the partially recrystallized alloys showed better corrosion resistance than fully recrystallized alloys. This would be related to the size and distribution of the second phase particles.

• Proceedings of the KIEE Conference
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• 1999.07d
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• pp.1968-1970
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• 1999

본 연구에서는 RF 마그네트론 스퍼터링법으로 CoNbZrPd 비정질 연자성 박막을 제조하여 Pd의 첨가 효과와 자장중 열처리에 의한 특성 변화에 대해 연구하였다. Pd가 4.34 at% 첨가된 $Co_{87.56}Nb_{6.45}Zr_{1.65}Pd_{4.34}$ 박막은 비정질 구조이며 Pd 첨가에 의해 보자력은 0.54 Oe으로 감소하였으며, 이방성 자계는 10.45 Oe로 Pd를 첨가하지 않은 CoNbZr 비정질 박막 보다 특성이 향상되었다. $Co_{87.56}Nb_{6.45}Zr_{1.65}Pd_{4.34}$ 비정질 박막은 $400^{\circ}C$까지 비정질 상을 유지하고 있지만, 연자기 특성이 열화되어 보자력이 증가하고 이방성자계가 급격히 감소하였지만, 포화 자화는 크게 변화지 않았다.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.05b
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• pp.61-66
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• 1997

월성1호기 압력관의 수소흡수 관련 자료들을 분석하였으며, 캐나다 발전소들의 결과와도 비교하였다. 압력관의 수소흡수 특성은 압력관내 위치, 사용온도, 가동이력 등에 영향을 받아 Inlet 쪽보다는 Outlet 쪽이, 사용온도가 높을수록, 또한 가동에 따른 조사량이 증가할수록 수소흡수량이 증가하였다. 한편 압력관내로의 수소흡수 거동을 규명하기 위해 Zr-2.5wt%Nb 합금의 열처리 조직 차이에 따른 수소흡수특성을 분석하였다. 수소흡수는$\alpha$-Zr 상에 비해 $\beta$-Zr, $\beta$-Nb 상에 크게 영향을 받는 것으로 보인다. 또한 합금내의 수소량 증가가 압력관 부식특성 자체에 미치는 영향을 분석하기 위하여 열처리 시편에 일정량의 수소를 charging 시킨 후 부식시험을 수행하였다. Zr-2.5wt%Nb 합금의 부식거동은 미세조직에 가장 큰 영향을 받아$\alpha$-Zr과 $\beta$-Zr 상의 시편이$\alpha$-Zr과$\beta$-Nb 상의 시편에 비해 큰 부식속도를 보였다. 또한 시편내 150ppm 이하의 수소함량은 시편의 부식거동에 별다른 영향을 없거나, 부식속도를 약간 감소시키는 것으로 추정된다.

• Journal of the Korean Ceramic Society
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• v.34 no.6
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• pp.569-576
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• 1997

Electrically-induced strain and polarization studies of the (1-x)Pb(Mg1/3Nb2/3)O3-PbZrO3 crystalline solutions have been done. Dielectric constants with temperature were investigated for 0$\leq$x$\leq$0.95. With increasing PbZrO3 content the transition maxima were found to move to higher temperature region and DPT (Diffused Phase Transition) properties were decreased for x$\leq$0.60. Phase transition between ferroelectric states and antiferroelectric states was confirmed for 0.93$\times$10-3 for 0.4

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2003.11a
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• pp.64-71
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• 2003

In order to evaluate the effect of alloying elements (Nb and Sn) on the wear resistance of advanced Zr fuel claddings, sliding wear tests have been performed in room temperature air and water and these results were compared with those of commercial alloys such as Zircaloy-4, A and B alloys. As a result, the advanced Zr fuel claddings have a similar wear resistance compared with the commercial alloys. The wear resistance of the advanced Zr fuel claddings is closely releted to the content of Nb and Sn even though the effects of transition elements are involved in deforming wear properties. In the tested specimens with similar Sn content, wear volume became down to a minimum at $0.4\;wt\;\%$ Nb, then rapidly increased at 1.0 wt Nb. This behavior results in the variation of grain size with alloying contents. But Sn did not have a significant effect on the wear volume of advanced Zr fuel claddings below $1.1\;wt\%$. The relationship between alloying elements and wear behaviour was evaluated and discussed using material compatibility factor.

• Journal of Korean Dental Science
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• v.10 no.1
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• pp.10-21
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• 2017

Purpose: The purpose of this study was to investigate the electrochemical characteristics of nanotubular Ti-25Nb-xZr ternary alloys for dental implant materials. Materials and Methods: Ti-25Nb-xZr alloys with different Zr contents (0, 3, 7, and 15 wt.%) were manufactured using commercially pure titanium (CP-Ti), niobium (Nb), and zirconium (Zr) (99.95 wt.% purity). The alloys were prepared by arc melting in argon (Ar) atmosphere. The Ti-25Nb-xZr alloys were homogenized in Ar atmosphere at $1,000^{\circ}C$ for 12 hours followed by quenching into ice water. The microstructure of the Ti-25Nb-xZr alloys was examined by a field emission scanning electron microscope. The phases in the alloys were identified by an X-ray diffractometer. The chemical composition of the nanotube-formed surfaces was determined by energy-dispersive X-ray spectroscopy. Self-organized $TiO_2$ was prepared by electrochemical oxidation of the samples in a $1.0M\;H_3PO_4+0.8wt.%$ NaF electrolyte. The anodization potential was 30 V and time was 1 hour by DC supplier. Surface wettability was evaluated for both the metallographically polished and nanotube-formed surfaces using a contact-angle goniometer. The corrosion properties of the specimens were investigated using a 0.9 wt.% aqueous solution of NaCl at $36^{\circ}C{\pm}5^{\circ}C$ using a potentiodynamic polarization test. Result: Needle-like structure of Ti-25Nb-xZr alloys was transform to equiaxed structure as Zr content increased. Nanotube formed on Ti-25Nb-xZr alloys show two sizes of nanotube structure. The diameters of the large tubes decreased and small tubes increased as Zr content increased. The lower contact angles for nanotube formed Ti-25NbxZr alloys surfaces showed compare to non-nanotube formed surface. The corrosion resistance of alloy increased as Zr content increased, and nanotube formed surface showed longer the passive regions compared to non-treatment surface. Conclusion: It is confirmed that corrosion resistance of alloy increased as Zr content increased, and nanotube formed surface has longer passive region compared to without treatment surface.

• Korean Journal of Materials Research
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• v.11 no.8
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• pp.647-654
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• 2001

Effects of final annealing temperature on the precipitate and oxidation were investigated for the Zr-lNb and Zr-lNb-lSn-0.3Fe alloys. The microstructure and oxidation of both alloys were evaluated for the optimization of final annealing process of these alloys in the annealing temperature regime of 450 to $800^{\circ}C$. The corrosion test was performed under steam at $400^{\circ}C$ for 270 days in a static autoclave. The oxide formed was identified by low angle X-ray diffraction method. The $\beta$-Zr was observed at annealing temperature above $600^{\circ}C$. Above $600^{\circ}C$, the precipitate area volume fraction of Zr-lNb and Zr-1Nb-lSn-0.3Fe alloys appeared to be increased with increasing the final annealing temperature. The corrosion resistance of Zr-lNb was higher than that of Zr- lNb-lSn-0.3Fe alloy. The corrosion rate of both alloys were accelerated due to the formation and growth of $\beta$-Zr with increasing the annealing temperature.

• Proceedings of the Korean Nuclear Society Conference
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• 1995.05b
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• pp.745-752
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• 1995

고연소도 액체금속로용 금속연료를 개발하고자 U-l0wt%Zr 합금중 Zr 원소 대신에 X(:Si, Ta, Nb, W, Mo) 원소를 첨가한 U-7wt%Zr-3wt%X(:Si, Ta, Nb, W, Mo) 합금을 제조하여 미세조직에 미치는 합금원소 첨가의 영향을 조사하였다. 그 결과 U-7 wt%Zr-3wt%Si 합금을 제외한 모든 U-7wt%Zr-3wt%X(:Ta, Nb, W, Mo) 합금은 Matrix에 있어서 Laminar Structure를 그대로 유지하였다. U-7wt%Zr-3wt%Si 함금을 제외한 모든 U-7wt%Zr-3wt%X(:Ta, Nb, W, Mo) 합금의 주요한 상은 U-l0wt% Zr 합금과 마찬가지로 $\alpha$-U 및 $\delta$-UZr$_2$ 상이었다. U-7wt%Zr-3wt%X(:Ta, Nb, W, Mo) 합금은 U-l0wt%Zr 합금에 비해 Lamina Thickness가 크게 감소되었다. 특히 U-7wt%Zr-3wt%Mo 합금의 경우에 있어서는 U-l0wt%Zr 합금에 비해 1/3배 정도까지 Lamina Thickness가 크게 감소하였다. 이와 같은 합금원소 첨가에 의한 Laminar Structure의 미세화는 액체금속로강 금속연료내 Fission Gas의 Inter-connected Path가 보다 더 잘 형성됨으로 인해 Fission Gas Bubble에 대한 방출속도를 크게 증가시켜서 궁극적으로는 Fission Gas Bubble에 의한 Swelling을 저감시킬 것으로 기대된다.

• Korean Journal of Materials Research
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• v.12 no.5
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• pp.369-374
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• 2002

To investigate the corrosion behavior of Zr-1.0Nb-xSn (x=1.0, 1.5, 2.0 and 2.5wt. %)alloy system, the corrosion tests of Zr-1.0Nb-xSn alloys were carried out in steam at $400^{\circ}C$ for 125 days and in 70ppm LiOH solution at $360^{\circ}C$ for 180 days. The matrix microstructures of the test specimens were analyzed using TEM and the oxide structures on the test specimens were analyzed using XRD. It was found from the analyses that the more Sn content the alloy had, the faster it was corroded and with the increase of Sn content in the alloy the fraction of $t-ZrO_2$ to $m-ZrO_2$ was decreased. It was also found that the alloys having more Sn showed more dislocation density than those having less.