• Transactions of the Korean hydrogen and new energy society
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• v.9 no.3
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• pp.101-110
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• 1998

The change of hydrogen storage characteristics by substituting zirconium for a portion of titanium in Ti-Cr-V alloys has been studied. The zirconium substitution decreased the plateau pressure and hysteresis of the PC isotherm. However, it decreased the hydrogen storage capacity and increased slopping in PC isotherm by forming $Cr_2Zr$ phase. By modifying the composition ratio of titanium to chromium, thereby suppressing the formation of $Cr_2Zr$ phase, we got an alloy having very high hydrogen storage capacity. The heat treatment of the alloys improved the flatness of plateau very much without a decrease in the maximum and the effective hydrogen storage capacities.

• Corrosion Science and Technology
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• v.2 no.2
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• pp.68-74
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• 2003

The effects of Niobium on the structure and properties(especially electric properties) of passive film of Zirconium alloys in pH 8.5 buffer solution are examined by the photo-electrochemical analysis. For Zr-xNb alloys (x = 0, 0.45, 1.5, 2.5 wt%), photocurrent began to increase at the incident energy of 3.5 ~ 3.7 eV and exhibited the $1^{st}$ peak at 4.3 eV and the $2^{nd}$ peak at 5.7 eV. From $(i_{ph}hv)^{1/2}$ vs. hv plot, indirect band gap energies $E_g{^1}$= 3.01~3.47 eV, $E_g{^2}$= 4.44~4.91 eV were obtained. With increasing Nb content, the relative photocurrent intensity of $1^{st}$ peak significantly increased. Compared with photocurrent spectrum of thermal oxide of Zr-2.5Nb, It was revealed that $1^{st}$ peak in photocurrent spectrum for the passive film formed on Zr-Nb alloy was generated by two types of electron transitions; the one caused by hydrous $ZrO_2$ and the other created by Nb. Two electron transition sources were overlapped over the same range of incident photon energy. In the photocurrent spectrum for passive film formed on Zr-2.5Nb alloy in which Nb is dissolved into matrix by quenching, the relative photocurrent intensity of $1^{st}$ peak increased, which implies that dissolved Nb act as another electron transition source.

• Journal of the Korean Society for Heat Treatment
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• v.17 no.3
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• pp.151-164
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• 2004

The changes of microstructural and mechanical properties were evaluated for the high burn-up fuel claddings after the neutron irradiation of $1.8{\sim}3.1{\times}10^{20}n/cm^2$ (E>1.0 MEV) in HANARO research reactor. After the irradiation, the spot-type dislocations (a-type dislocations) were easily observed in most claddings, and the density of the dislocations was different depending on the grains and was higher at grain boundaries than within grains. As the final annealing temperature increased, the density of spot-type dislocations increased and the line-type dislocations (c-type dislocations) which was perpendicular to the <0002> direction, appeared sporadically in some claddings. However, the types of precipitates in the fuel claddings after the irradiation were not changed from that in unirradiated claddings. The mechanical properties including the hardness, strength and elongation after the irradiation were changed due to the formation of spot-type dislocations. That is, the increase in hardness and strength as well as the decrease in elongation after the irradiation was occurred simultaneously with increasing the final annealing temperature. Owing to the Nb contribution to the formation of spot-type dislocation during the irradiation, the increase in hardness and strength in higher Nb-contained Zr alloys after the irradiation was higher than that in lower Nb-contained Zr alloys.

• Journal of Periodontal and Implant Science
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• v.28 no.3
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• pp.401-408
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• 1998

Screw shaped implants of Titanium-13Zirconium-6Niobium(newly developed), Titanium-6Zirconium-6Sn-6Niobium(newly developed) and Titanium-6Aluminum-4Vanadium were machined with square top and inserted in rabbit bone for 3 months. Biomechanical tests(removal torque) showed Titanium-13Zirconium-6Niobium and Titanium-6Zirconium-6Sn-6Niobium to be more stable in the bone bed than those of Titanium-6Aluminum-4Vanadium. Titanium-13Zirconium-6Niobium implants demonstrated a mean removal torque of 31.59Ncm while Titanium-6Aluminum-4Vanadium demonstrated a mean removal torque of 25.27Ncm and Titanium-6Zirconium-6Sn-6Niobium revealed a mean removal torque of 37.44Ncm and were statistically significance in Wilcoxon Signed Rank test(P<0.05). Histomorphometrical comparisons were performed on $10\;{\mu}m$ thick undecalcified ground sections in the light microscope and Titanium-13Zirconium-6Niobium showed more mean bone-tometal contact ratio than to other twotitanium alloys but had no statistically significant differences were found among the three materials(P>0.01).

• Korean Journal of Materials Research
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• v.9 no.2
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• pp.188-194
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• 1999

To investigate the effect of niobium and tin on the mechanical properties of zirconium alloys, the tensile test and the microstructural analysis were performed on the Zr-based binary(Zr-xNb, Zr-xSn) and ternary(Zr-0.8Sn-xNb, Zr-0.4Nb-xSn) alloys. As the content of Nb or Sn element increased, the strengths of the Zr-based alloys tended to gradually increase. The increase of mechanical strength was remarkable strength was remarkable in the range more than the solubility of Nb and Sn. The strengthening effects were discussed on the basis of the solid solution hardening, the precipitate hardening, the grain size effect, and the texture effect. The mechanical strength is mainly controlled by the solid solution hardening and additionally by the precipitate hardening in the content more than solubility limit of Nb and Sn. The grain refinement also has a slight effect on the strength of the zirconium alloys with the addition of Nb and Sn. However, the texture effect can be excluded due to the same Kearns number regardless of the content of alloying elements.

• Nuclear Engineering and Technology
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• v.50 no.2
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• pp.237-245
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• 2018

Potential air ingress scenarios during accidents in nuclear reactors or spent fuel pools have raised the question of the influence of air, especially of nitrogen, on the oxidation of zirconium alloys, which are used as fuel cladding tubes and other structure materials. In this context, the reaction of zirconium with nitrogen-containing atmospheres and the formation of zirconium nitride play an important role in understanding the oxidation mechanism. This article presents the results of analysis of the interaction of the oxygen-preloaded niobium-bearing alloy $M5^{(R)}$ with nitrogen over a wide range of temperatures ($800-1400^{\circ}C$) and oxygen contents in the metal alloy (1-7 wt.%). A strongly increasing nitriding rate with rising oxygen content in the metal was found. The highest reaction rates were measured for the saturated ${\alpha}-Zr(O)$, as it exists at the metal-oxide interface, at $1300^{\circ}C$. The temperature maximum of the reaction rate was approximately 100 K higher than for Zircaloy-4, already investigated in a previous study. The article presents results of thermogravimetric experiments as well as posttest examinations by optical microscopy, scanning electron microscopy (SEM), and microprobe elemental analyses. Furthermore, a comparison with results obtained with Zircaloy-4 will be made.

• Korean Journal of Metals and Materials
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• v.47 no.12
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• pp.852-859
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• 2009

The manufacturing process of zirconium alloys is an import factor to increase their strength and corrosion resistance. In order to find an improved manufacturing process of zirconium alloys in both Zr-1Nb-1Sn-0.1Fe (Alloy-A) and Zr-1.5Nb-0.4Sn-0.2Fe-0.1Cr (HANA-4) for fuel guide tubes, sheet samples were prepared by applying two- and three-step processes that were controlled by an annealing and reduction condition. The mechanical strength and corrosion resistance of both alloys were increased by applying the twostep process rather than the three-step process. From a matrix analysis using TEM, the property improvement is related to the decrease of the precipitate mean diameter with an application of the two-step process. In a comparison of the strength and corrosion properties between Alloy-A and HANA-4, the performance of HANA-4 was feasible for application to fuel guide tubes.

• Proceedings of the Korean Nuclear Society Conference
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• 2001.05a
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• pp.313.1-313
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• 2001

• Proceedings of the Korean Nuclear Society Conference
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• 2002.05a
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• pp.256.1-256
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• 2002

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2006.10a
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• pp.81-82
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• 2006