• Korean Journal of Materials Research
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• v.26 no.12
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• pp.681-687
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• 2016

Zirconium(Zr) nuclear fuel cladding tubes are made using a three-time pilgering and annealing process. In order to remove the oxidized layer and impurities on the surface of the tube, a pickling process is required. Zr is dissolved in HF and $HNO_3$ mixed acid during the process and pickling waste acid, including dissolved Zr, is totally discarded after being neutralized. In this study, the waste acid was recycled by adding $BaF_2$, which reacted with the Zr ion involved in the waste acid; $Ba_2ZrF_8$ was subsequently precipitated due to its low solubility in water. It is very difficult to extract zirconium from the as-recovered $Ba_2ZrF_8$ because its melting temperature is $1031^{\circ}C$. Hence, we tried to recover Zr using an electrowinning process with a low temperature molten salt compound that was fabricated by adding $ZrF_4$ to $Ba_2ZrF_8$ to decrease the melting point. Change of the Zr redox potential was observed using cyclic voltammetry; the voltage change of the cell was observed by polarization and chronopotentiometry. The structure of the electrodeposited Zr was analyzed and the electrodeposition characteristics were also evaluated.

• Journal of the Korean Society for Heat Treatment
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• v.18 no.3
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• pp.164-171
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• 2005

Iodine-Induced Stress Corrosion Cracking (ISCC) properties of Zircaloy-4 and HANA4 developed in KAERI for the high burn-up nuclear fuel cladding were evaluated. To confirm the effect of final heat treatment on ISCC resistance of Zr-alloy, stress relieved and recrystallized specimens were prepared and tested. With the pre-cracked specimen at internal surface, ISCC crack propagation rates and threshold stress intensity factor ($K_{ISCC}$) based on the fracture mechanics were measured by internal pressurization test at $350^{\circ}C$ in iodine environment. $K_{ISCC}$ of Zircaloy-4 and HANA4 cladding were $3.3MPa{\cdot}m^{1/2}$ and $4.4MPa{\cdot}m^{1/2}$, respectively. Pitting corrosion at the crack surface was observed and it seemed that TG crack propagation was derived from the pitting.

• Journal of the Korean Vacuum Society
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• v.12 no.S1
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• pp.83-87
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• 2003

Zirconium oxide films have been synthesized by radio-frequency magnetron sputtering deposition on n-Si(001) substrate with metal zirconium target at variant $O_2$ partial pressures. The influences of $O_2$ partial pressures of the morphology, deposition rate, microstructure, and the dielectric constant of $ZrO_2$ have been discussed. The results show that deposition rate of $ZrO_2$ films decreases, the roughness, and the thickness of the native $SiO_2$ interlayer increases with the increase of $O_2$ partial pressure. $ZrO_2$ films synthesized at low $O_2$ partial pressure are amorphous and monoclinic polycrystalline in nanometer scale at low $O_2$ partial pressure. The relative dielectrics of $ZrO_2$ films are in the range of 12 to 25.

• Bulletin of the Korean Chemical Society
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• v.28 no.10
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• pp.1751-1755
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• 2007

The interaction of ammonium hydroxide (NH4OH) with zircaloy-4 (Zry-4) was investigated using X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES) methods. In order to study the surface chemistry of NH4OH/Zry-4 system, the binding energies of N1s, O1s and Zr3d electrons were monitored. The N1s peak intensity was remarkably increased by following cycles of Ar+ sputtering of NH4OH dosed Zry-4 surface at room temperature. Because the nitrogen stayed under the subsurface region was diffused out onto the Zry-4 surface after oxygen concentration was decreased. These could be occurred after the surface oxygen was diffused into the bulk or desorbed out from the surface until Ar+ fluence was 6.0 × 1016 Ar+/cm2 then the surface was relatively atomic deficient state. The O1s peak intensity was decreased by stepwise Ar+ sputtering. After many cycles of Ar+ sputtering, the peak intensities of Zr3d peaks did not change much but the shape of the peak clearly did change. This implies that the oxidation state of zirconium was changed during stepwise Ar+ sputtering of NH4OH/Zry-4. The Zr3d peak intensity of zirconium nitride (ZrNx) increased as the intensity of N1s (from zirconium nitride) increased but the Zr3d peak intensity of zirconium oxide (ZrOx) decreased due to the depopulation of the oxygen species on the surface region. We also observed that the peak intensity of Zr4+ was nearly same after Ar+ sputtering processes but the peak intensity of metallic zirconium increased compared to that of before the sputtering process was performed.

• Bulletin of the Korean Chemical Society
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• v.30 no.11
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• pp.2729-2734
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• 2009

We report here the surface behavior of zirconium oxide deposited on Si(100) substrate depending on the different substrate temperatures. The zirconium oxide thin films were successfully deposited on the Si(100) surfaces applying radio-frequency (RF) magnetron sputtering process. The obtained zirconium oxide films were characterized by X-ray photoelectron spectroscopy (XPS) for study about the chemical environment of the elements, X-ray diffraction (XRD) for check the crystallinity of the films, spectroscopic ellipsometry (SE) technique for measuring the thickness of the films, and the morphology of the films were investigated by atomic force microscope (AFM). We found that the oxidation states of zirconium were changed from zirconium suboxides ($ZrO_{x,y}$, x,y < 2) (x; higher and y; lower oxidation state of zirconium) to zirconia ($ZrO_2$), and the surface was smoothed as the substrate temperature increased.

• Journal of Powder Materials
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• v.14 no.1 s.60
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• pp.63-69
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• 2007

The present study was focused on the synthesis of a zirconium-based alloyed nanopowder by the plasma arc discharge process. The chemical composition, phase structure, particle size and hydrogen sorption property of the synthesized powders under various synthesis conditions were analyzed using XRF, XRD, SEM, XPS and the ASTM-F798 method. The chemical composition of the synthesized Zr-V-Fe-based powders approached that of the raw material with an increasing hydrogen fraction in the powder synthesis atmosphere. The synthesized $Zr_{55}V_{29}Fe_{16}$ powder consist of a mixed phase structure of the $Zr,\;ZrH_2,\;FeV\;and\;Zr(V_{1-x}Fe_{x})_2$ phases. This powder has an average particle size of about 20 nm. The synthesized $Zr_{55}V_{29}Fe_{16}$ nanopowder showed getter characteristics, even though it had a lower hydrogen sorption speed than the $Zr_{57}\;V{36}\;Fe_7$ getter powder. However, the synthesized Zr nanopowder with an average particle size of 20 nm showed higher hydrogen sorption speed than the $Zr_{57}\;V{36}\;Fe_7$ getter powder.

• Proceedings of the Korean Nuclear Society Conference
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• 2004.10a
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• pp.1015-1016
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• 2004

• Proceedings of the Membrane Society of Korea Conference
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• 2004.11a
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• pp.199-203
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• 2004

Fibrous arsenic (As) adsorbent was synthesized by loading zirconium (Zr) on fibrous phosphoric adsorbent that was directly synthesized by radiation-induced graft polymerization of 2-hydroxyethyl methacrylate phosphoric acid on polyethylene-coated polypropylene nonwoven fabric. Zirconium reacted with phosphoric acid grafted in the polyethylene layer. Zirconium density of the resulting adsorbent was 4.1 mmol/g. The breakthrough curve of As(V) adsorption was independent of the flow rate up to $1300\;h^{-1}$ in space velocity. The total capacity of As(V) was 2.0 mmol/g-adsorbent at pH of 2. The adsorbed Zr(IV) could be evaluated by 0.4 M sodium hydroxide solution because negligible Zr(IV) could be found in the eluted solution.

• Proceedings of the Korean Vacuum Society Conference
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• 2014.02a
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• pp.355.1-355.1
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• 2014

Zirconium nitride (ZrN)는 높은 녹는점과 기계적 강도 그리고 내식성을 가져 부품 산업계에서 hard coating에 이용된다. 또한 금속과 같은 전기 전도성을 가지므로 초고집적소자의 확산방지막에 이르기까지 많은 응용이 되고 있다. 본 실험에서는 Si 기판 위에rf magnetron sputter를 사용하여 Zr박막을 증착 하였으며 질소 유량을 변화시키며 Zirconium nitride 박막을 증착하였다. 증착된 박막의 질소 유량변화에 따른 nano-electrotribology 특성변화를 관찰하기 위해 nano-indenter를 사용하였다. 또한 Weibull statistics을 사용하여 박막의 균일성을 검증하였다. 질소 유량이 각각 0, 0.5, 5 sccm으로 증가하는 동안 surface hardness는 12.37, 10.49, 12.14 GPa로 변화하였다. 이때, 박막의 elastic modulus는 175.27, 163.94, 172.18 GPa로 각각 변화하였다. 이러한 결과는 질소 유량에 따라zirconium nitride가 여러 상으로 생성되는 것으로 해석할 수 있다.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.179-182
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• 2001

The chloride volatilization method for the recovery of zirconium and removal of uranium from zirconium containing metallic wastes formed in spent fuel reprocessing was studied using the simulated alloy waste, i.e. the mixture of Zr foil and UO$_2$/U$_3$O$_{8}$ powder. When the simulated waste was heated to react with chlorine gas at 350- l00$0^{\circ}C$, the zirconium metal changed to volatile ZrCl$_4$showing high volatility ratio (Vzr) of 99%. The amount of volatilized uranium increases at higher temperatures causing lowering of decontamination factor (DF) of uranium. This is thought to be caused by the chlorination of UO$_2$ with ZrCl$_4$vapor. The highest DF value of 12.5 was obtained when the reaction temperature was 35$0^{\circ}C$. Addition of 10 vol.% oxygen gas into chlorine gas was effective for suppressing the volatilization of uranium, while the volatilization ratio of zirconium was decreased to 68% with the addition of 20 vol.% oxygen. In the case of the mixture of Zr foil and U$_3$O$_{8}$, the V value of uranium showed minimum (44%) at 40$0^{\circ}C$ with chlorine gas giving the highest DF value 24.3. When the 10 vol.% oxygen was added to chlorine gas, the V value of zirconium decreased to 82% at $600^{\circ}C$, but almost all the uranium volatilized (Vu=99%), which may be caused by the formation of volatile uranium chlorides under oxidative atmosphere.ere.