• The Transactions of the Korean Institute of Electrical Engineers C
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• v.53 no.3
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• pp.143-148
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• 2004

This paper shows property conversion of water and removing characteristics of Escherichia coli for discharge tube with $ZrO_2$ beads. At the result of the removal characteristic experiments of Escherichia coli using the discharge tube with $ZrO_2$ beads, because the electric field is also increased when input voltage is increased, the removal characteristic of Escherichia coli was appeared relation connection to input voltage. And if a passing number of test water in discharge tube with $ZrO_2$beads is increased, the removal ratio of Escherichia coli is to be increased because passing number of electric field section is increased. And if diameter of $ZrO_2$beads is increased, the removal time of Escherichia coli is to be decreased because dielectric polalization of $ZrO_2$beads. Also, the removal ratio of Escherichia coli of the discharge tube with $ZrO_2$beads. is appeared higher than the removal ratio of the discharge tube without $ZrO_2$beads. And a satulation punt of ozone and $H_2$ $O_2$generation density inner water was appeared near 60[min].

• 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.

• Journal of the Korean Ceramic Society
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• v.29 no.8
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• pp.667-673
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• 1992

The alumina-zirconia composite powders of core particle ZrO2 coated with Al2O3 were prepared by the hydrolysis-deposition of the mixed aluminum salt solution of Al2(SO4)3-Al(NO3)3-Urea. The effects of hydrolysis reaction and coating parameters on characteristics of coated powders and composites were also investigated. The degree of coating could be estimated from the ratio of tetra-/mono-ZrO2 present at the room temperature after heat-treating coated powders at 120$0^{\circ}C$ and the result of TEM observations. When the content of ZrO2 in the dispersed coating system, the coating time, and the volume ratio of water/solution were 50 mg/g, 180 min, and 5, respectively the coating efficiency was maximum (the ratio of tetra-/mono-ZrO2 was 87/13). The relative densities of coated Al2O3-ZrO2 composites sintered at 1$650^{\circ}C$ for 4 hrs were about 91~98% and the maximum ratio of tetra-/mono-ZrO2 in Al2O3-20wt% ZrO2 composites was 62/38.

• Korean Journal of Materials Research
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• v.8 no.11
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• pp.1031-1037
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• 1998

To investigate the effect of cooling rate and annealing temperature on the corrosion of Zircaloy-4 and Zr-2. 5Nb alloys, autoclave corrosion tests were performed at $500^{\circ}C$ for the specimens prepared by various heat treatments. The specimens were heat-treated at $1050^{\circ}C$ for 30 minutes and cooled by ice-brine quenching, water quenching, oil quenching, air cooling, and furnace cooling. To investigate the effect of annealing temperature, the specimens were annealed at $\alpha$, ($\alpha$+$\beta$)-, and $\beta$-temperatures. It was observed from the $500^{\circ}C$ corrosion test that nodular corrosion occurred on the Zircaloy-4 alloy but did not occur on the Zr-2.5Nb alloy. The corrosion resistance of Zircaloy-4 increased with increasing the cooling rate. On the other hand, the corrosion resistance of Zr-2.5Nb decreased with increasing the cooling rate and the annealing temperature. It is suggested that corrosion resistance of Zircaloy-4 would be controlled by the distribution of Fe and Cr element in the matrix and precipitates, while that of Zr-2.5Nb alloy the niobium concentration and $\beta_{-Nb}$ phase.

• Journal of the Korean Vacuum Society
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• v.9 no.4
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• pp.341-345
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• 2000

We investigated the microstructures and the electrical properties of $ZrO_2$thin films deposited by reactive DC magnetron sputtering on (100) Si with different deposition conditions and annealing treatments. The refractive index of the $ZrO_2$ thin films increased with annealing temperatures and deposition powers, and approached to the ideal value of 2.0~2.2. The $ZrO_2$thin films deposited at the room temperature are amorphous, and the films are polycrystalline at the deposition temperature of $300^{\circ}C$. Both the thickness of the interfacial oxide layer and the root-mean-square (RMS) value of surface roughness increased upon annealing in the oxygen ambient. The Cmax value and leakage current value decreased with the increase of thickness of the interfacial oxide thickness.

• Transactions of Materials Processing
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• v.17 no.5
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• pp.364-372
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• 2008

In this study, the circumferential creep behaviors ofpilgered advanced Zirconium alloy tubes such as Zr-Nb-O and Zr-Nb-Sn-Fe were investigated in the temperature range of $400\sim500^{\circ}C$ and in the stress range of 80$\sim$150MPa. The test results indicate that the stress exponent for the steady-state creep rate of the Zr-Nb-Sn-Fe alloy decreases with the increase of stress(from 6$\sim$7 to 4), while that of the Zr-Nb-O alloy is nearly independent of stress(5$\sim$6). The activation energy of creep deformation is found to be nearly the same as the activation energy for Zr self diffusion. This indicates that the creep deformation may be controlled by dislocation climb mechanism in Zr-Nb-O. On the other hand, the transition of stress exponent(from 6-7 to 4) in Zr-Nb Sn-Fe strongly suggests the transition of the rate controlling mechanism at high stresses. The lower stress exponent at high stresses in Zr-Nb-Sn-Fe can be explained by the dynamic deformation aging effect caused by interaction of dislocations with Sn substitutional atoms.

• Korean Journal of Materials Research
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• v.24 no.5
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• pp.259-265
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• 2014

$ZrO_2$ films were coated on aluminum etching foil by the sol-gel method to apply $ZrO_2$ as a dielectric material in an aluminum(Al) electrolytic capacitor. $ZrO_2$ films annealed above $450^{\circ}C$ appeared to have a tetragonal structure. The withdrawal speed during dip-coating, and the annealing temperature, influenced crack-growth in the films. The $ZrO_2$ films annealed at $500^{\circ}C$ exhibited a dielectric constant of 33 at 1 kHz. Also, uniform $ZrO_2$ tunnels formed in Al etch-pits $1{\mu}m$ in diameter. However, $ZrO_2$ film of 100-200 nm thickness showed the withstanding voltage of 15 V, which was unsuitable for a high-voltage capacitor. In order to improve the withstanding voltage, $ZrO_2$-coated Al etching foils were anodized at 300 V. After being anodized, the $Al_2O_3$ film grew in the directions of both the Al-metal matrix and the $ZrO_2$ film, and the $ZrO_2$-coated Al foil showed a withstanding voltage of 300 V. However, the capacitance of the $ZrO_2$-coated Al foil exhibited only a small increase because the thickness of the $Al_2O_3$ film was 4-5 times thicker than that of $ZrO_2$ film.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.8 no.3
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• pp.518-523
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• 1998

The fracture toughness and hardness of 62 %$SiO_2-19%ZrO_2-9%Na_2O-10%B_2O_3$(wt%) glass ceramics system were investigated. As a result of DTA study to find crystallization temperature, an exothermic peak near $820^{\circ}C$ was observed. The optimum nucleation temperature and the optimum crystal growth temperature were determined by XRD and SEM analysis, and were approximately $650^{\circ}C$, $840^{\circ}C$ respectively. The fracture toughness of this zirconia glass ceramics was determined by Vickers Indentation Method. The hardness value was not changed with increasing of the heat treatment temperature, but fracture toughness value was increased up to $1.8 MPa{\cdot}m^{1/2}$ at $840^{\circ}C$, with increasing of heat treatment temperature.

• Journal of the Korean Ceramic Society
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• v.40 no.5
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• pp.415-422
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• 2003

BaZr $O_3$-based proton conductors in which B-site cations are partially substituted by Ce and Yb were fabricated by a solid state reaction method. The electrical properties of the specimens were measured by using impedance analyzer in dry air and wet air atmospheres. The electrical conductivity showed higher value in wet air than in dry air at below $600^{\circ}C$. As the Ce content increased, the electrical conductivity increased. Among four compositions, BaZ $r_{0.8}$C $e_{0.15}$Y $b_{0.05}$ $O_3$$_{-{\delta}}$ specimen showed the highest electrical conductivity,1.72$\times$10$^{-3}$ S$cm^{-1}$ /, at 80$0^{\circ}C$. In the low temperature region, the electrical conductivity was higher in wet air than in dry air. However, as the temperature increased, the proton conductivity reduced and thus the electrical conductivity showed similar value at approximately $700^{\circ}C$.

• Korean Journal of Materials Research
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• v.4 no.5
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• pp.510-515
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• 1994

Yttria-stabilized zirconia(YSZ) films were prepared onto p-type (100) silicon wafer by a plasma-enhanced metallorganic chemical vapor deposition(PE MO CVD) processing involving the application of vapor mixture of tri(2.2.6.6-tetramethyl-3, 5-heptanate) yttrium$[Y(DPM)_3]$, zirconiumtriflouracethyla cetonate$(Zr(tfacac)_4$ and oxygen gas. The x-ray diffraction(XRD) and fourier transform infrared spectra(FT1R) results showed that the deposited YSZ films had a single cubic phase. $Y_2O_3$ content of YSZ film was analyzed by PIXE(partic1e induced x-ray emission). The experimental results by PIXE revealed that 12.lmol%, 20.4mol% and 31.6mol% $Y_2O_3$ could be obtained as the $Y(DPM)_3$ bubbling temperature varied at $160^{\circ}C, 165^{\circ}C$ and $170^{\circ}C$ respectively. The increase of $Y(DPM)_3$ bubbling temperature caused shifting flat band voltage to have a negative value.