• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2003년도 춘계총회 및 연구발표회 초록집
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• pp.125.1-125
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• 2003

• 한국세라믹학회:학술대회논문집
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• 한국세라믹학회 2003년도 추계총회 및 연구발표회 초록집
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• pp.132.1-132
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• 2003

• 한국세라믹학회지
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• 제48권4호
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• pp.298-302
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• 2011

This study developed a pigment by doping Cr to Pyrochlore-type stannate crystals and investigated the chromogenic relationship in a glaze. Crystal phases of the pigment according to firing temperatures were analyzed by XRD, and the doping relationship was analyzed by Raman Spectroscopy. Color and reflection rate of the pigment were measured by UV-vis Spectrophotometer. Consequently, stannate characteristic band appeared at 307, 408, 505 and $755cm^{-1}$ until 0.1 mole substitution of $Cr_2O_3$. However, as amount of $Cr_2O_3$ increased, the stannate characteristic peak was decreased and shift happened at the left hand side due to Cr-dope. In composition of 0.12~0.14 mole substituted, the unreacted $Cr_2O_3$ stannate characteristic peak, which was not engaged, was shown. This result shows the maximum limit of solid solution was 0.1 mole $Cr_2O_3$. The color of the glaze, which was produced by adding 6 wt% of $Y_2Sn_{1.94}Cr_{0.06}O_7$ pigment in a lime or a lime-magnesia glaze and fired the mixture at $1260^{\circ}C$, was grayish pink with $L^*$ 70.29, $a^*$ 5.68 and $b^*$ 6.27. It showed gray with $L^*$ 68.82, $a^*$ 3.07and $b^*$ 8.13 for $Y_2Sn_{1.9}Cr_{0.1}O_7$.

• 한국세라믹학회지
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• 제39권10호
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• pp.988-993
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• 2002

Lanthanum Stannate Pyrochlore($La_2Sn_2O_7$) 촉매를 이용하여 $NO_x$ 제거를 위한 전기화학 촉매 셀을 제조하였다. 촉매전극은 수열합성법을 통해 합성한 $La_2Sn_2O_7$ 분말과 안정화 지르코니아(YSZ) 분말을 혼합하여 촉매층 페이스트를 제조한 후 이를 YSZ 디스크 고체전해질 위에 스크린프린팅하여 후막을 도포하였다. 위와 같이 제조한 전기화학 셀의 $NO_x$ 분해 실험은 galvanostat을 이용하여 셀에 일정한 전류를 인가하고 700${\circ}C$에서 NO 0.1%와 산소 2%의 반응가스에 대한 분해 정도를 gas chromatography와 NOx analyzer를 이용하여 측정을 하였다. 촉매 전극의 두께와 소성 온도에 따른 촉매전극의 미세구조가 $NO_x$ 분해에 미치는 영향과 전류량(0.05∼0.6A)에 따른 $NO_x$ 분해율을 측정하였다.

• 한국표면공학회지
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• 제53권2호
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• pp.53-58
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• 2020

In this study, we developed plasma electrolytic oxidation (PEO) process for aluminum 7075 alloy to improve the corrosion and mechanical properties. The electrolyte consists of potassium hydroxide and sodium silicate. Additionally, sodium stannate was added into the electrolyte to investigate its effect on PEO film formation. Titanium was used as the counter electrode. Plasma generation voltage reduced from 300V to 150 V by adding 4 g/L of sodium stannate. The thin oxide films were observed by SEM(Scanning Electron Microscopy)/EDS (Energy Dispersive Spectroscopy) for quantitative and qualitative analyses. XRD (X-ray diffraction) and XRF (X-ray Fluorescences) analyses were also carried out to identify oxide layer on aluminum 7075 surface. Vicker's hardness test was performed on the PEO-treated aluminum 7075 surface.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2012년도 추계총회 및 학술대회 논문집
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• pp.16-16
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• 2012

Mg and its alloys have been of great interest because of their low density of 1.7, 30% lighter than Al, but their wide applications have been limited because of their poor resistances against corrosion and/or abrasion. Corrosion resistance of Mg alloys can be improved by formation of anodic films using anodic oxidation method in aqueous electrolytes. Plasma electrolytic oxidation (PEO) is one of anodic oxidation methods by which hard anodic films can be formed as a result of micro-arc generation under high electric field. PEO method utilize not only substrate elements but also chemical components in electrolytes to form anodic films on Mg alloys. PEO films formed on AM50 magnesium alloy in an acidic fluozirconate electrolyte were observed to consist of mainly $ZrO_2$ and $MgF_2$. Liu et al reported that PEO coating on AM30 Mg alloy consists of $MgF_2$-rich outer porous layer and an MgO-rich dense inner layer. PEO films prepared on ACM522 Mg die-casting alloy in an aqueous phosphate solution were also reported to be composed of monoclinic $Mg_3(PO_4)_2$. $CeO_2$-incorporated PEO coatings were also reported to be formed on AZ31 Mg alloys in $CeO_2$ particle-containing $Na_2SiO_3$-based electrolytes. Magnesium tin hydroxide ($MgSn(OH)_6$) was also produced on AZ91D alloy by PEO process in stannate-containing electrolyte. Effects of $OH^-$, $F^-$, $PO{_4}^{3-}$ and $SiO{_3}^{2-}$ ions and alloying elements of Al and Sn on the formation of PEO films on pure Mg and Mg alloys and their protective properties against corrosion have been investigated in this work. $PO{_4}^{3-}$, $F^-$ and $SiO{_3}^{2-}$ ions were observed to contribute to the formation of PEO films but $OH^-$ ions were found to break down the surface films under high electric field. The effect of pulse current on the formation of PEO films will be also reported.

• 한국재료학회지
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• 제10권1호
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• pp.34-40
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• 2000

디지털형 압전/전왜 액츄에이터 응용을 위하여 상경계(반강유전상/강유전상) 조성인 $Pb_{0.94}Y_{0.04}[(Zr_0.6Sn_0.4)_{0.915}Ti_0.085]O_3$ (PYZST) 계를 택하여 과잉 PbO의 첨가량 및 소결 조건 변화에 따른 상전이 특성, 유전 특성 및 전기장 유기변형 특성을 연구하였다. 사방정 구조를 갖는 PYZST 세라믹스에서 과잉 PbO 첨가에 따른 결정구조의 변화는 거의 확인되지 않았으나, 소결 후 입자가 약간 작아지며 둥근 형태로 변화하였고 첨가량 증가에 따라 적정 소결온도는 감소하였다. 과잉 PbO의 첨가량이 증가함에 따라, 분극측정시 반강유전상이 보다 안정되는 경향을 보였고, 전계유도변형 측정시 인가전기장 제거상태에서의 변형의 형상기억성이 감소하고 디지털형 변형곡선 특성이 강화되었다. 또한 최대 유전상수와 전계 유기변형량은 감소하였으나 반면 상전이(반강유전상$\leftrightarrow$강유전상) 전기장 및 비저항은 증가하는 경향을 나타냈다. 이러한 결과는 과잉으로 첨가된 PbO에 의한 격자 결함반응 및 분역벽 이동 거동 가능성과 연관시켜 설명하였다.

• 한국표면공학회지
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• 제13권3호
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• pp.146-154
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• 1980

The effects of various electrodeposition conditions (deposition temperature and cathode current density) on preferred orientation and microhardness of electrodeposited Ni-Sn and Sn-Zn alloys were studied. At deposition temperatures from 25$^{\circ}$ to 95$^{\circ}C$ and constant cathode current density of 270 and 530 A/$m^2$ Ni-Sn and Sn-Zn were codeposited in chloride-fluoride acid and stannate-cyanide alkaline electrolyte bath respectively. Ni-Sn alloy deposited at temperatures from 25$^{\circ}$ to 35$^{\circ}C$ was composed of single phase of $Ni_3Sn_4$ with 73 wt.% Sn and the one deposited at temperatures from 45$^{\circ}$ to 95$^{\circ}C$ was made of multiphase mixture of NiSn, $Ni_3Sn_2$ and $Ni_3Sn_4$ with nearly equiatomic composition (65.5 wt.% Sn). The random orientation of thermody-namically metastable NiSn phase (hexagonal structure) predominated at deposition temperature range 25$^{\circ}$-45$^{\circ}C$, and the strong (110) preferred orientation was found at 65$^{\circ}$-85$^{\circ}C$ and then disappeared again at 95$^{\circ}C$. The microhardness of Ni-Sn deposits increased with deposition temperature up to 85$^{\circ}C$, and then decreased at constant cathode current density. The preferred orientation and the maximum microhardness were discussed in terms of lattice contractile stress which result from desorption of hydrogen atom absorbed in deposit lattice. The Sn content of Sn-Zn alloy deposits increased with deposition temperature up to 75$^{\circ}C$, and then decreased at constant cathode current density of 530 A/$m^2$. It also decreased with cathode current density up to 530 A/$m^2$, and then increased at constant deposition temperature of 25$^{\circ}C$. Sn-Zn alloy deposits were composed of two-phase mixture of ${beta}$-Sn and Zn. The preferred orientations of ${beta}$-Sn (tetragonal structure) changed with deposition temperature. The microhardness of Sn-Zn deposits decreased with deposition temperature. It also increased with cathode density up to 530 A/$m^2$, and then decreased at constant deposition temperature of 25$^{\circ}C$. The microhardness of Sn-Zn deposits was observed to be determinded more by the Sn content than by the preferred orientation.