• 대한화학회지
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• 제4권1호
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• pp.15-17
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• 1957

1. Preparation of Titanium tetrachloride; The following precesses were strictly followed as the preliminary step to obtain pure $TiOCl_2$, titanyl chloride; First, pure Titanium Oxide mixed with carbon is rolled into pills. After drying up perfectly, these pills are heated at 900∼1000${\circ}C$. And then the pills are subjected to the flow of $Cl_2$ gas in a quartz tube heated to 900-1000${\circ}C$. Thus Titanium tetrachloride is obtained. 2. Preparation of $TiOCl_2$ ; Yellowish trobrown solution is made by pouring 80 g of conc. HCl (sp.gr. 1.19) to 45 gr of Titanium tetrachloride (approx. 2 times of theoretical amount). Then this solution is kept settled for 5-days in a desiccator filled with phosphorous pentoxide at room temperature. As the colorless amorphous solid thus obtained is washed with aceton, 36.5 g of the pure salt are obtained. 3. Determination of composition. The analysis of the sample taken from the deposit desiccated gives the following data; (A) Qualitative analysis; a) $Ti(OH)_4$ is precipitated by adding NaOH in water solution of the salt. b) Adding $AgNO_3$ solution, the water solution of the salt gives white precipitate of AgCl. c) When acid and $H_2O_2$ are added, the solution turns its color to redish brown (This proves that $TiO^{++}$ was converted into $TiO^{++}$ by oxidation of $H_2O_2$. (B) Quantitative analysis; a) $Ti(OH)_4$ precipitated by $10{\%}$ NaOH isalitatsubjected consecutively to the filtration and ignition in porcelain crucible at approx. 1000${\circ}C$. , then $TiO_2$ thus formed is weighed and calculated into Ti content. b) Chlorine involved in water solution of the salt is determined by Vorhardt method. Result: The values obtained from previous analysis, devied by their atomic weight gives the following composition: Ti : Cl = 1 : 2 Therefore $TiOCl_2$ should be given as its molecular formula. 4. Summary. When $TiCl_4$ is additated into conc. HCl, $TiO^{++}$ formed exists as a stable form, and forms $TiOCl_2$. However $TiOCl_2$ is unstable to heating. When the temperature is raised to $65{\circ}C$the decomposition of the solution is accelerated, and gives $TiO_2$ aq. $TiOCl_2$ in addition is highly hygroscopic.

• Nuclear Engineering and Technology
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• 제52권8호
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• pp.1756-1763
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• 2020

The paper studies spark plasma sintering (SPS) of industrially used UO₂-based fuel containing integral fuel burnable absorber (IFBA) of neutrons Gd₂O₃. Densification dynamics of pristine UO₂ powder and the one added with 2 and 8 wt% of Gd₂O₃ under ultrasonication in liquid has been studied under SPS conditions at 1050, 1250, and 1450 ℃. Effect of sintering temperature on phase composition as well as on O/U stoichiometry has been investigated for UO₂ SPS ceramics. Sintering of uranium dioxide added with Gd₂O₃ yields solid solution (U,Gd)O₂, which is isostructural to UO₂. SEM with EDX and metallography were implemented to analyze the microstructure of the obtained UO₂ ceramics and composite UO₂-Gd₂O₃ one, particularly, open porosity, defects, and Gd₂O₃ distribution were studied. Microhardness, compressive strength and density were shown to reduce after addition of Gd₂O₃. Obtained results prove the hypothesis on formation of stable pores in the system of UO₂-Gd₂O₃ due to Kirkendall effect that reduces sintering efficiency. The paper expands fundamental knowledge on pros and cons of fuel fabrication with IFBA using SPS technology.

• 한국수소및신에너지학회논문집
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• 제22권2호
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• pp.161-167
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• 2011

Proton conductors have attracted considerable attention for solid oxide fuel cell (SOFC), hydrogen pump, gas sensor, and membrane separators. Doped $SrCeO_3$ exhibits appreciable proton conductivity in hydrogen-containing atmosphere at high temperature. However commercial realization has been hampered due to the reactivity of $SrCeO_3$ with $CO_2$. The chemical stability and proton conductivity are dependent on dopant type. The purpose of this work is to investigate chemical stability of $SrCe_{0.95}Gd_{0.05}O_{3-\alpha}-Ce_{0.9}Gd_{0.1}O_{2-\beta}$ composites in $CO_2$ and $H_2$ gases. Thermogravimetric analysis (TGA) was performed in gaseous $CO_2$ and electrical conductivity of the composites were also measured between 500 and $900^{\circ}C$ in air and $H_2$ atmosphere. $SrCe_{0.95}Gd_{0.05}O_{3-\alpha}-Ce_{0.9}Gd_{0.1}O_{2-\beta}$ composite membranes showed good chemical stability of in $CO_2$ atmosphere and high conductivity at hydrogen condition. The hydrogen permeation of $SrCe_{0.95}Gd_{0.05}O_{3-\alpha}-Ce_{0.9}Gd_{0.1}O_{2-\beta}$ composite membranes was investigated as a function of volumetric content of $SrCe_{0.95}Gd_{0.05}O_{3-\alpha}$. The $SrCe_{0.95}Gd_{0.05}O_{3-\alpha}-Ce_{0.9}Gd_{0.1}O_{2-\beta}$(6:4) membrane with a thickness of 1.0 mm showed the highest hydrogen permeability with the flux reaching of 0.12 $ml/min{\cdot}cm^2$ at $800^{\circ}C$ in 100%$H_2/N_2$ as feed gas.

• 전기화학회지
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• 제10권3호
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• pp.207-212
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• 2007

IT-SOFC(중저온형 고체산화물 연료전지)의 공기극으로 적합한 PSCF3737의 물질 특성을 파악하고 그 특성을 이용하여 낮은 ASR을 갖기 위한 소결 온도 및 두께 최적화에 관한 연구를 수행하였다. 분말 사이즈 및 상형성을 고려할 때 GNP 방법으로 합성된 분말의 하소 온도는 $1000^{\circ}C$가 적합함을 알 수 있었다. 산소 분압에 따른 ASR 변화 실험을 통하여 PSCF3737의 저항 성분을 전극 자체의 특성과 관련된 중간 주파수 대역(${\sim}10^2Hz$)과 산소의 확산에 영향 받는 낮은 주파수 대역(${\sim}10^{-1}Hz$) 2가지로 분류할 수 있었다. 공기극의 특성 실험을 통하여 소결 온도는 $1200^{\circ}C$가 가장 적합하며 공기극의 두께는 2번 스크린 프린팅 된 $27\;{\mu}m$가 가장 적합함을 알 수 있었다. 이를 토대로 EIS 측정을 하면 $700^{\circ}C$에서 $0.115\;{\Omega}cm^2$의 낮은 ASR값을 얻을 수 있었다.

• 한국수산과학회지
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• 제15권4호
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• pp.271-282
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• 1982

The browning development, mainly through the Maillard reaction, occurring in the dried fish meat products during storage causes reduction of the nutritional value due to the loss of the essential amino acid such as available lysine as well as off -flavor resulting in the deterioration of the food quality thus shortening the shelflife. In the work, the changes in the amount of available lysine, extractable nitrogenous compounds (nonprotein-N, amino-N, trimethylamine oxide, trimethylamine, and free lysine) and development of browning were measured to assess the relationship between the shelflife and the quality loss in dried filefish under the steady state conditions (35,45, and $55^{\circ}C;a_{w}'s$ of 0.44 0.52, 0.65 and 0.75 at each temperature) and fluctuating temperature condition of $35/55^{\circ}C$ will. alternating 7 day periods at each water activity. The results indicated that the amount of available lysine and extractable nitrogenous compounds except TMA decreased rapidly with increasing temperatures and water activities while the rate of available lysine and extractable nitrogenous compounds must be involved in the initial stage of brown pigment formation. The available lysine loss of the dried filefish products stored under the fluctuating temperature conditions was greater than that stored under its fixed mean temperature, $45^{\circ}C$. The activation energies for lysine loss obtained from the Arrhenius plot ranged 6.9 to 4.4 Kcal/mol and $Q_{10}$ values at $40^{\circ}C$ were 1.4 to 1.2. The values for browning were 15.7 to 14.4 Kcal/mol and 2.2 to 2.0 respectively. Shelf-life, defined as the time to reach 0.15 O. D./g solid or the limit of off-color deterioration by browning reaction, was extented longer than the halflife of Iysine loss, actually corresponding $75\%$ loss of available lysine. This suggested that the halflife of lysine loss might not be adequate to assess the shelf-life of the food system with high potential of protein, nonproteinous nitrogen compounds, and lipids.

• 한국자기학회지
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• 제6권4호
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• pp.204-210
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• 1996

제철소의 부산물인 mill scale과 $Fe_{2}O_{3}$, 그리고 이들의 혼합물을 사용하여 M형 ferrite를 제조하였다. $Fe_{2}O_{3}$와 $BaCO_{3}$의 몰비를 5.2~6.0으로 변화시킨 혼합물의 하소 및 소결은 각각 $1150^{\circ}C,\;1250^{\circ}C$에서 2시간 행하였으며, 하소시에 mill scale 중의 불순물 성분인 $SiO_{2},\;Al_{2}O_{3},\;MgO,\;CaO\;및\;Na_{2}O$를 적당량 첨가한 시편으로 자기적 특성과 형상을 조사하였다. $Na_{2}O$를 첨가한 시편은 미반응의 $Fe_{2}O_{3}$와 중간 화합물인 $BaFe_{2}O_{4}$의 영향으로 자기적 특성이 감소하였으나, $BaO.5.6Fe_{2}O_{3}$ 조성에 $SiO_{2}$와 $Al_{2}O_{3}$의 첨가는 특성의 증진을 보였으며, 특히 $Al_{2}O_{3}$는 $M_{s}$ 값은 감소시켰으나 $_{B}H_{c}$ 값을 증가시켰다. BM($BaCo_{3}$와 mill scale의 혼합물)과 BFM($BaCO_{3},\;Fe_{2}O_{3}$, mill scale의 혼합물) 소결 시편의 ${(BH)}_{max}$는 각각 0.86, 1.04 MGOe였으며, $440^{\circ}C$ 부근에서 자기 특성의 변화를 보였다.

• 한국광물학회지
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• 제22권2호
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• pp.153-162
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• 2009

석간주는 적색과 적갈색 등 붉은 빛을 띠는 전통 광물성 안료로 주성분은 산화철이다. 석간주의 광물학적 특성과 기능성을 연구하기 위해서, 문헌에 옛 산지로 나와있는 울릉도 주토굴에서 석간주를 채취하였다. 울릉도주토굴의 석간주광석은 감람석현무암과 각섬석조면암 경계면에서 단속적으로 산출하며, 적갈색 또는 황갈색을 띠고 대체로 점토질이며 부분적으로 암편을 함유하고 있다. 석간주광석 중 적색은 적철석에 의한 것이며, 황갈색은 훼리하이드라이트에 의한 것이다. 울릉도석간주광석의 색상을 결정하는 산화철광물들은 고토양중에서 함철 수용액으로부터 훼리하이드라이트라는 광물로 침전되었으나 부분적으로 적철석으로 전이되었다. 석간주광석을 전통방식에 의해 안료로 제작하여 목재에 재현한 색상은 전통 건축물에서 측정한 붉은색 색상과 유사하였다. 울릉도석간주안료의 내습기능과 방염기능은 화학석간주안료에 비해 월등히 우수한 것으로 확인되었으며 연소시험에서 화학석간주안료는 발화와 연소를 촉진시키는 결과를 보였다. 울릉도석간주안료가 함유된 배지에서 목재부후균의 성장이 저지되는 경향을 보여 울릉도석간주는 방부성을 지닌 채색안료로 판단된다.

• 한국표면공학회지
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• 제42권1호
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• pp.26-33
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• 2009

Recently ultra-supercritical steam power plants operate at $1000^{\circ}F$ ($538^{\circ}C$) and 3500 psi (24.1 MPa). Thermal efficiency of power plant will be increased about 2% if steam temperature increases from $1000^{\circ}F$ to $1150^{\circ}F$ ($621^{\circ}C$). In this study valve materials Incoloy901 (IC901) and Inconel718 (IN718) were nitrided to improve the surface hardness and solid lubrication function of the valve materials. The hardness of both IC901 and IN718 increased about two times by ion nitriding. IC901, IN718 and their nitrided specimens were corroded under ultra super-critical condition (USC) of $621^{\circ}C$. and 3600 psi (24.8 MPa) for 2000 hours. Oxidations of both IC901 and IN718 were very small due to the formation of protective oxide layer on the surface. But the corrosion resistance of both nitrided specimens decreased because of the formation of non-protective nitride layer of $Fe_{4}N$, $Fe_{2}N$ and CrN on the surface layer. The hardness of both nitrided IC901 and IN718 at $20{\mu}m$ depth from the surface decreased about 30% and 20% respectively by USC 2000 hours.

• 전기화학회지
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• 제13권3호
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• pp.211-216
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• 2010

전해액 상용성의 boron trifluoride lithium methacrylate ($BF_3$LiMA)를 기본으로 하는 겔 고분자 전해질 (gel polymer electrolytes, GPE)에서 $BF_3$LiMA의 농도가 이온전도도, 전기화학적 안정성에 미치는 영향을 AC impedance 측정법과 linear sweep voltammetry (LSV)를 통하여 평가하였다. 그 결과 $BF_3$LiMA가 4wt% (고분자함량 21 wt%)일 때, 상온 이온전도도가 $5.3{\times}10^{-4}Scm^{-1}$로서 가장 높게 관찰되었으며 4 wt% 전후로 다시 감소하였다. $BF_3$LiMA 기반의 GPE는 음이온이 고정되어 있는 자기-도핑형 계열로서 우수한 전기화학적 안정성을 확인하였다. 한편 $BF_3$LiMA 기반 GPE는 리튬금속과 비교적 불안정한 계면반응성을 보여주었지만 흑연/GPE/흑연, LCO/GPE/LCO에서는 높은 계면안정성을 형성하였다. 따라서 $BF_3$LiMA 기반의 GPE를 통하여 높은 상온 이온전도도와 전기화학적 안정성 및 흑연과 LCO 양극산화물에 대한 우수한 계면특성을 확보할 수 있었다.

• 한국재료학회지
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• 제11권5호
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• pp.339-344
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• 2001

코발트 산화물 박막을 전극으로 하여 Pt/Ti/Si 기판위에 Co$_3$O$_4$/LiPON/Co$_3$O$_4$로 구성된 전고상의 박막형 슈퍼캐패시터를 제작하였다. 각각의 Co$_3$O$_4$박막은 반응성 dc 마그네트론 스퍼터를 이용하여 $O_2$/[Ar+O$_2$] 비를 증가 시키며 성장시켰고, 비정질 LiPON 고체전해질 박막은 순수한 질소분위기 하에서 rf 스퍼터링으로 성장시켰다. 비록 벌크 타입의 슈퍼캐패시터에 비해 낮은 전기용량 (5-25mF/$\textrm{cm}^2$-$\mu\textrm{m}$)을 가졌지만, Co$_3$O$_4$/LiPON/Co$_3$O$_4$ 구조로 제작된 전고상 박막형 슈퍼캐패시터는 벌크 타입과 비슷한 거동을 나타내었다 0-2V의 전압구간, 50$\mu\textrm{A}/\textrm{cm}^2$의 전류밀도에서 약 400사이클 까지 안정한 방전용량을 유지함을 관찰할 수 있었다 이러한 전고상 박막형 슈퍼캐패시터의 전기화학적 특성은 $O_2$/[Ar+O$_2$] 비에 의존하는데, 이러한 의존성을 구조적, 전기적 특성 및 표면특성을 분석하여 설명하였다.