• Journal of the Korean Ceramic Society
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• v.34 no.3
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• pp.225-232
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• 1997

The performance characteristics of high rate discharge LiSOCl2 cells are highly affected by carbon cathode. During the cell discharge, SOCl2 reduction takes place at the porous carbon cathode, resulting in the precipitation of reaction products, mainly LiCl, within the pores of the substrate. This leads to eventual passivation of the cathode surface and resulting cell failure. To improve the cathode performance, we ex-amined discharge reactions of cathodes (half-cell, 50 mA/$\textrm{cm}^2$ constant current) with various surface density and thickness. The carbon cathode with the optimum capacity for our application is surface density 0.04 g/$\textrm{cm}^2$ and thickness 1.4mm carbon. The carbon cathode with surface density 0.04g/$\textrm{cm}^2$ and thickness 1.4 mm exhibits decreased polarization, increased discharge duration time and capacity (Ah/$\textrm{cm}^2$) as compared with that with surface density 0.04g/$\textrm{cm}^2$ and thickness 0.8mm. The porosities analyses on the two carbon cathodes show that total pore volume of the carbon cathode with thickness 1.4 mm is larger than that with thickness 0.8mm. The increased volume of mesopores (0.05$\mu$m~0.5$\mu$m) and macropores(>0.5$\mu$m) is ob-served with the carbon cathode with thickness 1.4mm as compared with that with thickness 0.8mm, which can be related with the observed capacity increase. We observed LiCl crystals, cubic crystallites and fused, plate-like aggregates, and some elemental S as discharge products by EDS and XRD.

• Applied Chemistry for Engineering
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• v.10 no.1
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• pp.6-11
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• 1999

Dialkylamine (di-)nitrobenzoates as vapor corrosion inhibitor were synthesized with dialkylamines and (di-)nitrobenzoic acids. The compounds were analyzed by elemental analyzer, FT-IR and $^1H$-NMR spectrophotometer. Corrosion inhibition of synthetic compounds and additives [$(NH_4)_2CO_3$, $NaHCO_3$] against ferrous and non-ferrous metal was investigated by potentiostatic method [1% (w/v) corrosion inhibitor in 1M $Na_2SO_4$ aqueous solution] respectively. For corrosion inhibition of ferrous metal, dialkylamine 4-nitrobenzoates were better inhibitor than dialkylamine 3, 5-dinitrobenzoates, the passivating current density ($i_p$) of dialkylamine 4-nitrobenzoate was shown $4.78mA/cm^2$. While, for non-ferrous metal, dialkylamine 3, 5-dinitrobenzoates were better, those of dipropylamine 3, 5-dinitrobenzoate and hexamethyleneimine 3, 5-dinitrobenzoate were shown 36 and $37mA/cm^2$. Additive effect of $(NH_4)_2CO_3$ and $NaHCO_3$ for corrosion inhibition of ferrous metal was excellent but that of non-ferrous metal was not. Optimum ratios of diethylamine 4-nitrobenzoate with $(NH_4)_2CO_3$ and $NaHCO_3$ were 4 : 6 and 5 : 5 (V/V), and passivating current densities ($i_p$) of the mixtures were shown 0.26 and $0.85mA/cm^2$, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.12
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• pp.3748-3754
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• 2009

An integral head loss test in a test apparatus was conducted to simulate chemical effects on a head loss across a strainer in a pressurized water reactor (PWR) containment water pool after a loss of coolant accident (LOCA). The test was conducted during 30 days in the condition of a short spray, a long spray, and no materials with chemical effects. The result exhibited that the head loss was affected on amounts of the exposed materials according to spray conditions. XRD analysis of the collected precipitates showed that the precipitates were phosphate compounds. Comparison of the head loss with dissolved species concentration showed that high increase rate of the head loss resulted from the corrosion of aluminum and zinc but slow increase rate of the head loss resulted from the precipitates induced by Si, Mg, and Ca from leaching reaction at NUKON and concrete after passivation of metal specimens.

• Journal of the Korean Vacuum Society
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• v.15 no.1
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• pp.89-96
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• 2006

Recent ULSI and multilevel structure trends in microelectronic devices minimize the line width down to less than $0.25{\mu}m$, which results in high current densities in thin film interconnections. Under high current densities, an EM(electromigration) induced failure becomes one of the critical problems in a microelectronic device. This study is to improve thin film interconnection materials by investigating the EM characteristics in Ag, Cu, Au, and Al thin films, etc. EM resistance characteristics of Ag, Cu, Au, and Al thin films with high electrical conductivities were investigated by measuring the activation energies from the TTF (Time-to-Failure) analysis. Optical microscope and XPS (X-ray photoelectron spectroscopy) analysis were used for the failure analysis in thin films. Cu thin films showed relatively high activation energy for the electromigration. Thus Cu thin films may be potentially good candidate for the next choice of advanced thin film interconnection materials where high current density and good EM resitance are required. Passivated Al thin films showed the increased MTF(Mean-time-to-Failure) values, that is, the increased EM resistance characteristics due to the dielectric passivation effects at the interface between the dielectric overlayer and the thin film interconnection materials.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2001.04a
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• pp.34-34
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• 2001

열CVD법에 의하여 아세틸렌 가스를 탄소 원으로 사용한 탄소 나노튜브의 성장거동을 조사하였다. 닉켈 분말의 직경을 15nm 내지 90nm 범위로 조정하여 기판 에 촉매로 배열하였다. 탄소 나노튜브는 질소, 수소, 알곤, 암모니아 등 여러가지의 가스 분위기에서 증착되었으며 이들 가스의 혼합 분위기가 탄소나 노튜브의 성장에 미치는 영향을 조사하였다. 증착은 대기압 압력하에서 85$0^{\circ}C$ 의 온도에서 이루어졌다. 순수한 질소 분위기에서는 탄소 나노튜브의 성장이 이루어지지 않고 두꺼운 탄소 층이 기판 위에 중착되었다. 이 조건에서는 탄소로 뒤덮혀진 닉켈 입자가 탄소 나노튜브 형성의 촉매 역할을 담당하지 못했다. 그러나 질소와 수소의 혼합분위기에서는 수소의 농도가 증가함에 따라 탄소 나노튜브의 성장이 증진되었다. 순수한 수소 분위기에서는 일정한 방향이 없이 꼬여진 탄소 나노튜브가 성장되었다. 탄소 나노튜브의 성장은 분위기 가스로 암모니아를 사용하였을 때 훨씬 더 증진되었다. 수직으로 배열된 탄소 나노튜료를 암모니아 분위기에서는 성장시킬 수 있었으나 암모니아와 같은 비율의 수소와 질소 가스의 혼합 분위기 하에서 는 탄소 나노튜브의 성장을 얻을 수 없었다. 이러한 결과를 여기에서는 닉켈 촉매의 표면에 과도하게 석출된 탄소의 촉매 passivation으로 설명하였다. 탄소 나노튜브의 증착을 위해서는 아세틸렌 가스의 분해율이 너무 과도하지 않게 즉 촉매의 표면이 과도한 탄소의 증착으로 수동태화 되지않도록 조절되어야 한다는 것이다. 이 연구결과는 분위기 가스의 조성이 탄소 나노튜브의 성장에 있어서 그 반웅 kinetics에 큰 영향을 미친다는 것을 잘 보여주고 있다. 또한 암모니아 분위기에서는 촉매 닉켈입자 표면에 질화물층이 형성되어 탄소 나노튜브의 성장에 영향을 미쳤다는 것도 알 수 있었다.며 실제 가공업체에서도 터짐 문제가 발견되지 않았다. 결론적으로 표면층의 인장강도가 패션/구부림에 가장 중요한 변수로 작용하며 어떠 한 형태로 표면층의 인장강도를 향상시킬 경우 침엽수 펄프는 재생펄프로 대체가 가능 할 것으로 판단된다.하는 통계기법 중의 하나인 주성분회귀분석을 실시하였다. 주성분 분석은 여러 개의 반응변수에 대하여 얻어진 다변량 자료의 다차원적인 변 수들을 축소, 요약하는 차원의 단순화와 더불어 서로 상관되어있는 반응변수들 상호간 의 복잡한 구조를 분석하는 기법이다. 본 발표에서는 공정 자료를 활용하여 인공신경망 과 주성분분석을 통해 공정 트러블의 발생에 영향 하는 인자들을 보다 현실적으로 추 정하고, 그 대책을 모색함으로써 이를 최소화할 수 있는 방안을 소개하고자 한다.금 빛 용사 둥과 같은 표면처리를 할 경우임의 소재 표면에 도금 및 용 사에 용이한 재료를 오버레이용접시킨 후 표면처리를 함으로써 보다 고품질의 표면층을 얻기위한 시도가 이루어지고 있다. 따라서 국내, 외의 오버레이 용접기술의 적용현황 및 대표적인 적용사례, 오버레이 용접기술 및 용접재료의 개발현황 둥을 중심으로 살펴봄으로서 아직 국내에서는 널리 알려지지 않은 본 기 술의 활용을 넓이고자 한다. within minimum time from beginning of the shutdown.및 12.36%, $101{\sim}200$일의 경우 12.78% 및 12.44%, 201일 이상의 경우 13.17% 및 11.30%로 201일 이상의 유기의 경우에만 대조구와 삭제 구간에 유의적인(p<0.05) 차이를 나타내었다.는 담수(淡水)에서 10%o의 해수(海水)로 이주된지 14일(日) 이후에 신장(腎臟)에서 수축된 것으로 나타났다. 30%o의 해수(海水)에 적응(適應)된 틸라피아의 평균 신사구체(腎絲球體)의 면적은 담수(淡水)에

• Korean Chemical Engineering Research
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• v.46 no.3
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• pp.619-625
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• 2008

The effects of thermal cycling on residual stresses in both inorganic passivation/insulating layer that is deposited by plasma enhanced chemical vapor deposition (PECVD) and organic thin film that is used as a bonding adhesive are evaluated by 4 point bending method and wafer curvature method. $SiO_2/SiN_x$ and BCB (Benzocyclobutene) are used as inorganic and organic layers, respectively. A model about the effect of thermal cycling on residual stress and bond strength (Strain energy release rate), $G_c$, at the interface between inorganic thin film and organic adhesive is developed. In thermal cycling experiments conducted between $25^{\circ}C$ and either $350^{\circ}C$ or $400^{\circ}C$, $G_c$ at the interface between BCB and PECVD $ SiN_x $ decreases after the first cycle. This trend in $G_c$ agreed well with the prediction based on our model that the increase in residual tensile stress within the $SiN_x$ layer after thermal cycling leads to the decrease in $G_c$. This result is compared with that obtained for the interface between BCB and PECVD $SiO_2$, where the relaxation in residual compressive stress within the $SiO_2$ induces an increase in $G_c$. These opposite trends in $G_cs$ of the structures including either PECVD $ SiN_x $ or PECVD $SiO_2$ are caused by reactions in the hydrogen-bonded chemical structure of the PECVD layers, followed by desorption of water.

• Journal of Technologic Dentistry
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• v.30 no.1
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• pp.25-31
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• 2008

Cp-Ti and Ti-6Al-4V alloys commonly used dental implant materials, particularly for orthopaedic and osteosynthesis because of its suitable mechanical properties and excellent biocompatibility. This alloys have excellent corrosion behavior in the clinical environment. The first factor to decide the success of dental implantation is sufficient osseointegration and high corrosion resistance between on implant fixture and its surrounding bone tissue. In this study, in order to increase corrosion resistance and biocompatibility of Cp-Ti and Ti-6Al-4V alloy that surface of manufactured alloy was coated with TiN by RF-magnetron sputtering method. The electrochemical behavior of TiN coated Cp-Ti and Ti-6Al-4V alloy were investigated using potentiodynamic (EG&G Co, PARSTAT 2273. USA) and potentiostatic test (250mV) in 0.9% NaCl solution at 36.5 $\pm$ 1$^{\circ}C$. These results are as follows : 1. From the microstructure analysis, Cp-Ti showed the acicular structure of $\alpha$-phase and Ti-6Al-4V showed the micro-acicular structure of ${\alpha}+{\beta}$ phase. 2. From the potentiodynamic test, Ecorr value of Cp-Ti and Ti-6Al-4V alloys showed -702.48mV and -319.87mV, respectively. Ti-6Al-4V alloy value was higher than Cp-Ti alloy. 3. From the analysis of TiN and coated layer, TIN coated surface showed columnar structure with 800 nm thickness. 4. The corrosion resistance of TiN coated Cp-Ti and Ti-6Al-4V alloys were higher than those of the non-coated Ti alloys in 0.9% NaCl solution from potentiodynamic test, indicating better protective effect. 5. The passivation current density of TiN coated Cp-Ti and Ti-6Al-4V alloys were smaller than that of the noncoated implant fixture in 0.9% NaCl solution, indicating the good protective effect resulting from more compact and homogeneous layer formation.

• Journal of the Korean Electrochemical Society
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• v.4 no.1
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• pp.6-9
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• 2001

[ $SiO_2$ ] effect on the electrochemical properties of polymeric gel electrolytes(PGEs) reinforced with glass fiber cloth(GFC) was investigated . PGEs were composed of polyacrylronitrile(PAN), poly(vinylidenefluoride-co-hexafluoropropylene) (P(VdF-co-HFP)), $LiClO_4$ and three kind of plasticizer(ethylene carbonate, dietyl carbonate, propylene carbonate). $SiO_2$ was added to PGEs in the weight fraction of 10, 20, $30\%$ respectively. PGEs containing $SiO_2$ showed conductivity of over $10^{-3}S/cm\;at\;23^{\circ}C$ and electrochemical stability window to 4.8V. In the impedance spectra of the cells, which were constructed by lithium metals as electrodes, interfacial resistance increased due to growth of passivation layer during storage time and remarkable difference was not observed with content of $SiO_2$. In the impedance spectra of the lithium ion polymer batteries consisted of $LiClO_2$ and mesophase pitch-based carbon fiber(MCF), ohmic cell resistance of $SiO_2-free$ PGE was changed continuously with number of cycle, but those of $SiO_2-dispersed$ PGEs were not. Discharge capacity of the PGE containing $20wt\%\;SiO_2$ showed 132 mAh/g at 0.2C rate and $85\%$ of discharge capacity was retained at 2C rate.

• Journal of the Microelectronics and Packaging Society
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• v.25 no.3
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• pp.31-36
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• 2018

This research scrutinizes the reason of failure after pressure cooker test (PCT) for DRAM device. We use the physical inspecting tools, such as microscope, SEM and TEM, and finally find the discolor phenomenon, corrosion of Al and delamination of inter-metal dielectric (IMD) in the failed devices after PCT. Furthermore, we discover the abnormal $Al_XO_Y$ layer on Al through the careful additional measurements. To find the reason, we evaluate the effect of package ball size and pinhole in passivation layer. Unfortunately, those aren't related to the problems. We also estimate halide effect of Al. The halogens such like Cl are contained within EMC material. Those result in the slight improving of PCT characteristics but do not perfectly solve the problems. We make a hypothesis of Galvanic corrosion. We can find the residue of Ti at the edge of pad open area. We can see the improving the PCT characteristics by the time split of repair etch. The possible mechanism of the PCT failure can be deduced as such following sequence of reactions. The remained Ti reacts on the pad Al by Galvanic corrosion. The ionized Al is easily react with the $H_2O$ supplied under PCT environment, and finally transfers to the abnormal $Al_XO_Y$ layer.

• Journal of Adhesion and Interface
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• v.21 no.3
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• pp.107-112
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• 2020

Recently, the atomically thin transition-metal dichalcogenide (TMD) semiconductors have attracted much attention owing to their remarkable properties such as tunable bandgap with high carrier mobility, flexibility, transparency, etc. However, because these TMD materials have a significant drawback that they are easily degraded in an ambient environment, various attempts have been made to improve chemical stability. In this research article, I report a method to improve the air stability of WSe₂ one of the TMD materials via surface passivation with an h-BN insulator, and its application to field-effect transistors (FETs). With a modified hot pick-up transfer technique, a vertical heterostructure of h-BN/WSe₂ was successfully made, and then the structure was used to fabricate the top-gate bottom-contact FETs. The fabricated WSe₂-based FET exhibited not only excellent air stability, but also high hole mobility of 150 ㎠/Vs at room temperature, on/off current ratios up to 3×10⁶, and 192 mV/decade of subthreshold swing.