• 한국세라믹학회지
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• 제46권2호
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• pp.189-199
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• 2009

The Powder characteristics and sintering behavior of $SiO_2$ coated $BaTiO_3$ were studied. $BaTiO_3$ powders were synthesized by the liquid mix method developed by Pechini, and silica coating was prepared by alkoxide hydrolysis method with TEOS and ethanol. The particle size of the $BaTiO_3$ powders was 35 nm and the thickness of the $SiO_2$ coating layer was 5 nm. As the $SiO_2$ content increased, the $SiO_2$ layers improved the powder dispersion by increasing electrostatic repulsion between the $BaTiO_3$ particles. Effects of MgO coating on microstructure and dielectric properties of $BaTiO_3$ have been studied compared with mechanically MgO mixed $BaTiO_3$. MgO coated $BaTiO_3$ particles were prepared by a homogeneous precipitation method using $MgCl_2\cdot 6H_2O$ and urea. MgO coated $BaTiO_3$ exhibited homogeneous microstructure compared with mixed samples. XRD analysis revealed that Mg substitution for the Ti site in the MgO mixed sample was much greater than in the coated one. Electrical properties of MgO mixed and coated $BaTiO_3$ were affected by the diffusion behavior of Mg in $BaTiO_3$ lattice.

• Journal of Electrochemical Science and Technology
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• 제9권3호
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• pp.176-183
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• 2018

In this study, a $Li_2ZrO_3$ coated $Li[Ni_{0.8}Co_{0.15}Al_{0.05}]O_2$ (NCA) cathode was applied to an all-solid-state cell employing a sulfide-based solid electrolyte. Sulfide-based solid electrolytes are preferable for all-solid-state cells because of their high ionic conductivity and good softness and elasticity. However, sulfides are very reactive with oxide cathodes, and this reduces the stability of the cathode/electrolyte interface of all-solid-state cells. $Li_2ZrO_3$ is expected to be a suitable coating material for the cathode because it can suppress the undesirable reactions at the cathode/sulfide electrolyte interface because of its good stability and high ionic conductivity. Cells employing $Li_2ZrO_3$ coated NCA showed superior capacity to those employing pristine NCA. Analysis by X-ray photoelectron spectroscopy and electron energy loss spectroscopy confirmed that the $Li_2ZrO_3$ coating layer suppresses the propagation of S and P into the cathode and the reaction between the cathode and the sulfide solid electrolyte. These results show that $Li_2ZrO_3$ coating is promising for reducing undesirable side reactions at the cathode/electrolyte interface of all-solid-state-cells.

• 한국결정성장학회지
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• 제8권2호
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• pp.292-298
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• 1998

출발원료로 ferric nitrate, ethylene glycol, acethyl acetone 혼합용액을 사용하여 dip-coating된 ${\alpha}-Fe_2O_3$ 막을 제조하였다. coating을 위한 혼합용액의 시간 경과에 따른 용액내의 가교(polymerization) 효과를 관찰하기 위해서 적외선 분광기(FT-IR)를 사용하였고, 막 형성시 유기물 분해 및 결정화 시작온도를 확인하기 위하여 FT-IR, XRD, DSC 등을 이용하여 분석을 행하였다. 또한 AFM과 SEM을 통하여 각 조건에서 제조된 막의 표면상태 및 두께 변화에 대하여 관찰되었다.

• Tribology and Lubricants
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• 제22권6호
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• pp.335-341
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• 2006

This paper reports the wear characteristics of two types of coating materials, which are $Cr_2O_3$ and $ZrO_2$, by coated plasma thermal spray method. The wear test was carried out under air, grease, and bearing fluid conditions. The wear testing machine of a pin-on disk type were used to measure friction forces, friction coefficients and the weight losses of the coating specimens on the various sliding velocity and loading condition. The wear surface of specimens were observed by scanning electron microscope (SEM) photographs.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2000년도 제32회 추계학술대회 정기총회
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• pp.80-88
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• 2000

The plasma spray technics has known as one of the surface modification methods to improve the mechenical properties or the functional charactristics of materials. This paper has been aimed to investigate the effects of plasma sprayed conditions, such as spray distance and arc power level, on sliding wear properties of plasma sprayed $Al_2$O$_3$-40%TiO$_2$coating layer. The sliding wear test using pin-on-disc type wear machine, has been conducted in several sliding speed for coating layer sparyed under different conditions. The result of this paper is that the wear resistance of plasma sprayed $Al_2$O$_3$-40%TiO$_2$coating layer is fluctuated with tile spray distance and the arc power level. The wear resiatance could be improved with decreasing the spray distance and with increasing the arc power level.

• Journal of Welding and Joining
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• 제21권4호
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• pp.46-55
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• 2003

TiO$_2$-WO$_3$(8.2wt%) coatings were prepared by the APS (Atmospheric Plasma Spraying) process to clarify the relationship between the process parameters(H$_2$ gas flow rate of plasma 2nd gas and spraying distance) of the APS coating and photo-decomposition efficiency kinetics of the MB(methylene blue) aqueous solution decomposition and to understand the effect of addition of WO$_3$ on photocatalytic properties of TiO$_2$ sprayed coating. Further, the temperature and velocity of flying particles were measured by DPV-2000 to investigate the relationship between microstructure of coatings and process parameters. Properties of coatins were investigated by XRD, SEM, XPS, RAMAN, UV/VIS spectrometer. In case of the TiO$_2$-WO$_3$(8.2wt%) coating, it had a lower anatase fraction than that of pure-TiO$_2$ coatings because of flying in the higher temperature plasma plume by the heavy weight of TiO$_2$, WO$_3$. And, when WO$_3$ added powders were spayed, the doping effects of W ions substituted into the Ti ion sites was not occured during melting and solidification cycles of spraying. It was found that the addition of WO$_3$ was ineffective effective on increasing photo-decomposition efficiency of TiO$_2$ sprayed coating.

• 한국세라믹학회지
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• 제31권1호
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• pp.17-24
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• 1994

Al2O3-ZrO2(ZTA) composites were fabricated by a surface-induced coating of the precursor for the ZrO2 phase on the kinetically stable colloid particles of Al2O3. The fabricated composites were characterized by a uniform spatial distribution of the dispersed ZrO2 phase and by the absence of large ZrO2 grains throughout the Al2O3 matrix. The fracture toughness (KIC) and the bending strength of ZTA composites sintered at 1$600^{\circ}C$, respectively, were 5.6 MPa.m1/2 (for 20 wt% ZrO2) and 600 MPa (for 15wt% ZrO2). The fraction of tetragonal ZrO2 phase decreases as the total content of ZrO2, suggesting that both the stress-induced tlongrightarrowm transformation and the microcrack nucleation contribute to the toughening of the ZTA composites fabricated by the surface-induced coating.

• 한국안광학회지
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• 제8권2호
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• pp.111-117
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• 2003

국내외 썬글라스 반미러 코팅렌즈의 광학적 특성을 파악하기 위해, 분광광도계를 이용하여 반미러 코팅렌즈의 반사율을 측정하였으며, Macleod 프로그램을 이용해 계산한 결과와 비교 분석하였다. 또한 황금 색깔이 나는 TiN을 이용한 반미러 코팅렌즈를 설계하였고, 광학특성을 조사하였다. 반미러 코팅렌즈의 분석결과, 은색 투톤(two tone) 반미러 코팅은 금속 크롬(Cr)을 사용하였으며 경도를 증가시키기 위하여 크롬위에 $SiO_2$(또는 $Al_2O_3$)를 증착하여 사용하였다. 크롬 위에 증착되는 $SiO_2$의 두께는 10nm 정도가 적정한 것으로 판단된다. 칼라 반미러 코팅의 경우 디자인 결과는 각각 다음과 같다 ; blue 계열은 [air|$SiO_2$(66.3)|$TiO_2$(129.0)|$SiO_2$(62.9)|$SiO_2$(26.0)|$TiO_2$(120.3)|$SiO_2$(9.1)|glass]이며, gold 계열은 [air|$SiO_2$(60.6)|$TiO_2$(86.2)|$SiO_2$(13.5)|$TiO_2$(86.8)|$SiO_2$(214.38)|glass]이며, green 계열은 [air|$SiO_2$(74.3)|$TiO_2$(75.8)|$SiO_2$(44.3)|$TiO_2$(11.6)|$SiO_2$(160.8)|$TiO_2$(12.9)|$SiO_2$(183.3)|$TiO_2$(143.8)|glass]이며, silver 계열은 [air|$SiO_2$(21.2)|$TiO_2$(49.7)|$SiO_2$(149.3)|glass]이다. white 반미러 코팅인 경우는 [air|$SiO_2$(17nm)|$TiO_2$(43nm)(또는 $ZrO_2$)|$SiO_2$(87nm) polysiloxane($4.46{\mu}m$)|glass or CR-39]이며, 가시광선 영역(400~700 nm)에서 평균 19%의 반사율을 가지며 흡수가 적기 때문에 약 80%의 투과율을 보이는 white 타입의 반미러가 되게 된다. 황금빛 색깔을 띠는 반미러 코팅렌즈의 설계에 있어서 [air|$SiO_2$(170nm)|TiN(15nm)|glass]가 되면 CIE 좌표값은 거의 [air|Au(150nm)|glass]의 좌표값과 유사해지는 것을 볼 수 있었다.

• 전기화학회지
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• 제14권2호
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• pp.77-82
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• 2011

[Li,La]$TiO_3$ 코팅용액의 pH를 조절하여 이에 따른 코팅된 $Li[Ni_{0.35}Co_{0.3}Mn_{0.35}]O_2$ 양극활물질의 전기화학적 특성을 관찰하였다. 산화물인 양극분말은 접촉하고 있는 용액의 pH에 따라 표면 전하를 띄게 되는데 양이온인 코팅물질을 균일하게 반응시키기 위해서는 적절한 pH 조절을 통해 양극분말 표면을 음전하 상태로 조절해 주는 것이 필요하다. SEM, TEM 분석을 통해 코팅용액의 pH에 따른 코팅층의 형상변화를 관찰하였으며 다양한 전류밀도로 충전과 방전을 실시하여 코팅용액의 pH에 따른 방전용량, 사이클 특성, 고율특성을 분석하였다. 임피던스잴 cyclic voltammogram 측정을 통해 코팅용액의 pH에 따른 코팅층의 내부저항 변화를 관찰하였으며 이것을 전기화학적 특성과 연관됨을 확인하였다.

• Corrosion Science and Technology
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• 제5권2호
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• pp.45-51
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• 2006

Properties of the anode for cathodic protection need low overvoltage for oxygen evolution and high corrosion resistance. It is well known that DSA (Dimensionally Stable Anode) has been the best anode ever since. DSA is mainly composed of $RuO_2$, $IrO_2$, $ZrO_2$, $Co_2O_3$, and also $Ta_2O_5$, $TiO_2$, $MnO_2$ are added to DSA for better corrosion resistance. The lifetime of DSA for cathodic protection is also one of the very important factors. $RuO_2$, $IrO_2$, $RhO_2$, $ZrO_2$ are well used for life extension, and many researches are focused on life extension by lowering oxygen evolution potential and minimizing dissolution of oxide coatings. This work aims to evaluate the influence of constituents of MMO and coating cycles and $ZrO_2$ coating on the electrochemical properties and lifetime of DSA electrodes. From the results of lifetime assessment in the anodes coated with single component, $RuO_2$ coating was more effective and showed longer lifetime than $IrO_2$ coating. Also, an increased coating cycle and an electrochemically coated $ZrO_2$ could enhance the lifetime of a DSA.