• New & Renewable Energy
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• v.1 no.1 s.1
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• pp.64-71
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• 2005

The stability of alumina-coated NiO cathodes was studied in $Li_{0.62}/K_{0.38}$ molten carbonate electrolyte. Alumina was effectively coated on the porous Ni plate using galvanostatic pulse plating method. The deposition mechanism of alumina was governed by the concentration of hydroixde ions near the working electrode, which was controlled by the temperature of bath solution. Alumina-coated NiO cathodes were formed to $A1_2O_3-NiO$ solid solution by the oxidation process and their Ni solubilities were were than that of NiO up to the immersion time of 100h. However, their Ni solubilities increased and were similar to that of the bare NiO cathode after 100h. It was because aluminum into the solid solution was segregated to $\alpha-LiAlO_2$ on the NiO and its Product did not Play a role of the Physical barrier against NiO dissolution.

• Proceedings of the KIEE Conference
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• 2005.07c
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• pp.2001-2003
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• 2005

Various organic acid were used in order to prepare new metalorganic deposition solution for high quality $REBa_2Cu_3O_{7-{\delta}}$ (RE=Y, Eu, Gd) films. Prepared fluorine free MO precursor solution was coated on single crystal (001) $LaAlO_3$ (LAO) by dip coating method. Processing parameters such as oxygen partial pressure, water vapor, ramping rate and pyrolysis temperature etc havebeen controlled in order to make high $J_c$ films with a good epitaxial relationship with substrate. 0.5 micron-thick film was obtained by single coating and no crack appeared after calcination. Oxygen partial pressure was varied in the range of $100{\sim}1,000 ppm$ and conversion heat treatment was carried out at the temperature of $725{\sim}765^{\circ}C$. A critical transition temperature $(T_{c0})$ of 90K and a critical transport current density $(J_c)$ of $>0.5MA/cm^2$ (77K and self-field) were demonstrated for the YBCO film on (001) oriented LAO substrates with a thickness of 0.5 micron. $I_c$ was determined by utilizing a transport measurement. SEM and XRD investigations confirmed that films were grown epitaxially onto the LAO single crystal substrate. It is thought that fluorine free new MOD solutionis promising for high quality REBCO films.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.12
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• pp.1147-1152
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• 2013

In this study, the effect of an insulation coating on the start time of a linear region is theoretically investigated when an insulation-coated hot-wire is used for the transient hot-wire method (THWM). For this purpose, important parameters affecting the start time of the linear region are presented from an analytical solution of temperature-rise for an insulation-coated hot-wire. Furthermore, a critical time to ignore the influence of important parameters is studied. The theoretical results indicate that the effect of the insulation coating rapidly disappears with a decrease in the wire radius, coating thickness, thermal diffusivity of insulation material or an increase in the thermal conductivity of the insulation material. The results of this study will be helpful for selecting a proper start time of the linear region for the THWM using insulation-coated hot-wires.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.2
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• pp.608-613
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• 2010

This study is on development of UV-cured water soluble coating composition which have more improved anti-cigar burning to prevent a surface of PVC tile from damage of heat. To make an anti-cigar burning coating solution, thermostable agent that synthesize main materials phosphorus compound, guanidine and ammonium phosphate dibasic used temporary flame retardants, changing their contents from 10 to 30wt% against quantities of resin and compounded. After coating PVC tiles using bar-coating method that can adjust a thickness, we estimated surface properties of coated layer such as anti-cigar burning, adhesive power, chemical resistance, thickness of coating, and so on. Results showed that a coating composition added 30 wt% of phosphorus compound and coated with No.12 bar-coater had the best optimized surface property in anti-cigar burning effect, adhesive power and chemical resistance. Also, we could find anti-cigar burning effect was improved as thermostable agents content and coating thickness increased.

• Journal of Surface Science and Engineering
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• v.49 no.2
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• pp.211-217
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• 2016

Boride coating applied on steam turbine parts of power plants has provided good particle erosion resistance under temperature of $550^{\circ}C$, but it isn't able to protect the parts effectively any more in ultra super critical (USC) steam turbine which is being operated up to temperature of $650^{\circ}C$. To ensure stable durability for USC steam turbine parts, an alternative coating replacing boride coating should be developed. In this study, multi-component boride coatings containing elements such as chromium (Cr) and vanadium (V) were formed on base metal (B50A365B) using thermochemical treatment method called by pack cementation. The thermochemical treatments involve consecutive diffusion of boron(B) and Cr or/and V using pack powders containing diffusion element sources, activators and diluents. The top layer of Cr-boride coating is primarily consisted of $Cr_2B_3$ and $Cr_5B_3$, while that of V-boride coating is mostly consisted of $VB_2$ and $V_2B_3$. The (Cr,V)-boride coating is consisted of $Cr_2B_3$, $Cr_5B_3$ and $V_2B_3$ mostly. The top surfaces of 3 multi-component boride coatings show hardness of $3200-3400H_v$, which is much higher than that of boride, about $1600-2000H_v$. In 5 wt.% NaCl solution immersion tests, the multi-component boride coatings show much better corrosion resistance than boride coating.

• Journal of Magnetics
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• v.19 no.3
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• pp.227-231
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• 2014

We fabricated textured polycrystalline $CoFe_2O_4$ thin films on $Pt(111)/TiO_2/SiO_2/Si$ substrate through a sol-gel method. We varied the thickness of the films, by using precursor solutions with different concentrations of 0.1, 0.2, and 0.3 M, and by depositing 5, 8, or 10 layers on the substrate by spin-coating. X-ray diffraction spectra indicated that when the precursor concentration of the solution was higher than 0.1 M, the spin-coated films were preferentially oriented in the <111> direction. Inspection of the surface morphology by scanning electron microscopy revealed that $CoFe_2O_4$ thin films prepared with 0.2 M solution and 5-time spin-coatings had smoother surface, as compared to the other conditions. Each coating had an average thickness of about 50 nm. The magnetic properties measured by vibrating sample magnetometer showed magnetic anisotropy, as evidenced from the difference in the in-plane and out-of-plane hysteresis loops, which we attributed to the textured orientation of the $CoFe_2O_4$ thin films.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.26 no.8
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• pp.620-623
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• 2013

The carbon nanotube / poly-vinylidene fluoride (CNT/PVDF) composite films for the nano-generator devices were fabricated by spray coating method using the CNT/PVDF solution, which was prepared by adding PVDF pellets into the CNT dispersed N-Methyl-2-pyrroli-done (NMP) solution. The flexible CNT/PVDF composite films were investigated by the scanning electron microscopy, which revealed that the CNTs were uniformly dispersed in the PVDF matrix and thickness of the films was approximately $20{\mu}m$. Fourier transform infra-red spectra were used to investigate crystal structure of the as-spray-coated CNT/PVDF films, and we found that they revealed extremely large portion of the ${\beta}$ phase PVDF. The capacitance of the CNT/PVDF films increased by adding CNTs into the PVDF matrix, and finally saturated. However, the resistance didn't show any saturation effect in the CNT concentration range of 0~4 wt%. Finally, the resulting nano-generator devices revealed reasonable current output after given mechanical stress.

• Journal of the Korean Ceramic Society
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• v.37 no.7
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• pp.665-672
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• 2000

The ferroelectric YMnO3 thin films were prepared by MOD(metal-organic decomposition) method with Y- and Mn-acetylacetonate as starting materials. Thin films were grown on various substrates by spin-coating technique. The crystalline phases of the thin films were identified by X-ray diffractometer as a function of heat-treatment temperature, pH of coating solution and substrate. In addition, the effect of Mn/Y molar ratio(0.8~1.2) on the formation of hexagonal-YMnO3 phase was investigated. In forming highly c-axisoriented hexagonal-YMnO3 single phase, the Pt coated Si substrate was more effective than the bare Si substrate, and the optimum heat-treatment condition was at 82$0^{\circ}C$ for 30 min. Higher Mn/Y molar ratio within 0.8~1.2 and pH of YMnO3 precursor solution within 0.5~2.5 favored formation of ferroelectric hexagonal phase rather than orthorhombic phase. Leakage current density of the hexagonal-YMnO3 thin film formed on Pt(111)/TiO2/SiO2/Si substrate was low enough as 0.4~4.0$\times$10-8(A/$\textrm{cm}^2$) at 5 V and its remanent polarization(Pr), calculated from the P-E hysteresis loop, was 3 nC/$\textrm{cm}^2$.

• Journal of Pharmaceutical Investigation
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• v.28 no.1
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• pp.7-13
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• 1998

The captopril microcapsules were prepared and were investigated by measuring their size distribution using Scanning Electron Microscopy(SEM) and dissolution of captopril. Cetyl alcohol microcapsules prepared by emulsion melted-cooled method with various ratios of drug to cetyl alcohol were spherical and uniform. The release rate of cetyl alcohol microcapsules was decreased proportionally as the content of cetyl alcohol increased but, the particle size of microcapsules was increased. The surface of cetyl alcohol microcapsules was comparatively rough as drug content increased. Pellet type microcapsules were prepared using fluidized-bed coating system by spraying captopril solution on nonpareil-seeds followed by applying $Eudragit^{\circledR}$ RS solution containing propylene glycol as a plasticizer. The release rate of drug from pellet type microcapsules decreased as the content of $Eudragit^{\circledR}$ RS increased.

• Journal of Electrochemical Science and Technology
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• v.10 no.2
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• pp.223-230
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• 2019

A facile method for surface coating with $Li_2TiF_6$ which has a high lithium-ion conductivity, on $LiMn_2O_4$ spinel cathode material for high performance lithium ion batteries. The surface coating is performed by using a co-precipitation method with $Li_2CO_3$ powder and $H_2TiF_6$ solution under room temperature and atmospheric pressure without special equipment. Total coating amount of $Li_2TiF_6$ is carefully controlled from 0 to 10 wt.% based on the active material of $LiMn_2O_4$. They are evaluated by a systematic combination of analyses comprising with XRD, SEM, TEM and ICP. It is found that the surface modification of $Li_2TiF_6$ is very beneficial to high cycle life and excellent rate capability by reducing surface failure and supporting lithium ions transportation on the surface. The best coating condition is found to have a high cycle life of $103mAh\;g^{-1}$ at the 100th cycle and a rate capability of $102.9mAh\;g^{-1}$ under 20 C. The detail electrochemical behaviors are investigated by AC impedance and galvanostatic charge and discharge test.