• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.10 no.3
• /
• pp.211-218
• /
• 2000

$PbZrO_3$precursor was prepared for the spin coating on the Pt/Ti/$SiO_2$/Si substrate. Two different heat treatment methods were used and the differencies were studied. One of the method is that the films were inserted into the furnace for 30 minutes and the other is that the films were annealed by rapid thermal annealing (RTA) for 1 minute at the same temperatures. We also examined the tendency of crystallization by annealing at the fixed temperature, $700^{\circ}C$ as a function of time, namely during 1, 10, 20, and 30 minitues, respectively. The optimum conditions for the crystallization of these films were at $550^{\circ}C$ during 30 min. and at $700^{\circ}C$ during 10 min. in muffle furnace and at $650^{\circ}C$ during 1 min in RTA furnace. The best condition for making good quality grains needs 30 min. at $700^{\circ}C$.

• Journal of Hydrogen and New Energy
• /
• v.17 no.2
• /
• pp.204-211
• /
• 2006

The electrolyte in the solid oxide fuel cell must be dense enough to avoid gas leakage and thin enough to reduce the ohmic resistance. In order to manufacture the thin and dense electrolyte layer, 8 mol% $Y_2O_3$ stabilized-$ZrO_2$ (8YSZ) electrolyte layers were coated on the porous tubular substrate by the novel vacuum slurry dip-coating process. The effects of the slurry concentration, presintering temperature, and vacuum pressure on the thickness and the gas permeability of the coated electrolyte layers have been examined in the vacuum slurry coating process. The vacuum-coated electrolyte layers showed very low gas permeabilities and had thin thicknesses. The single cell with the vacuum-coated electrolyte layer indicated a good performance of $495\;mW/cm^2$, 0.7 V at $700^{\circ}C$. The experimental results show that the vacuum dip-coating process is an effective method to fabricate dense thin film on the porous tubular substrate.

• Journal of the Korean Ceramic Society
• /
• v.39 no.9
• /
• pp.851-856
• /
• 2002

Tribological behavior of plasma-sprayed $Cr_2O_3$-based coatings containing $MoO_3$ at 450$^{\circ}C$ was investigated to understand the influence of $MoO_3$. A reciprocal disc-on-plate type tribo-tester was employed to examine fricition and wear behavior of the specimens. The microstructure and phase composition of the coating was characterized with Transmission Electron Microscopy(TEM). The TEM analysis indicated that $MoO_3$ was dispersed into the grain boundary, resulting in the increase of the hardness and density of the coating. Worn surfaces were investigated by scanning electron microscopy and chemistry of the worn surfaces was analyzed using a X-ray Photoelectron Spectrometer(XPS). The results showed that the friction coefficient of the $MoO_3$-added coatings was lower than that without $MoO_3$ addition. The larger protecting layers were observed at the worn surface of plasma spray coated specimens with $MoO_3$ composition in the protecting layer appears to be more favorable in reducing the friction.

• Journal of the Korean Ceramic Society
• /
• v.41 no.2
• /
• pp.136-142
• /
• 2004

A homogeneous and stable ZnO sol was prepared by dissolving the zinc acetate dihydrate(Zn(CH$_3$COO)$_2$$.$2H$_2$O) in solution of isopropanol((CH$_3$)$_2$$.$CHOH) and monoethanolamine(MEA:H$_2$NCH$_2$CH$_2$OH). ZnO thin films were prepared by sol-gel spin-coating method and investigated for c-axis preferred orientation and physical properties with preheating temperature. The c-axis growth had a difference as increaing preheating temperature. ZnO thin film preheated at 275$^{\circ}C$ and post-heated at 650$^{\circ}C$ was highly oriented along the (002) plane. After preheating at 200∼300$^{\circ}C$ and post-heating at 650$^{\circ}C$, the transmittance of ZnO thin films by UV-vis. measurement was over 85% in visible range and exhibited absorption edges at about 370 nm. The optical band gap energy was obtained about 3.22 eV, The photoluminescence emission characteristics of ZnO thin film preheated at 275$^{\circ}C$ and post-heated at 650$^{\circ}C$ was found to orange emission(620 nm, 2.0 eV) by PL measurement, which revealed the possibility for application of inorganic photoluminescence device.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.11 no.3
• /
• pp.138-145
• /
• 2012

The material used in this study is dielectric and ferrite. Because of the unique characteristics of the material, it is easily exposed to external shocks and pressure, which cause damage to the product. However, after being processed under high-temperature environment repeatedly, the mechanical strength of the product is greatly increased due to the change of the electrical properties. In this paper, dielectric and bonded ferrite material was tested for the material properties. The equipment for this experiment was produced and tested to allow Cylindrical and Three-dimensional geometry of the product for the vacuum deposition. For Cylindrical shape of the product, in order to obtain the equivalent film thickness, the device is constructed in a vacuum chamber which gives arbitrary revolving and rotating capability. The electrical performance of the product is obtained through this process as well. However, as mentioned above, with repeating processes under high temperature and exposure to external environment, the product is easy to be broken. This experiment has enabled us to find out a stable condition to apply the communication of the RF high frequency to each of the core elements, such as Ferrite and Dielectric which is then used for the mechanical strength of the Raw material, hetero-junction material, Hetero-junction Ag Coating material and hetero-junction Ag Coating SiO2 Coating material respectively.

• Journal of Magnetics
• /
• v.2 no.1
• /
• pp.16-21
• /
• 1997

Those were investigated, the crystallographic, morphological, and magnetic properties of barium ferrite film (SiO2/Si substrate) prepared by sol-gel dip coating. Appropriate sol was prepared by dissolvin barium and iron nitrate in ethylene glycol at 80$^{\circ}C$. To obtain the films, thermally oxidized p-type silicon substrate with (111) of crystallographic orientation were dipped into the sol, dried at 250$^{\circ}C$ to remove organic material, and heated at 800$^{\circ}C$ for 3 hours in air for the crystallization of barium ferrite. It was found that the particles of barium ferrite formed on the substrate exhibited needle-like shape placing parallel to the substrate and its c-axis is long axis direction. There was tendency that the coercive force in horizontal direction to the substrate was higher than that in vertical direction to it. This tendency was profound in large thickness.

• Journal of the Korean Graphic Arts Communication Society
• /
• v.16 no.3
• /
• pp.61-80
• /
• 1998

To investigate in influence of photosensitizer used with benzophenone(BP) in the curing rate and physical properties of UV curable hard coating on plastic, we prepared UV curable clear and pigmented coatings with DEA, DMA, NPM and TEA as photosensitizer, respectively. The curing rate calculated from the decrease of the absorbance of acrylic double bond measured by FT-IR spectroscopy increased s follows; DEA>DMA>NPM>TEA. this order could be explained by the reactivity of diethylamino group of DEA and the ease of formation of activated complex between BP and photosensitizer during the curing process. In UV curable pigmented coatings, the order of curing rate increased as follows; DEA>DMA>TEA>NPM. It was found that the curing rate of the pigmented coating can be increased by light scattering of TiO$_2$. The hardness of coating film cured by photosensitization of DEA and DMA is higher than other photosensitizers due to the crosslinking reaction of DEA and DMA radical bound to polymer backbone.

• Journal of the Korean Ceramic Society
• /
• v.47 no.2
• /
• pp.113-116
• /
• 2010

The silica coated $Fe_3O_4$ nanoparticles have been synthesized using a micro-emulsion method. The $Fe_3O_4$ nanoparticles with the sizes 6 nm in diameter were synthesized by thermal decomposition method. Hydrophobic $Fe_3O_4$ nanoparticles were coated silica using surfactant and tetraethyl orthosilicated (TEOS) as a $SiO_2$ precursor. Shell thickness of silica coated $Fe_3O_4$ can be controlled (11~20 nm) through our synthetic conditions. The $Fe_3O_4$ and silica coated $Fe_3O_4$ nano powders were characterized by transmission electron microscopy (TEM), x-ray diffraction (XRD) and vortex magnetic separation (VMS).

• Journal of the Korean Ceramic Society
• /
• v.34 no.3
• /
• pp.314-322
• /
• 1997

The thin film processing and the applicability as a IMD material of SiO2 aerogels providing ultralow dielec-tric properties were studied. The SiO2 aerogel films with 0.5g/㎤ density (78% porosity) and 4000~21000$\AA$ thickness could be prepared at 25$0^{\circ}C$ and 1160 psig by supercritical drying of wet-gel films, which were spin-coated at the spin rate of 1000~7000 rpm on p-Si(111) wafer under the isopropanol atmosphere. The optimum viscosity of polymeric SiO2 sols for spin coating was in the range of 10~14 cP. The main fac-tors being able to control the film thickness and microstructures were found to be sol concentration, spin rpm, and aging time of wet-gel films. The dielectric constant of the SiO2 aerogel thin film was around 2.0 low enough to be applied to the next generation semiconductor device beyond the giga level.

• Journal of the Korea Furniture Society
• /
• v.26 no.2
• /
• pp.122-129
• /
• 2015

In previous study, VOC emission characteristics of coating materials for wood finishing were conducted and results showed that eco-friendly products has about 15~46% lower TVOC emission than typical products. In this study, lower TVOC emitted coating materials were applied on pine and then changes of VOC emission characteristics from pine with treatments were determined. Non-treated pine emitted $604.7{\mu}g/m^2h$ of TVOC that contained 66% of NVOC ($399.7{\mu}g/m^2h$). However, $V_2$ finished pine showed no NVOC emission rather than AVOC emission that consisted of Toluene, Ethylbenzene, m,p-Xylene, o-Xylene, 1,2,4- Trimethylbenzene. All coating materials inhibited ${\alpha}$-Pinene emission which originally from pine, but waterborne stain ($W_1$ and $W_3$) showed lower disruption of that emission. Moreover, $W_3$/wood showed higher NVOC emission such as ${\alpha}$-Terpinol, Terpinen-4-ol which are known as antioxidant substrates. Based on results, VOC emission characteristic of pine was significantly affected by coating materials with negatively in terms of ${\alpha}$-Pinene emission or positively in terms of NVOC emission. Therefore, coating material is important factor for indoor air quality when it would apply on wood products. For the future study, VOC emission characteristic of coated wood will be conducted continuously.