• Journal of the Korean Society for Heat Treatment
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• v.35 no.5
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• pp.262-269
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• 2022

In order to process materials such as engineering plastics, which are difficult to mold due to their high strength compared to conventional polymer materials, it is necessary to improve the hardness and strength of parts such as screws and barrels of injection equipment in extrusion system. High-velocity oxygen fuel (HVOF) process is well known for its contribution on enhancement of surface properties. Thus in this study, using the HVOF process, WC coating layers of different thicknesses were bonded to the surface of S30C substrate by controlling the movement speed of the spray nozzle and each property was evaluated to decide the optimization condition. Through the results, the thickness of WC coating layer increased from 0 to 200 ㎛ maximum, along with the decrement of nozzle movement speed and the surface hardness get increased. Especially, the coated layer with the thickness over 180 ㎛ under the nozzle speed 500 mm/s had high hardness than thinner layer. In addition, the amount of wear consumed per unit time was also significantly reduced due to the formation of the coating layer.

• The Journal of the Korea Contents Association
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• v.21 no.12
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• pp.918-925
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• 2021

The perovskite solar cell is a next-generation solar cell that replaces the existing silicon solar cell. It is a solar cell device using an organic-inorganic hybrid material having a perovskite structure as a photoactive layer. It has advantages for the process and has shown rapid efficiency improvement over the past decade. In the process of commercialization of such perovskite solar cells, research and development for a large-area coating method should be carried out. As one of the large-area perovskite solar cell large-area coating methods, the slot-die coating method was studied. By using a meniscus to pass over the substrate and coating the solution, the 3D printer was equipped with a meniscus so that it could be coated. Variables that act during coating include bed temperature, coating speed, N₂ blowing interval, N₂ blowing height, N₂ blowing intensity, etc. By controlling these, the perovskite absorption layer was manufactured and the coating conditions for manufacturing large-area devices were optimized.

• Journal of the Korean institute of surface engineering
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• v.30 no.4
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• pp.248-254
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• 1997

The sulfidation behavior of a sputter-deposited amorphous coating of 69.0%Nb-16.9Ni-11.9%Al-2.2%Si (at.%) has been investigated as a funtion of temperature.(973-1173K) in pure sulfur pressure of 0.01atm. The sulfidation kinetics of the casting obyed the parabolic rate low over the whole temperature ranges studied. The stlfidation rate increased with the temperature, as expected. The sulfide scale, the composition of which was $Al_2S_3,\;NbS_2,\;Ni_{3-x}S_2\;and\;FeCrS_4$, formed on the amorphous coating was primarily bilayered. Both the outer fastgrowing non-protective 4Al_2S_3$scale and the inner slowly-growing protective $NbS_2$,/TEX> scale and the inner slowly-growing protective $NbS_2$ scale had some Fe and Cr dissolution, which evidently came from the base substrate alloy of stainless steel type 304. Belows the coating, Kirkendall void formation was noticed. Nevertheless, a dramatic improvement of sulfidation resistance was achieved by sputter-depositing Nb-2 Ni-Al-Si layer on the stainless steel 304.

• Journal of the Korean Home Economics Association
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• v.40 no.10
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• pp.77-85
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• 2002

This study was conducted to evaluate the efficiency of various fabrics in protecting from solar radiation and ultraviolet radiation(UV). Six kinds of fabrics were selected and examined in singles or doubles. It was studied how the materials and the thickness of air layer between the fabric and the floor affected the protection efficiency of fabrics from sunlight. The results were as followes; 1) Protection from solar radiation: In the case of over 2 cm air layer, doubled fabric composed of aluminum coating-nylon and white or black polyester/cotton(T/C) was the most protective(p<0.001). In the case of 0 cm air layer, the case without fabric and white T/C were more effective(p<0.001). And the thicker the air layer the more effective the protection. 2) Protection from UV : Doubled fabric composed of aluminum coating-nylon and black T/C was the most protective(p<0.001) and the thinner the air layer the more effective the protection(p<0.001).

• Advances in materials Research
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• v.1 no.3
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• pp.233-243
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• 2012

Thermal reactive diffusion coating of vanadium carbide on DIN 2714 steel substrate was performed in a molten borax bath at $950-1050^{\circ}C$. The coating formed on the surface of the substrate had uniform thickness ($1-12{\mu}m$) all over the surface and the coating layer was hard (2430-2700 HV), dense, smooth and compact. The influence of the kinetics parameters, temperature and time, has been investigated. Vanadium carbide coating was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDX) and X-ray diffraction analysis (XRD). The corrosion resistance of the coating was evaluated by potentiodynamic polarization in 3.5% NaCl solution. The results obtained showed that decrease of coating microhardness following increasing time and temperature is owing to the coarsening of carbides and coating grain size.

• Journal of the Microelectronics and Packaging Society
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• v.29 no.1
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• pp.61-66
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• 2022

This study is to increase the surface area and maximize the effect of the catalyst by coating a nanometersized metal catalyst material on the anode layer using atomic layer deposition (ALD) technology. ALD process is known to produce uniform films with well-controlled thickness at the atomic level on substrates. We measured the performance by coating metals (Ni) on Ni/YSZ, which is the most widely known anode material for solid oxide fuel cells. ALD coatings began to show a decrease in cell performance over 3 nm coatings.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.10 no.6
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• pp.146-151
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• 2011

Wax spin coating is a part of several wafer handling processes in the silicon wafer polishing station. It is important to ensure the wax layer free of contamination to achieve the high degree of planarization on wafers after wafer polishing. Three-dimensional air flow characteristics in a wax spin coater are numerically investigated using computational fluid dynamics techniques. When the bottom of the wax spin coater is closed, there exists a significant recirculation zone over the rotating ceramic block. This recirculation zone can be the source of wax layer contamination at any rotational speed and should be avoided to maintain high wafer polishing quality. Thus, four air suction ducts are installed at the bottom of the wax spin coater in order to control the air flow pattern over the ceramic block. Present computational results show that the air suction from the bottom is quite an effective method to remove or minimize the recirculation zone over the ceramic block and the wax coating layer.

• Korean Journal of Materials Research
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• v.14 no.8
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• pp.558-564
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• 2004

In order to improve the low hardness and low wear resistance of Ti-6Al-4V alloy, plasma carburization treatment and CrN film coating were carried out. Effects of the plasma carburization and CrN coating were analyzed and compared with the non-treated alloy by mechanical and creep tests. After plasma carburization and CrN coating treatments, the carburized layer was about 150 ${\mu}m$ in depth and CrN coated layer was about 7.5 ${\mu}m$ in thickness. Hardness value of about $H_{v}$ 402 of the non-treated alloy was improved to $H_{v}$ 1600 and 1390 by plasma carburization and CrN thin film coating, respectively. Stress exponent(n) was decreased from 9.10 in CrN coating specimen to 8.95 in carburized specimen. However, the activation energy(Q) was increased from 242 to 250 kJ/mol. It can be concluded that the static creep deformation for Ti-6Al-4V alloy is controlled by the dislocation climb over the ranges of the experimental conditions.

• Proceedings of the KWS Conference
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• 2005.11a
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• pp.262-264
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• 2005

$Bi_{2}Sr_{2}CaCu_{2}O_{x}$(Bi-2212) and $Bi_{2}Sr_{2}Ca_{2}Cu_{3}O_{y}$(Bi-2223) high-$T_{c}$ superconductor(HTS) coating have been prepared by plasma spraying and heaat treatment. The Bi-2212 HTS coating later is synthesized through the peritectic reaction between Sr-Ca-Cu oxide coating layer and Bi-Cu oxide coating later, and $Bi_{2}Sr_{2}CaCu_{2}O_{y}$(Bi-2212) superconducting phase grow by partial melting process. The superconducting characteristic depends strongly on the conditions of the partial melting process. the Bi-2212 HTS layer consists of the whiskers grown in the diffusion direction. Above the 2212 layer, Bi-2223 phase and secondary phase was observed. The secondary phase is distributed uniformly over the whole surface. This is caused to the microcrack on the coatings surface. Despite everything, the film shows superconducting with an onset $T_{c}$ of about 115K. There are two changes steps. One changes (1step) at 115K is due to the diamagnetism of the Bi-2223 phase and the other changes (2step) at 78K is due to the diamagnetism of the Bi-2212 phase.

• Membrane Journal
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• v.11 no.2
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• pp.83-88
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• 2001

A methodology for enhancing the bond strength of a coating layer with a support has been established in preparing low-pressure reverse osmosis mO) hollow fiber which would experience shear badly in flowing feed un it. Prior to coating process, the support membrane, ultrafiltratiun polysulfone(PS) hollow fibers was pretreated with a reaction solution containing glutaraldehyde (GAl which has a good affinity to the suppurt membrane material as well as a reactivity to some of the cunstituents of cuating layer subsequently formed on the support by interfacial polymerization. Therefore, the reactant GA distributed unifonnly over the support layer through the pretreatment could provide a strong adhesive bond between the coating layer and the support, sticking fast to the support membrane through physical bond and, at the same time, connecting its functional group with the coating laycr by chemical bonding. Due to the strong adhesive bond, the resulting hollow fiber membrane showed an excellent long-tcnn stability in pcnneation.