• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.2
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• pp.585-591
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• 2013

A robot automation system for coating uniformly a big radiator used in PPS(Packaged Power Station), which consists of 6-axis robot with spray gun, travelling vehicle, supply device of coating paint and thinner with pressured air, HMI controller and robot path OLP(Off-Line Programming), was developed. Experimental results on an optimum operation condition show that a coating thickness is $43{\mu}m$, which is satisfied to a design reference of $25-100{\mu}m$. A productivity of the developed coating robot automation system based on OLP is about 12.6 times of that of manual operation.

• Journal of the Society of Naval Architects of Korea
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• v.47 no.5
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• pp.743-749
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• 2010

Multi-nozzle spray painting procedure of the inorganic zinc shop primer was established in order to obtain uniform film thickness. The shop primer paint prevents the corrosion of steel block during shipbuilding. When the dry film thickness of shop primer is insufficient, rust will be generated on the steel block. Otherwise, thick coating of shop primer may be a problem of weld defect. So, it is important to obtain the uniform film thickness of shop primer. The uniformity of dry film thickness is affected by spray speed, distance from spray gun to target surface and overlapping span of spray path. In order to uniformly maintain coating thickness of shop primer, the coating procedure was established based on the correlation of shop primer spray variables.

• Journal of the Korean institute of surface engineering
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• v.55 no.6
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• pp.441-447
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• 2022

Silicon-based materials are one of the most promising anode active materials in lithium-ion battery. A carbon layer decorated on the surface of silicon particles efficiently suppresses the large volume expansion of silicon and improves electrical conductivity. Carbon coating through chemical vapor deposition (CVD) is one of the most effective strategies to synthesize carbon- coated silicon materials suitable for mass production. Herein, we synthesized carbon coated SiOx via pilot scale CVD reactor (P-SiO_x@C) and carbon coated SiO_x via industrial scale CVD reactor (I-SiO_x@C) to identify physical characteristic changes according to the CVD capacity. Reduced size silicon domains and local non-uniform carbon coating layer were detected in I-SiO_x@C due to non-uniform temperature distribution in the industrial scale CVD reactor with large capacity, resulting in increased surface area due to severe electrolyte consumption.

• 한국신재생에너지학회:학술대회논문집
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• 2010.11a
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• pp.37.2-37.2
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• 2010

Electrostatic spray deposition is an innovative coating technique that produces fine, uniform, self-dispersive (due to the Coulombic repulsion), and highly wettable, atomized drops. Copper-indium salts are dissolved in an alcohol-based solvent, which is then electrostatically sprayed onto a moderately heated, molybdenum-coated substrate. Solvent flowrates range from 0.02 to 5 ml/hr under applied voltages of 1 to 20 kV yielding drop sizes around a few hundred nanometers. By comparing the scanning electron miscrscope images of coated samples, the substrate temperature, applied voltage, solvent flowrate, and nozzle-substrate distance are demonstrated to be the primary parameters controlling coating quality. Also, the most stable electrostatic spray mode that reliably produces uniform and fine drops is the cone-jet mode with a Taylor cone issuing from the nozzle.

• Journal of the Korean Society of Visualization
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• v.9 no.4
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• pp.41-46
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• 2011

Oxygen sensitive functional particles(OSParticle) were fabricated by three different methods for using the particles as oxygen sensors and PIV tracers. The used methods were a physical coating method, an ion-exchange method and a dispersion polymerization method. The physical coating method is dipping $SiO_2$ hollow particles into dye solution then drying. This method is very simple, but particles are not uniform in diameter and luminescence. The particles fabricated by the ion-exchange method have very uniform diameter and well doped. However, it can not be used in water since the particles are hydrophobic. In case of the dispersion polymerization method, the diameter of OSParticles is quite uniform. The diameter of OSParticles can be changed by controlling the quantity of AIBN (2,2'-azobis isobutyronitrile). For the purpose of dissolved oxygen concentration measurement in micro scale water flows, the dispersion polymerized OSParticles turn out to be the most superior functional particles. The luminescent intensity of OSParticles was tested with the variation of dissolved oxygen concentration in water samples. As a result, the luminescent intensity of OSParticles is monotonically decreased with increasing DO (Dissolved oxygen) concentration of water.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1534-1538
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• 2011

Uniform, hollow nanosilica spheres were prepared by the chemical coating of cationic polystyrene (cPS) with tetraethylorthosilicate (TEOS), followed by calcination at 600 $^{\circ}C$ under air. cPS was synthesized by surfactant-free emulsion polymerization using 2,2'-azobis (2-methyl propionamidine) dihydrochloride as the cationic initiator, and poly(vinyl pyrrolidone) as a stabilizer. The resulting cPS spheres were 280 nm in diameter, and showed monodispersion. After coating, the hollow silica product was spherically shaped, and 330 nm in diameter, with a narrow distribution of sizes. Dispersion was uniform. Wall thickness was 25 nm, and surface area was 96.4 $m^2/g$, as determined by BET. The uniformity of the wall thickness was strongly dependent upon the cPS surface charge. The effects of TEOS and ammonia concentrations on shape, size, wall thickness, and surface roughness of hollow $SiO_2$ spheres were investigated. We observed that the wall thicknesses of hollow $SiO_2$ spheres increased and that silica size was simultaneously enhanced with increases in TEOS concentrations. When ammonia concentrations were increased, the irregularity of rough surfaces and aggregation of spherical particles were more severe because higher concentrations of ammonia result in faster hydrolysis and condensation of TEOS. These changes caused the silica to grow faster, resulting in hollow $SiO_2$ spheres with irregular, rough surfaces.

• Transactions of the Korean hydrogen and new energy society
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• v.23 no.6
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• pp.573-580
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• 2012

Corrosion resistance and basic physical properties of solid tantalum are not comparable to most of the structural metallic materials. The relative high cost and melting temperature of tantalum are obstacles to be widely applied to general engineering processes. Electrodeposition in molten salt enables compact and uniform tantalum coating. In this study, Ta was coated onto base metal (SUS316L) with different current densities (0.5, 5, $20mA/cm^2$) by using MSE (Molten Salt Electrodeposition). In this study, it showed that deposition efficiency and microstructure of Ta coating layer were strongly depended on current density. In the case of the current density of $5mA/cm^2$, densest microstructure was obtained. The current density above $5mA/cm^2$ caused non-uniform microstructure due to rapid deposition rate. Dense microstructure and intact coating layer contributed to significant corrosion resistance enhancement.

• Journal of the Korean institute of surface engineering
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• v.49 no.1
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• pp.62-68
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• 2016

A chromium-free Ce-based conversion coating formed by immersion in a solution containing cerium chloride and nitric acid on AZ31 magnesium alloy has been studied. The effects of acid pickling on the morphology and the corrosion resistance of the cerium conversion coating were investigated. The corrosion resistance of the conversion coating prepared on AZ31 Mg alloy after organic acid pickling was better than that of inorganic acid pickling. The morphology of the conversion-coated layer was observed using optical microscope and SEM. Results show that the conversion coatings are relatively uniform and continuous, with thickness 1.0 to $1.1{\mu}m$. The main elements of the conversion coating of AZ31 Mg alloy are Mg, O, Al, Ce and Zn by EDS analysis. The electrochemical polarization results showed that the Ce-based conversion coating could reduce the corrosion activity of the AZ31 Mg alloy substrates in the presence of chloride ions.

• Corrosion Science and Technology
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• v.22 no.4
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• pp.297-303
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• 2023

This study aimed to evaluate hydrogen permeation behaviors of pre-strained twinning-induced plasticity steel with or without Zn coating using electrochemical permeation technique. In contrast to un-strained and 30% strained samples, permeation current density was measured in the 60% strained sample. Tensile pre-straining at 60% involved microstructural modifications, including a high level of dislocation density and stacking fault with a semi-coherent twin boundary, which might provide a high diffusion path for hydrogen atoms. However, reproducibility of measurements of hydrogen permeation current was low due to non-uniform deformation and localized stress concentration. On the other hand, the permeation current was not measured in pre-strained TWIP steel with Zn coating. Instead, numerous blisters with some cracks were observed on the surface of the coating layer. In locally damaged Zn coating under tensile straining, hydrogen atoms could relatively easily permeate through the coating layer. However, they were trapped at the interface between the coating layer and the substrate, which might delay hydrogen penetration into the steel substrate.

• Journal of the Korean institute of surface engineering
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• v.57 no.1
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• pp.14-21
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• 2024

For this study, CrAlN multilayer coatings were deposited on SKD61 substrates using a multi-arc ion plating technique. The structural characteristics of the CrAlN multilayer coatings were evaluated using X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). Additionally, the adhesion of the coatings was assessed through scratch testing, and the mechanical strength was evaluated using nanoindentation and tribometric tests for frictional properties. The results show that the CrAlN multilayer coatings possess a uniform and dense structure with excellent mechanical strength. Hardness measurements indicated that the CrAlN coatings have high hardness values, and both the coating adhesion and wear resistance were found to be improved compared to CrN. The addition of aluminum is anticipated to contribute to enhanced durability and wear resistance.