• Journal of Korea Foundry Society
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• v.15 no.4
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• pp.360-367
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• 1995

Effects of metal coating treatment on SiC particle on wetting behavior and interfacial strength were studied. Experimental variables are included types of coated metallic films such as Cu and Ni-P, and temperatures of heat-treatment under vacuum. The experimental results concerning wetting phenomena of liquid Al on SiC, showed that coating treatment of metallic film on SiC particles remarkably improves the wetting behavior of liquid Al on SiC, especially in the case of Ni-P coating. The interfacial strength of Al/SiC composites made of coated SiC plate was higher than that of the composite with non-coated SiC plate although the coating treatment was not perfect.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.17 no.9
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• pp.953-959
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• 2004

BaTiO$_3$ powder has been applied in so much electronic ceramics. Therefore, as recent, the method to add or coat additive will be needed BaTiO$_3$ powder. As a kind of the method, the coating of BaTiO$_3$ powder was considered. In this study, during BaTiO$_3$ powder was coated by BaTiO$_3$ sol, gelation path was experimented. Standard coating condition was set for homogeneous coating. The phase of the gel was deferent by gelation path. It was confirmed the amorphous gel was made in BaTiO$_3$ phase easily at low temperature. In the amorphous gel, particle growth was shown at 900$^{\circ}C$, because crystallization temperature was low. The optimal ratio of sol and powder was at 10 vol% for the homogeneous coating.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.48 no.1
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• pp.27-33
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• 2016

This study was carried out in order to investigate the effect of binder properties in pre-coating layer on the characteristics of top-coating layer and print mottle of coated paper. Four different latices were used as a binder in pre-coating layer, and coating color prepared with a same formulation was applied for top-coating. The properties and print mottle of coated paper were evaluated. It was found that glass transition temperature (Tg) was the important factor to control the properties of pre- and top-coating layer. PPS roughness of coated paper was decreased and paper gloss was increased with applying binder which has lower Tg. Properties of top-coating layer were affected by the binder used in pre-coating layer. Print mottle of coated paper was improved with using binder which has lower Tg in pre-coating layer. These results indicate that final printability and properties of top-coating layer can be improved with using suitable binder in pre-coating layer.

• Particle and aerosol research
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• v.9 no.3
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• pp.163-171
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• 2013

Soot particles emitted from combustion processes are often coated by non-absorbing organic materials, which enhance the global warming effect of soot particles. It is of importance to study the condensation characteristics of soot particles experimentally and theoretically to reduce the uncertainty of the climate impact of soot particles. In this study, the condensational growth of soot particles in a tubular coater was modeled by a one-dimensional (1D) plug flow model and a two-dimensional (2D) laminar flow model. The effects of 2D heat and mass transports on the predicted particle growth were investigated. The temperature and coating material vapor concentration distributions in radial direction, which the 1D model could not accounted for, affected substantially the particle growth in the coater. Under the simulated conditions, the differences between the temperatures and vapor concentrations near the wall and at the tube center were large. The neglect of these variations by the 1D model resulted in a large error in modeling the mass transfer and aerosol dynamics occurring in the coater. The 1D model predicted the average temperature and vapor concentration quite accurately but overestimated the average diameter of the growing particles considerably. At the outermost grid, at which condensation begins earliest due to the lowest temperature and saturation vapor concentration, condensing vapor was exhausted rapidly because of the competition between condensations on the wall and on the particle surface, decreasing the growth rate. At the center of the tube, on the other hand, the growth rate was low due to high temperature and saturation vapor concentration. The effects of Brownian diffusion and thermophoresis were not high enough to transport the coating material vapor quickly from the tube center to the wall. The 1D model based on perfect radial mixing could not take into account this phenomenon, resulting in a much higher growth rate than what the 2D model predicted. The result of this study indicates that contrary to a previous report for a thermodenuder, 2D heat and mass transports must be taken into account to model accurately the condensational particle growth in a coater.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.3
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• pp.219-224
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• 2020

Al₂O₃ powders with particle sizes of 0.35 ㎛, 0.5 ㎛, 1.5 ㎛, and 2.5 ㎛ are deposited onto glass and Cu substrates using the aerosol deposition (AD) process. The deposition characteristics of Al₂O₃ films using those four types of Al₂O₃ powders are investigated to determine the influence of the particle size on the films. To observe detailed micro-structures of the films, the cross-section and surface morphology are observed. Then, the crystalline size and internal strain are calculated from X-ray diffraction peaks in order to confirm the hammering effect as well as the micro-strain during the AD deposition. From the above results, deposition mechanisms related to the particle size are studied. The results of this study indicate the optimal particle size and formation mechanisms for dense Al₂O₃ film with a smooth surface roughness as well as for a porous Al₂O₃ film with a rough surface roughness.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.12
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• pp.1033-1038
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• 2006

We carried out the experiments on particle deposition onto the cleanroom wall panels. And then we investigated the particle deposition characteristic coefficients for electrostatic voltages and particle size. It was found that there is little difference in characteristics of the particle deposition between the steel panel and the anti-static coating panel. In case of that the particle size is under $1.0{\mu}m$, the particle deposition characteristic coefficient becomes larger as the electrostatic voltage induced to the cleanroom wall panel is increasing. Where in case of that the particle size is over $3.0{\mu}m$, the particle deposition characteristic coefficients do not show any differences with the electrostatic voltages. It is due to that the electrostatic force is the major particle transport mechanism for submicron particles, while the gravitational settling is the major particle transport mechanism for overmicron particles when the electro-static voltages are induced to the cleanroom wall panel.

• Journal of Welding and Joining
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• v.15 no.1
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• pp.116-124
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• 1997

A scope of this study is to establish the optimum plasma spray conditions for fine ($5\mu\textrm{m}$) $Al_2O_3$ powder. However, the flowability of the $Al_2O_3$ powder is not so good because of irregular particle shape and fine particle size. Therefore, powder feeding system was modified by 1) change of powder feeding line material from polymer to copper 2) shorten the powder feeding tube length 3) heating the powder feeding system to $80^{\circ}C$4) vibrating the powder feeding line continuously, in order to feed the fine powder homogeneously. The homogeneous powder feeding conditions were obtained with the modified powder feeding system by controlling the powder carrier gas flow and the powder flow rate indicator. The best plasma spraying conditions for the fine $Al_2O_3$ powder were found out as 40kw gun power, 80 g/min. powder feed rate and 50 mm working distance after characterizing the microstructure, hardness and wear loss of the $Al_2O_3$ coating layer.

• Particle and aerosol research
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• v.12 no.3
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• pp.73-80
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• 2016

Bioaerosol inactivation becomes important as people recognize the significance on the health effects of bioaerosols. There are several ways to inactivate such bioaerosols such as antimicrobial filters, UV, etc. For the on-filter-inactivation, proper antimicrobial materials coating should be applied. Recently, air ions are adopted to effectively reduce germ and virus activity. Limitations arise when each method is applied separately. Coating materials can experience chemical instability over time and temperature. Ionizers can generate ozone to prepare high ion concentrations. Combinations of developed techniques to enhance the inactivation efficiency were suggested. Researches on the air sterilization are reviewed and outlook is highlighted. Proper techniques such as combinations of filter material coating and air ion generation can be used to make air quality better for human living.

• Bulletin of the Korean Chemical Society
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• v.29 no.3
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• pp.623-626
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• 2008

Spin-coating electrostatic self-assembly (SCESA) is utilized to fabricate a single layer of carboxylic-acid-coated Pd nanoparticles (NPs) (D??5 nm) on an oppositely charged surface. The packing density of a NP monolayer formed on a rotating solid substrate (3000 rpm) was examined with regards to various parameters, including the particle concentration, the pH, and the ionic strength of the solution. Initially, the packing density grew exponentially with increases in the particle concentration, up to a maximum value (of 8.4 ´ 1011/cm2) at 1.2 wt%. The packing density was also found to increase drastically as the pH decreased and the ionic strength of the solution increased; these trends can be attributed to a reduction in the interparticle repulsions among the NPs in the solution and on the substrate. The best result of this study was achieved in a 1.2 wt% solution at pH 8; under these conditions, an NP monolayer with the highest density (namely, 1.6 ´ 1012/cm2) was obtained.

• Journal of the Korean Ceramic Society
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• v.50 no.6
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• pp.460-465
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• 2013

Plate-shaped inorganic particles are coated onto a stainless steel substrate by the electrophoretic deposition of a precursor slurry which includes the inorganic particles of $Al_2O_3$ and polymer resin in mixed solvents to mimic the abalone shell structure, which is a composite of plate-shaped inorganic particles and organic interlayer binding materials with a layered orientation. The process parameters of the electrophoretic deposition include the voltage, coating time, and conductivity of the substrate. In addition, the suspension parameters are the particle size, concentration, viscosity, conductivity, and stability. We prepared an organic-inorganic composite coating with a high inorganic solid content by arraying the plate-shaped $Al_2O_3$ particles and electrophoretic resin via an electrophoretic deposition method. We analyzed the effect of the slurry composition and the electrophoretic deposition process parameters on the physical, mechanical and thermal properties of the coating layer, i.e., the thickness, density, particle orientation, Young's modulus and thermogravimetric analysis results.