• Applied Chemistry for Engineering
• /
• v.25 no.2
• /
• pp.174-180
• /
• 2014

A plasma hydrophobic coating on commercial fish feed was conducted to prolong the floating time of feed, thereby enhancing the feed consumption rate and reducing the contamination of water in fish farms. The hydrophobic coating on the fish feed was prepared using an atmospheric-pressure dielectric barrier discharge (DBD) plasma with hexamethyldisiloxane (HMDSO), toluene and n-hexane as the precursors. The effect of the parameters such as input power, precursor type and coating time on the coating performance were examined. The physicochemical properties of the coating layer were analyzed using a Fourier transform infrared (FTIR) spectrometer and a contact angle (CA) analyzer. The water CA increased after the coating preparation, indicating that the surface changed from hydrophilic to hydrophobic. The FTIR characterization revealed that the hydrophobic layer was comprised of functional groups such as $CH_3$, Si-O-Si and Si-C. As a result of the hydrophobic coating, the floating time of the fish feed increased from several seconds to 3 minutes, which suggested that the plasma coating method could be a viable means for practical applications. Compared to the water CA measured as soon as the coating layer was prepared, the 6-day aged sample exhibited a substantial CA increase, confirming the aging effect on the improvement of the hydrophobicity.

• Journal of the Korea Convergence Society
• /
• v.12 no.4
• /
• pp.201-206
• /
• 2021

Damage to the highly pathogenic avian influenza virus(H5N1) continues to increase, but there is a lack of antiviral research. In this study, we analyze antiviral properties on H5N1 by coating Cu/TiO2 photocatalyst on polyethylene films. The specimen was manufactured a photocatalyst master batch and coated both sides of the 3-layer polyethylene fabric at 280℃ from the extrusion coating machine. The results showed a 99.9% decrease in the Staphylococcus aureus and Escherichia coli. In particular, H5N1 type highly pathogenic avian influenza viruses, which is capable of human infection, has been found to decrease 99.9% within five minutes of contact with Cu/TiO2 films. Antibacterial effects of films coated with photocatalyst are known, but this study also confirmed the antiviral effects.

• Journal of Surface Science and Engineering
• /
• v.49 no.1
• /
• pp.1-13
• /
• 2016

This review deals with one of the surface modification techniques, chemical conversion coating and particularly cerium-based conversion coatings (CeCC) as a promising substitute for chromium and phosphate conversion coating on magnesium and its alloys. The CeCCs are commonly considered environmentally friendly. The effects of surface preparation, coating thickness, bath composition, and e-paint on the corrosion behavior of CeCCs have been studied on the AZ31 magnesium alloy. This review also correlates the coating microstructural, morphological, and chemical characteristics with the processing parameters and corrosion protection. Results showed that the as-deposited coating system consists of a three layer structure (1) a nanocrystalline MgO transition layer in contact with the Mg substrate, (2) a nanocrystalline CeCC layer, and (3) an outer amorphous CeCC layer. The nanocrystalline CeCC layer thickness is a function of immersion time and cerium salt used. The overall corrosion protection was crucially dependent on the presence of coating defects. The corrosion resistance of AZ31 magnesium alloy was better for thinner CeCCs, which can be explained by the presence of fewer and smaller cracks. On the other hand, maximum corrosion protection was achieved when AZ31 magnesium samples with thin CeCCs are e-painted. The e-paint layer further restricts and hinders the movement of chloride and other aggressive ions present in the environment from reaching the magnesium surface.

• Journal of Surface Science and Engineering
• /
• v.50 no.6
• /
• pp.465-472
• /
• 2017

The ingot fabrication conditions related with the thermal shock bearing phase and microstructure have investigated for the rare earth zirconate ceramic material, lanthanum gadolinium zirconate, as a thermal barrier coating using electron beam evaporation method. The thermal shock resistance of the prepared ingot was evaluated by high energy electron beam irradiation. The rare earth zirconate ceramic powder was prepared by controlling the raw material powder composition of $La_2O_3$, $Gd_2O_3$ and $ZrO_2$ so as to have a composition of $(La_{0.3}Gd_{0.7})_2Zr_2O_7$ which was selected from the former study. Ingot samples were prepared under two conditions. The first condition is prepared by sintering the prepared powder mixture to form an ingot. The second condition is prepared by calcining the prepared powder mixture to form a composite phase and then sintering to form an ingot. X-ray diffraction(XRD) and Scanning Electron Microscope(SEM) were used to analyze phase forming behavior and microstructure of ingot samples. Nanoindentation method used to obtain elastic modulus and hardness of each ingot specimen. Also the stress distribution of ingot was simulated by using FEM method assuming the ingot surface was exposed to electron beam. As a results, in the case of an ingot having a network-shaped microstructure in which relatively coarse pores are included, it seems that the thermal shock resistance was higher than in the case of an ingot having a microstructure composed of relatively fine grains only or particles with the similar level size when the high energy electron beam irradiation.

• Journal of the Korea Organic Resources Recycling Association
• /
• v.32 no.1
• /
• pp.49-59
• /
• 2024

Biodegradable coating urea plays an important role in reducing the non-pollutants in agroecosystems, maximizing the plant nutrient utilization efficiency and slow-releasing nitrogen. Herein, the objective of this study was to investigate the nitrogen-releasing patterns and greenhouse gas emissions on different biodegradable coating urea. The treatments consisted of the control as an application of chemical fertilizers, NBCF as the non-biodegradable coating urea, NB60, and MDS as biodegradable coating urea. As a result of this study, the maximum accumulated total nitrogen (TN) concentration in the NBCF was higher at 33% than one in the NB60 during the precipitation periods. Its leaching period in the NCBF was prolonged for day 10 compared to the NB60. TN and NO₃-N releasing patterns in the NBCF and NB60 were fitted well on linear types(R²≥0.991), but their control and MDS were fitted well on Sigmoid curves(R²≥0.994) with high releasing concentration in the MDS compared to the control during leaching periods. For the greenhouse gas emissions, CH₄ emissions in the NBCF, NB60, and MDS were increased at 0.38%, 11.36%, and 5.91%, and N₂O emissions were also increased at 50.5%, 32.4%, 58.8% as compared to the control, respectively. Therefore, application of biodegradable polymer coating urea might mitigate the non-point pollutants in agro-ecosystem.

• The Journal of Advanced Prosthodontics
• /
• v.1 no.1
• /
• pp.47-55
• /
• 2009

STATEMENT OF PROBLEM. A few of studies which compared and continuously measured the stability of various surface treated implants in the same individual had been performed. PURPOSE. We aim to find the clinical significance of surface treatments by observing the differences in the stabilization stages of implant stability. MATERIAL AND METHODS. Eight different surface topographies of dental implants were especially designed for the present study. Machined surface implants were used as a control group. 4 nano-treated surface implants(20 nm $TiO_2$ coating surface, heat-treated 80 nm $TiO_2$ coating surface, CaP coating surface, heat treated CaP coating surface) and 3 micro-treated surface implants [resorbable blast media(RBM) surface, sandblast and acid-etched(SAE) surface, anodized RBM surface] were used as experiment groups. All 24 implants were placed in 3 adult dogs. $Periotest^{(R)}$ & ISQ values measured for 8 weeks and all animals were sacrificed at 8 weeks after surgery. Then the histological analyses were done. RESULTS. In PTV, all implants were stabilized except 1 failed implants. In ISQ values, The lowest stability was observed at different times for each individual. The ISQ values were showed increased tendency after 5 weeks in every groups. After 4 to 5 weeks, the values were stabilized. There was no statistical correlation between the ISQ values and PTV. In the histological findings, the bone formation was observed to be adequate in general and no differences among the 8 surface treated implants. CONCLUSIONS. In this study, the difference in the stability of the implants was determined not by the differences in the surface treatment but by the individual specificity.

• Bulletin of the Korean Chemical Society
• /
• v.31 no.12
• /
• pp.3723-3729
• /
• 2010

We investigated the high-excitation voltage cathodoluminescence (CL) performance of blue light-emitting (ZnS:Ag,Al,Cl) and green light-emitting (ZnS:Cu,Al) phosphors coated with metal oxides ($SiO_2$, $Al_2O_3$, and MgO). Hydrolysis of the metal oxide precursors tetraethoxysilane, aluminum isopropoxide, and magnesium nitrate, with subsequent heat annealing at $400^{\circ}C$, produced $SiO_2$ nanoparticles, an $Al_2O_3$ thin film, and MgO scale-type film, respectively, on the surface of the phosphors. Effects of the phosphor surface coatings on CL intensities and aging behavior of the phosphors were assessed using an accelerating voltage of 12 kV. The MgO thick film coverage exhibited less reduction in initial CL intensity and was most effective in improving aging degradation. Phosphors treated with a low concentration of magnesium nitrate maintained their initial CL intensities without aging degradation for 2000 s. In contrast, the $SiO_2$ and the $Al_2O_3$ coverages were ineffective in improving aging degradation.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2009.10a
• /
• pp.995-997
• /
• 2009

$In_2O_3$ thin-film transistors (TFTs) were fabricated on various dielectrics [$SiO_2$ and self-assembled nanodielectrics (SANDs)] by spin-coating a $In_2O_3$ film precursor solution consisting of methoxyethanol (solvent), ethanolamine (EAA, base), and $InCl_3$ as the $In^{3+}$ source. Importantly, an optimized film microstructure characterized by the high-mobility $In_2O_3$ 004 phase, is obtained only within a well-defined base: $In^{3+}$ molar ratio. The greatest electron mobilities of ~ 44 $cm^2$, for EAA:$In^{3+}$ molar ratio = 10, $V^{-1}s^{-1}$, is measured for $n^+$-Si/SAND/$In_2O_3$/Au devices. This result combined with the high $I_{on}:I_{off}$ ratios of ~ $10^6$ and very low operating voltages (< 5 V) is encouraging for high-speed applications.

• Proceedings of the IEEK Conference
• /
• 1998.10a
• /
• pp.605-608
• /
• 1998

In this paper, we have investigated the pyroelectric characteristics of the $20\mu\textrm{m}-thick$ $LiTaO_3$ single crystal with black coating by using the nondestructive dynamic method. The $LiTaO_3shows$ the maximum pyroelectric coefficient (${\gamma}$) of $1.56$\times$10-8C/\textrm{cm}^2K$ at 40Hz and the responsivity (Rv) is 488V/W at 2Hz. The noise equivalent power (NEP) is obtained as 3.95$\times$10-10W/√Hz at 40Hz. The detectivity (D*) is obtained divided by the sample area and estimated to be 5.6$\times$108cm√Hz/W at 40Hz. These results, shows that the $LiTaO_3$ single crystals are the best candidates to pyroelectric IR sensors.

• Korean Chemical Engineering Research
• /
• v.47 no.2
• /
• pp.150-156
• /
• 2009

Plasma Display Panels(PDPs) require to have improved luminous efficiency, low manufacturing cost, and high image quality to compete with other flat display devices such as Liquid Crystal Displays(LCDs) and organic light-emitting diodes(OLEDs). In addition, the diversity of product line-up may be needed for high market share. In this paper, the optical characteristics of typical green phosphor for PDP application are reviewed and the problem-based solution will be proposed. We also shortly describe the principle of 3D-PDPs which are promising. Then, the requirement of green phosphor for 3D-PDP application is summarized and research achievement, as of now, is described. The typical problems of $Zn_2SiO_4:Mn$ phosphor, which is the most well-known, are the negatively charged surface property and the long decay time, which leads to unstable discharge in green cell and afterimage. These problems were solved by coating the phosphor surface with metallic oxide. It was found that $Al_2O_3$ would be the best material for $Zn_2SiO_4:Mn$ phosphor. It gives longevity as well as low operating voltage due to the charging effect in green cells. Also, new phosphors, $(Y,\;Gd)Al_3(BO_3)_4:Tb$ and $(Mg,\;Zn)Al_2O_4:Mn$ phosphor are proposed for increasing the luminance and reducing the decay time, which are capable to apply for 3D-PDP application.