• Proceedings of the KWS Conference
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• 2009.11a
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• pp.95-95
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• 2009

Zinc coatings provide the most effective and economical way of protecting steel against corrosion. There are three types of galvanizing lines typically used in production line in galvanizing industries,Galvanize (GI) coating (Zn-0.1-0.3%Al), Galfan coating (Zn-5%Al), Galvalume(GL) coating (45%Zn-Al). In continuous Galvanizing lines, the immersed bath hardware (e.g. bearings, sink, stabilizer, and corrector rolls, and also support roll arms and snout tip) are subjected to corrosion and wear failure. Understanding the reaction of these materials with the molten Zn alloy is becomes scientific and commercial interest. To investigate the reaction with molten Zn alloys, static immersion test performed for 4, 8, 16, and 24 Hr. Two different baths used for the static immersion, which are molten Zn and molten Zn-55%Al. Microstructures characterization of each of the materials and intermetallic layer formed in the reaction zone was performed using optical microscope, SEM and EDS. The thickness of the reaction layer is examined using image analysis to determine the kinetics of the reaction. The phase dominated by two distinct phase which are eutectic carbide and matrix. The morphology of the intermetallic phase formed by molten Zn is discrete phase showing high dissolution of the material, and the intermetallic phase formed by Zn-55wt%Al is continuous. Aluminum reacts readily with the materials compare to Zinc, forming iron aluminide intermetallic layer ($Fe_2Al_5$) at the interface and leaving zinc behind.

• Tribology and Lubricants
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• v.38 no.3
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• pp.101-108
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• 2022

The structure and properties of tetrahedral amorphous carbon (ta-C) coatings depend on the main process parameters and bending angles of the magnetic field filter used in the filtered cathodic vacuum arc (FCVA). During the process, it is possible to effectively control the plasma flux of carbon ions incident on the substrate by controlling the arc discharge current, thereby influencing the mechanical properties of the coating film. Furthermore, we can control the size and amount of large particles mixed during carbon film formation while conforming with the bending angle of the mechanical filter mounted on the FCVA; therefore, it also influences the mechanical properties. In this study, we consider tribological characteristics for filtered bending angles of 45° and 90° as a function of arc discharge currents of 60 and 100 A, respectively. Experiment results indicate that the frictional behavior of the ta-C coating film is independent of the bending angle of the filter. However, its sliding wear behavior significantly changes according to the bending angle of the FCVA filter, unlike the effect of the discharge current. Further, upon changing the bending angle from 45° to 90°, abrasive wear gets accelerated, thereby changing the size and mixing amount of macro particles inside the coating film.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.251-252
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• 2012

Recently, the growing interest in organic microelectronic devices including OLEDs has led to an increasing amount of research into their many potential applications in the area of flexible electronic devices based on plastic substrates. However, these organic devices require a gas barrier coating to prevent the permeation of water and oxygen because organic materials are highly susceptible to water and oxygen. In particular, high efficiency OLEDs require an extremely low Water Vapor Transition Rate (WVTR) of $1{\times}10^{-6}g/m^2$/day. The Key factor in high quality inorganic gas barrier formation for achieving the very low WVTR required ($1{\times}10^{-6}g/m^2$/day) is the suppression of defect sites and gas diffusion pathways between grain boundaries. In this study, we developed an $Al_2O_3$ nano-crystal structure single gas barrier layer using a Neutral Beam Assisted Sputtering (NBAS) process. The NBAS system is based on the conventional RF magnetron sputtering and neutral beam source. The neutral beam source consists of an electron cyclotron Resonance (ECR) plasma source and metal reflector. The Ar+ ions in the ECR plasma are accelerated in the plasma sheath between the plasma and reflector, which are then neutralized by Auger neutralization. The neutral beam energies were possible to estimate indirectly through previous experiments and binary collision model. The accelerating potential is the sum of the plasma potential and reflector bias. In previous experiments, while adjusting the reflector bias, changes in the plasma density and the plasma potential were not observed. The neutral beam energy is controlled by the metal reflector bias. The NBAS process can continuously change crystalline structures from an amorphous phase to nano-crystal phase of various grain sizes within a single inorganic thin film. These NBAS process effects can lead to the formation of a nano-crystal structure barrier layer which effectively limits gas diffusion through the pathways between grain boundaries. Our results verify the nano-crystal structure of the NBAS processed $Al_2O_3$ single gas barrier layer through dielectric constant measurement, break down field measurement, and TEM analysis. Finally, the WVTR of $Al_2O_3$ nano-crystal structure single gas barrier layer was measured to be under $5{\times}10^{-6}g/m^2$/day therefore we can confirm that NBAS processed $Al_2O_3$ nano-crystal structure single gas barrier layer is suitable for OLED application.

• Journal of the Korean Ceramic Society
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• v.40 no.12
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• pp.1202-1207
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• 2003

Using a recently developed Hybric Plasma-Particle Accelerating Impact Deposition (HP-PAID) process, synthesis of nanostructured silicon coatings has been investigated by injecting vapor-phase TEOS (tetraethosysilane, (C$_2$H$\_$5/O)$_4$Si) into an Ar hybrid plasma. The plasma jet with reactants was expanded through nozzle into a deposition chamber, with the pressure dropping from 700 to 10 torr. Ultrafine particles accelerated in the free jet downstream of the nozzle, deposited by an inertial impaction onto a temperature controlled substrate. By using this process, nanostructured amorphous silicon coatings with grain size smaller than 10 nm could be synthesized. These samples were annealed in an Ar and crystallized at 900$^{\circ}C$ for 30 min. TEM analysis showed that the annealed coatings were also composed of nanoparticles smaller than 10 nm, which showed a good consistency that the average grain size of 7 nm was also estimated from a peak shift of 2.39 cm$\^$-1/ and Full Width at Half Maximum (FWHM) 5.92 cm$\^$-1/ of Raman analysis. The noteworthy is that a strong PL peak at 398 nm was also obtained for this sample, which indicates that the deposited coatings also contained 3∼4 nm nanostructured grains.

• Korean Journal of Materials Research
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• v.16 no.4
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• pp.225-230
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• 2006

Nanoimprint lithography (NIL) is a novel method of fabricating nanometer scale patterns. It is a simple process with low cost, high throughput and resolution. NIL creates patterns by mechanical deformation of an imprint resist and physical contact process. The imprint resist is typically a monomer or polymer formulation that is cured by heat or UV light during the imprinting process. Stiction between the resist and the stamp is resulted from this physical contact process. Stiction issue is more important in the stamps including narrow pattern size and wide area. Therefore, the antistiction layer coating is very effective to prevent this problem and ensure successful NIL. In this paper, an antistiction layer was deposited and characterized by PECVD (plasma enhanced chemical vapor deposition) method for metal stamps. Deposition rates of an antistiction layer on Si and Ni substrates were in proportion to deposited time and 3.4 nm/min and 2.5 nm/min, respectively. A 50 nm thick antistiction layer showed 90% relative transmittance at 365 nm wavelength. Contact angle result showed good hydrophobicity over 105 degree. $CF_2$ and $CF_3$ peaks were founded in ATR-FTIR analysis. The thicknesses and the contact angle of a 50 nm thick antistiction film were slightly changed during chemical resistance test using acetone and sulfuric acid. To evaluate the deposited antistiction layer, a 50 nm thick film was coated on a stainless steel stamp made by wet etching process. A PMMA substrate was successfully imprinting without pattern degradations by the stainless steel stamp with an antistiction layer. The test result shows that antistiction layer coating is very effective for NIL.

• Journal of Surface Science and Engineering
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• v.34 no.2
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• pp.105-114
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• 2001

$Al_2$$O_3$ coatings were deposited on M2 high speed steels by the plasma enhanced chemical vapor deposition (PECVD) process, using a gas mixture of AlC1$_3$, $H_2$, $CO_2$ and Ar $Al_2$$O_3$ coatings had interference color and showed amorphous phase. $A1_2$X$A1_3$/($Ti_{0.5}$ /$Al_{0.5}$ )N double layer coatings were produced in the sequence of substrate $NH_3$ plasma pretreatment, ($Ti_{0.5}$$Al_{0.5}$)N depoition process, $Al_2$$O_3$ deposition process. $Al_2$ $O_3$/( $Ti_{0.5}$A $l_{0.5}$)N double layer coatings showed NaCl structure in ( $Ti_{0.5}$A $l_{0.5}$)N layer and amorphous phase in A1$_2$ $O_3$ layer. It was shown that $Al_2$ $O_3$ columns continuously grew onto ( $Ti_{0.5}$A $l_{0.5}$)N columns. ( $Ti_{0.5}$A $l_{0.5}$)N single coating and $Al_2$ $O_3$/( $Ti_{0.5}$A $l_{0.5}$)N double layer coating were oxidized at $700^{\circ}C$, 80$0^{\circ}C$, 90$0^{\circ}C$ for 1hr, 3hr in atmosphere. At 80$0^{\circ}C$, single layer coatings were oxidized, which were examined substrate oxide particle. But $Al_2$ $O_3$/ ( $Ti_{0.5}$A $l_{0.5}$)N double layer coatings maintained the asdeposited state. Therefore, $Al_2$ $O_3$/ ( $Ti_{0.5}$A $l_{0.5}$)N double layer coatings have moreexcellent oxidation resistance than ( $Ti_{0.5}$A $l_{0.5}$)N single layer coatings.X> 0.5/)N single layer coatings.s.

• Archives of Pharmacal Research
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• v.20 no.6
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• pp.555-559
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• 1997

The three different batches of an oral sustained release melatonin (MT) delivery system were prepared by aqueous-based fluid-bed coating of the sugar spheres for the evaluation of in vitro release characteristics and plasma concentration profiles in human subjects. The MT contents in 20% coated sugar spheres of three batches (B1, B2 and B3) were $3.3{\pm}0.08$, $2.4{\pm}0.1$ and $2.5{\pm}0.13$ mg per gram of coated sugar spheres, respectively. The release profiles of three different batches had a very similar fashion. However, the release profiles of three different batches had a very similar fashion. However, the release half-lives $(T_{50%})$ of MT from B1, B2 and B3 was $3.70{\pm}0.2$, $5.2{\pm}0.2$ and $4.9{\pm}0.07h$, respectively. Plasma concentration profiles of sustained release 0.2mg melatonin-loaded sugar spheres containing 10% immediate release melatonin in gelatin capsules (B1 and B2) were then evaluated in human subjects. The in vivo plasma concentration profies of the two batches (B1 and B2) were very similar each other and located between the physiological endogenous ranges. The time to reach the peak concentration $(T_max)$ was more advanced in case of B1 when compared to B2. However, there was no statistically significant difference in the maximum concentration $(C_max)$ and the area under the curve (AUC) between B1 and B2. The AUC of melatonin-loaded sugar spheres containing 10% and 20% immediate release MT in human subjects had a good linearity between dose and AUC, regardless of the fraction of immediate release MT, indicating the first order elimination process of MT within these doses. The current oral sustained release MT delivery system may be utilized to treat circadian rhythm disorders if it is proven to be more clinically useful when compared to immediate release MT.

• Applied Chemistry for Engineering
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• v.32 no.6
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• pp.653-658
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• 2021

Polyvinylidene fluoride (PVDF) is a promising coating material because of its outstanding processability. The PVDF coating, however, has limitations in anti-corrosion application due to its weak hydrophobicity compared to that of other fluoropolymers. In this study, plasma fluorination was performed using carbon tetrafluoride (CF₄) gas to improve anti-corrosion properties of PVDF. The fluorine content and hydrophobicity of PVDF were investigated in different CF₄ flow rates, followed by the determination of anti-corrosion properties. The fluorine content on the surface of the PVDF film increased by up to 46.70%, but the surface free energy was independent of CF₄ flow rate. Meanwhile, the surface roughness of the PDVF film tended to increase by up to 150% and then decrease with increasing CF₄ flow rate. It is considered that the plasma fluorination affects the surface free energy due to the introduction of fluorine functional groups and surface etching. In addition, the degree of corrosion of the PVDF-coated Fe plate was significantly reduced from 49.2% to 19.0% compared to that of the uncoated Fe plate. In particular, the degree of corrosion of the fluorinated PVDF-coated Fe plate was 13.6%, which was 28.4% lower than that of the PVDF-coated Fe plate, showing improved anti-corrosion protection.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.13 no.1
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• pp.36-40
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• 2003

The diamond-like nanocomposite (DLN) thin films were deposited on Si substrates using $CH_4/(C_2H_5O)_4Si/H_2$/Ar gas mixtures as source gases by the plasma enhanced chemical vapor deposition (PECVD). The chemical structure and microstructure of grown films were investigated and their tribological properties were evaluated by a ball-on-plate type tribometer. The deposited DLN films mainly consisted of diamond-like a-C:H and quartz-like a-Si:O networks. The DLN films had a good agreement with tribological coating applications due to their extremely low friction coefficients and low wear rates.

• Korean Journal of Materials Research
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• v.28 no.3
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• pp.135-141
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• 2018

Stainless steel is being used in various industries such as automobile and aerospace for its cheap manufacturing cost and excellent mechanical properties. However, stainless steel failed to stably protect a specimen with a $Cr_2O_3$ protective layer at temperatures above $1000^{\circ}C$. Thus, improving the high temperature flame resistance of the specimen through additional surface coating was needed. In this study, multilayer coatings of YSZ and $Al_2O_3$ were performed on SUS 304 specimens using pack cementation coatings and thermal plasma spray. The multilayer coated specimen showed enhanced thermal properties due to the coated layers. The microstructures and phase stability are discussed together with flame conditions at $1350^{\circ}C$.