• Journal of Surface Science and Engineering
• /
• v.41 no.4
• /
• pp.169-173
• /
• 2008

The objective of this study is to coat the $SiO_2$ layer uniformly on the ZnS:Cu phosphors by using Sol-Gel method. From results of SEM micrographs observation, XRD and XPS analysis, it could be confirmed that $SiO_2$ layer was relatively well coated on ZnS:Cu particles. $Ag_2S$ was used as a decoding chemical to analyze the dense and uniform coating performance of $SiO_2$ layer on phosphor particles. It could be concluded that phosphors synthesized from our two step replacement method showed strong blue peak comparing to other method and rather weak green peak also. Obtained particle size of phosphors were about 20m diameter. Luminescence properties of the phosphors were examined by photoluminescence spectra at the excitation wavelength of 270 nm.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2002.07a
• /
• pp.133-155
• /
• 2002

1. Quasicrystalline powders shows exotic physical and mechanical p properties 2. Applications: structural application: strengthening particles for composites C Coating application: wear resistance, low friction coefficient 3. For thermal spaying: material loss during process should be c considered to control chemical composition of deposit 4. Friction coefficient is strongly dependent on contact geometry F Friction coefficient from pin on plate: 0.1-0.2 Friction coe야icient from flat on plate: about 0.46. 5. Quasicrystalline materials show lower friction coefficient but higher w wear rate than corresponding values of $Cr_20_3$ coated layer. 6. Amorphous coating seems to be promising

• Journal of Korean Vacuum Science & Technology
• /
• v.3 no.1
• /
• pp.74-78
• /
• 1999

For a high efficient field emission display (FED), the specific vacuum conditions below 10-7 Torr should be required. However, because the FED has the geometrical restriction due to its micro size, the thin film getters can be proposed for chemical pumping as a way to reduce impurity gases in the panel. The thin film getters, developed by employing the coating of new materials such as NI or Pt on getter surface, can be used without any activation process and show the enhanced sorption characteristics. Especially, using the Zr (1${\mu}{\textrm}{m}$) thin film getters with the Pt surface layer, the significant gettering for various active gases could be achieved from 9$\times$10-5 Torr to 1$\times$10-6 Torr or below. this good sorption properties is mainly contributed to the surface coating layer which shows the catalytic effect for gas dissociation and protects the getter materials against oxidation.

• Journal of the Korean Society for Precision Engineering
• /
• v.16 no.5 s.98
• /
• pp.145-150
• /
• 1999

We have studied on the tribological characteristics of surface modification by Arc Ion Implantation(AIP) coating method. Coating materials were deposited by the Titanium carbide(TiC) and Titanium nitride(TiN). An experimental process was established to determine the tribological characteristics of friction and wear behaviour with the variation of applied load, temperature and the time by the Falex friction and wear test machine. The results, It can be improved that when the surface modification of hard coatings(TiC, TiN) was deposited steel, the tribological characteristics become better. It is argued that improved because of excellence of the anti-wear, the extreme pressure properties and the heat stability.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
• /
• 2001.11a
• /
• pp.322-330
• /
• 2001

The plasma-sprayed 8％Y$_2$O$_3$-Zirconia coating was studied to know the relationship between phase transformation and wear properties after several heat treatment. Wear tests were carried out with ball on disk on 50N, 70N, 90N. The specimen in this study was cast iron and tests were performed on room temperature. The transformation of phase and residual stress was measured by x-ray diffraction method(XRD) and worn surface were observed by SEM.

• Korean Journal of Materials Research
• /
• v.13 no.9
• /
• pp.625-630
• /
• 2003

Increasing environmental concerns require to solve the problem produced due to the use of heavy metals in coating formulations. Therefore, it is necessary to develop new coating strategy employing inherently conducting polymers such as Polyaniline(PANI). Polyaniline films were electrosynthesized by oxidation of aniline on cold rolled and weathering sheets using the potentiostatic mode from an aqueous oxalic acid medium. Potentiodynamic polarization curves were obtained for cold rolled and weathering sheets in the aqueous solution of 3% sodium chloride. The structure and properties of polyaniline film were elucidated using SEM, DSC, SST. A high corrosion resistance of polyaniline films were observed with a gain of the corrosion potential around 600-900 mV positive in the substrate covered with polyaniline than in the case without it.

• Journal of the Korean Society for Heat Treatment
• /
• v.5 no.1
• /
• pp.1-12
• /
• 1992

In order to improve adhesive force of TiN film, we sputtered titanium as interlayer before TiN deposition by Plasma Enhanced Chemical Vapour Deposition. We observed changes of hardness and adhesion at a various thickness of titanium interlayer and also examined analysis. At the critical thickness of the titanium interlayer(about $0.2{\mu}$), adhesive force of TiN films were promoted mostly. But over the critical thickness, a marked reduction of adhesive force was showed, because of the internal stress of titanium interlayer. From AES analysis, the adhesion improvement of TiN films was mainly caused by nitrogen diffusion into titanium interlayer during TiN deposition process which relieved stress concentration at TiN coating-substrate interface.

• Journal of Surface Science and Engineering
• /
• v.48 no.4
• /
• pp.169-173
• /
• 2015

$CuInSe_2$ thin films which have been widely used for thin solar cells as a light absorber were prepared by hydrazine solution processing, and their microstructural properties were investigated. Hydrazine $CuInSe_2$ precursor solutions were prepared by dissolving $Cu_2S$, S, $In_2Se_3$ and Se powder in hydrazine solvent. Multilayer $CuInSe_2$ chalcopyrite phase thin films were prepared by repeating spin-coating process using the precursor solution. Unfortunately, the presence of the interfaces between each $CuInSe_2$ layer formed by multi-layer coating impeded grain growth across the interface. Here, by doing simple interface engineering to solve the limited grain growth issue, the large grained (${\sim}1{\mu}m$) $CuInSe_2$ thin films were obtained.

• Journal of Surface Science and Engineering
• /
• v.27 no.3
• /
• pp.134-142
• /
• 1994

$Al_2O_3$coatings on mild steel substrate by plasma spray process were produced to evaluate microstructural characterization and mechanical properties. As-coated $Al_2O_3$coating samplessd were subjected to two heat treat-ment conditions : ⅰ) annealing under vacuum circumstance, ⅱ) hot press treated condition. The two heat treat-ed coatings were investigated in terms of microhardness, adhesion strength, wear resistance, porosity forma-tion, and microstructures. In the case of the coatings which were subject to preparation step ⅰ, the porosity in the coating was decreased with the increase of temperature ($700^{\circ}C$-$1100^{\circ}C$), and the wear resistance, microhardnesss and adhesion strength were increased with the increase of temperature. On the other hand, in the case of the coatings which were subject to preparation step ⅱ, wear resistance and adhesion strength were improved with the increase of temperature and pressure. Experimental measurements of coatings which were produced by both preparation conditions were enhanced compare to those of as-coated coatings.

• Fibers and Polymers
• /
• v.7 no.2
• /
• pp.105-111
• /
• 2006

Coating the fibre surface by in situ oxidative chemical polymerisation of polypyrrole (using $FeCl_3$ as oxidant) is a readily industrial applicable way to give electrical properties to wool with good ageing stability [1], although pre-treatments are required to avoid damage of the cuticle surface due to the acidic condition of the process. FT-IR and EDX analysis reveal that organic sulphonates and sulphates, used as dopants, are absorbed by wool, while chlorine ions are preferably embedded on the polypyrrole layer. The resulting electrical conductivity seems mainly due to the presence of chlorine as counter-ion of polypyrrole; nevertheless, the presence of arylsulphonate in the polymerisation bath increases the electrical conductivity of the coating layer.