• Journal of the Korean institute of surface engineering
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• v.53 no.2
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• pp.53-58
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• 2020

In this study, we developed plasma electrolytic oxidation (PEO) process for aluminum 7075 alloy to improve the corrosion and mechanical properties. The electrolyte consists of potassium hydroxide and sodium silicate. Additionally, sodium stannate was added into the electrolyte to investigate its effect on PEO film formation. Titanium was used as the counter electrode. Plasma generation voltage reduced from 300V to 150 V by adding 4 g/L of sodium stannate. The thin oxide films were observed by SEM(Scanning Electron Microscopy)/EDS (Energy Dispersive Spectroscopy) for quantitative and qualitative analyses. XRD (X-ray diffraction) and XRF (X-ray Fluorescences) analyses were also carried out to identify oxide layer on aluminum 7075 surface. Vicker's hardness test was performed on the PEO-treated aluminum 7075 surface.

• Journal of the Korean institute of surface engineering
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• v.32 no.1
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• pp.43-48
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• 1999

Oxidation behavior of 304 and 316 stainless steels was studied. After solution heat treatment, specimens were polished up to 1$mu \textrm{m}$ using $Al_2O_3$ powder and then subjected to oxidation between $300^{\circ}C$ and 50$0^{\circ}C$ in dry air. TEM and EDS were used for analyzing the components and structure of oxide film. TEM analysis of oxide film revealed that thin amorphous Fe oxide ($Fe_2O_3$) was formed on the top of surface while polycrystalline (Cr, $Fe_2O_3$ was formed below the amorphous Fe oxide layer. The specimens oxidized at $500^{\circ}C$ showed that 316 stainless steel had higher oxidation resistance than 304 stainless steel. These results suggest that Mo component of 316 stainless steel suppresses the formation of Cr carbide which may result in a local Cr depleted area.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.10
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• pp.844-850
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• 2002

Linearly graded profiles on the field area oxide are frequently used in power integrated circuits to reduce the surface electric field when power devices are operated in forward or reverse blocking modes. It is shown here that tapered windows can be made using the difference of etch rates between the bottom and the top layer of TEOS film. Annealed TEOS films are etched at a lower rate than the TEOS film without annealing Process. The fast etching layer results in window walls having slopes in the range of 25$^{\circ}$∼ 80$^{\circ}$ with respect to the wafer surface. Taper etching technique by annealing the TEOS film applies to high voltage LDMOS, which is compatible with CMOS process, due to the minimum changes in both of design rules and thermal budget.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2018.06a
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• pp.142.1-142.1
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• 2018

This research presents a new field effect transistor (FET) by using liquid crystal gate dielectric with remote gate. The fabrication of thin-film transistors (TFTs) was used Indium tin oxide (ITO) for the source, drain, and gate electrodes, and indium gallium zinc oxide (IGZO) for the active semiconductor layer. 5CB liquid crystal was used for the gate dielectric material, and the remote gate and active layer were covered with the liquid crystal. The output and transfer characteristics of the LC-gated TFTs were investigated.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.63-64
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• 2000

The low-temperature Si oxidation kinetics by inductively coupled oxygen plasma has been studied. Linear rate constants had negative values when the oxide growth rate was described by linear-parabolic growth law. The analysis of transverse-optical mode frequencies and etch rates indicated that the density of surface oxide was lower than that of bulk oxide. The oxidation kinetics could be explained qualitatively by assuming a surface layer with larger diffusion coefficient and a bulk layer with smaller diffusion coefficient.

• Journal of Magnetics
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• v.22 no.1
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• pp.100-103
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• 2017

We studied the microstructure and magnetic properties of Fe nanosized powder synthesized by the pulsed wire evaporation method. The x-ray diffraction spectrum confirmed that this powder had a pure ${\alpha}$-Fe phase. Scanning electron microscope and transmission electron microscope measurements indicated that the prepared powder had uniform spherical shape with core-shell structure. The mean powder size was about 35 nm and the thickness of the surface passivation layer was about 5 nm. Energy dispersive X-ray spectroscopy measurement indicated that the surface passivation layer was iron oxide. Magnetic field dependent magnetization measurement at room temperature showed that the maximum magnetization of the prepared powder was 177.1 emu/g at 1 T.

• Journal of the Korean institute of surface engineering
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• v.31 no.5
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• pp.278-285
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• 1998

Alloys of Ti-15Mo-5Zr-3Al(wt%) were oxidized in air between 700 and $900^{\circ}C$. It was found that the oxidation resistance is much better than that of either commercially available pure Ti-6Al-4V(wt%) alloys. The oxide scales were primarily composed of thick Ti-ox-ides which were formed by the inward diffusion of oxygen from the atmosphere. At higher temperatures a thin $\alpha$-$Al_2O_3$ layer was formed on Ti-oxides owing to the outward diffusion of Al from the base alloys. Molybdenum, the noblest metal among the alloy components, was predominantly present behind the oxide-substrate interface. Zirconium, an oxygen active metal, was present at both the oxide layer and the substrate.

• Transactions of the Society of Information Storage Systems
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• v.9 no.1
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• pp.22-27
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• 2013

In this paper we are presenting a architecture of Co ion decorated graphene oxide as an electrode for supercapacitor application. Graphene oxide, which is exfoliated by oxidant from graphite, is the material for solving the problem of mass production and coating on the surface of working electrode. The $Co^{2+}$ ions are coated by using layer by layer(LBL) method on graphene oxide foam. The metal ion decorated graphene oxide shows enhanced capacitance performance when tested as supercapacitor electrode, showing the specific capacitance of $827Fg^{-1}$.

• Journal of the Korean Vacuum Society
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• v.7 no.1
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• pp.59-65
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• 1998

Multi-layer diamond-like carbon (DLC) films were deposited by 13.56 MHz r.f. PACVD method. Multi-layer DLC film was composed of 2.5 $mu extrm{m}$ thick pure DLC filml and 0.2$\mu\textrm{m}$ thick Si incorporated DLC (Si-DLC) film as a surface layer. Tribological behaviors of the multi-layer DLC film were investigated with a ball-on-disk type tribometer in ambient atmosphere using AISI 52100 steel ball. Low friction coefficient (<0.1) period increased with increasing the Si content in the surface Si-DLC film. The wear rate after 44,000 cycles and 158,400 cycles were the $2.5\times10^{-8}\sim1.8\times10^{-7}\textrm{mm}^3$/rev. and $7.1\times10^{-9}\sim1.8\times10^{-8}\textrm{mm}^3$/rev.,respectively. The wear rate of the multi-layer DLC film after 158,400 cycles was about 2 times smaller than that of pure DLC films of 2.7 $\mu\textrm{m}$ thickness. This high wear resistance and low friction coefficient was caused by the formation of Si oxide layer on the wear scar surface, as confirmed by the debris composition analysis. It was further shown that this si oxide debris layer on the wear scar surface is formed again even after removing the debris of the steel ball, which maintain the low friction coefficient between multi-layer DLC films and steel ball.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2001.06a
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• pp.50-50
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• 2001