• 한국표면공학회지
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• 제53권2호
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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.

• 한국표면공학회지
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• 제32권1호
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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.

• 한국전기전자재료학회논문지
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• 제15권10호
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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.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2018년도 춘계학술대회 논문집
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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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• 한국정보디스플레이학회 2000년도 제1회 학술대회 논문집
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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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• 제22권1호
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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.

• 한국표면공학회지
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• 제31권5호
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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.

• 정보저장시스템학회논문집
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• 제9권1호
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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 $827Fg^{-1}$.

• 한국진공학회지
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• 제7권1호
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• pp.59-65
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• 1998

13.56MHz를 사용하는 r.f.PACVD(Plasma assisted chemical vapor deposition)방법 으로 다층 다이아몬드상 카본(DLC)필름을 Si wafer기판 위에 합성하였다. 다층 DLC필름은 2.5$\mu$m두께의 순수한 DLC필름과 0.2$\mu$m두께의 Si이 함유된 Si-DLC필름으로 구성되었으 며, ball on disk type의 tribometer를 이용하여 대기 중에서 다층 DLC필름의 마모거동을 고 찰하였다. 표면층으로 합성된 Si-DLC필름내의 Si함량이 증가함에 따라 다층 DLC필름과 AISI52100 steel ball 사이에 0.1 이하의 낮은 마찰계수를 유지하는 기간이 증가하였다. 44,000cycle과 158,400cycle의 마모실험 후 측정된 다층 DLC필름의 마모율은 각각 $2.5\times10^{-8}\sim1.8\times10^{-7}\textrm{mm}^3$/rev.과 $7.1\times10^{-9}\sim1.8\times10^{-8}\textrm{mm}^3$/rev.로 나타났다. 158,400cycle의 마모실험 후 측정된 마모율은 내마모 특성이 우수한 DLC필름보다도 2배 정도 우수한 것으로 나타났 다. 마모시험에 의해 형성된 debris의 조성을 분석한 결과, 이런 낮은 마찰계수와 우수한 내 마모 특성은 steel ball의 wear 표면을 덮고 있는 Si oxide debris층의 형성에 따른 결과로 판단되었다. 또한, 이러한 steel ball의 wear scar표면에 형성된 debris층을 제거하여도, 새로 운 Si oxide debris층이 wear scar표면에 다시 생성되어 낮은 마찰계수를 유지하고 있었다.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2001년도 춘계학술발표회 초록집
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• pp.50-50
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• 2001