• 정보저장시스템학회논문집
• /
• 제3권3호
• /
• pp.118-122
• /
• 2007

Phase-change wet-etching technology using GeSbTe phase-change films is developed. Selective etching between an amorphous and a crystalline phase can be carried out with an alkaline etchant of NaOH. Etching selectivity is dependent not only on the concentration of the alkaline etchant but also on the film structure. Specifically, metal films for heat control cause marked effects on the etching properties of GeSbTe film. Surviving amorphous pits can be obtained with Al metal layer, however etched amorphous pits are seen with Ag metal layer. An opposite selective etching behavior can be observed between samples with two different metal layers.

• Corrosion Science and Technology
• /
• 제10권1호
• /
• pp.37-42
• /
• 2011

Aluminum was electrochemically etched in acid solution and the surface area was magnified by the formation of etch pits. Etched aluminum was covered with a compact and dense dielectric oxide film by anodization and applied to the aluminum electrolytic capacitor electrode. Capacitance of aluminum electrolytic capacitor is closely related with surface area, which depends on size and number of etch pits. Size of etch pits need to be controlled because inside of the pits can be buried by the formation of dielectric oxide film. In this work, the effect of ultrasound pretreatment on the aluminum etch pit formation and capacitance were investigated. Additionally, the relationship between the second etching effect on pit size and capacitance was studied.

• 한국표면공학회지
• /
• 제30권1호
• /
• pp.44-56
• /
• 1997

Influence of electrochemical etching conditions on capacitance gain of aluminium electrolytic on capacitor foil has been investigated by etching cubic textured high purity aluminum foil in dilute hydrochloric acid. Uniformly distributed etch pit tunnels on aluminum surface have been obtained by pretreatment aluminium foil in 10% NaOH solution for 5 minutes followed by electrochemical etching. Electrostatic capacitance of etched aluminium foil anodized to high voltage increased with the increase of current density, total charge, temperature and concentration of electrolyte up to maximum CV-value and then deceased. Election optical observation of the etched foil revealed that the density of etch of etch pits increased with the increase of current density and concentration of electrolyte. this increase of etch pit density enlarged of the increase of capacitance. However, abnormal high current density and high electrolyte concentration induced the local dissolution of the foil surface which resulted the decrease of foil capacitance.

• 공업화학
• /
• 제25권1호
• /
• pp.53-57
• /
• 2014

본 연구에서는 micro-contact printing을 통하여 니오븀 호일 표면 위에 균일한 에칭 pits를 형성하였다. 균일한 보호층을 형성하고자 전해연마의 효과를 확인하였으며, 기존의 $O_2$ 플라즈마 공정 없이 손쉽게 균일한 에칭 pits를 형성시킬 수 있는 조건을 확인하였다. 메탄올 혼합 전해질을 사용하여 10 min 동안 에칭을 진행한 결과 니오븀 호일 표면 위에 지름과 간격이 각각 $10{\mu}m$와 $5{\mu}m$로 잘 정렬된 에칭 pits를 관찰하였다.

• 한국세라믹학회지
• /
• 제41권7호
• /
• pp.493-496
• /
• 2004

The chemical etching of sapphire substrates was peformed to produce smooth surfaces on an atomic scale. The sapphire sur-face etched by using a $H_2$S $O_4$ solution showed a pit-free morphology and was yen smooth as much as $\sigma$$_{rms}$=0.13 nm, that etched by using a mixture of $H_2$S $O_4$ and $H_3$P $O_4$ contained large pits with $\sigma$$_{rms}$=0.34 nm. The $\sigma$$_{rms}$’s and the number of the pits increased with increasing etching temperature. The sapphire etched by using $H_2$S $O_4$ at 32$0^{\circ}C$ had the best surface. These results provide important information on the effects of etching treatment on the structural properties of sapphire for the growth of high-quality epilayers.ayers.

• 한국주조공학회지
• /
• 제25권3호
• /
• pp.134-141
• /
• 2005

To overcome the undesirable deformation, peeling off and geometrical restrictions which were mainly caused by differences in thermal expansion coefficients during the cladding of aluminum strip and stainless strip, new processing method based on vacuum die casting is designed and implemented in fabricating Al/Fe-17wt%Cr steel(stainless steel). To increase cast-bonding ability, the surface of Fe-17wt%Cr steel is electrochemically etched to have optimum pit size and density. The optimum conditions to generate best pit are as follows: Solution: 1 M $Fecl_{3}$+1 M Nacl, Addition: $CuCl_{2}+HCl$, Current density: 80 $mA/cm^{2}$, Total current: 400 $coulomb/cm^{2}$, AC frequency :60 Hz.

• 한국전기전자재료학회논문지
• /
• 제19권4호
• /
• pp.344-349
• /
• 2006

A sublimation epitaxial method, referred to as the Closed Space Technique (CST) was adopted to produce thick SiC epitaxial layers for power device applications. We aimed to systematically investigate the dependence of SiC epilayer quality and growth rate during the sublimation growth using the CST method on various process parameters such as the growth temperature and working pressure. The etched surface of a SiC epitaxial layer grown with low growth rate $(30{\mu}m/h)$ exhibited low etch pit density (EPD) of ${\sim}2000/cm^2$ and a low micropipe density (MPD) of $2/cm^2$. The etched surface of a SiC epitaxial layer grown with high growth rate (above $100{\mu}m/h$) contained a high EPD of ${\sim}3500/cm^2$ and a high MPD of ${\sim}500/cm^2$, which indicates that high growth rate aids the formation of dislocations and micropipes in the epitaxial layer. We also investigated the Schottky barrier diode (SBD) characteristics including a carrier density and depletion layer for Ni/SiC structure and finally proposed a MESFET device fabricated by using selective epilayer process.

• 대한소아치과학회지
• /
• 제30권2호
• /
• pp.238-244
• /
• 2003

본 연구는 치면열구전색재의 충전량이 미세누출에 미치는 영향을 비교분석할 목적으로 실시되었다. 6개의 군으로 나누어 각각 다른 충전량, 치면 전처리, 충전재를 적용하여 미세누출 양상을 비교하였다. 60개의 제 3대구치를 3개의 군으로 나누어 각 군당 20개씩 시편을 구성하였다. 각 치아는 교합면을 두 부분으로 나누어 한 부위는 충전재의 폭이 1mm이하가 되도록 충전하고(1, 3, 5군), 나머지 한 부위는 2mm이상 되도록 충전을 하였다(2, 4, 6군). 1, 2군은 산처리후 Helioseal F로 치면열구전색을 실시하였고, 3, 4군은 산처리후 상아질 접착제로 치면 전처리한 후 Helioseal F로, 5, 6군은 유동성 복합레진인 Tetric Flow로 치면 열구전색을 실시하였다. 500회의 열순환 및 색소침투 후, 미세누출도를 관찰하고 비교분석하여 다음과 같은 결론을 얻었다. 1. 동일한 충전폭을 적용하였을 경우, 미세누출도는 5군<3군<1군과 6군<4군<2군의 순으로 나타났으나 유의한 차이는 아니었다(p>0.05). 2. 동일한 재료와 치면처리를 하되, 충전폭만을 달리한 군들, 즉 1군과 크군, 3군과 4군, 5군과 6군간의 미세누출도에서는 유의한 차이를 보였다(p<0.05). 3. 미세누출은 전색재의 물성, 상아질 접착제 전처리 여부 보다 전색재의 충전량에 더 많은 영향을 받았다.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2005년도 추계학술대회 논문집 Vol.18
• /
• pp.338-339
• /
• 2005

The wider surface of the aluminum foil, electrochemically very important and it is necessary to increase the surface area. A study has been made of the fabrication condition for etching cube texture of high purity aluminium foil and of electrochemical etching of the aluminium foil. In the present work, it is shown there exists a relation between the influence of the pre-treatment time in the NaOH & HCI solution and $H_2SO_4$ concentration in the conversion solution. Also effect of temperature during AC etching was also studied. Result of the etched aluminum film is shown in the typical SEM images. Its electrochemical characteristics were investigated by cyclic voltammetry. And effects of current density and frequency is also reported. Cyclic voltammogram showed that the protective oxide film was formedon the inner surfaces of etch pit. the frequency influence resistance of oxide film in AC etching.

• 한국주조공학회지
• /
• 제19권5호
• /
• pp.410-418
• /
• 1999

To overcome the undesirable deformation, peeling off and geometrical restrictions which were mainly caused by differences in thermal expansion coefficients during the cladding of aluminum strip and stainless strip, new processing method based on vacuum die casting is designed and implemented in fabricating Fe-17wt%Cr steel (stainless steel). To increase cast-bonding ability, the surface of Fe-17wt%Cr steel is electrochemical etched to have optimum pit size (above 0.2 mm) and pit density (above 30%). The implementation of vacuum die casting by using surface treated stainless steel (Fe-17wt%Cr Steel) produces good trial products having acceptable cast-bonding ability. The enabling conditions for cast-bonding are pouring temperature $690^{\circ}C$, filling speed 30 m/sec and casting pressure $800\;kg/cm^2$. The microscopic observation of cast-bonded Al/Fe-17wt%Cr steel does not show any evidence of intermetallic compounds. The bonding strength of trial products is $150-400\;kg/cm^2$ and this is stronger than conventionally cladded metal having $30-70\;kg/cm^2$.