• 한국재료학회지
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• 제17권5호
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• pp.244-249
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• 2007

The properties of anodized films on aluminum 6061 alloy in single electrolyte of sulfuric acid and mixed electrolyte of sulfuric-boric acid and sulfuric-boric-nitric acid have been studied. Polarization tests in NaC solution were used to investigate the corrosion performance. Characteristics of film formation and surface morphology were examined by optical microscopy, FE-SEM and EDS. The results obtained have indicated that oxide films growth have been promoted by nitric acid and anodized films in mixed electrolyte have superior corrosion resistance. In case of anodic films formed in mixed electrolyte, some grooves and numerous crazings were also observed at the surface.

• 한국전기전자재료학회논문지
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• 제15권1호
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• pp.7-14
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• 2002

In this paper, neutral networks are used to build models of oxide film etched In CHF$_3$/CF$_4$ with a magnetically enhanced reactive ion etcher(MERIE). A statistical 2$\^$4-1/ experimental design plus one center point was used to characterize relationships between process factors and etch responses. The factors that were varied include radio frequence(rf) power, pressure, CHF$_3$ and CF$_4$ flow rates. Resultant 9 experiments were used to train neural networks and trained networks were subsequently tested on its appropriateness using additionally conducted 8 experiments. A total of 17 experiments were thus conducted for this modeling. The etch responses modeled are dc bias voltage, etch rate and etch uniformity A qualitative, good agreement was obtained between predicted and observed behaviors.

• Tribology and Lubricants
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• 제11권4호
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• pp.35-44
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• 1995

Within the practical ranges of speed and load, the formation of transfer films and the consequent effects on the friction and wear behavior of ceramic materials during repeated pass sliding contact were studied. These tests were done using $Al_{2}O_{3}$, SiC and $Si_{3}N_{4}$ with the cylinder-on-flat test configuration. The three pairings behaved differently, even if some wear mechanisms were common to the three systems. The $Al_{2}O_{3}$ pair showed the least wear in overall conditions, followed by the $Si_{3}N_{4}$ pair in harder sliding conditions. The wear of SiC was very high at severe loading. In case of $AL_{2}O_{3}$ and $Si_{3}N_{4}$, the transfer film, whenever formed, is strongly attached, enough to resist being wiped off by the slider. As a consequence, the formation of this f'fim leads to a decrease in the wear rate because of the protecting role of the film. The presence of the film at the contact interface also results in high friction. Also, the wear rate of each ceramics is related to the frictional power provided by load, speed and friction.

• 한국표면공학회지
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• 제47권5호
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• pp.252-256
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• 2014

The TiAlCrSiN film was deposited on the WC-20%TiC-10%Co carbide, and its oxidation behavior was examined at $700-1000^{\circ}C$. It displayed relatively good oxidation resistance owing to the formation of $TiO_2$, $Al_2O_3$, $Cr_2O_3$, and $SiO_2$ up to $900^{\circ}C$. However, at $1000^{\circ}C$, the fast oxidation rate and partial oxidation of WC in the substrate led to the formation of the thick, fragile oxide scale.

• Applied Biological Chemistry
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• 제22권2호
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• pp.91-96
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• 1979

합성방부제 대신 몇가지 생약재를 사용하여 간장의 방부효과를 실험하고 아울려 생약재중 방부효과가 인정되는 황백을 첨가한 인공합성배지에서 산막효모 이외 2종의 미생물의 발육상태를 검토한 결과를 요약하면 다음과 같다. 1. 양조간장에 생약재 첨가효과는 대조구에서는 2일후부터 균막이 형성되었으나 황백분말 0.5% 첨가구에서는 8일후, 1.0% 첨가구에서는 12일후에 균막이 형성되었다. 2. 화학간장에 생약재 첨가의효과는 대조구에서는 2일후부터 균막형성이 시작되었으나 황백분말 0.5% 첨가구에서는 6일후에, 1.0% 첨가구에서는 8일후에 균막이 형성되었다. 3. 목향과 장뇌분말의 첨가는 다소 균발육억제 효과가 인정되었으나 기타 생약재는 그 효과를 인정할 수 없었다. 4. 합성배지에 황백(黃栢) extract 첨가효과는 산막효모가 0.5% 첨가배지에서 5일간 발육이 억제되었고 황국균은 3일간, 납두균은 4일간 억제되었다. 5. 15%식염을 함유한 합성배지에서의 황백(黃栢) extract 첨가의 효과는 산막효모, 황국균, 남두균 같이 0.3%첨가로 5일간 균발육이 억제되었다.

• 한국표면공학회지
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• 제52권5호
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• pp.265-274
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• 2019

Formation behavior of PEO (Plasma Electrolytic Oxidation) films on AZ31 Mg alloy was investigated under application of 310 Hz AC as a function of $Na_3PO_4$ concentration from 0.02 M to 0.2 M. Film formation voltage and in-situ observation of arcs generated on the specimen surface were recorded with time, and surface morphologies of the PEO films were investigated using optical microscopy, confocal scanning laser microscopy and scanning electron microscopy. PEO film formation voltage decreased linearly with increasing $Na_3PO_4$ concentration which is attributed to the increase of solution pH. PEO films were grown uniformly over the entire surface in $Na_3PO_4$ solutions between 0.05 M and 0.1 M. However, non-uniform PEO films with white spots were formed in $Na_3PO_4$ solutions containing more than 0.1 M. Thickness and roughness of PEO films on AZ31 Mg alloy increased linearly with increasing $Na_3PO_4$ concentration and their increasing rates appeared to be much higher under 1 M than above 1 M. The experimental results suggest that phosphate ions can contribute to the formation of PEO films but higher $Na_3PO_4$ concentration more than 1 M results in local damages of PEO films due to repeated generation of white arcs at the same surface site of AZ31 Mg alloy.

• 산업기술연구
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• 제22권B호
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• pp.13-20
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• 2002

The purpose of this study is to investigate the effect of acid fog on the rust formation behavior of weathering steel (SMA50) which is used in uncoated bridges. Weathering steel didn't form the passive film under the environment of acid fog(pH5,6), whereas the environment of distilled water formed the protective oxide film. Therefore, the construction of weathering steel under the environment extremely exposed to SOx and NOx which are the main compositions of acid fog is not adequate. Fatigue limits of weathering steel under acid fog environment are remarkably decreased as compared with environment of distilled water. The corrosive constituents in acid fog has piled up the corrosion products on specimen surface and generated the corrosion pits. Because of the high stress concentration arising at this corrosion pit, relatively low fatigue limits were obtained for acid fog specimens.

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

• 전자공학회논문지A
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• 제28A권1호
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• pp.85-90
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• 1991

MoSi$_2$ was formed by RTA (Rapid Thermal Annealing at 600-1200$^{\circ}C$) under Ar ambient from the Mo-Si mixture film which was deposited on single and poly-Si substrates. The MoSi$_2$ film was investigated by SEM, X-ray diffractometer, four-points probe and AES profile. It was found that the resistivity, the surface roughness, and the formation temperature of MoSi$_2$ were independent on the type of Si substrates. The formation of MoSi$_2$ started from 800$^{\circ}C$ and the phse transformation was completed at 1000$^{\circ}C$. The stable MoSi$_2$ with the resistivity of 74${\mu}{\Omega}$-cm was formed at 1200$^{\circ}C$.

• 대한기계학회논문집A
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• 제32권1호
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• pp.13-20
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• 2008

The purpose of this study is to investigate the effect of acid fog on the rust formation behavior of weathering steel (SMA50) which is used in un-coated bridges. Weathering steel didn't form the passive film under the environment of acid fog(pH5,6), whereas the environment of distilled water formed the protective oxide film. Therefore, the construction of weathering steel under the environment extremely exposed to SOx and NOx which are the main compositions of acid fog is not adequate. Fatigue limits of weathering steel under acid fog environment are remarkably decreased as compared with environment of distilled water. The corrosive constituents in acid fog has piled up the corrosion products on specimen surface and generated the corrosion pits. Because of the high stress concentration arising at this corrosion pit, relatively low fatigue limits were obtained for acid fog specimens.