• Journal of the Korean GEO-environmental Society
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• v.12 no.11
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• pp.51-57
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• 2011

The calcium hydroxide($Ca(OH)_{2}$) which is flowed into the deteriorated tunnel by groundwater is reacted with carbon dioxide($CO_{2}$) and the vehicle's exhaust gas ($SO_{3}$). So its by-products are precipitated at the drainage pipe and these cause the drainage clogging. Most by-products are composed of $CaCO_{3}$ with calcite from a chemical experiment. The purpose of this study is mainly focused on comparison of attachment on each material of drainage pipe (teflon-coated steel pipe, silicon-Oil coated pipe, acrylic pipe and PVC pipe). The test was progressed to disembogue the CaO aqueous solution and tunnel outflow into each of the pipes. The experimental results show that the most produced scale pipe is PVC material and the followings are Acrylic pipe, Silicon-Oil coating pipe and Teflon coating pipe. But the long-term test results showed that teflon-coated steel pipe had a problem with durability because soil which was contained in the tunnel outflow occurred detachment of coating and corrosion of the steel pipe.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.765-773
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• 2000

The degradation of humic acid using $TiO_2$ coatings was studied, $TiO_2$ coatings were prepared by dip-coating method. Sol solutions for coating were prepared by mixing the gel, which can be produced by the reaction of $TiOCl_2$ and $NH_4OH$ solution, and hydrogen peroxide solution, and hydrolysis of titanium tetraisopropoxide (TTIP). It was shown from XRD that coatings from sol aged at $100^{\circ}C$ for 18h with titanium peroxo solution were crystallized to anatase in the range of temperatures of $25^{\circ}C$ to $500^{\circ}C$. In contrast, those coated from TTIP were crystallized to anatase at temperature above $400^{\circ}C$. So the sols originated from $TiCl_4$ can be applied for not only on the heat-resistance substrates but on the plastic substrates. Thickness and the quality of the films were dependent on the withdrawing speed, the concentration of sol, and the number of coating. The films showed various interference colors depending on the thickness of them. In the case that the films coated 2 times at withdrawing speed of 2.5cm per minute by 0.2M sol, the films had a transparent light blue color with thickness of around 50nm. It was known from the result of photo-degradation by $TiO_2$ coatings using humic acid that the removal efficiency of $COD_{cr}$ was over 85% after illumination of $UV/H_2O_2$ for 40min. and that of UV/VIS absorbable materials was over 95%.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2017.05a
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• pp.105-105
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• 2017

actuator system은 조선, 제철, 석유화학 및 중공업 등 다양한 분야에서 각종 유량 및 공기압 등을 제어하는 밸브에 필수적으로 사용되는 핵심 부픔이다. 최근 유정 개발 등 해양구조물 설치 조절이 복잡화 되면서 본 부품이 해양산업에 사용되는 빈도가 증가하고 있다. 이 경우 본 부품이 염분이 많은 바닷물 또는 주변 환경에 직접 노출되기 때문에 내식성이 매우 엄격하게 관리되고 있다. 본 부품에 부식이 발생할 경우 control system의 작동을 지배하는 구성 품에 부식이 발생하여 actuator로서 기능을 상실하여 오동작이나 설비 가동이 중단되는 사례가 빈번하다. 현재 본 부품의 내식성 향상을 위해서는 금속기 표면에 페인트를 사용하는 방법이 가장 널리 사용되고 있는 방법이다. 이 경우 금속 표면과 도장 면과의 사이에 기포발생이나 이물질 유입 등으로 인한 밀착성이 감소되거나 blister 등으로 인하여 도장 코팅 면이 박리되는 사례가 빈번하다. 이를 방지하기 위해서 최근 고 밀착성 내식용 도장 방법을 적용하고 있으나, 이 방법으로 도장한 부품의 표면에 충격 등으로 인한 결함이 발생할 경우 pitting corrosion 등 급격한 부식이 발생하여 이에 대한 근본족인 대책 수립이 절실한 실정이다. 본 연구에서는 근본적으로 금속기 표면과 밀착성이 우수한 화성피막 용액을 이용하여 희생양극에 의한 내식성을 확보하고, 다양한 용도에 적합한 색상 도료를 화성피말 위에 적용하여 화성피막 층의 보호 및 actuator의 목적에 맞는 도장을 하였다. 희생 양극효과를 극대화 할 수 있는 최적 화성피막 층은 $15{\mu}m$이며 이때 1,000시간 이상의 내식성을 확보하였다. 이 경우 이론적인 내식 수명은 2년으로 추정할 수 있었다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.12
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• pp.6973-6979
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• 2014

To mitigate global warming and climate change, many countries are investing massively on the development of CCS technology, which is assumed to be the key technology to reduce $CO_2$ emissions. CCS technology is comprised of the capture, transport, and storage processes. During the capture process, impurities other than $CO_2$ are inevitably flowed into the $CO_2$ stream. In the present study, corrosion characteristics of a phosphate coated tube for $CO_2$ transportation was investigated with a $CO_2$ stream composed of $CO_2$, $H_2O$, $SO_2$, and $NO_2$. The test specimen was a phosphate coated steel tube, which was filled with $CO_2$ stream with the impurities mentioned above. SEM-EDS analysis is conducted to investigate the corrosion behavior. The results showed that although the H2O concentration did not exceed the solubility limit, corrosion occurred in the specimen, which has an inflow of $SO_2$ or $NO_2$. This suggests that the $SO_2$, $NO_2$ and $H_2O$ concentration should be strictly controlled. These results suggest that the $SO_2$ and $NO_2$ concentration should be controlled below 175ppm and 65ppm, respectively.

• Conservation Science in Museum
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• v.13
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• pp.23-31
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• 2012

The object artifacts of this study are the iron artifacts owned by the Kyunghee University Central Museum. The surfaces of the iron artifacts are opaque due to the coated materials which are presumed to be paraffin or bee's wax while they are plate-shaped and exist in thickly exfoliated condition caused by severe corrosion developed on the overall surfaces. Therefore, in order to remove the coated materials away from the surfaces of the artifacts rather safely, reversibility tests have been carried out and the conservation treatment was performed upon the basis of and in application of the experimental results. The study methodologies are that: first, the FT-IR analysis was carried out to determine the ingredients of the coating-treated material on the surface; second, by applying various kinds of organic solvents, the kinds of agents that allow the artifact's surface-coating material to be reversible have been identified through experiments; third, the most suitable agent for removing coating material was selected and applied to the real artifacts on the basis of the results of the reversibility tests. Results from the study: first, as a result of the FT-IR analysis, the coating agent used on the artifacts was identified to be of the same ingredients as those of paraffin; second, among organic solvents, xylene, toluene, trichloroethylene and methyl alcohol were identified to be usable for dissolving paraffin whereas toluene was judged to be the most suitable for removing the coating agent; third, when applying the selected agents on the real artifacts, due to the fact that removing the whole paraffin might cause the artifact to disintegrate, the paraffin of only the part that covered the surfaces opaquely was removed using cotton swab or gauze, thus completing the conservation treatment.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.208-208
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• 2012

최근 환경문제가 많이 제기되면서 친환경적 운송수단인 자전거 개발과 관련하여 다양한 기술개발이 이루어지고 있다. 그 중 고부가가치의 서스펜션 포크의 프레임에 고기능성 표면처리로 Arc ion plating deposition system (AIPDS)을 이용하여 부식, 내마모 특성이 뛰어난 TiN 박막을 증착시켰다. AIPDS는 기존의 arc system과 달리 다원계 소재 코팅 공정조건 확립을 위하여 chamber wall에 2개의 rectangular type sputter source를 장착하고 소재의 pre-treatment 용 linear type ion source를 설치하였다. 장비의 Chamber 중앙에는 pipe형 arc cathode를 설치하였으며, 그 주위를 anode 역할을 하는 copper 코일로 감아 이는 발생한 arc를 target인 cathode 축을 중심으로 방향성을 가지고 회전하여 진행 할 수 있도록 유도 하였다. 이 시스템에서 증착된 TiN 박막은 bias 전압 변화에 따른 박막의 구조 및 물성을 평가하였다. XRD 장비를 통하여 TiN 박막의 상분석을 진행하였고, 마모테스터, 원자현미경, 마이크로 비커스 경도기 등을 이용하여 기계적 특성을 평가하였다.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.1481-1482
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• 2011

현재 고온 및 부식 침식 환경에 사용되는 재료는 부품의 내구성 및 신뢰성이 수명에 절대적인 영향을 준다. 따라서 내열성, 내식성의 문제를 해결하기 위한 재료의 개발과 함께 표면특성 향상을 위한 코팅기술이 지속적으로 발전되고 있다. 본 연구에서는 전기접점재료의 중요한 특성인 저항 고온 고강도 고내식의 특성을 가지는 차세대 복합소재로써 Mo-Cu를 Magnetron Sputtering 법을 이용하여 박막을 제조하였다. Sputtering 변수로는 파워, 온도, Gas, 공정시간, 조성으로 정하였고 변수에 따른 박막의 특성을 분석하였다. 분석으로는 내열, 내식, 경도, XRD, SEM, EDX, EPMA, 면저항을 측정 하여 조건별 비교 분석하였다.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.22 no.6
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• pp.895-900
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• 2013

Several plasma spray and metallurgical surface coatings such as $Al_2O_3$, $Cr_2O_3$, WC-Ni, and chromizing coating have been examined for their application in environments with high temperature, wear, and corrosion. The chromizing coating is different from others coatings in the manufacturing process the surface. These coatings' characteristics were tested experimentally, and the results were compared. WC-Ni shows good performance against thermal barrier, wear, and corrosion and is one of the best candidates for the environment considered herein. These coatings were studied for their application in the steel manufacturing industry. The most commonly required functions in this industry are thermal and wear resistance.

• Corrosion Science and Technology
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• v.13 no.6
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• pp.224-232
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• 2014

Effect of pretreatments on the graphene coated bipolar plate of proton exchange membrane fuel cell(PEMFC) was investigated in simulated environments for PEMFC by using electrochemical measurement techniques. Interfacial contact resistance(ICR) between the graphene coated bipolar plate and the gas diffusion layer(GDL) was measured. The value of ICR decreased with an increase in compaction stress($20N/cm^2{\sim}220N/cm^2$). ICR of graphene coated bipolar plate was higher than that of bare 316L stainless steel. However, Potentiodynamic measurement results showed that the corrosion resistance of graphene coated bipolar plate was higher than that of bare 316L stainless steel. $H_2SO_4$ acid pretreatment was the most effective among various pretreatments. The lowest ICR and the corrosion current density were obtained when using $H_2SO_4$ solution pretreatment.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2009.05a
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• pp.225-225
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• 2009

천연해수 중에서 음극방식에 의해 형성된 석회질 막은 장기적으로 외부 부식 환경을 차단하여 피방식체인 강재를 부분적으로 보호하거나 음극방식에 필요한 전류밀도를 감소시키는 역할을 하기도 한다. 한편 이렇게 형성된 석회질막 자체의 밀착력은 매우 취약하여 정상적인 막으로의 기능 수행이 곤란하다. 본 연구에서는 해수 환경 중 형성된 석회질 코팅막의 성분, 조직 및 결정구조 등을 분석하여 밀착성 향상에 기여할 것으로 추정되는 인자를 평가 선정함은 물론 제작 제어를 검토하였다.