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해양환경 중 음극전류 프로세스에 의해 강판에 형성된 석회질 피막의 특성 분석
박준무(Jun-Mu Park),강재욱(Jae Wook Kang),최인혜(In-Hye Choi),이승효(Seung-Hyo Lee),문경만(Kyung-Man Moon),이명훈(Myeong-Hoon Lee) 한국표면공학회 2016 한국표면공학회지 Vol.49 No.2
Cathodic protection is widely recognized as the most cost effective and technically appropriate corrosion prevention methodology for the port, offshore structures, ships. When applying the cathodic protection method to metal facilities in seawater, on the surface of the metal facilities a compound of calcium carbonate(CaCO₃) or magnesium hydroxide(Mg(OH)₂) films are formed by Ca<SUP>2+</SUP> and Mg<SUP>2+</SUP> ions among the many ionic components dissolving in the seawater. And calcareous deposit films such as CaCO₃ and Mg(OH)₂ etc. are formed by the surface of the steel product. These calcareous deposit film functions as a barrier against the corrosive environment, leading to a decrease in current demand. On the other hand, the general calcareous deposit film is a compound like ceramics. Therefore, there may be some problems such as weaker adhesive power and the longer time of film formation uniting with the base metal. In this study, we tried to determine and control the optimal condition through applying the principle of cathodic current process to form calcareous deposit film of uniform and compact on steel plate. The quantity of precipitates was analyzed, and both the morphology, component and crystal structure were analyzed as well through SEM, EDS and XRD. And based on the previous analysis, it was elucidated mechanism of calcareous deposit film formed in the sacrificial anode type (Al, Zn) and current density (1, 3, 5 A/㎡) conditions. In addition, the taping test was performed to evaluate the adhesion.
박준무(Jun-Mu Park),이승효(Seung-Hyo Lee),우상균(Sang-Kyun Woo),추인엽(In-Yeop Chu),이명훈(Myeong-Hoon Lee) 한국표면공학회 2018 한국표면공학회지 Vol.51 No.5
Harsh seawater environment is subdivided into marine atmosphere, splash zone, tidal zone, submerged zone and bottom of sea depending on the exposed part. Since corrosion rate depends on the conditions of the exposed parts, proper protection and maintenance for each parts are essential for long-term use of steel structures in seawater environment. For steel structures which were installed in Shiwha Lake, a special maintenance system is required to guarantee its long-term durability and safety. As the tidal power plant has recently been operated, the salinity has risen due to the rapid influx of seawater upstream into Sihwa Lake and the corrosion tendency of the structure is variable according to the water level fluctuation. In this study, corrosion properties of steel structures under water level fluctuation was evaluated by corrosion rate measurement, visual inspection and natural potential measurement and their durability and life management were discussed in view of the effect of variation in of seawater level fluctuations in Shihwa Lake.
해수 중 펄스 전착 프로세스 의해 제작한 석회질 피막의 결정구조 제어 및 특성 평가
박준무,이승효,Park, Jun-Mu,Lee, Seung-Hyo 한국표면공학회 2019 한국표면공학회지 Vol.52 No.2
As an anti-corrosion method in seawater, cathodic protection is widely recognized as the most effective and technically appropriate corrosion prevention methodology for marine structures against harsh corrosive environment. When applying the cathodic protection in seawater, the surface of the metal facilities the formation of compounds of $CaCO_3$ and $Mg(OH)_2$. These mixed compounds are generally called 'calcareous deposits'. This layer functions as a barrier against the corrosive environment and functions to further inhibit the corrosion process and then leading to a decrease in current demand for cathodic protection. However, calcareous deposit films are partially formed on the surface of the cathode and there are some difficulties to maintain both a corrosion resistance for a long period of time and a strong adhesion between deposits and base metal. In this study, the pulse electrodeposition process was applied to improve adhesion and corrosion resistance of the calcareous deposit films, and to solve the problem of hydrogen embrittlement at high current density. The uniform and compact calcareous deposit films were prepared by pulse electrodeposition process, and their properties were characterized using various surface analytical techniques together with electrochemical methods.
PVD법에 의해 제작한 Al-Mg 코팅 강판의 내식성에 미치는 Mg 함량 및 열처리의 영향
강재욱(Jae Wook Kang),박준무(Jun-Mu Park),황성화(Sung-Hwa Hwang),이승효(Seung-Hyo Lee),문경만(Kyung-Man Moon),이명훈(Myeong-Hoon Lee) 한국표면공학회 2016 한국표면공학회지 Vol.49 No.2
This study was intended to investigate the effect of the amount of magnesium addition and heat treatment in the Al-Mg coating film in order to improve corrosion resistance of aluminum coating. Al-Mg alloy films were deposited on cold rolled steel by physical vapor deposition sputtering method. Heat treatment was fulfilled in an nitrogen atmosphere at the temperature of 400°C for 10 min. The morphology was observed by SEM, component and phase of the deposited films were investigated by using GDLS and XRD, respectively. The corrosion behaviors of Al-Mg films were estimated by exposing salt spray test at 5 wt.% NaCl solution and measuring polarization curves in deaerated 3 wt.% NaCl solution. With the increase of magnesium content, the morphology of the deposited Al-Mg films changed from columnar to featureless structure and particle size was became fine. The x-ray diffraction data for deposited Al-Mg films showed only pure Al peaks. However, Al-Mg alloy peaks such as Al₃Mg₂ and Al12Mg17 were formed after heat treatment. All the sputtered Al-Mg films obviously showed good corrosion resistance compared with aluminum and zinc films. And corrosion resistance of Al-Mg film was increased after heat treatment.
문경만(Kyung-Man Moon),정재현(Jae-Hyun Jeong),박준무(Jun-Mu Park),이명훈(Myeong-Hoon Lee),백태실(Tae-Sil Baek) 한국표면공학회 2016 한국표면공학회지 Vol.49 No.6
Many surface protection methods have been developed to apply to constructional steels which have been used under severe corrosive environments. One of these methods, hot dip galvanizing is being widely used to the numerous constructional steels such as a guard rail of high way, various types of structural steel for manufacturing ship and for some other industrial fields etc.. Recently, the cost of zinc is getting higher and higher, thus, it is considered that improvement of hot dip galvanizing process to reduce the cost of production should be developed possibly. In this study, additives such as acid cleaning solution, NH₄OH, Al(OH)₃ and H₂O₂ were added to flux solution, and omission of water washing treatment after acid cleaning was investigated with some types of flux solutions added with some additives mentioned above. The decrement of pH by adding the acid cleaning solution could be controlled due to neutralization reaction with addition of NH₄OH. The flux solution added with both NH₄OH and Al(OH)₃ exhibited nearly the same color and pH value as those of orignal flux solution with no added, and the sample dipped to the flux solution which was added with additives mentioned above indicated a relatively good corrosion resistance compared to other samples. However, the flux solution added with NH₄OH, Al(OH)₃ and H₂O₂ exhibited a different color, sediment and a bad corrosion resistance. Consequently, it is considered that omission of water washing treatment may be able to perform by adding optimum additives to the original flux solution.
탄소/현무암 섬유강화 하이브리드 복합재료의 성형과 기계적 특성 평가
이진우 ( Jin Woo Lee ),김윤해 ( Yun Hae Kim ),정민교 ( Min Kyo Jung ),윤성원 ( Sung Won Yoon ),박준무 ( Jun Mu Park ) 한국복합재료학회 2014 Composites research Vol.27 No.1
탄소섬유 복합재료는 내열성 및 우수한 기계적 특성을 가지고 있는 우수한 재료이지만 가격이 비싼 결점이 있다. 따라서 본 연구에서는 높은 기계적 강도를 가지며, 가격이 비싸지 않은 재료의 개발을 위해 탄소섬유에 현무암 섬유를 첨가하여 하이브리드 복합재료를 제작하였다. 현무암 섬유의 함유 비율이 높아질수록 강도는 감소하였으며, 탄소의 강화재 비율이 80% 정도에서 CFRP와 유사한 강도를 얻을 수 있었다. 또한 섬유 각각을 적층하여 복합재료를 제작하는 것 보다 섬유사를 혼합시켜 제작한 복합재료에서 더 우수한 기계적 특성을 얻을 수 있었다. Carbon Fiber Reinforced Plastic (CFRP) has strong and superb material properties, especially in mechanical and heat-resisting aspects, but the drawback is its high price. In this study, we made a hybrid composite using carbon fiber and basalt fiber, which is expected to attribute to its strong material properties and its financial benefits. We found out that the higher the content of basalt fiber included, the lower the intensity, and carbon`s intensity contents of 80% showed the similar intensity level as that of CFRP. Besides it was possible to get a better mechanical properties using the composite that included the mixed fiber, instead of using a composition of separate fibers filed.