PVD 법에 의한 Al 금속의 박막제작과 그 전기화학적 특성에 관한 연구

문경만,충맹웅 ( Kyung Man Moon,Takeo Oke ) 한국부식방식학회 1994 Corrosion Science and Technology Vol.23 No.1

용사 도막의 내식성에 관한 전기화학적 평가

문경만,신중하,이명훈,이성렬,김윤해,Moon, Kyung-Man,Shin, Joong-Ha,Lee, Myung-Hoon,Lee, Sung-Yul,Kim, Yun-Hae 한국마린엔지니어링학회 2010 한국마린엔지니어링학회지 Vol.34 No.5

There are many surface protection methods for numerous steel structures being used under severely corrosive environment, one of them, metallizing(thermal spray) is a available protection method which is comparatively and recently developed for surrface protection of various steel structures. However coating film obtained by spraying is to be needed increasingly more good corrosion resistance due to accelerating of environmental contamination. In this study, coating films(DFT:$200{\mu}m$) are performed with arc spray by wire metal and their types of films are pure zinc, pure aluminum, alloy film(Al:Zn=85:15) and alloy film(Al:Zn=95:5). And corrosion resistance of their films was investigated with electrochemical methods in seawater solution. Pure aluminum film showed a relatively somewhat good corrosion resistance compared to among those of other films and alloy films also showed a good corrosion resistance compared to pure zinc film. Especially it was observed that pure aluminum film showed a comparatively good corrosion resistance than that of alloy film named as galvarium spray(Al:Zn=85:15) in seawater solution. Morphology of corroded surface of pure zinc film appeared the pattern like intergranlar corrosion, however films of pure aluminum and alloy metal showed a general corrosion pattern. 가혹한 부식환경 하에 사용되어 지고 있는 다양한 강구조물에 대해서 많은 표면방식법이 있다. 그 중의 한방법인 용사는 다양한 강구조물의 표면방식을 위하여 비교적 최근에 개발된 유용한 방식법이다. 그러나 용사피막도 환경오염의 가속화에 따라 점차 더욱 좋은 내식성을 필요로 하고 있다. 본 연구에서는 아아크 용사에 의해서 도막두께 $200{\mu}m$의 피막을 만들었으며, 피막의 종류는 순 아연,순 알류미늄, 합금피막(Al:Zn=85:15) 및 (Al:Zn=95:5)의 합금피막이었다. 그리고 이들 피막의 내식성을 해수용액에서 전기화학적인 방법으로 고찰 하였다. 순 알류미늄 피막은 다른 피막에 비해서 비교적 상당히 좋은 내식성을 보였다. 그리고 합금피막도 역시 순 아연피막에 비해서 좋은 내식성을 보였다. 특히 순 알류미늄 피막은 갈바륨 용사라고 알려진 합금피막(Al:Zn=85:15)보다 해수용액에서 내식성이 상대적으로 좋았음이 관찰되었다. 순 아연의 부식된 표면양상은 입게부식의 형태를 나타내었으나 순 알류미늄과 합금피막은 균일부식의 형태를 나타내었다.

AC8A 알루미늄 합금 주조재의 열처리에 의한 특성 평가(Ⅱ)

문경만(Kyung-Man Moon),정재현(Jae-Hyun Jeong),이명훈(Myeong-Hoon Lee),백태실(Tae-Sil Baek) 한국동력기계공학회 2016 동력시스템공학회지 Vol.20 No.5

Aluminum alloys have been widely used in engine materials, cold & hot-water storage vessels and piping etc., Furthermore, the aluminum alloy of AC8A have been widely used in mold casting material of engine piston for various vehicles because of its properties of temperature, wear and corrosion resistance. Therefore, it is considered that evaluation of corrosion resistance as well as wear resistance of AC8A material is also important to improve its property and to prolong its lifetime. In previous paper, the effect of solution(510℃:4hrs) and tempering(190℃: 16, 24, and 36 hrs)heat treatments to corrosion resistance and hardness were investigated using electrochemical method. In this study, in order to examine completely the effect of the tempering hours to hardness variation and corrosion resistance, the results of solution(510℃:4hrs) and tempering(190℃: 2, 4, 8 and 12hrs)heat treatments to hardness and corrosion resistance were investigated using electrochemical method. The hardness decreased with solution heat treatment compared to mold casting condition, but its value increased with tempering heat treatment. Furthermore, the corrosion resistance increased with decreasing of the hardness, and decreased with increasing of the hardness reversely. And the tempering heat treatment temperature at 190℃ for 8 hrs exhibited the highest value of the hardness and also indicated the highest corrosion current density. However, the values of hardness and corrosion current density was again increasingly decreased with increasing of .tempering hours than 8 hrs, Consequently, it is suggested that decision of the optimum. tempering hours is very important to improve the corrosion or wear resistance.

배기밸브 보수 용접부의 부식 특성에 관한 전기화학적 연구

문경만(KYUNG-MAN MOON),이규환(KYU-HWAN LEE),조황래(HWANG-RAE CHO),이명훈(MYUNG-HOON LEE),김윤해(YUN-HAE KIM),김진경(JIN-GYEONG KIM) 한국해양공학회 2008 韓國海洋工學會誌 Vol.22 No.3

The diesel engine of the merchant ship has been operated in severe environments more and more, because the temperature of the exhaust gas of a combustion chamber is getting higher and higher with increasing use of heavy oil of low qualify, due to the significant increase in the price of oil in recent some years. As a result, the degree of wear and corrosion between exhaust valve and seat ring is more serious compared to other engine parts. Thus the repair welding of exhaust valve and seat ring is a unique method to prolong the life of the exhaust valve, from an economical point of view. In this study, the corrosion property of both weld metal and base metal was investigated using electrochemical methods such as measurement of corrosion potential, cathodic and anodic polarization curves, cyclic voltammogram, and polarization resistance in 5% H2SO4 solution. The test specimen was a part of an exhaust valve stem being welded as the base metal, using various welding methods. In all cases, the corrosion resistance as well as hardness of the weld metal zone was superior to the base metal. In particular, plasma welding showed relatively good properties for bath corrosion resistance and hardness, compared to other welding methods. In the case of DC SMAW (Shielded metal arc welding), corrosion resistance of the weld metal zone was better than that of the base metal, although its hardness was almost same as the base metal.

수돗물의 전기분해에 의해서 생성된 알카리수의 pH가 SS 400강의 부식특성에 미치는 영향

문경만(Kyung-Man Moon),류해전(Hae-Jeon Ryoo),김윤해(Yun-Hae Kim),정재현(Jae-Hyun Jeong),백태실(Tae-Sil Baek) 한국해양공학회 2017 韓國海洋工學會誌 Vol.31 No.3

Many rivers and seas have been affected by environmental contamination. Therefore, city water supplies often require a high-degree purification treatment to provide safe drinking water. However, in order to achieve a high-degree purification treatment, a large amount of chlorine has to be added to sterilize city drinking water. The added chlorine reacts chemically with water and forms hypochlorous and chlorine ions. The hypochlorous ionizes with hypochlorous ions and hydrogen ions. As a result, the city water contains a large amount of chlorine ion. As such, when city water is used with domestic boilers, many kinds of heat exchangers, and the engines of vehicle and ships, there are often corrosion problems. In this study, alkali water was electrochemically made by electrolysis of city water, and corrosion properties between alkali and city water were investigated with an electrochemical method. Most of the chlorine ions are thought to not be contained in the alkali water because the alkali water is created in the cathodic chamber with an electrolysis process. In other words, the chlorine ion can be mostly removed by its migration from a cathodic chamber to an anodic chamber. Moreover, the alkali water also contains a large amount of hydroxide ion. The alkali water indicated relatively good corrosion resistance compared to the city water and the city water exhibited a local corrosion pattern due to the chlorine ion created by a high-degree purification treatment. In contrast, the alkali water showed a general corrosion pattern. Consequently, alkali water can be used with cooling water to inhibit local corrosion by chlorine ions in domestic boilers, various heat exchangers and the engine of ships and for structural steel in a marine structure.

희생양극의 수명에 미치는 인접 강파일의 음극방식 영향

문경만(KYUNG-MAN MOON),이규환(KYU-HWAN LEE),조황래(HWANG-RAE CHO),이명훈(MYUNG-HOON LEE),김윤해(YUN-HAE KIM),김진경(JIN-GYEONG KIM) 한국해양공학회 2008 韓國海洋工學會誌 Vol.22 No.3

There are two cases when the life of a sacrificial anode is shortened from the designed life: one case results from self-corrosion of the anode due to contamination by sea water in the other case, however, electrical current to protect some given steel piles overflows to protect other, adjacent non-protected steel piles. In this study, the variation of polarization potential of nine steel piles, being protected cathodically and with anode-producing current between anode and steel piles, was investigated. Parameters were varied, such, as the eighth and ninth steel piles eitherconnected electrically or not, and whether the ninth steel pile was protected by anode of sacrificial anode or not. The current produced by the sacrificial anode decreased when the ninth steel pile was cathodically protected by the anode of another pile. However, produced current increased when the ninth steel pile was not connected to another anode. The study concludes that the life of a sacrificial anode can be prolonged or shortened depending on whether adjacent steel piles are cathodically protected or riot.

Laser 용접한 스테인리스강의 용접부위의 부식특성에 관한 평가

문경만(Kyung-Man Moon),원종필(Jong-Pil Won),박동현(Dong-Hyun Park),김윤해(Yun-Hae Kim),이명훈(Myung-Hoon Lee),김진경(Jin-Gyeong Kim) 한국해양공학회 2012 韓國海洋工學會誌 Vol.26 No.4

Laser welding was carried out on austenitic 304 (STS 304) and 2 APU stainless steels. In this case, the differences between the corrosion caracteristics of th welding zones of the two stainless steels were investigated using electrochemical methods. The Vickers hardness values of the weld metal (WM) zones in both cases, the STS 304 and 22 APU stainless steels, showed relatively higher values than those of other welding zones. The corrosion current densities of the heat affected zone (HAZ) of the 22 APU and the base metal (BM) zone of the STS 304 exhibited the highest values compared to the other welding zones. It is generally accepted that whe STS 304 stainless steel is welded using a general welding method, intergranular corrosion is often observed at the grain boundary because of its chromium depletion area. However, when laser welding was performed on both the STS 304 and 22 APU stainless steels, no intergranular corrosion was observed at any of the welding zones. Consequently, it is considered that the intergranular corrosion of stainless steel can be controlled with the application of laser welding.

304 스테인리스강의 용접부위의 부식특성에 관한 전기화학적 평가

문경만(Kyung-Man Moon),김윤해(Yun-Hae Kim),김종도(Jong-Do Kim),이명훈(Myung-Hoon Lee),김진경(Jin-Gyeong Kim) 한국해양공학회 2009 韓國海洋工學會誌 Vol.23 No.4

Two kinds of welding methods are used for austenitic 304 stainless steel: laser welding and TIG welding. The difference in the corrosion characteristics if the welded zone between these two welding methods was investigated using electrochemical methods, such as corrosion potential measurements, polarization curves, cyclic voltammograms, etc. The Vickers hardnesses if all the welded zones (WM: Weld Metal, HAZ: Heat Affected Zone, BM: Base Metal) showed relatively higher values in the case if laser welding than for TIG welding. Furthermore, the corrosion current densities if all the welding zones showed lower values compared to TIG welding. In particular, the corrosion current density if the HAZ with TIG welding had the highest value if all the welding zones, which suggests that chromium depletion due to the formation if chromium carbide appears in the HAZ, which is in the range of the sensitization temperature. Thus, it can easily be corroded with a more active anode. Consequently, we found that the corrosion resistance if all of the welding zones for austenitic 304 stainless steel could apparently be improved by using Loser welding.

22APU 스테인리스강의 용접부위의 부식특성에 관한 전기화학적 평가

문경만(Kyung-Man Moon),김윤해(Yun-Hae Kim),이성열(Sung-Yul Lee),김종도(Jong-Do Kim),이명훈(Myung-Hoon Lee),김진경(Jin-Gyeong Kim) 한국마린엔지니어링학회 2009 한국마린엔지니어링학회지 Vol.33 No.8

용사 도막의 내식성에 관한 전기화학적 평가

문경만(Kyung-Man Moon),신중하(Joong-Ha Shin),이명훈(Myung-Hoon Lee),이성렬(Sung-Yul Lee),김윤해(Yun-Hae Kim) 한국마린엔지니어링학회 2010 한국마린엔지니어링학회지 Vol.34 No.4

가혹한 부식환경 하에 사용되어 지고 있는 다양한 강구조물에 대해서 많은 표면방식법이 있다. 그 중의 한방법인 용사는 다양한 강구조물의 표면방식을 위하여 비교적 최근에 개발된 유용한 방식법이다. 그러나 용사피막도 환경오염의 가속화에 따라 점차 더욱 좋은 내식성을 필요로 하고 있다. 본 연구에서는 아아크 용사에 의해서 도막두께 200㎛의 피막을 만들었으며, 피막의 종류는 순 아연,순 알류미늄, 합금피막(Al:Zn=85:15) 및 (Al:Zn=95:5)의 합금피막이었다. 그리고 이들 피막의 내식성을 해수용액에서 전기화학적인 방법으로 고찰 하였다. 순 알류미늄 피막은 다른 피막에 비해서 비교적 상당히 좋은 내식성을 보였다. 그리고 합금피막도 역시 순 아연피막에 비해서 좋은 내식성을 보였다. 특히 순 알류미늄 피막은 갈바륨 용사라고 알려진 합금피막(Al:Zn=85:15)보다 해수용액에서 내식성이 상대적으로 좋았음이 관찰되었다. 순 아연의 부식된 표면양상은 입게부식의 형태를 나타내었으나 순 알류미늄과 합금피막은 균일부식의 형태를 나타내었다. There are many surface protection methods for numerous steel structures being used under severely corrosive environment, one of them, metallizing(thermal spray) is a available protection method which is comparatively and recently developed for surrface protection of various steel structures. However coating film obtained by spraying is to be needed increasingly more good corrosion resistance due to accelerating of environmental contamination. In this study, coating films(DFT:200㎛) are performed with arc spray by wire metal and their types of films are pure zinc, pure aluminum, alloy film(Al:Zn=85:15) and alloy film(Al:Zn=95:5). And corrosion resistance of their films was investigated with electrochemical methods in seawater solution. Pure aluminum film showed a relatively somewhat good corrosion resistance compared to among those of other films and alloy films also showed a good corrosion resistance compared to pure zinc film. Especially it was observed that pure aluminum film showed a comparatively good corrosion resistance than that of alloy film named as galvarium spray(Al:Zn=85:15) in seawater solution. Morphology of corroded surface of pure zinc film appeared the pattern like intergranlar corrosion, however films of pure aluminum and alloy metal showed a general corrosion pattern.