Corrosion resistance of water repellent aluminum surfaces with various wetting morphologies

Song, Kyounghwan,Kim, Inkyu,Bang, Soosik,Jung, Jung-Yeul,Nam, Youngsuk Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.467 No.-

<P><B>Abstract</B></P> <P>We investigated the improved corrosion resistance of micro/nanostructured aluminum surfaces by varying wetting morphologies. By combining the wet-chemical oxidation schemes and low surface energy coating, we induced three different wetting morphologies including superhydrophilic, Cassie-mode superhydrophobic and Wenzel-mode hydrophobic on micro/nanostructured aluminum surfaces. The superhydrophilic oxide layers provided approximately 30–76% improvement in the corrosion resistance compared to untreated ones. When a hydrophobic coating was added to the oxide layers and Cassie-mode superhydrophobicity was induced, all types of samples showed over 95% increase in the corrosion resistance compared with untreated ones. When the air trapped on the superhydrophobic surfaces was removed in a vacuum environment, the corrosion resistance decreased but still provided 70–98% increase compared with untreated ones. The present work showed that the superhydrophobic treatment is a very effective way to improve the corrosion resistance but the proper choice of the passivation layer and hydrophobic coating can provide a meaningful increase in the corrosion resistance. The present work further clarified the high corrosion resistance of superhydrophobic aluminum surfaces and will help to develop practical anti-corrosion resistance surfaces.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The effects of various wetting morphologies on the corrosion resistance were quantified. </LI> <LI> The importance of the air trapping was clarified by forcing the Cassie-to-Wenzel wetting transition. </LI> <LI> The effects of oxide barriers, hydrophobic coating and air layer on the corrosion resistance were analyzed. </LI> <LI> This work helps to estimate the effects of the surface degradation of anti-corrosion surfaces. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

수중 경화형도료의 부식특성에 관한 전기화학적 고찰

오민석(Min-Seok Oh),이명훈(Myung-Hoon Lee),이성렬(Syung-YUl Lee),김윤해(YUn Hae Kim),문경만(Kyung-Man Moon) 대한조선학회 2011 대한조선학회 학술대회자료집 Vol.2011 No.6

Many protection methods such as surface coating, electric protection or some other methods etc. have been applied to numerous steel structures being widely used in continental and marine areas to control corrosion of those structures in economic point of view. And most of those steel structures are mainly protected by coating methods. However, some steel piles being under seawater are generally protected by electric protection method, that is, either as an impressed current or as a sacrificial anode method. Furthermore, environmental contamination may be resulted in increasing severe corrosive environment, which, in turn, cause to be accelerated corrosion of the steel structures. Subsequrntly, coated steel structures would deteriorate more rapidly than the designed life time due to acid rain caused by air pollution etc. Therefore coating for the marine plant exposed to the seawater, that is, underwater hardening paintg is increasingly required to a fast dryness as well as a high corrosion resistance. In this study five types of underwater hardening paints are prepared with different resin series and additives. And their corrosion and water resistances were investigated with electrochemical methods such as corrosion potential, polarization curves, impedance and cyclic voltammogram measurements etc.. Even though, it is generally accepted that corrosion resistance of a bare steel tends to increase with shifting the corrosion potential in the noble direction, however, the corrosion resistance of the sample with coating relatively exhibited a better tendency when had lower corrosion potential in this study. Corrosion current density was also decreased with decreasing the diffusion limiting current density, which may mean that there is a somewhat relation between corrosion and water resistance. S sample of a ceramic resin series relatively showed the best corrosion as well as water resistance among those of samples, while the worst corrosion and water resistance were observed for the R sample of epoxy resin series. Corrosion and water resistance of those samples tended to be deteriorated with increasing immersion days, and their corrosion and water resistances are considered to be apparently improved by the types of resin and additives.

Characteristics of a Stack Separator Prepared from Composites of Stainless Steel and TiNx for Fuel Cells

Farkhod R. Turaev,Sung Bum Park,Taeho Bahn,Sung Jin Kim,Jung-Ho Ahn,홍태환 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.3

A stack separator made from carbon or carbon composites has many advantages, such as electrochemical stability, low density, low contact resistance and good corrosion resistance. However, it has some weak points, including higher thickness and low manufacturing reliability. Therefore, many attempts have been made to fabricate a stack separator from materials that have low-cost, high manufacturing reliability and corrosion resistance. It is very important to take into account that it is very difficult to achieve good corrosion resistance of a stack separator at high temperatures. Therefore, many researchers have tried to use expensive materials that are high temperature and corrosion resistant superalloys. In this paper, the fabrication of a stack separator made of low-price metal and TiNx is investigated. Stainless steel, which is a low-price, corrosion resistant metal and TiNx are used as a reinforcement support to reveal high heat resistance and corrosion resistance and to decrease the hydrogen permeability. We fabricated the plates for use as stack separators reinforced by TiNx by mixing stainless-steel powders with 2 % of nano-sized TiNx. Spark plasma sintering (SPS) was chosen for sintering the composites. The physical properties of the specimens were analyzed by performing hardness tests, biaxial strength tests and shear strength tests. The electrochemical properties, such as the corrosion resistance and the hydrogen permeability, were also investigated. The microstructures of the specimens were investigated by using eld-emission scanning electron microscopy and the proles of the chemical compositions were analyzed by using energy dispersive X-Ray analysis. A stack separator made from carbon or carbon composites has many advantages, such as electrochemical stability, low density, low contact resistance and good corrosion resistance. However, it has some weak points, including higher thickness and low manufacturing reliability. Therefore, many attempts have been made to fabricate a stack separator from materials that have low-cost, high manufacturing reliability and corrosion resistance. It is very important to take into account that it is very difficult to achieve good corrosion resistance of a stack separator at high temperatures. Therefore, many researchers have tried to use expensive materials that are high temperature and corrosion resistant superalloys. In this paper, the fabrication of a stack separator made of low-price metal and TiNx is investigated. Stainless steel, which is a low-price, corrosion resistant metal and TiNx are used as a reinforcement support to reveal high heat resistance and corrosion resistance and to decrease the hydrogen permeability. We fabricated the plates for use as stack separators reinforced by TiNx by mixing stainless-steel powders with 2 % of nano-sized TiNx. Spark plasma sintering (SPS) was chosen for sintering the composites. The physical properties of the specimens were analyzed by performing hardness tests, biaxial strength tests and shear strength tests. The electrochemical properties, such as the corrosion resistance and the hydrogen permeability, were also investigated. The microstructures of the specimens were investigated by using eld-emission scanning electron microscopy and the proles of the chemical compositions were analyzed by using energy dispersive X-Ray analysis.

수중 경화형도료의 부식특성에 관한 전기화학적 고찰

문경만(Kyung-Man Moon),오민석(Min-Seok Oh),이명훈(Myung-Hoon Lee),이성렬(Syung-Yul Lee),김윤해(Yun-Hae Kim) 한국해양공학회 2011 韓國海洋工學會誌 Vol.25 No.2

Many protection methods such as surface coating, electric protection, or other methods have been applied to the numerous steel structures widely used in continental and marine areas to control their corrosion, which is done from an economic point of view. Most of these steel structures are primarily protected by coating methods. However, some steel piles under seawater are protected by the electric protection method, that is, either using an impressed current or a sacrificial anode method. Furthermore, environmental contamination may cause a severely corrosive environment, which, in turn, causes the accelerated corrosion of steel structures. Subsequently, coated steel structures could deteriorate more rapidly than the designed lifetime because of the acid rain caused by air pollution, etc. Therefore, a coating of marine paint exposed to seawater, that is, underwater hardening painting, is increasingly required to be fast drying as well as highly corrosion resistant. In this study, five types of underwater hardening paints were prepared with different resin series and additives. Their corrosion and water resistances were investigated using electrochemical methods such as corrosion potential, polarization curves, impedance and cyclic voltammogram measurements, etc. Even though it is generally accepted that the corrosion resistance of bare steel tends to increase with a shift of the corrosion potential in the noble direction, the corrosion resistance of a sample with a coating exhibited a relatively better tendency when it had a lower corrosion potential in this study. The corrosion current density was also decreased with a decrease in the diffusion limiting current density, which may mean that there is some relationship between corrosion and water resistance. The S sample of the ceramic resin series showed the relatively best corrosion and water resistance among those of samples, while the worst corrosion and water resistance were observed for the R sample of the epoxy resin series. The corrosion and water resistance of those samples tended to deteriorate with an increase in the immersion days, and their corrosion and water resistances were considered to be apparently improved by the types of resin and additives.

Effect of Heat Treatment on the Grooving Corrosion Resistance of ERW Pipes

Lee, Jongkwon,Lee, Jaeyoung,Lim, Soohyun,Park, Jihwan,Seo, Bomin,Kim, Seonhwa 한국부식방식학회 2002 Corrosion Science and Technology Vol.31 No.3

The v-sharp grooving corrosion of ERW(electrica1 resistance welding) steel pipes limited their wide application in the industry in spite of their high productivity and efficiency. The grooving corrosion is caused mainly by the different microstructures between the matrix and weld that is formed during the rapid heating and cooling cycle in welding. By this localized corrosion reaction of pipes, it evolves economic problems such as the early damage of industrial facilities and pipe lines of apartment, and water pollution. Even though the diminishing of sulfur content is most effective to decrease the susceptibility of grooving corrosion, it requires costly process. In this study, improvement of grooving corrosion resistance was pursuited by post weld heat treatment in the temperature range between 650℃ and 950℃. Also, the effect of heat input in the welding was investigated. By employing chromnoarnperometry and potentiodynarnic experiment, the corrosion rate and grooving corrosion index(α) were obtained. It was found that heat treatment could improve the grooving corrosion resistance. Among them, the heat treated at 900°C and 950℃ had excellent grooving corrosion resistance. The index of heat treated specimen at 900℃ and 950℃ were 1.0, 1.2, respectively, which are almost immune to the grooving corrosion. Potential diffmnce after the heat treatment between base and weld metal was decreased considerably. While the as-received one measured 61 - 71 ㎷, that of the 900℃ heat treated steel pipe measured only 1O㎷. The results were explained and discussed.

전기저항 용접강관의 홈부식 거동에 대한 후열처리의 영향

박지환,서보민,이종권 대한금속재료학회 2003 대한금속·재료학회지 Vol.41 No.1

The welding characteristics and grooving corrosion resistance of electrical resistance welded steel pipes were studied. The macrostructures revealed that optimal width of bond layer for welding was 80-90 μm, while those formed with low heat input showed negligible bond layer. However, metal flow and heat affected zone did not show any appreaciable differences as long as welding bead were formed. The grooving corrosion, which is typical corrosion form in the steel pipes, is caused mainly by the different microstructures between the matrix and weld those are formed during the rapid heating and cooling cycle in welding. Even though the diminishing of sulfur content is most effective to decrease the susceptibility of grooving corrosion, it requires costly process. In this study, improvement of grooving corrosion resistance was pursued by post weld heat treatment in the temperature range between 650℃ and 950℃. By employing chromno-amperometry and potentiodynamic experiments, the corrosion rate and grooving corrosion index(α) were obtained. It was found that heat treatment could improve the grooving corrosion resistance. Among them, the heat treatment at 900℃ and 950℃ endowed excellent grooving corrosion resistance. The index of heat treated specimen at 900℃ and 950℃ were average 1.2, which are almost immune to the grooving corrosion according to KS. Potential differences between base and weld metal were decreased considerably after the heat treatment. While the as-welded one measured 61∼71mV, that of the 900℃ heat treated steel pipe measured only 10 mV.

Effect of coating thickness on modifying the texture and corrosion performance of hot-dip galvanized coatings

H. Asgari,M.R. Toroghinejad,M.A. Golozar 한국물리학회 2009 Current Applied Physics Vol.9 No.1

Hot-dip galvanized zinc coating is the most frequently used among coatings to protect steel against corrosion. When coated steel sheets are subjected to a corrosive environment, its corrosion behaviour is affected by texture and microstructure variations. The aim of this research work was to study the texture and corrosion resistance of hot-dip galvanized zinc coatings affected by the coating thickness and chemical composition of the zinc bath. Texture of the coatings was evaluated employing X-ray diffraction whilst its corrosion behaviour was analyzed using Tafel polarization test. Experimental results showed that (00.2) basal texture component would be weakened by increasing the lead content of the zinc bath and coatings with strong (00.2) texture component have lower corrosion current density than the coatings with weak (00.2) texture component. Furthermore, it was inferred that by increasing the thickness of the coatings with the same content of lead in the zinc bath, the relative intensity of (00.2) texture component and corrosion resistance of the coatings would be decreased and conversely, relative intensity of (20.1) high angle pyramidal planes and (10.0) prism planes would be increased due to establish a balance between surface and strain energies. Besides, five types of morphology were observed on the surface of hot-dip galvanized coatings in dull and bright spangles. Finally, it was recognized that the main corrosion product of the salt spray test is Simonkolleite. Hot-dip galvanized zinc coating is the most frequently used among coatings to protect steel against corrosion. When coated steel sheets are subjected to a corrosive environment, its corrosion behaviour is affected by texture and microstructure variations. The aim of this research work was to study the texture and corrosion resistance of hot-dip galvanized zinc coatings affected by the coating thickness and chemical composition of the zinc bath. Texture of the coatings was evaluated employing X-ray diffraction whilst its corrosion behaviour was analyzed using Tafel polarization test. Experimental results showed that (00.2) basal texture component would be weakened by increasing the lead content of the zinc bath and coatings with strong (00.2) texture component have lower corrosion current density than the coatings with weak (00.2) texture component. Furthermore, it was inferred that by increasing the thickness of the coatings with the same content of lead in the zinc bath, the relative intensity of (00.2) texture component and corrosion resistance of the coatings would be decreased and conversely, relative intensity of (20.1) high angle pyramidal planes and (10.0) prism planes would be increased due to establish a balance between surface and strain energies. Besides, five types of morphology were observed on the surface of hot-dip galvanized coatings in dull and bright spangles. Finally, it was recognized that the main corrosion product of the salt spray test is Simonkolleite.

황산,염산 복합 내식강 개발: 2, 현장 적용성 평가를 통한 개발강의 신뢰성 검증

박선아 ( Sun Ah Park ),장승익 ( Seung Ik Jang ),김정구 ( Jung Gu Kim ),이병호 ( Byoung Ho Lee ),윤정봉 ( Jung Bong Yoon ) 대한금속재료학회(구 대한금속학회) 2014 대한금속·재료학회지 Vol.52 No.11

A newly developed low-alloy corrosion-resistant steel shows superior properties to sulfuric and hydrochloric acid dew-point corrosion as well as excellent mechanical properties, weldability and machinability with attention to low cost and high efficiency. In addition, welding materials which can accommodate the corrosion-resistant properties and mechanical properties of newly developed low-alloy corrosion-resistant steel have also been developed. Generally, to assess corrosion performance of developed steels, specimens were evaluated by laboratory corrosion tests in a simulated field environment. However, a flue gas desulfurization (FGD) system included several environmental parameters such as change of corrosion environment depending on shutdown/ operation of power plants, location of steels in facilities and velocity of a moving fluid. Therefore, to verify the reliability of newly corrosion-resistant steel, plant qualification test is necessary. In an actual environment, new developed low-alloy corrosion-resistant steel was proved to have better corrosion resistance than the other steels (existing corrosion-resistant steels and ordinary carbon steel). (Received July 26, 2014)

Corrosion Resistance of Cr-bearing Rebar to Macrocell Corrosion Caused by Concrete Cover Crack

Tae, Sung-Ho,Lee, Han-Seung,Noguchi, Takafumi,Ujiro, Takumi,Shin, Sung-Woo The Iron and Steel Institute of Japan 2006 ISIJ international Vol.46 No.7

<P>Artificial cracks were made in the cover concrete of specimens embedding ten types of steel rebars having different Cr contents with the aim of developing Cr-bearing steel rebars resistant to macrocell corrosion environments induced by cracking in cover concrete. The cracks were subjected to intensive penetration of carbon dioxide (carbonation specimens) and chloride ions (chloride attack specimens) to form macrocells. Both groups of specimens were then subjected to accelerated corrosion curing, during which the macrocell corrosion current density was measured. The corrosion area and corrosion loss were also measured at the end of 105 cycles of this accelerated curing. In a macrocell corrosion environment induced by localized carbonation, the minimum Cr content of rebars required for corrosion resistance was 7%. Rebars with a Cr content of 11% were proven corrosion-resistant in a chloride ion concentration macrocell with a concentration difference of not more than 3 kg/m<SUP>3</SUP>.</P>

부식전위 기준에 의한 철근콘크리트 구조물의 부식진단의 위험성에 관한 고찰

정진아 ( Jin A Jeong ) 한국부식방식학회(구 한국부식학회) 2015 Corrosion Science and Technology Vol.14 No.3

Corrosion of steel reinforcement is a major factor in the deterioration of harbour and bridge structure. Steel corrosion in concrete must be checked for assessing the condition of a reinforced concrete structure. There are several ways how to measure the corrosion condition of reinforced concrete, but the corrosion potential measurement is a very simple, rapid, cost-effective and non-destructive technique to evaluate the severity of corrosion in reinforced concrete structure, therefore commonly used by engineers. However some particular situations may not relate to the reinforcement corrosion probability and a simple comparison of the corrosion potential data with the ASTM C876 Standard on steel reinforcement corrosion probability could be meaningless and not give reliable informations because of environment factors as oxygen concentration, chloride content, concrete resistance. Therefore this paper explains the risk of corrosion assessment in reinforced concrete structure and how many factors can affect the reliability of the corrosion potential data.