• Journal of Environmental Science International
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• v.11 no.5
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• pp.445-454
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• 2002

Material exposure experiments were performed to evaluate the relationship between air pollution and material corrosion rates based on collaboration with researchers in China, Japan, and Korea. Qualitative and quantitative atmospheric corrosion was estimated from damage caused to bronze, copper, steel, marble, cedar, cypress, and lacquer plates exposed to outdoor and indoor conditions in certain East Asian cities. The effects of atmospheric and meteorological factors on the damage to the copper plates and marble pieces were estimated using a regression analysis. The results indicated that sulfur dioxide produced the most destruction of the materials, especially in South Korea and China. In Japan, the copper plates were damaged as a result of natural conditions and sea salt. Copper was also found to be damaged by the surface deposition of sulfur and chlorine. Meanwhile, marble was substantially degraded by gaseous sulfur dioxide, yet sulfate ions in rain had no effect. Accordingly, the analysis of air pollution from the perspective of material damage was determined to be very useful in evaluating and substantiating the intensity of air pollution in East Asia.

• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.721-726
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• 2003

The Durability of Concrete Structure is serverely degraded due to mainly carbonation, sulfate attack and chloride ion diffusion in concrete. The ultimate purpose of this study is to obtain how much the durability of Concrete Structure is improved according to the variation of physical properties in concrete or the frequency of surface coating on concrete. Where, variation of physical properties is a water-cement ratio or amount of air. The experiments are the chliride ion diffusion test, the lapid corrosion test, the lapid carbonation test, the test on resistance to freezing and thawing. Finally, this study shows that the effect by the surface coating method is better than the variation of physical properties in concrete.

• Journal of the Korean institute of surface engineering
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• v.15 no.4
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• pp.218-225
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• 1982

The effects of ferrous ion on the properties of bright nickel electrodeposit were exa-mined. Iron exists as ferrous ion (Fe+2) and ferric ion (Fe+3) in the bath, a portion of the former tend to be oxidized to the somewhat harmful ferric ion. Iron was added to bath as the ferrous sulfate, ferrous ion prevented from the oxidation with citric acid. It was found that the hardness was increased as the concentration of ferrous ion, the ductility was slightly increased too. The appearance can obtain the wide bright deposits within 4g/$\ell$. The corrosion resistance drastically dropped from 5g/$\ell$ In the case of considering the effect of ferrous ion on the corrosion resistance and the appearance, the allowable limits is 4g/$\ell$, if the reductant is used.

• Journal of the Korean Applied Science and Technology
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• v.28 no.2
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• pp.140-145
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• 2011

Cationic gemini-surfactant, namely 1,4-butane-bis(N-alkanoyloxyethyl-N,Ndimethyl)-diammonium bromide was synthesized and their inhibition effect on corrosion of mild steel in 1 M HCl solution was tested by weight loss method. The synthesized product was confirmed by FT-IR and $^1H-NMR$ spectroscopy. Surface tensions were measured by surface tensiometer Sigma 70. Their c.m.c. values evaluated by surface tension method was $4.1{\times}10^{-5}{\sim}5.4{\times}10^{-5}$ mol/L. The Krafft point of the these surfactants were <0~$10.7^{\circ}C$. The emulsifying properties of synthesized cationic gemini surfactants and sodium dodecyl sulfate (SDS), tetradecyl trimethyl ammonium bromide (TTAB) was investigated. Of these, 1,4-butane-bis(N-lauroyloxyethyl-N,N-dimethyl)- diammonium bromide, CGL 14-4-14 has been confirmed as a good emulsifier. The inhibition efficiency increases by increasing cationic gemini surfactant concentration. As a result, these surfactants are expected to be applied as corrosion inhibitors.

• Journal of the Korean Applied Science and Technology
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• v.31 no.1
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• pp.1-6
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• 2014

Gemini type of cationic surfactant, namely ${\alpha},{\omega}$-alkane-bis(N-lauroyloxyethyl-N,N-dimethyl)-diammonium bromide was synthesized and confirmed by FT-IR and $^1H$-NMR spectroscopy. Their inhibition effect on corrosion of mild steel in 1 M HCl solution was tested by weight loss method. Surface tensions were measured by surface tensiometer Sigma 70. Their c.m.c. values evaluated by surface tension method was $4.01{\times}10^{-5}{\sim}4.99{\times}10^{-5}mol/L$. The Krafft point of the these surfactants were < $0^{\circ}C$. The emulsifying properties of synthesized cationic gemini surfactants and sodium dodecyl sulfate (SDS), tetradecyl trimethyl ammonium bromide (TTAB) was investigated. Of these, ${\alpha},{\omega}$-alkane-bis(N-lauroyloxyethyl-N,N-dimethyl)-diammonium bromide has been confirmed as a good emulsifier. The inhibition efficiency increases by increasing cationic gemini surfactant concentration. As a result, these surfactants are expected to be applied as corrosion inhibitors.

• Microbiology and Biotechnology Letters
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• v.30 no.1
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• pp.86-90
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• 2002

Cooling water sampled at Pohang Steel Company, Korea, was used to study the effect of biocide (NaOCl) on biofilm formation and metal corrosion. Planktonic microorganisms were killed in the presence of biocide (0.2％ NaOCl) within 1.5 h, but not sessile microorganisms in biofilms even after one week. Black color of biofilms, possibly due to the activity of sulfate reducing bacteria, were made with the natural cooling waters, while orange color of biofilms were formed when cooling waters were autoclaved or when 0.2％ NaOCl was added to the natural cooling waters. Microbially influenced corrosion rate in black color of biofilms was 2.3 fold higher than that in orange color of biofilms.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.399-402
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• 2000

When concrete structures are built in marine environment, they may be deteriorated and have the poor durability and quality caused by steel corrosion or by chemical attack of magnesium or sulfate ions. Especially, Mg ions contained in seawater make concrete surface weaken by chemical reaction with $Ca(OH)_2$ In this study, a concrete structure built in 1947 was investigated to estimate the factors, especially chemical attack, which can cause concrete to deteriorate. Furthermore, the instrumental analysis methods such as XRD and ESEM were performed to find the reactants in concrete under marine environment.

• Journal of Conservation Science
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• v.29 no.2
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• pp.187-196
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• 2013

This study is on the corrosion of iron objects caused by sulfides in undersea environment. The corrosion state of objects in seawater and their damage state after underwater and left in highly humid air were studied. The samples of this study were four iron objects which had been taken out from undersea mud layer located in Taean Mado, Chungcheongnamdo. SEM-EDS and XRD analyse on the objects to check whether they have sulfides or not. The result of analysis suggested that the major component of corrosion product generated in undersea deposit soil is sulfur(S) and iron sulfide(FeS) is formed as sulfide. However, there was no clear corrosion on the surface of objects which was exposed to sea water because of the impact of concretion which covered the surface. In order to check the damage status of iron objects after they had been taken out of sea water, exposure tests in high humidity environment and dehumidified environment were done on the corrosion products. The result of the test suggested that the oxidization of iron sulfide corrosion product makes iron sulfate ($FeSO_4$) and sulfuric acid ($H_2SO_4$) and they can cause secondary corrosion of iron objects. Therefore, it is believed that the iron sulfide corrosion product of iron objects taken out from underwater environment should be removed by all means and the keeping environment of the iron objects should also maintain dehumidified state.

• Journal of the Korea Institute of Building Construction
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• v.22 no.6
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• pp.663-672
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• 2022

The purpose of this study is to evaluate the magnesium sulfate resistance of a geopolymer mixed with rice husk powder. General concrete, silica fume mixed concrete, and binary blended geopolymer were selected as comparison targets to confirm the magnesium sulfate resistance, and sulfate deterioration was calculated using the compressive strengths with ages. In addition, the weight change rate and the relative dynamic coefficient of the geopolymer were comparatively analyzed, and the degree of etteringite formation was confirmed using X-ray diffraction analysis. the experiment, the geopolymer mixed with 10% rice husk powder showed 10.8% higher compressive strength than concrete with silica fume when submerged for 56 days. Also, the geopolymer mixed with rice husk powder showed a small weight change rate of 0.9 to 1.45%. composition after immersion in magnesium sulfate through X-ray diffraction analysis, it was observed that a small amount of ettringite was dispersed in the geopolymer containing rice husk powder. Thus, there is a high correlation with the corrosion resistance of magnesium sulfate

• Clean Technology
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• v.23 no.3
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• pp.223-236
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• 2017

As the use of waste and biomass increases in a power generation boiler, high temperature corrosion (HTC) problems of boiler heat exchangers are becoming very important. Chlorine of the low-rank fuels is mainly responsible for the HTC issues, which typically occur in the surface of high temperature heat exchanger like a superheater or reheater. In order to mitigate the problem, various approaches have been proposed in terms of design modification, material improvement, fuel pre-treatment and additive utilization. In this study, the current state of research and development focused on the additive method was investigated.