• Corrosion Science and Technology
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• 제9권2호
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• pp.74-80
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• 2010

For the purpose of applying a hot-dip Zn-6mass%Al-3mass%Mg alloy coated steel sheet (ZAM) to automotive body materials, a laboratory study of the general properties required for inner and outer panels of automotive bodies was performed. Even with only light coating weight, ZAM showed an excellent corrosion resistance in terms of both cosmetic and perforation corrosion compared to the currently used materials for automotive bodies, GI70 and GA45. In our study, it was confirmed that ZAM exhibits as good as or better properties than GI70 in terms of spot weldability and press formability. Furthermore, since the same corrosion resistance can be achieved with less coating weight by applying ZAM, laser weldability is better than GI and GA.

• Structural Engineering and Mechanics
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• 제41권5호
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• pp.645-662
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• 2012

Deteriorative effects of steel corrosion on the structural response of reinforced concrete are simulated for varying degrees of corrosion. The simulation approach is based on a three-dimensional irregular lattice model of the bulk concrete, in which fracture is modeled using a crack band approach that conserves fracture energy. Frame elements and bond link elements represent the reinforcing steel and its interface with the concrete, respectively. Polylinear stress-slip properties of the link elements are determined, for several degrees of corrosion, through comparisons with direct pullout tests reported in the literature. The link properties are then used for the lattice modeling of reinforced concrete beams with similar degrees of corrosion of the main reinforcing steel. The model is successful in simulating several important effects of steel corrosion, including increased deflections, changes in flexural cracking behavior, and reduced yield load of the beam specimens.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2017년도 추계 학술논문 발표대회
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• pp.90-91
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• 2017

Concrete can be used semi-permanently unless the steel is corroded. However, the concrete exposed to the marine environment is exposed to sea breeze, so chloride ions penetrate into the concrete and the steel is corroded accordingly. In order to solve these problems, there is a method of increasing the covering depth of the concrete and an application of the epoxy paint to the steel. In this study, the hydrotalcite type corrosion inhibitor was mixed with the concrete and the compressive strength, chloride diffusion coefficient and the corrosion properties of the steel were examined.

• Applied Microscopy
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• 제52권
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• pp.10.1-10.15
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• 2022

The effect of carbon doping contents on the microstructure, hardness, and corrosion properties of heat-treated AISI steel grades of plain carbon steel was investigated in this study. Various microstructures including coarse ferrite-pearlite, fine ferrite-pearlite, martensite, and bainite were developed by different heat treatments i.e. annealing, normalizing, quenching, and austempering, respectively. The developed microstructures, micro-hardness, and corrosion properties were investigated by a light optical microscope, scanning electron microscope, electromechanical (Vickers Hardness tester), and electrochemical (Gamry Potentiostat) equipment, respectively. The highest corrosion rates were observed in bainitic microstructures (2.68-12.12 mpy), whereas the lowest were found in the fine ferritic-pearlitic microstructures (1.57-6.36 mpy). A direct correlation has been observed between carbon concentration and corrosion rate, i.e. carbon content resulted in an increase in corrosion rate (2.37 mpy for AISI 1020 to 9.67 mpy for AISI 1050 in annealed condition).

• 한국환경과학회지
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• 제7권3호
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• pp.361-368
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• 1998

The structure such as building and cultural properties was composed of various materials like wood, metal and stone that have been utilized and exposed to air, wind and rain far a long time. However, because of their special characteristics as structure, collecting of samples that may involve their destruction cannot be permitted, ever for material analysis. Therefore, h order to study the Influence of atmospheric pollution on structure, atmospheric corrosion tests were achieved by making use of materials(bronze. ancient copper, copper, steel and marble) in field exposure tests. Atmospheric exposure sites are selected from places which are characterized by urban, rural, Industrial and marine enoronments In Northeast Asia. According to the results of atmospheric corrosion tests: The corrosion rates of Industrial states In china were more serious than other sampling sites. In the correlation of meteorological factors. wet hours was defiled as Intogeacted hours under that atmospheric temperature is above $0^{\circ}C$ and relative humidity in above 80% that has a great influence on corrosion tests of materials in case of a short time. The relative humidity was above about 75% that resulted in great increase of corrosion rates. In the esimation of corrosion rates between materials, corrosion rates of steel was about thirty times and decuple larger than that of other materials excluding marble in unshelterd exposure and In sheltered exposure.

• Journal of Welding and Joining
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• 제18권6호
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• pp.48-54
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• 2000

The corrosion properties of Ni-Cr-W-Mo-B alloy sprayed by the high velocity oxy-fuel spraying (HVOF) was studied as a function of heat treatment by using both potentiodynamic polarization and immersion tests in the H₂SO₄ solution. The mechanical property was also evaluated by a microhardness tester. Microstructural characteristics of te as-sprayed and annealed coatings at 550, 750 and 950℃ have been analyzed by means of OM, XRD, SEM and TEM. The results showed that the corrosion resistance was improved by increasing the annealing temperature. As-sprayed coating had metastable and heterogeneous phases such as amorphous, nanocrystalline and very refined grain and precipitates, which induced a localized corrosion. The localized corrosion occurred preferentially at the unmelted particles which were composed of Ni matrix and Cr, W and Mo riched phase segregated in the boundaries. As annealing temperature was increased, the microstructure had shown some changes - reduction of porosity and s[plat boundary decomposition and crystallization of amorphous/nanocrystalline phases, grain coarsening,, formation and growth of precipitates such as {TEX}$M_{23}C_{6}${/TEX} and {TEX}$M_{7}C_{3}${/TEX}. In addition, the compositional difference between matrix and boundary phases gradually disappeared, which changed the corrosion type from localized corrosion to general corrosion and thus enhanced corrosion resistance.

• Corrosion Science and Technology
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• 제18권5호
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• pp.168-174
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• 2019

The sol-gel methodology has been applied successfully in the synthesis of a novel hybrid coating based on dimethoxymethyl-n-octadecylsilane precursor. The newly synthesized parent coating was functionalized further with two commercially-available corrosion-inhibitive pigments Moly-$white^{(R)}$ 101-ED and Hfucophos $Zapp^{(R)}$, applied to mild steel panels, and immersed continuously in 3.5% NaCl electrolytic solution for 288 h. The corrosion protection performance of the prepared functional coatings was evaluated using electrochemical impedance spectroscopy (EIS) and DC polarization techniques. An enhancement in the barrier properties has been revealed from the electrochemical characterization data of the hybrid films, in comparison with untreated mild steel substrates following long-term immersion in 3.5% NaCl. The corrosion resistance properties of the newly developed coatings over mild steel substrates found to be largely dependent on the type of the loaded inhibitive pigment in which the Moly-white inhibitor has a positive impact on the corrosion protection performance of the parent coating, while an opposite behavior was observed upon mixing the base polymeric matrix with the commercially-available Zapp corrosion inhibitor.

• 한국구조물진단유지관리공학회 논문집
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• 제4권1호
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• pp.121-129
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• 2000

In general. service life of the sea-shore concrete structures is largely influenced by the corrosion of reinforcing steel due to the chloride contamination, and the penetration of chloride ions into concrete is governed by concrete condition state as a micro-structure. In this study, characteristics of chloride diffusion in concrete are analyzed in accordance with the mixing properties and durability of concrete, by considering the facts that micro-structure of concrete varies with the mixing properties and can indirectly be analyzed by using the durability test. In order to predict the service life of existing concrete structures, chloride diffusion equation for the concrete structures under various service conditions and the major parameters used in that equation are formulated as the mathematical models. Based on the results of chloride diffusion analysis in accordance with the mixing properties and durability of concrete and mathematical models formulated in this study, a prediction system is developed to predict the corrosion initiation of reinforcing steel in the sea-shore concrete structures.

• 한국구조물진단유지관리공학회 논문집
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• 제9권2호
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• pp.191-198
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• 2005

철근의 부식율에 따른 철근 콘크리트 보의 구조적 성능 저하를 정량적으로 고찰하기 위하여 실험 및 해석을 수행하였다. 이를 위하여 먼저 부식철근의 인장실험과 부착성능 실험을 통하여 철근의 부식율에 따른 항복강도와 탄성계수 및 부착성능을 정량적으로 산정할 수 있는 구성방정식을 구성하고, 인장주근이 부식된 RC보 실험결과와 산출된 부식모델을 반영한 비선형 해석 결과와 비교하였다. 결론적으로 본 연구에서 제시된 철근부식 모델을 이용한 비선형 해석을 통하여 인장주근이 부식된 철근 콘크리트 보의 휨 거동을 합리적으로 예측할 수 있음을 검증하였다.

• 자원리싸이클링
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• 제7권5호
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• pp.52-57
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• 1998

현재 구조용 합금으로는 최경량화인 Mg-Li-Al합금의 내식성에 미치는 Si의 영향을 전기화학적 분극시험에 의하여 조사하였다. 전기화학적 분극시험은 ${KH}_{2}{PO}_{5}$·NaOH 완충용액으로 pH7로 고정한 0.03% NaCl 전해액에서 Mg-Li-Al(A4)합금과 Mg-Li-Al에 Si을 0.48 wt% 첨가한 (S5)합금에 대하여 전류밀도에 따른 전위의 변화를 측정하였다. 실험 결과 미량의 Si를 첨가한 Mg-Li-Al-Si 합금의 경우가 Si을 첨가하지 않은 Mg-Li-Al 합금의 경우보다 부식속도가 증가하였으며, 부식생성물의 분포범위도 넓었고 생성량도 많았다. 이러한 실험결과를 고려해 볼 때, Mg-Li-Al 합금에 미량이지만 Sidl 첨가됨으로써 Mg-Li-Al 합금의 내식성이 감소된다고 판단된다. 따라서 강도특성이 향상을 목적으로 첨가하는 Si의 첨가량에 대해서는 적절한 양의 조정이 필요하다.