• 제목/요약/키워드: Surface corrosion

검색결과 2,604건 처리시간 0.029초

염수 환경에서 Inconel 718의 국부 부식 거동 (Localized Corrosion Behavior of Inconel 718 in a Chloride-Containing Aqueous Solution)

  • 이준섭;이예진;권순일;신정호;이재현
    • Corrosion Science and Technology
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    • 제20권6호
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    • pp.361-366
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    • 2021
  • Localized corrosion behavior of Ni-based Inconel 718 alloy was investigated by electrochemical anodic polarization techniques in NACE TM 0177 A solution of 5 wt% NaCl + 0.5 wt% acetic acid at room temperature. After the solution heat treated at 1080 ℃ for 2.5 h, Inconel 718 was age-hardened at 780 ℃ for 8 h. The microstructure of the alloy surface was investigated by optical microscopic or scanning electron microscopic technique. The austenitic phase with the presence of metal carbides was observed on the surface of Inconel 718. Metal-carbides such as Nb-Mo and Ti-carbide with diameters of approximately 10 and 3 ㎛, respectively, were formed in Inconel 718. Anodic polarization results revealed that localized corrosion was observed at the interface between austenitic phase of a substrate and metal carbides. Difference in electrochemical property between a metal carbide and an austenitic substrate could provide an initiation site for localized corrosion of Inconel 718 surface.

새로운 히드라존에 의한 염화물 오염 합성 콘크리트 공극 솔루션에서 철근의 부식 억제에 대한 통찰력 (Insights into the corrosion inhibition of steel rebar in chloride-contaminated synthetic concrete pore solutions by a new hydrazone)

  • 하산 르가즈;이한승
    • 한국건축시공학회:학술대회논문집
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    • 한국건축시공학회 2022년도 봄 학술논문 발표대회
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    • pp.101-102
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    • 2022
  • A new hydrazone derivatives namely (E)-N'-(4-(dimethylamino)benzylidene)-2-(5-methoxy-2-methyl-1H-indol-3-yl)acetohydrazide (HIND) has been confirmed for mitigating the corrosion of the steel rebar exposed to chloride contaminated synthetic concrete pore solution (ClSCPS). The mitigation of corrosion properties has been characterized by weight loss and electrochemical methods (Electrochemical impedance, Potentiodynamic polarization studies) as well as surface observations. The presence of HIND in the ClSCPS decreased the corrosion of steel rebar by adsorption of HIND molecules on the surface of the steel rebar. The optimal HIND concentration was 0.5 mmol/L, corresponding to an inhibition efficiency of 88.4%. The use of HIND enables the corrosion process to have a higher energy barrier. X-ray photo electron spectroscopy (XPS), atomic force microscopy (AFM), scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS), and X-ray diffraction (XRD) spectroscopy interpretations confirmed that HIND mitigates the corrosion attack on the surface steel rebar.

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천연가스 수송용 API 5L-X65강 용접부의 부식거동에 관한 연구 (On Corrosion Behaviors in Welded Zone of API 5L-X65 Steel for Natural Gas Transmission)

  • 조상근;송한섭;공유식;김영대
    • 한국해양공학회지
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    • 제18권5호
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    • pp.50-56
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    • 2004
  • This study is on the constant-current stress corrosion test, related to the load stress, in both the welded and non-welded zones of high tensile strength steel that is used for natural gas transmission. The surface corrosion pattern of the welded zone of API 5L-X65 specimens for natural gas transmission showed general corrosion and narrow pitting, and the pitting was increased with load stress. Initially, the average relative electrode potential and the average relative current of the high tensile strength steel, used for natural gas transmission specimens, were decreased rapidly, and the average relative electrode potential was higher and the average relative current was lower in welded zone, compared to base metal. The average relative electrode potential was decreased with load stress, and the average relative current was somewhat increased by increasing the load stress. The corrosion rate was less in welded zone, compared to base metal, and the corrosion rate was decreased by increasing the load stress.

TiN 이온 플레이팅한 강판의 내식성에 관한 연구(III)-Ni 및 Ti 하지코팅두께의 영향- (Corrosion Behavior of TiN Ion Plated Steel Plate(III)-Effects of Ni and Ti interlayer thickness-)

  • 한전건;연윤모
    • 한국표면공학회지
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    • 제26권2호
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    • pp.55-62
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    • 1993
  • The effect of interlayer coating thickness of Ni and Ti on corrosion behavior was studied for TiN ion plat-ed steel plate. Interlayer coating was carried out in a single and bi-layer to a various thickness combination prior to final TiN coating. Corrosion behavior was evaluated by anodic polarization test in 1N H2SO4 as well as salt spray test. Ni interlayer coating was effectived in reducing corrosion current density of active region and Ti interlayer coating over Ni coating reduced the anodic corrosion current density by an order of 4 with increasing the thickness of Ti up to$ 3\mu\textrm{m}$. The improvement of corrosion resistance by Ni/Ti interlayer coating was attributed to the effective prevention of penetration of active corrosion agent resulting from the inherent corrosion resistance of Ni and Ti. Putting corrosion behavior was observed from salt spray test result for all specimens and corrosion resistance at salt atmosphere was enhanced with increasing Ni and Ti thickness, Cor-lay TiN coating was spalled out by the generation of corrosion products.

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Effects of pH and Chloride Concentration on Corrosion Behavior of Duplex Stainless Steel and Titanium Alloys Ti 6Al 2Nb 1Ta 1Mo at Elevated Temperature for Pump Impeller Applications

  • Aymen A., Ahmed;Ammar Yaseen, Burjes;Ammar Yaseen, Burjes
    • Corrosion Science and Technology
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    • 제21권6호
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    • pp.454-465
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    • 2022
  • The objective of this study was to determine effects of temperatures and pH of sodium chloride solution with MgCl2 ions on corrosion resistance of duplex stainless-steel X2CrNiMoN22-5-3 (DSS) and Ti 6Al 2Nb1Ta1Mo (Ti). Effects of sodium chloride concentration on corrosion resistance were also studied. Corrosion behavior and pitting morphology of duplex stainless steel (DSS) and Ti alloys were evaluated through potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). It was found that a decrease in pH significantly reduced the corrosion resistance of both alloys. Changes in chloride concentration and temperature had more substantial impact on corrosion behavior of DSS than on Ti alloys. Pitting corrosion was formed on DSS samples under all conditions, whereas crevice corrosion was developed on Ti samples with the presence of magnesium chloride at 90 ℃. In conclusion, magnesium chloride ions in an exceedingly strong acidity solution appear to interact with re-passivation process at the surface of these alloys and influence the resulting surface topography.

Comparative analysis of modeling approaches for sulfide-induced corrosion of copper disposal canisters in a 3-dimensional domain

  • Heejae Ju;Nakkyu Chae;Jung-Woo Kim;Hong Jang;Sungyeol Choi
    • Nuclear Engineering and Technology
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    • 제56권8호
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    • pp.3385-3396
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    • 2024
  • Copper canisters are commonly employed to contain HLW for the long-term, making it crucial to understand how corrosion affects the canister. This study conducted a comparative analysis of two widely used calculation methods for modeling canister corrosion within a 3-D DGR domain. The first method, termed transport-limited corrosion, assumes an immediate sulfide-copper reaction and has been traditionally used due to its conservative nature. The second method, known as the potential-limited corrosion, considers coupled redox reactions at the canister surface and computes corrosion rates through anodic current density. From the results, we found that the edge of the canister geometry and the omission of electrochemical kinetics impose critical limitations with the transport-limited corrosion method. These limitations include the singularity problem, excessive sensitivity to the curvature of the canister's edge, and an inability to evaluate the distribution of corrosion rate over the canister surface as a function of the sulfide concentration. On the other hand, the potential-limited corrosion method avoided the limitations found in the other method. Since the factors relating to these limitations are critical to the design and optimization of the copper disposal canister, careful consideration when selecting appropriate calculation methods for corrosion will be required.

$CaCO_3$침전능 조절에 의한 금속시편에서의 부식방지 (The Corrosion Control Using CCPP(Calcium Carbonate Precipitation Potential )Index in Metallic Coupons)

  • 이재인;임진경;서상훈;김동윤;신춘환
    • 한국환경과학회지
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    • 제9권6호
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    • pp.505-509
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    • 2000
  • The purpose of this study was to evaluate the effects of $Ca(OH)_2$ and $CO_2$ additions on the corrosion of metal coupons(ductile iron, galvanized steel, copper and stainless steel). Corrosion rate and released metal ion concentration of ductile iron and galvanized steel decreased by adjusting alkalinity, calcium hardness and pH with $Ca(OH)_2$ & $CO_2$ additions on copper and stainless steel were less than those on ductile iron and galvanized steel. When ductile iron coupon was exposed to water treated with Ca(OH)$_2$&$CO_2$, additions, the main components of corrosion product formed on its surface were $CaCO_3$ and $Fe_2 O_3 or Fe_2 O_4$ which often reduce the corrosion rate by prohibiting oxygen transport to the metal surface.

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합금도금강판의 수적에 의한 표면층의 부식기구에 관한 연구 (A Study on the Corrosion Mechanism by the Moisture on the Surface Layer of the Alloys Coated Steel Sheet)

  • 김영호;김순경;전언찬
    • 한국기계가공학회지
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    • 제1권1호
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    • pp.71-78
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    • 2002
  • Since the early 1980's the use of zinc-aluminum alloy-coated steel sheet(Galvalume) for vehicular corrosion protection has increased drastically. It is consisting of 55%Al-43.4% Zn-1.6%Si. Galvalume has a good corrosion resistance, heat reflectivity and shiny appearance, which has a dendritic structure of alloy layer. It has a good corrosion resistance due to dendritic structure. But, this also has a weak point against moisture during long period of transportation as sheeted and or coiled without any relation of chromating on the surface of steel sheet or not because of high humidity and temperature. Here, We studied the corrosion mechanism by the moisture.

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반복하중을 받는 배관용 강재의 피로수명에 미치는 부식의 영향 (Effect of Corrosion on Fatigue Life of Piping material under Repeating Load)

  • 박경동;안재필
    • 한국마린엔지니어링학회:학술대회논문집
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    • 한국마린엔지니어링학회 2005년도 후기학술대회논문집
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    • pp.228-229
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    • 2005
  • The compressive residual stress, which is induced by shot peening process, has the effect of increasing the intrinsic fatigue strength of surface and therefore would be beneficial in reducing the probability of fatigue damage. However, it was not known that the effect of shot peening in corrosion environment. In this study, the effect of shot peening on corrosion fatigue crack growth of sping steel immersed in 6% $FeCl_3$ solution and corrosion characteristics with considering fracture mechanics. The results of the experimental study corrosion fatigue characteristics of spring steel are as follows; the fatigue crack growth rate of the shot peening material was lower than of the un peening material. And fatigue life shows more improvement in the shot peening material than un peening material. This is because the compressive residual stress of surface operate resistance of corrosion fatigue crack propagation. It is assumed that the shot peening process improve corrosive resistance and mechanical property.

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원자로 냉각재 펌프용 재료의 화학 제염 공정 시 적용 가능성 평가 (Evaluation of application possibility in chemical decontamination of materials for reactor coolant pump)

  • 김정일;김기준;김성종
    • Journal of Advanced Marine Engineering and Technology
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    • 제31권1호
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    • pp.84-94
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    • 2007
  • As a reactor coolant pump(RCP) is operated in the nuclear power system for a long time. so its surface is continuously contaminated by radioactive scales. In order to perform regular or emergency repair about RCP internals a special decontamination process should be used to reduce the radiation from the RCP surface by means of chemical cleaning. In this study, applicable possibility in chemical decontamination for RCP was investigated on the various materials. The STS 304 showed the best electrochemical properties for corrosion resistance than other materials. However, the pitting corrosion was slightly generated in both STS 415 and STS 431 with the increasing numbers of cycle and intergranular corrosion were sporadically observed. The size of their pitting corrosion and intergranular corrosion were also increased with increasing cycle numbers.