• 제목/요약/키워드: Surface corrosion

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원자로 냉각재 펌프용 스테인리스강에 대한 화학적 제염 공정 개발 (Development of Chemical Decontamination Process of Stainless Steel for Reactor Coolant Pump)

  • 김성종;한민수;김정일;김기준
    • 한국표면공학회지
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    • 제40권5호
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    • pp.234-240
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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 maintain for RCP internals, a special chemical decontamination process should be used to reduce the radiation from the RCP surface. In this study, applicable possibility in chemical decontamination for RCP was investigated for the various stainless steels. The stainless steel (STS) 304 showed the best electrochemical properties for corrosion resistance and the lowest weight loss ratio in chemical decontamination process model 3-1 than other materials. However, the pitting corrosion was generated in both STS 415 and STS 431 with the increasing numbers of cycle. The intergranular corrosion in STS 415 was sporadically observed. The sizes of their pitting corrosion were also increased with increasing cycle numbers.

EDTA.2Na를 이용한 구리 부식생성물의 화학세정 및 NALCO-39L에 의한 표면처리효과 (Chemical Cleaning of Copper Corrosion Product Using EDTA.2Na Salt and Effect of Surface Treatment by NALCO-39L)

  • 이한철;이창우;현성호
    • 한국안전학회지
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    • 제14권1호
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    • pp.86-92
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    • 1999
  • This study was carried out to investigate the effect of chemical cleaning of corrosion product on cooling system made of copper as a basic material and using cooling water as pure water. We studied chemical cleaning condition that minimizes the influence on basic material by means of EDTA solution so as to eliminate the slurry in cooling system. In addition, the proper amount of NALCO-39L (Nitrite-Borate-BZT mixture) as a inhibitor was determined in order to protect the copper in cooling system against corrosion after chemical cleaning and the effect of corrosion resistance on the copper surface treated was excelent in comparison with surface untreated. As a result, we found that the main components of sludge in cooling system produced by corrosion of copper were $Cu_2O$, CuO, Cu, and Fe. The optimum condition of chemical cleaning was 400ppm EDTA solution at $60^{\circ}C$. Inhibitor concentration needed to treat the surface of pure copper was 15~20ppm per unit area and corrosion rate of copper treated with 500ppm inhibitor solution for 72 hrs at $60^{\circ}C$ was remarkably decreased as compared with that of pure copper.

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k-means 클러스터링을 이용한 강판의 부식 이미지 모니터링 (Corrosion Image Monitoring of steel plate by using k-means clustering)

  • 김범수;권재성;최성웅;노정필;이경황;양정현
    • 한국표면공학회지
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    • 제54권5호
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    • pp.278-284
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    • 2021
  • Corrosion of steel plate is common phenomenon which results in the gradual destruction caused by a wide variety of environments. Corrosion monitoring is the tracking of the degradation progress for a long period of time. Corrosion on steel plate appears as a discoloration and any irregularities on the surface. In this study, we developed a quantitative evaluation method of the rust formed on steel plate by using k-means clustering from the corroded area in a given image. The k-means clustering for automated corrosion detection was based on the GrabCut segmentation and Gaussian mixture model(GMM). Image color of the corroded surface at cut-edge area was analyzed quantitatively based on HSV(Hue, Saturation, Value) color space.

콘크리트의 소수성 표면처리를 통한 철강 보강재의 내식성 향상 (Enhancement of Corrosion Resistance of Steel Reinforcement in Concrete by Hydrophobic Surface Treatments)

  • 조현빈;신동민;서은혜;이욱진;이정훈
    • 한국표면공학회지
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    • 제53권6호
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    • pp.300-305
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    • 2020
  • Corrosion of reinforcement steel rebar is a serious problem in a wide range of concrete application for buildings and infrastructures. Hydrophobizing surface treatments, such as self-assembled monolayer coating, edible oil-impregnation and silicone oil-impregnation were applied to solidified concrete. The hydrophobizing of concrete significantly reduces an absorption and transportation of water toward a steel rebar in concrete, so that the corrosion resistance of the steel rebar. In particular, the silicone oil-impregnation not only forms the hydrophobic monolayer on the concrete but also fills the inter-connected pores of concrete, thus the corrosion of steel rebar is significantly inhibited compared to the self-assembled monolayer coating and edible oil-impregnation. Therefore, the silicone oil-impregnation can be a promising candidate for preventing corrosion of steel rebar in concrete for durable performance and safety.

슈퍼픽셀 DBSCAN 군집 알고리즘을 이용한 용융아연도금 강판의 부식이미지 분석 (Corrosion image analysis on galvanized steel by using superpixel DBSCAN clustering algorithm)

  • 김범수;김연원;이경황;양정현
    • 한국표면공학회지
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    • 제55권3호
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    • pp.164-172
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    • 2022
  • Hot-dip galvanized steel(GI) is widely used throughout the industry as a corrosion resistance material. Corrosion of steel is a common phenomenon that results in the gradual degradation under various environmental conditions. Corrosion monitoring is to track the degradation progress for a long time. Corrosion on steel plate appears as discoloration and any irregularities on the surface. This study developed a quantitative evaluation method of the rust formed on GI steel plate using a superpixel-based DBSCAN clustering method and k-means clustering from the corroded area in a given image. The superpixel-based DBSCAN clustering method decrease computational costs, reaching automatic segmentation. The image color of the rusty surface was analyzed quantitatively based on HSV(Hue, Saturation, Value) color space. In addition, two segmentation methods are compared for the particular spatial region using their histograms.

전해연마한 슈퍼오스테나이트 스테인리스강의 해수온도에 따른 전기화학적 특성 연구 (Investigation of the Electrochemical Characteristics of Electropolished Super Austenite Stainless Steel with Seawater Temperature)

  • 황현규;김성종
    • Corrosion Science and Technology
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    • 제22권3호
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    • pp.164-174
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    • 2023
  • Electropolishing technology uses an electrochemical reaction and improves surface roughness, glossiness, and corrosion resistance. In this investigation, electropolishing was performed to improve the corrosion resistance of super austenitic stainless steel. As a result of electropolishing, surface roughness (0.16 ㎛) was improved by about 76.5% compared to mechanical polishing (0.68 ㎛). In addition, the electropolished surface was smooth because the average and variance values of the depth histogram were small. Tafel analysis was performed after a potentiodynamic polarization experiment with seawater temperature, and the microstructure was compared and analyzed. The corrosion current density at 30 ℃, 60 ℃, and 90 ℃ was reduced by 0.083 ㎂/cm2, 0.296 ㎂/cm2, and 0.341 ㎂/cm2, respectively. Pitting occurred in the mechanical polished specimen at 30 ℃, but partial intergranular corrosion was observed in the electropolished specimen, and pitting occurred predominantly at both 60 ℃ and 90 ℃. In addition, the damage depths of the electropolished specimen were shallower than those of mechanical polishing at 30 ℃ and 60 ℃, but the opposite result was seen at 90 ℃.

MoS2 코팅된 치과용 임플란트의 표면특성과 생체적합성 (Surface Characteristics and Biocompatibility of MoS2-coated Dental Implant)

  • 권민기;이준식;김미은;최한철
    • Corrosion Science and Technology
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    • 제23권1호
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    • pp.72-81
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    • 2024
  • The Ti-6Al-4V alloy is widely used as an implant material due to its higher fatigue strength and strengthto-weight ratio compared to pure titanium, excellent corrosion resistance, and bone-like properties that promote osseointegration. For rapid osseointegration, the adhesion between the titanium surface and cellular biomolecules is crucial because adhesion, morphology, function, and proliferation are influenced by surface characteristics. Polymeric peptides and similar coating technologies have limited effectiveness, prompting a demand for alternative materials. There is growing interest in 2D nanomaterials, such as MoS2, for good corrosion resistance and antibacterial, and bioactive properties. However, to coat MoS2 thin films onto titanium, typically a low-temperature hydrothermal synthesis method is required, resulting in the synthesis of films with a toxic 1T@2H crystalline structure. In this study, through high-temperature annealing, we transformed them into a non-toxic 2H structure. The implant coating technique proposed in this study has good corrosion resistance and biocompatibility, and antibacterial properties.

가압형 경수로 압력용기 재료인 저합금강의 동적 붕산 부식 실증 연구 (Dynamic Boric Acid Corrosion of Low Alloy Steel for Reactor Pressure Vessel of PWR using Mockup Test)

  • 김성우;김홍표;황성식
    • Corrosion Science and Technology
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    • 제12권2호
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    • pp.85-92
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    • 2013
  • This work is concerned with an evaluation of dynamic boric acid corrosion (BAC) of low alloy steel for reactor pressure vessel of a pressurized water reactor (PWR). Mockup test method was newly established to investigate dynamic BAC of the low alloy steel under various conditions simulating a primary water leakage incident. The average corrosion rate was measured from the weight loss of the low alloy steel specimen, and the maximum corrosion rate was obtained by the surface profilometry after the mockup test. The corrosion rates increased with the rise of the leakage rate of the primary water containing boric acid, and the presence of oxygen dissolved in the primary water also accelerated the corrosion. From the specimen surface analysis, it was found that typical flow-accelerated corrosion and jet-impingement occurred under two-phase fluid of water droplet and steam environment. The maximum corrosion rate was determined as 5.97 mm/year at the leakage rate of 20 cc/min of the primary water with a saturated content of oxygen within the range of experimental condition of this work.

Stress distribution on the real corrosion surface of the orthotropic steel bridge deck

  • Kainuma, Shigenobu;Jeong, Young-Soo;Ahn, Jin-Hee
    • Steel and Composite Structures
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    • 제18권6호
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    • pp.1479-1492
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    • 2015
  • This study evaluated the localized stress condition of the real corroded deck surface of an orthotropic steel bridge because severe corrosion damage on the deck surface and fatigue cracking were reported. Thus, a three-dimensional finite element (FE) analysis model was created based on measurements of the corroded orthotropic steel deck surface to examine the stress level dependence on the corrosion condition. Based on the FE analysis results, it could be confirmed that a high stress concentration and irregular stress distribution can develop on the deck surface. The stress level was also increased by approximately 1.3-1.5 times as a result of the irregular corroded surface. It was concluded that this stress concentration could increase the possibility of fatigue cracking in the deck surface because of the surface roughness of the orthotropic steel bridge deck.

Evaluation on the Corrosion Resistance of Three Types of Galvanizing Steels in 1% H2SO4 Solution

  • Moon, Kyung-Man;Lee, Sung-Yul;Lee, Myeong-Hoon;Jeong, Jae-Hyun;Baek, Tae-Sil
    • 한국표면공학회지
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    • 제49권3호
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    • pp.245-251
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    • 2016
  • Galvanizing method has been extensively used to the numerous constructional steels such as a guard rail of high way, various types of structural steel for ship building and various types of steels for the industrial fields etc.. However, the galvanized structures would be inevitably corroded rapidly with increasing exposed time because an acid rain due to environmental contamination has been much dropped more and more. Therefore, it has been made an effort to improve the corrosion resistance of the galvanizing film through various methods. In this study, comparison evaluation on the corrosion resistance of three types of the samples, that is, the hot dip galvanizing with pure zinc(GI), the hot dip galvanizing of alloy bath with zinc and aluminum(GL) and the pure zinc galvanizing steel immersed again to chromate treatment bath(Chro.)were investigated using electrochemical methods in 1% $H_2SO_4$ solution. The Chro. and GI samples exhibited the highest and lowest corrosion resistance respectively in 1% $H_2SO_4$ solution, however, the GI sample revealed the highest impedance at 0.01 Hz due to its high resistance polarization caused by corrosion products deposited on the surface, while Chro. sample exhibited the lowest impedance at 0.01 Hz because of little corrosion products on the surface. Consequently, it is suggested that the chromate treated steel has a better corrosion resistance in acid environment compared to pure galvanizing(GI) or galvalume(GL) steels.