• 제목/요약/키워드: Corrosion measurement

검색결과 432건 처리시간 0.026초

산질화 표면에서의 액적 증발 열전달 성능 분석 (Analysis of Heat Transfer Performance of Oxi-nitriding Surface during Droplet Evaporation)

  • 김대윤;이성혁
    • 한국분무공학회지
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    • 제24권4호
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    • pp.203-208
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    • 2019
  • In general, the oxi-nitriding method is well known as such a surface treatment way for substantial enhancement in corrosion resistance, even comparable to that of titanium. However, there are still lacks of information on thermal performance of the oxi-nitriding surface being of additional compound layers on the base substrate. Above all, the quantitative measurement of its thermal performance still was not evaluated yet. Thus, the present study experimentally measures the thermal resistance of the oxi-nitriding surface during droplet evaporation and then estimates heat transfer performance with the use of the onedimensional heat transfer model in vertical direction. From the experimental results, it is found that the total evaporation time slightly increased with the thermal resistance caused by the oxi-nitriding layer, showing a maximum difference of approximately 20% with that of the bare surface. Although the heat transfer performance of oxi-nitriding surface became slightly lower than that of the bare surface, the oxi-nitriding surface exhibits much better heat transfer performance compared to titanium.

Ni-Cr-B-Si계 비정질 용사피막의 제조 및 특성 (Fabrication and Characteristics of Thermal Sprayed Ni-Cr-B-Si System Amorphous Coatings)

  • 정하윤;김태형;박경채
    • Journal of Welding and Joining
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    • 제17권4호
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    • pp.53-59
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    • 1999
  • Amorphous alloys have also been called glassy alloys or non-crystalline alloys. They are made by the rapid solidification. The solidification occurs so rapid that the atoms are frozen in their liquid configuration. There are unique magnetic, mechanical, electrical and corrosive behaviors which result form their amorphous structure. In the study. amorphous coatings were manufactured with Ni-Cr-B-Si powders by flame spray. Measurement of hardness, were resistance, corrosion resistance and observation of microstructures and XRD, DSC were performed to investigate characteristics of amorphous coatings. The experimental results obtained as follow: 1) Amorphous powders could not be manufactured with the spraying in the spraying in the liquid nitrogen. But, amorphous coatings could be manufactured with the rotation cooling method by liquid nitrogen. In the fabrication of amorphous coatings, major factor was the rapid cooling by rotation of the substrate. 2) Hardness of coatings was obtained Hv 960 by formation of amorphous phase. But, wear resistance decreased. That was due to porosity in the coatings by the rapid cooling. 3) In the case of corrosion resistance, amorphous coatings were superior to air-cooled coatings. That was due to formation of amorphous phase. 4) After amorphous coatings were heat-treated at 520℃ for 1hr. hardness increased 80% and wear resistance increased 30% comparing with air cooled coatings. These were due to crystallization of amorphous phase and decrease of porosity by heat-treatment.

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Mechanical and Antibacterial Properties of Copper-added Austenitic Stainless Steel (304L) by MIM

  • Nishiyabu, Kazuaki;Masai, Yoshikaze;Ishida, Masashi;Tanaka, Shigeo
    • 한국분말재료학회지
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    • 제9권4호
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    • pp.227-234
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    • 2002
  • For the austenitic stainless steel (304L) manufactured by metal injection molding(MIM), the effects of copper content and sintering temperature on the mechanical properties, antibacterial activities, corrosion resistance, and electric resistances were investigated. The specimens were prepared by injection molding of the premixed powders of water-atomized 304 L and Cu with poly-acetyl binders. The green compacts were prepared with various copper contents from 0 to 10 wt.% Cu, which were debound thermally at 873 K for 7.2 ks in $N_2$gas atmosphere and subsequently sintered at various temperatures from 1323 K to 1623 K for 7.2 ks in Ar gas atmosphere. The relative density and tensile strength of the sintered compacts showed the minimum values at 5 and 8 wt.% Cu, respectively. Both the relative density and the tensile strength of the specimen with 10 wt.% Cu sintered at 1373 K showed the highest values, higher than those of copper-free specimen. Antibacterial activities investigated by the plastic film contact printing method for bacilli and the quantitative analysis of copper ion dissolved in water increased as the increase of the copper content to stainless steels. It was also verified by the measurement of pitting potential that the copper addition in 304 L could improve the corrosion resistance. Furthermore the electric conductivity increased with the increase of copper content.

Damage identification of belt conveyor support structure using periodic and isolated local vibration modes

  • Hornarbakhsh, Amin;Nagayama, Tomonori;Rana, Shohel;Tominaga, Tomonori;Hisazumi, Kazumasa;Kanno, Ryoichi
    • Smart Structures and Systems
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    • 제15권3호
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    • pp.787-806
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    • 2015
  • Due to corrosion, a large number of belt conveyors support structure in industrial plants have deteriorated. Severe corrosion may result in collapse of the structures. Therefore, practical and effective structural assessment techniques are needed. In this paper, damage identification methods based on two specific local vibration modes, named periodic and isolated local vibration modes, are proposed. The identification methods utilize the facts that support structures have many identical members repeated along the belt conveyor and there exist some local modes within a small frequency range where vibrations of these identical members are much larger than those of the other members. When one of these identical members is damaged, this member no longer vibrates in those modes. Instead, the member vibrates alone in an isolated mode with a lower frequency. A damage identification method based on frequencies comparison of these vibration modes and another method based on amplitude comparison of the periodic local vibration mode are explained. These methods do not require the baseline measurement records of undamaged structure. The methods is capable of detecting multiple damages simultaneously. The applicability of the methods is experimentally validated with a laboratory model and a real belt-conveyor support structure.

가공 배전선의 열화를 검출하기 위한 솔레노이드 와전류 센서의 실험적 연구 (An Experimental Study on a Solenoid Eddy Current Sensor to inspect Deteriorations in Overhead Distribution Lines)

  • 김성덕
    • 조명전기설비학회논문지
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    • 제13권1호
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    • pp.77-85
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    • 1999
  • 이 논문은 가공 배전선에서 단선, 극심한 국부부식이나 아연손실과 같은 열화상태를 검사하기 위하여 솔레노이드 와전류 센서를 이용한 비파괴검사 시스템의 실험적인 연구에 대하여 다룬다. ACSR과 ACSR-OC에 대한 부식기구가 검토되고 코일과 시료의 구조적인 파라미터들을 검사하기 위하여, 솔레노이드 센서의 임피던스도 간단히 해석된다. 정전류원, 신호처리 장치 및 모터 구동장치로 구성된 측정시스템이 제작되었다. 이 장비는 연속적으로 센서 출력을 검출하고 검사 도체의 결함을 추정하는 성능이 있다. 그 결과, 관통형 코일의 와전류 센서가 가공 배전선의 열화에 의한 직경 변화를 효과적으로 추정할 수 있음을 밝혔다.

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CFD APPLICATION TO THE REGULATORY ASSESSMENT OF FAC-CAUSED CANDU FEEDER PIPE WALL THINNING ISSUE

  • Kang, Dong-Gu;Jo, Jong-Chull
    • Nuclear Engineering and Technology
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    • 제40권1호
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    • pp.37-48
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    • 2008
  • Flow fields inside feeder pipes have been simulated numerically using a CFD (computational fluid dynamics) code to calculate the shear stress distribution, which is the most important factor in predicting the local regions of feeder pipes highly susceptible to FAC (flow-accelerated corrosion)-induced wall thinning. The CFD approach, with schemes used in this study, to simulate the flow situations inside the CANDU feeder pipes has been verified as it showed a good agreement between the investigation results for the failed feedwater pipe at Surry unit 2 plant in the U.S. and the CFD calculation. Sensitivity studies of the three geometrical parameters, such as angle of the first and second bends, length of the first span between the grayloc hub and the first bend, and length of the second span between the first and the second bends have been performed. CFD analysis reveals that the local regions of feeder pipes of Wolsung unit 1 in Korea, on which wall thickness measurements have been performed so far, are not coincident with the worst regions predicted by the present CFD analysis located in the connection region of straight and bend pipe near the inlet part of the bend intrados. Finally, based on the results of the present CFD analysis, a guide to the selection of the weakest local positions where the measurement of wall thickness should be performed with higher priority has been provided.

탈지 정도에 대한 방청유-금속 계면의 영향성 평가 (Study on Evaluation of Degrease Performance on the Interface between Oil and Alloy)

  • 최원영;김문수;유현석;송연균;정용균;최진섭
    • 한국표면공학회지
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    • 제54권6호
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    • pp.371-379
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    • 2021
  • The use of anti-corrosive oil (AC) is inevitable for production of industrial steels to prevent corrosion. The AC is degreased before application of steels, which crucially effects on final products, such as automobile, electricity etc. However, qualitative/quantitative evaluation of degreasing performance are steal insufficient. In this study, degreasing performance of anti-corrosive oil on steel have been studied through X-ray photon spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS). Commercial automotive steels (AMS) are coated with 4 different anti-corrosive oils (namely AC1-AC4). In XPS, intensity of C1s peak remained after degreasing indirectly indicates incomplete degreasing. Thus, higher C1s peak intensity means less effective degreasing by degreasing agent. peak intensity of C1s peak shows opposite tendency of peak intensity of O1s. We found that EIS analysis is not applicable to mild steel (such as AMS1) due to corrosion during measurement. However, alloy steel can be fully analyzed by EIS and XPS depth profile.

다구찌 설계를 이용한 듀플렉스 스테인리스강 S31083용 DL-EPR 시험용액의 최적화 (Optimization of DL-EPR Test Solution for Duplex Stainless Steel S31083 Using Taguchi Design)

  • 정광후;김성종
    • Corrosion Science and Technology
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    • 제20권2호
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    • pp.77-84
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    • 2021
  • This study aims to optimize the DL-EPR test solution for duplex stainless steel S31083 using the Taguchi design. The test solution parameters applied to the Taguchi design are H2SO4, NaCl, KSCN concentration, and temperature. In the experimental design, an orthogonal array of 4 levels 4 factor L16(44) was used. Output values for the orthogonal array were used for resolution (degree of sensitization) and selective etch (Ia) values. The optimal test solution conditions were selected by comparing the normalized S/N ratio for the two reaction properties. As a result, the H2SO4 and NaCl were identified as the main factors influencing the sensitivity measurement, but the delta statistics showed that the KSCN concentration and temperature had relatively low influence. The optimal condition was identified as 1.5 M H2SO4+0.03 M KSCN+1.5M NaCl at 30 ℃. The degree of sensitization presented a tendency to depend on the heat treatment temperature and time in the optimal test solution. This investigation confirmed the possibility of optimizing the experiment solution for the DL-EPR test of stainless steel using the Taguchi technique.

Electrochemical Studies on Corrosion Inhibition Behaviour of Synthesised 2-acetylpyridine 4-ethyl-3-thiosemicarbazone and Its Tin(IV) Complex for Mild Steel in 1 M HCl Solution

  • Hazani, Nur Nadira;Mohd, Yusairie;Ghazali, Sheikh Ahmad Izaddin Sheikh Mohd;Farina, Yang;Dzulkifli, Nur Nadia
    • Journal of Electrochemical Science and Technology
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    • 제10권1호
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    • pp.29-36
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    • 2019
  • Corrosion inhibition by synthesised ligand, 2-acetylpyridine 4-ethyl-3-thiosemicarbazone (HAcETSc) and its tin(IV) complex, dichlorobutyltin(IV) 2-acetylpyridine 4-ethyl-3-thiosemicarbazone ($Sn(HAcETSc)BuCl_2$) on mild steel in 1 M hydrochloric acid (HCl) was studied using weight loss measurement, potentiodynamic polarisation, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). The inhibition efficiency increases by increasing the inhibitor concentrations. The polarisation study showed that both synthesised compounds were mixed type inhibitors. The electrochemical impedance study showed that the presence of inhibitors caused the charge transfer resistance to increase as the concentration of inhibitors increased. The adsorption of these compounds on mild steel surface was found to obey Langmuir's adsorption isotherm with the free energy of adsorption ${\Delta}G{^o}_{ads}$ of -3.7 kJ/mol and -7.7 kJ/mol for ligand and complex respectively, indicating physisorption interaction between the inhibitors and 1 M HCl solution.

델타스폿용접을 이용한 이종소재 웰드본딩공정 시 표면 거칠기 부여 가공방법의 영향 (Effect of Surface Roughness on Weld-bonding Process using Heterogeneous Materials)

  • 김영현;김재웅;김지선;김영곤;표창민
    • 한국기계가공학회지
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    • 제19권11호
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    • pp.102-108
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    • 2020
  • The demand for lightweight materials and high-strength steel has rapidly increased to help reduce the weight of a vehicle body; it improves the fuel efficiency of automobiles and provides passenger safety. Additionally, as the material becomes thinner, the demand for its resistance against corrosion becomes higher. Hence, the application of the surface-treated steel sheet has surged rapidly. In this study, a weld bonding experiment using a delta spot welding machine is performed on a thin sheet of a different material (Al6061-T6/GA440). The thickness of the material was kept at 1 mm to reduce the weight of the automobile body parts. Additionally, the purpose of this study is to control the heat input by applying the welding conditions of a multi-stage pressure pattern to improve corrosion resistance shear strength. The analysis of nugget diameter measurement, shear tensile test, and salt spray test was performed to achieve the aim.