• 제목/요약/키워드: potentiodynamic

검색결과 369건 처리시간 0.025초

Enhanced Corrosion Resistance of WC-Co with an Ion Beam Mixed Silicon Carbide Coating

  • 여순목;박재원
    • 한국진공학회:학술대회논문집
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    • 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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    • pp.193-193
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    • 2011
  • Strong adhesion of a silicon carbide (SiC) coating to a WC-Co substrate was achieved through an ion beam mixing technique and the corrosion resistance of the SiC coated WC-Co was investigated by means of a potentiodynamic electrochemical test. In a 1 M NaOH solution, the corrosion current density of SiC-coated WC-Co after heat treatment at 500$^{\circ}C$ was about 50 times lower than that for the as-received WC-Co. In addition, the corrosion resistance systematically increases with increasing the SiC coating thickness. On the other hand, for a 0.5 M H2SO4 solution, the corrosion current density for SiC-coated WC-Co was about 3 times lower than that for the as-received WC-Co. We discuss the physical reasons for the changes in the corrosion current density with the different electrolytes.

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Effect of Microstructure on Corrosion Behavior of TiN Hard Coatings Produced by Two Grid-Attached Magnetron Sputtering

  • Kim, Jung Gu;Hwang, Woon Suk
    • Corrosion Science and Technology
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    • 제5권1호
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    • pp.15-22
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    • 2006
  • The introduction of two-grid inside a conventional process system produces a reactive coating deposition and increases metal ion ratio in the plasma, resulting in denser and smoother films. The corrosion behaviors of TiN coatings were investigated by electrochemical methods, such as potentiodynamic polarization test and electrochemical impedance spectroscopy (EIS) in deaerated 3.5% NaCl solution. Electrochemical tests were used to evaluate the effect of microstructure on the corrosion behavior of TiN coatings exposed to a corrosive environment. The crystal structure of the coatings was examined by X-ray diffractometry (XRD) and the microstructure of the coatings was investigated by scanning electron microscopy (SEM) and transmission electron spectroscopy (TEM). In the potentiodynamic polarization test and EIS measurement, the corrosion current density of TiN deposited by two grid-attached magnetron sputtering was lower than TiN deposited by conventional magnetron type and also presented higher Rct values during 240 h immersion time. It is attributed to the formation of a dense microstructure, which promotes the compactness of coatings and yields lower porosity.

산화피막이 있는 철근의 분극곡선의 거동에 대한 연구 (The Study on the Behavior of Polarization curve of Reinforcement with Oxidation Layer)

  • 한정섭
    • 한국해양공학회지
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    • 제14권1호
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    • pp.60-66
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    • 2000
  • In order to study for corrosion behavior of reinforcing steel with oxidation layer. Experiments were done with various NaCl concentrations and with immersion time in simulated concrete pore solution(SPS) the characteristics of corrosion behavior were measured by polarization resistance method and cyclic potentiodynamic method. reinforcements were coated by epoxy except corrosion without oxidation layer and it also showed two anodic-nose. by the result of potention dynamic test the potential curve shift to low with time and anodic-nose was appeared with 3% NaCl solution after 15 days. By result of cyclic Potentiodynamic test the type of corrosion was different accoding to concentration.

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마이크로 드로플릿 셀 기법을 이용한 예민화 된 304 스테인리스강의 미세전기화학 특성 (Micro-electrochemical Characteristics of Sensitized 304 Stainless steel Using Micro-droplet cell Techniques)

  • 김규섭;이재봉
    • Corrosion Science and Technology
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    • 제9권6호
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    • pp.300-309
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    • 2010
  • The influences of sensitization on localized corrosion resistance of 304 stainless steel, were investigated, using micro-dropletcell techniques. Micro-droplet cell allows one to align the micro-electrode to the desired spot of the working electrode and measure directly local current with the potentiodynamic polarization, linear polarization and a.c. impedance. Micro-electrochemical tests were carried out inside of the grain and on grain boundaries separately. It was found that sensitization decreased the pitting potential, increasing corrosion current density around grain boundaries. Galvanic current density was also measured between grain and grain boundaries.

스프링클러 동배관의 공식부식 발생원인 (Investigation on Causes of Pitting Corrosion in Sprinkler Copper Tubes)

  • 이재봉;정호석
    • Corrosion Science and Technology
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    • 제13권1호
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    • pp.6-14
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    • 2014
  • Copper metal is widely used in tubes installed in sprinkler water services because of its excellent corrosion resistance. Copper corrosion is considered to be insignificant in water system and the incident of copper pipeline failure is relatively low. However, pitting corrosion is a major problem with all copper tubes. In this study, leaked sprinkler copper tubes were collected from three different locations and examined on the causes of pitting corrosion of copper tubes in sprinkler water plumbing systems. Electrochemical tests such as potentiodynamic polarization, as well as surface and chemical analyses were performed. Results show that pitting corrosion of copper tubes were found as Type I pitting that the carbon film formed on the copper tubes have a harmful effects, causing the pinhole failure in the pipe and resulting in leakage of water. The contermeasures on Type I pitting corrosion of copper tubes were proposed.

Cu ECMP 공정에서의 전해질 특성평가 (Characterization of Electrolyte in Electrochemical Mechanical Planarization)

  • 권태영;김인권;박진구
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2006년도 하계학술대회 논문집 Vol.7
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    • pp.57-58
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    • 2006
  • Chemical-mechanical planarization (CMP) of Cu has used currently in semiconductor process for multilevel metallization system. This process requires the application of a considerable down-pressure to the sample in the polishing, because porous low-k films used in the Cu-multilevel interconnects of 65nm technology node are often damaged by mechanical process. Also, it make possible to reduce scratches and contaminations of wafer. Electrochemical mechanical planarization (ECMP) is an emerging extension of CMP. In this study, the electrochemical mechanical polisher was manufactured. And the static and dynamic potentiodynamic curve of Cu were measured in KOH based electrolyte and then the suitable potential was found.

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인발률에 따른 자동차 냉각 배관용 Al 합금의 부식 특성에 관한 연구 (Effect of Drawing Rate on the Corrosion Behavior of Al Alloy Tubes for Automotive Cooling System)

  • 박병준;김정구;안승호;곽동호;손현수
    • 대한금속재료학회지
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    • 제46권8호
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    • pp.489-494
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    • 2008
  • The effect of drawing rate on the electrochemical properties of 3003 Al alloys in 5 wt.% NaCl solution was investigated by electrochemical techniques (potentiodynamic polarization test, potentiostatic polarization test, electrochemical impedance spectroscopy (EIS)) and surface analyses (OM, SEM, EDS). Four kinds of automotive pipe materials were prepared (raw material, drawing rate = 5, 10, 15%). As the drawing rate of Al alloy tube increased, the pitting corrosion resistance increased due to the enrichment of Al oxides on the surface.

Micro-droplet cell을 이용한 Fe-17Cr 합금의 공식 발생에 대한 연구 (A Study on the Initiation of Pitting Corrosion of Fe-17Cr Alloy Using Micro-Droplet Cell Technique)

  • 김재중;이재봉
    • 대한금속재료학회지
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    • 제46권12호
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    • pp.809-816
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    • 2008
  • The influences of various parameters such as inclusions, surface roughness, exposed areas and chloride ion concentrations on the initiation of pitting of Fe-17Cr alloy were investigated, using micro-droplet cell technique. Micro-droplet cell allows one to align the micro-electrode to the desired spot of the working electrode and measure directly local currents with the potentiodynamic polarization. Micro electrochemical tests were carried out at the inclusions after EDX analysis of inclusion. EDX analysis identified inclusions as Cr-oxides. It was found that some active inclusions among Cr-oxide inclusions acted as initiation sites for pitting corrosion. In addition, the rougher surface and the denser chloride ion concentration offered easier pit initiation sites, causing the more susceptible to pitting corrosion.

Ag925의 전기화학적 특성에 미치는 네오디뮴 함량의 영향 (Effect of Neodymium concentration on electrochemical properties of 925 silver)

  • 신병현;정승진;정원섭
    • 한국표면공학회지
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    • 제54권2호
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    • pp.71-76
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    • 2021
  • Ag925, silver with added copper, is popular alloy due to its low price. However, it has a difficult to use because of the low corrosion resistance. In various alloys, neodymium (Nd) works as an element to improve corrosion resistance by reacting with interstitial elements in the alloy. When 1.5 wt. % Neodymium was added to Ag925, the potential on the activated polarization in a potentiodynamic polarization test was increased from -0.15 V to -0.05 V. Ag925 with added neodymium showed the passivation after activation polarization. But When the potential increased around 50 mV, the current density is increased to 3 × 10-3. Ag925 with the 1.5 wt. % Nd had the low corrosion rate.

알루미늄 5052 합금의 산화피막 성장 및 내식성 연구 (Study on Corrosion and Oxide Growth Behavior of Anodized Aluminum 5052 Alloy)

  • 지혜정;정찬영
    • 한국표면공학회지
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    • 제51권6호
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    • pp.372-380
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    • 2018
  • Anodization techniques are widely used in the area of surface treatment of aluminum alloys because of its simplicity, low-cost and good corrosion resistance. In this study, we investigated the relationship between the properties (porosity and thickness) of anodic aluminum oxide (AAO) and its corrosion behavior. Aluminum 5052 alloy was anodized in 0.3 M oxalic acid at $0^{\circ}C$. The anodizing of aluminum 5052 was performed at 20 V, 40 V and 60 V for various durations. The corrosion behavior was studied in 3.5 wt % NaCl using potentiodynamic polarization method. Results showed that the pore diameter and thickness increased as voltage and anodization time increased. The relatively thick oxide film revealed a lower corrosion current density and a higher corrosion potential value.