• Title/Summary/Keyword: potentiodynamic

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Corrosion Behavior of Casting Aluminum Alloys in H2SO4 Solution (H2SO4 수용액에서의 주조용 알루미늄 합금들의 부식거동)

  • Woo, Sang-Hyun;Son, Young-Jin;Lee, Byung-Woo
    • Journal of Power System Engineering
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    • v.20 no.3
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    • pp.17-21
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    • 2016
  • The corrosion behavior of aluminum alloys in the $H_2SO_4$ solution was investigated based on potentiodynamic techniques. Electrochemical properties, such as corrosion potential($E_c$), passive potential($E_p$), corrosion current density($I_c$), corrosion rate(mpy), of Al-Mg-Si, Al-Cu-Si and Al-Si alloys were characterized at room temperature. Passive aluminum oxide film, which including $Al_2(SO_4)_3$ and $3Al_2O_34SO_38H_2O$, were uniformly formed on the surface via the reaction of Al with $SO{_3}^{2-}$ or $SO{_4}^{2-}$ ions in the $H_2SO_4$ solution and the dependence of the corrosion behavior on the alloying element was discussed. The selective leaching of alloy element increased with increasing Cu content in the aluminum alloys.

Effects of Hafnium Addition on the Pitting Corrosion Behavior of Ti Alloys in Electrolyte Containing Chloride Ion (염소이온 함유된 용액에서 Ti합금의 부식특성에 미치는 Hafnium함량의 영향)

  • Kim, Sung-Hwan;Choe, Han-Cheol
    • Corrosion Science and Technology
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    • v.11 no.5
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    • pp.191-195
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    • 2012
  • The aim of this study was to investigate effects of hafnium content on the corrosion behavior of Ti alloys in electrolyte containing chloride ion. For this study, Ti-Hf binary alloys contained 10 wt%, 20 wt% and 30 wt% Hf were manufactured in a vacuum arc-melting furnace and subjected to heat treatment for 12h at $1000^{\circ}C$ in an argon atmosphere. The pitting corrosion behavior of the specimens was examined through potentiodynamic and potentiostatic tests in 0.9 wt% NaCl electrolyte at $36.5{\pm}1^{\circ}C$. The corrosion morphology of Ti-xHf alloys was investigated using optical microscopy (OM) and X-ray diffractometer (XRD). From the optical microstructures and XRD results, needle-like martensite ($\alpha$') phases of the Ti-xHf alloys increased with an increase of Hf addition. Corrosion current density $(I_{corr})$ and current density $(I_{300mV})$ in passive region decreased, whereas, corrosion potential increased with Hf content. At the constant potential ($300mV_{SCE}$), current density decreased as time increased.

Electrochemical Corrosion Failure of ITO-Coated PET Film for Display Application

  • Farooq, Hina;Kim, Hye-young;Byeon, Jai-Won
    • Journal of Applied Reliability
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    • v.17 no.1
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    • pp.72-77
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    • 2017
  • Purpose: The electrochemical corrosion behavior of tin oxide film coated on PET substrates has been studied under varying concentrations of acrylic acid to investigate possible corrosion in contact with the acidic environment. Method: Potentiodynamic test was performed for a commercial ITO/PET film in 0.1, 0.3, and 0.5 M of acrylic acid. The surface morphology was analyzed by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS). Results: Potentiodynamic test results showed an increase in Icorr and decrease in Ecorr value with increasing concentration of acid. Microscopic evaluation suggested the presence of certain deep cracks on the surface of the film in addition with a severe acidic attack. Conclusion: Exposure of ITO to acrylic acid resulted in the stress corrosion cracking of ITO film due to the mechanical mismatch between brittle inorganic ITO fim and a compliant organic PET substrate leading to the subsequent failure of the film.

Electrochemical Polarization Characteristics and Effect of the CMP Performances of Tungsten and Titanium Film by H2O2 Oxidizer (H2O2 산화제가 W/Ti 박막의 전기화학적 분극특성 및 CMP 성능에 미치는 영향)

  • Na, Eun-Young;Seo, Yong-Jin;Lee, Woo-Sun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.18 no.6
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    • pp.515-520
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    • 2005
  • CMP(chemical mechanical polishing) process has been attracted as an essential technology of multi-level interconnection. Also CMP process got into key process for global planarization in the chip manufacturing process. In this study, potentiodynamic polarization was carried out to investigate the influences of $H_2O_2$ concentration and metal oxide formation through the passivation on tungsten and titanium. Fortunately, the electrochemical behaviors of tungsten and titanium are similar, an one may expect. As an experimental result, electrochemical corrosion of the $5\;vol\%\;H_2O_2$ concentration of tungsten and titanium films was higher than the other concentrations. According to the analysis, the oxidation state and microstructure of surface layer were strongly influenced by different oxidizer concentration. Moreover, the oxidation kinetics and resulting chemical state of oxide layer played critical roles in determining the overall CMP performance. Therefore, we conclude that the CMP characteristics tungsten and titanium metal layer including surface roughness were strongly dependent on the amounts of hydrogen peroxide oxidizer.

Study on the Effects of Oxidant on Chemical Passivation Treatment of Low Nickel Stainless Steel (저니켈 스테인리스강의 화학적 부동태막 형성에 산화제가 미치는 영향)

  • Choi, Jong-Beom;Lee, Kyung-Hwang;Yun, Yong-Sup
    • Journal of the Korean institute of surface engineering
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    • v.51 no.3
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    • pp.172-178
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    • 2018
  • In this paper, effects of potassium permanganate, pottasium dichromate, sodium molybdate on lean duplex stainless steel were studied by GDOES, OCP, potentiodynamic curves. The stainless steels were chemically passivated in each nitric acid solutions containing 4wt.% oxidants for 1 hour. As a result, when potassium dichromate or sodium molybdate was added, content of Fe was decreased and content of Cr was increased. Consequently, corrosion resistance of passive film was increased. But in case of potassium permanganate was added, contrastively, content of Fe was increased and content of Cr was decreased. So corrosion resistance was decreased. Adding sodium molybdate in nitric acid for chemical surface treatment process was the most effective among oxidants and also it showed the most stable anti-corrosion in SST.

Effect of β-Blocker Inhibitors on Aluminum Corrosion (알루미늄 부식에 대한 베타-차단제 억제제 효과)

  • Fouda, A. S.;El-Ewady, G. Y.;Shalabi, K.
    • Journal of the Korean Chemical Society
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    • v.55 no.2
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    • pp.268-278
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    • 2011
  • Corrosion of aluminum in 0.1 M HCl solution in the absence and presence of ${\beta}$-blocker inhibitors (atenolol, propranolol, timolol and nadolol) was investigated using weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The inhibition efficiency increased with inhibitor concentration and decreased with rise of temperature. Potentiodynamic polarization curves revealed that they acted as cathodic inhibitors. Some thermodynamic parameters were calculated and discussed. All inhibitors were adsorbed on Al surface obeying Frumkin isotherm. All EIS tests exhibited one capacitive loop which indicates that the corrosion reaction is controlled by charge transfer process. The inhibition efficiencies of all test methods were in good agreement.

Ginger Extract as Green Corrosion Inhibitor for Steel in Sulfide Polluted Salt Water

  • Fouda, Abd El-Aziz S.;Nazeer, Ahmed Abdel;Ibrahim, Mohamed;Fakih, Mohamed
    • Journal of the Korean Chemical Society
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    • v.57 no.2
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    • pp.272-278
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    • 2013
  • Extract of ginger has been evaluated as a green inhibitor for the corrosion of steel in sulfide polluted NaCl solution using potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. Potentiodynamic polarization measurements showed that this extract acts as a mixed type inhibitor but mainly inhibits the cathodic reaction. The inhibition efficiency was found to increase with inhibitor concentration reaching to approximately 83.9% using 250 ppm of ginger. Nyquist plots show a single capacitive loop in uninhibited and inhibited solutions. From EFM the causality factors are very close to theoretical values which indicate that the measured data are of good quality. The adsorption process of the studied extract on steel surface obeys Temkin adsorption isotherm. The results obtained from the different electrochemical techniques were in good agreement which prove the validity of these tools in measurement of corrosion rate. Ginger extract has no effect on Escherichia Coli and can be applied safely on waste water treatment plants.

Electrochemical Evaluation of Si-Incorporated Diamond-Like Carbon (DLC) Coatings Deposited on STS 316L and Ti Alloy for Biomedical Applications

  • Kim, Jung-Gu;Lee, Kwang-Ryeol;Kim, Young-Sik;Hwang, Woon-Suk
    • Corrosion Science and Technology
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    • v.6 no.1
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    • pp.18-23
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    • 2007
  • DLC coatings have been deposited onto substrate of STS 316L and Ti alloy using r.f. PACVD (plasma-assisted chemical vapor deposition) with a mixture of $C_{6}H_{6}$ and $SiH_{4}$ as the process gases. Corrosion performance of DLC coatings was investigated by electrochemical techniques (potentiodynamic polarization test and electrochemical impedance spectroscopy) and surface analysis (scanning electron microscopy). The electrolyte used in this test was a 0.89% NaCl solution of pH 7.4 at temperature $37^{\circ}C$. The porosity and protective efficiency of DLC coatings were obtained using potentiodynamic polarization test. Moreover, the delamination area and volume fraction of water uptake of DLC coatings as a function of immersion time were calculated using electrochemical impedance spectroscopy. This study provides the reliable and quantitative data for assessment of the effect of substrate on corrosion performance of Si-DLC coatings. The results showed that Si-DLC coating on Ti alloy could improve corrosion resistance more than that on STS 316L in the simulated body fluid environment. This could be attributed to the formation of a dense and low-porosity coating, which impedes the penetration of water and ions.

Effect of Flow Rate on Erosion Corrosion Damage and Damage Mechanism of Al5083-H321 Aluminum Alloy in Seawater Environment (해수 환경에서 Al5083-H321 알루미늄 합금의 침식부식 손상에 미치는 유속의 영향과 손상 메카니즘)

  • Kim, Young-Bok;Kim, Seong-Jong
    • Corrosion Science and Technology
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    • v.19 no.3
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    • pp.115-121
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    • 2020
  • In this study, erosion tests and erosion-corrosion tests of Al5083-H321 aluminum alloy were conducted at various flow rates in seawater. The erosion tests were conducted at a flow rate of 0 to 20 m/s, and erosion-corrosion tests were performed by potentiodynamic polarization method at the same flow rate. Characteristic evaluation after the erosion test was conducted by surface analysis. Characteristic evaluation after the erosion-corrosion test was performed by Tafel extrapolation and surface analysis. The results of the surface analysis after the erosion test showed that surface damage tended to increase as the flow rate increased. In particular, intermetallic particles were separated due to the breakdown of the oxide film at 10 m/s or more. In the erosion-corrosion test, the corrosion current density increased as the flow rate increased. Additionally, the surface analysis showed that surface damage occurred in a vortex shape and the width of the surface damage tended to increase as the flow rate increased. Moreover, damage at 0 m/s, proceeded in a depth direction due to the growth of pitting corrosion, and the damaged area tended to increase due to acceleration of the intermetallic particle loss by the fluid impact.

A Study of Localized Corrosion Mechanisms in the Multilayered Coatings by Cathodic Arc Deposition (음극아크증착법으로 합성한 다층박막의 국부부식 기구에 관한 연구)

  • 김호건;안승호;이정호;김정구;한전건
    • Journal of the Korean institute of surface engineering
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    • v.36 no.4
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    • pp.301-306
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    • 2003
  • Multilayered WC-Ti/suv $1-x/Al_{x}$ N coatings were deposited on AISI D2 steel using cathodic arc deposition (CAD) method. These coatings contain structural defects such as pores or droplets. Thus, the substrate is not completely isolated from the corrosive environment. The growth defects (pores, pinholes) in the coatings are detrimental to corrosion resistance of the coatings used in severe corrosion environments. The localized corrosion behavior of the coatings was studied in deaerated 3.5 wt.% NaCl solution using electrochemical techniques (potentiodynamic polarization test) and surface analyses (GDOES, SEM, AES, TEM). The porosity was calculated from the result of potentiodynamic polarization test of the uncoated and coated specimens. The calculated porosity is higher in the $WC-Ti_{0.6}$ $Al_{0.4}$ N than others, which is closely related to the packing factor. The positive effects of greater packing factor act on inhibiting the passage of the corrosive electrolyte to the substrate and lowering the localized corrosion kinetics. From the electrochemical tests and surface analyses, the major corrosion mechanisms can be classified into two basic categories: localized corrosion and galvanic corrosion.