• Title/Summary/Keyword: Borate buffer solution

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Hydrodynamic and Atmospheric Effects on Corrosion of Zinc in Borate Buffer Solution (Borate 완충용액에서 아연의 부식에 대한 대류와 대기의 영향)

  • Chung, Se-Jin;Kim, Youn-Kyoo
    • Journal of the Korean Chemical Society
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    • v.55 no.4
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    • pp.575-580
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    • 2011
  • It was investigated into the effects on zinc corrosion of the rotation speed of Zn-RDE and the oxygen concentration in borate buffer solution. Zinc corrosion was heavily influenced on the rotation speed of electrode and the oxygen concentration. We have suggested the disproportion reaction following the reversible one electron transfer as the corrosion mechanism of zinc.

Corrosion and Passivation of Nickel Rotating Disk Electrode in Borate Buffer Solution (Borate 완충용액에서 니켈 회전원판전극의 부식과 부동화)

  • Kim, Younkyoo
    • Journal of the Korean Chemical Society
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    • v.57 no.5
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    • pp.533-539
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    • 2013
  • The electrochemical corrosion and passivation of Ni rotating disk electrod in borate buffer solution was studied with potentiodynamic and electrochemical impedance spectroscopy. The mechanisms of both the active dissolution and passivation of nickel and the hydrogen evolution in reduction reaction were hypothetically established while utilizing the Tafel slope, impedance data, the rotation speed of Ni-RDE and the pH dependence of corrosion potential and current. Based on the EIS data, an equivalent circuit was suggested. In addition, carefully measured were the electrochemical parameters for specific anodic dissolution regions. It can be concluded from the data collected that the $Ni(OH)_2$ oxide film, which is primarily formed by passivation, is converted to NiO by dehydration under the influence of an electrical field.

Hydrodynamic and Oxygen Effects on Corrosion of Cobalt in Borate Buffer Solution (Borate 완충용액에서 코발트의 부식에 대한 대류와 산소의 영향)

  • Kim, Younkyoo
    • Journal of the Korean Chemical Society
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    • v.58 no.5
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    • pp.437-444
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    • 2014
  • The electrochemical corrosion and passivation of Co-RDE in borate buffer solution was studied by Potentiodynamic and electrochemical impedance spectroscopy. The mechanisms of both the active dissolution and passivation of cobalt and the hydrogen evolution in reduction reaction were hypothetically established while utilizing the Tafel slope, the rotation speed of Co-RDE, impedance data and the pH dependence of corrosion potential. Based on the EIS data, an equivalent circuit was suggested. In addition, the electrochemical parameters for specific anodic dissolution regions were carefully measured. An induction loop in Nyquist plot measured at the open-circuit potential was observed in the low frequency, and this could be attributed to the adsorption-desorption behavior in the corrosion process.

Hydrodynamic Effects on Corrosion and Passivation of Copper in Borate Buffer Solution (Borate 완충용액에서 구리의 부식과 부동화에 미치는 대류 영향)

  • Chon, Jung-Kyoon;Kim, Youn-Kyoo
    • Journal of the Korean Electrochemical Society
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    • v.10 no.1
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    • pp.14-19
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    • 2007
  • The corrosion and passivation of copper was investigated with the copper rotating disk electrode(Cu-RDE) in borate buffer solution. It has been observed with the mixed potential theory that the corrosion potential for the rotation rate increase under the convective diffusion condition was increased. It was suggested that the chemical intermediates and product 13. the copper oxidation were $Cu(OH)_{ads},\;{Cu(OH)_2}^-,\;Cu_2O,\;Cu(OH)_2,\;and\;CuO$.

Growth Kinetics and Electronic Properties of Passive Film of Zinc in Borate Buffer Solution (Borate 완충용액에서 아연의 부동화 피막의 생성 과정과 전기적 특성)

  • Chung, Se-Jin;Kim, Youn-Kyoo
    • Journal of the Korean Chemical Society
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    • v.56 no.1
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    • pp.47-53
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    • 2012
  • We have investigated the growth kinetics and electronic properties of passive film of zinc in borate buffer solution. The oxide film formed in passivation process of zinc has showed the electronic properties of n-type semiconductor based on the Mott-Schottky equation. And it was found out that the oxide film consisted ZnO and $Zn(OH)_2$ was composed of deep and shallow donors.

Atmospheric Effects on Corrosion of Iron in Borate Buffer Solution (Borate 완충용액에서 철의 부식에 대한 대기의 영향)

  • Kim, Hyun-Chul;Kim, Younkyoo
    • Journal of the Korean Chemical Society
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    • v.56 no.6
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    • pp.673-678
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    • 2012
  • Using potentiodynamic and linear polarization method, the atmospheric effect on the corrosion of iron in borate buffer solution was investigated. The corrosion of iron was heavily influenced by the degree of oxygen concentration. The supply of reduction current was increased by the reduction of dissolved oxygen, and the corrosion potential of iron was shifted to the positive side. The $OH^-$ ion, which was produced through the reduction of either water or oxygen, significantly increased the $OH^-$ ion concentration inside of the electrical double layers of iron electrode, and facilitated the adsorption of $OH^-$ ion on the surface of the iron electrode. The adsorption of $OH^-$ ion on the iron electrode can be explained either by Langmuir isotherm or by Temkin logarithmic isotherm.

Growth Kinetics and Electronic Properties of Passive Film of Nickel in Borate Buffer Solution (Borate 완충용액에서 니켈 산화피막의 생성 과정과 전기적 성질)

  • Kim, Younkyoo
    • Journal of the Korean Chemical Society
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    • v.58 no.1
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    • pp.9-16
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    • 2014
  • In a borate buffer solution, the growth kinetics and the electronic properties of passive film on nickel were investigated, using the potentiodynamic method, chronoamperometry, and single- or multi-frequency electrochemical impedance spectroscopy. The oxide film formed during the passivation process of nickel has showed the electronic properties of p-type semiconductor, which follow from the Mott-Schottky equation. It was found out that the passive film ($Ni(OH)_2$) of Ni formed in the low electrode potential changes to NiO and NiO(OH) while the electrode potential increases.

Growth Kinetics and Electronic Properties of Passive Film of Cobalt in Borate Buffer Solution (Borate 완충용액에서 코발트 산화피막의 생성 과정과 전기적 성질)

  • Park, Hyunsung;Kim, Younkyoo
    • Journal of the Korean Chemical Society
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    • v.61 no.6
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    • pp.320-327
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    • 2017
  • In a borate buffer solution, the growth kinetics and the electronic properties of passive film on cobalt were investigated, using the potentiodynamic method, chronoamperometry, and single-frequency electrochemical impedance spectroscopy. It was found out that the unstable passive film ($Co(OH)_2$) and CoO of Co formed in the low electrode potential changes to $Co_3O_4$ and CoOOH while the electrode potential increases. And the composition of the passive films was varied against the applied potential and oxidation time. The oxide film formed during the passivation process of cobalt has showed the electronic properties of p-type semiconductor, which follow from the Mott-Schottky equation.