A Signature in the Current during Early Events in the Pitting Corrosion of Aluminum

Bargeron, C. B.; Givens, R. B.

doi:10.1149/1.2123830

Cited by 14 publications

(15 citation statements)

References 9 publications

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“…The reader will note that the fundamental event in passivity breakdown, according to the PDM, is the formation of a cation vacancy condensate at the m/bl interface. The formation of such blisters as the precursors to passivity breakdown on aluminum has been detected and described by Bargeron and Givens and by McCafferty et al, amongst others [68,69,70,71,72,73,74]. Indeed, the present findings are entirely in concert with that previous work and provide an analytical basis for the vacancy condensation mechanism for passivity breakdown.…”

Section: Discussionsupporting

confidence: 88%

“…At that point (potential, E c ), vacancy condensation occurs and continues around the periphery of the blister. The initial condensation point may be nanoscopic, but the radius of the blister increases with the square root of time and quickly grows to a micron size, as observed by Bargeron and Givens and others [68,69,70,71,72,73,74], with the size being determined by the rate of dissolution and the mechanical integrity of the cap. Thus, at some point during this expansion, the blister (remnants of the dissolving barrier layer) fractures and allows the electrolyte to penetrate into the blister, resulting in the emission of gas (H 2 , H 2 S, NH 3 and CH 4 , corresponding to oxide, sulfide, nitride, and carbide precipitates, respectively), as reported by Bargeron and Givens) [69,70,71].…”

Section: Discussionmentioning

confidence: 81%

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Studies on Pitting Corrosion of Al-Cu-Li Alloys Part II: Breakdown Potential and Pit Initiation

et al. 2019

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Prediction of the accumulated pitting corrosion damage in aluminum-lithium (Al-Li) is of great importance due to the wide application of these alloys in the aerospace industry. The Point Defect Model (PDM) is arguably one of the most well-developed techniques for evaluating the electrochemical behavior of passive metals. In this paper, the passivity breakdown and pitting corrosion performance of AA 2098-T851 was investigated using the PDM with the potentiodynamic polarization (PDP) technique in NaCl solutions at different scan rates, Cl− concentrations and pH. Both the PDM predictions and experiments reveal linear relationships between the critical breakdown potential (Ec) of the alloy and various independent variables, such as a C l − and pH. Optimization of the PDM of the near-normally distributed Ec as measured in at least 20 replicate experiments under each set of conditions, allowing for the estimation of some of the critical parameters on barrier layer generation and dissolution, such as the critical areal concentration of condensed cation vacancies (ξ) at the metal/barrier layer interface and the mean diffusivity of the cation vacancy in the barrier layer (D). With these values obtained—using PDM optimization—in one set of conditions, the Ec distribution can be predicted for any other set of conditions (combinations of a Cl − , pH and T). The PDM predictions and experimental observations in this work are in close agreement.

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Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 81%

Studies on Pitting Corrosion of Al-Cu-Li Alloys Part II: Breakdown Potential and Pit Initiation

et al. 2019

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“…17,18 Other workers have shown that under potentiostatic control the current from single active pits often shows rapid multiple transient events. [19][20][21] Bargeron and Givens observed very high frequency current events up to 4000 Hz and suggested they were caused by the oxide layer separating from the metal substrate. 19 Lillard found multiple events with Be occurring at about 1 Hz for a ͑0001͒ orientation.…”

Section: Resultsmentioning

confidence: 99%

“…[19][20][21] Bargeron and Givens observed very high frequency current events up to 4000 Hz and suggested they were caused by the oxide layer separating from the metal substrate. 19 Lillard found multiple events with Be occurring at about 1 Hz for a ͑0001͒ orientation. He attributes the localization of these events to properties of the repassivation layer or development of a local solution chemistry which produces a memory of where the previous events took place.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Noise during Pitting Corrosion of Aluminum in Chloride Environments

Sasaki¹,

Levy²,

Isaacs³

2002

Electrochem. Solid-State Lett.

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Aluminum shows vigorous fluctuations in current and potential in chloride containing media close to its pitting potential. To determine the source of this noise, we used aqueous solutions, gels with a pH indicator, and currents between interconnected electrodes, to locate pits and study currents generated at freely corroding potentials. We demonstrated that there is a transition in the characteristics of the noise. Transitions occur when pits continue to remain active, and also when more than one active pit is present because of the electrochemical communication that takes place between them. The major source of current and potential transients with aluminum is due to the growth process in active pits, rather than metastable pitting at the passive surface.Aluminum and its alloys are susceptible to pitting corrosion in chloride environments. Fluctuations in potential and/or current are observed that are associated with the pitting processes. 1-6 These fluctuations generally are termed electrochemical noise, and have been predominantly interpreted in terms of metastable pitting events. The present study concludes that care must be taken in analyzing these events in this manner, because, in general, most of the noise is a result of the growth process of active pits.Fluctuations or electrochemical noise have been related to a wide range of corrosion phenomena. [2][3][4][5][6][7][8][9][10][11] The objective of many studies has been to derive the mechanisms involved in the breakdown of passivity and the initiation of pitting. The processes taking place during the pitting of stainless steel 7-11 are better understood than the pitting of aluminum. It is generally accepted for stainless steels that electrochemical transients are due to an initiation process, a short period during which the pit grows, and repassivation of the metastable pit. [7][8][9][10][11] The open-circuit potential ͑OCP͒ during metastable pitting of stainless steel in a NaCl solution shows a rapid drop, followed by a significantly slower rise to the original value. The current for the early stages of pit growth is derived from the interfacial capacitance of the entire passive surface. 8 The slow recovery in potential after repassivation of a metastable pit is due to recharging of the capacitance by the cathodic oxygen reduction reaction. Thus, the electrochemical transients in stainless steel can be modeled as the consequence of superposition of these metastable pit events. 2,8 However, the open-circuit electrochemical noise of aluminum often shows features of a buffered potential, 12,13 indicating that the mechanisms during the pitting processes are different from those of stainless steels. As described below, we demonstrate that the electrochemical transients during the pitting of aluminum initially originate from processes similar to those on stainless steel, but later are dominated by the electrochemistry within the pit and the interactions between pits once a number of pitting sites remain active. ExperimentalTest electrodes were fabricated from Ͼ...

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“…The reason for this capacitance drop does not lie in the dielectric behaviour, but can be evaluated from the equivalent series circuit suggested e.g. in Reference [1,3] as a capacitance dissipation effect of the MnO 2 electrolyte and circuit inductance. The relation between the maximum DF and the capacitance cut-off frequency is valid in this case also.…”

Section: Real Capacitor ε /Capacitance and Df Frequency Dependencesmentioning

confidence: 99%

Polarization and fluctuation characteristics of tantalum solid electrolyte capacitors

Zednicek¹,

Šikula²,

Hruška³

et al. 1998

Qual. Reliab. Engng. Int.

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A new method of tantalum capacitor testing and reliability prediction is presented based on the analysis of polarization mechanisms and noise characteristics. Polarization mechanisms of the Ta2O5 dielectric layer include electron polarization, fast ion polarization and ion relaxation polarization. Impurities usually add a fourth polarization type, migration polarization, which is effective in the mHz–kHz frequency region. © 1998 John Wiley & Sons, Ltd.

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A Signature in the Current during Early Events in the Pitting Corrosion of Aluminum

Abstract: not Available.

Cited by 14 publications

References 9 publications

Studies on Pitting Corrosion of Al-Cu-Li Alloys Part II: Breakdown Potential and Pit Initiation

Studies on Pitting Corrosion of Al-Cu-Li Alloys Part II: Breakdown Potential and Pit Initiation

Electrochemical Noise during Pitting Corrosion of Aluminum in Chloride Environments

Polarization and fluctuation characteristics of tantalum solid electrolyte capacitors

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