Characterization of surface composition on Alloy 22 in neutral chloride solutions

Zagidulin, Dmitrij; Zhang, Xiangrong; Zhou, Jigang; Noël, James J.; Shoesmith, David W.

doi:10.1002/sia.5204

Cited by 34 publications

(33 citation statements)

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“…It has been demonstrated previously [41][42][43] that the PDM can readily explain the observations of the passive state on Alloy-22. Characterization work 41,[44][45][46] has demonstrated that the passive film on Alloy-22 has a distinct layered structure with the inner layer primarily comprising Cr(III) oxide, so it is assumed in the optimization that point defective Cr 2 O 3 is the principal composition of the barrier layer. Fig.…”

Section: Results and Analysis By Numerical Optimizationmentioning

confidence: 99%

The Kinetics of Nucleation of Metastable Pits on Metal Surfaces: The Point Defect Model and Its Optimization on Data Obtained on Stainless Steel, Carbon Steel, Iron, Aluminum and Alloy-22

Lü

Engelhardt

Kursten

et al. 2016

J. Electrochem. Soc.

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The theory of the kinetics of metastable pit nucleation in terms of the Point Defect Model (PDM) has been applied the first time to describing the evolution of the nucleation rate of metastable pits on a variety of metallic substrates. The PDM successfully accounts for the experimental data that have been reported in the literature on stainless steel, carbon steel, iron, aluminum, and Alloy-22, and which are judged to be reliable and reproducible. Important fundamental parameters related to metastable pitting such as total number density of pitting nucleation sites, dissolution time of the cap over the pit, energy related to absorption of the aggressive ions into oxygen vacancies in the surface of the barrier layer, vacancy condensation rate, and the time at which the nucleation rate of metastable pits is maximum were obtained from the optimization of the PDM on the experimental data, as reported in the present paper. The values obtained for those parameters are in good agreement with values and observations reported elsewhere. The present work successfully demonstrates the capacity of the PDM in accounting for experimental observations of metastable pitting and that the PDM can be applied as an underlying theory for studying and understanding metastable pitting on metal surfaces. The passive state is not perfectly protective and passivity breakdown occurs for various reasons, giving rise to enhanced general corrosion rate or to localized corrosion. Localized passivity breakdown is especially of great concern, because it results in the nucleation and propagation of pits and the subsequent nucleation and growth of cracks provided that there is sufficient tensile stress in the system to initiate crack nucleation at the stress raiser represented by the pit. Metastable pitting, in which passivity breakdown occurs followed immediately by repassivation, is now well-accepted as being an integral part of the process of pitting corrosion on a metal or alloy, culminating in the accumulation of damage via the development of stable pits. It is also well-recognized that repassivation reflects the failure on the part of the pit nucleus to establish a spatial separation between the local cathode and the local anode with the former occurring on the external surfaces and the latter taking place in the nucleus, which is necessary for the buildup and maintenance of the aggressive conditions of high [Cl − ] and high [H + ] (low pH) that cause the pits to grow as stable pits, until they, too, die via delayed repassivation (due to the inability of the pit to maintain separation of the local cathode and the local anode, because of the limited availability of resources of the cathodic depolarizer on the external surfaces).Numerous authors have reported metastable pit nucleation rate data measured under more-or-less well-defined conditions. Williams et al.1-3 reported a good proportional correspondence for Type 304L SS between the nucleation frequency of metastable pits and the frequency of occurrence of propagating (stable) pits, that ...

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Section: Results and Analysis By Numerical Optimizationmentioning

confidence: 99%

The Kinetics of Nucleation of Metastable Pits on Metal Surfaces: The Point Defect Model and Its Optimization on Data Obtained on Stainless Steel, Carbon Steel, Iron, Aluminum and Alloy-22

Lü

Engelhardt

Kursten

et al. 2016

J. Electrochem. Soc.

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“…This suggests the kinetics of film growth are dominantly controlled by the Cr and Mo contents, as observed previously for other Ni-Cr-Mo alloys. [38][39]41 For Ni-Cr-Mo alloys, [38][39]41 the oxide film owes its passivity to its Cr/Mo content, which enforces the formation of an inner Cr(III) oxide barrier layer and an outer, dominantly hydroxide, Mo(VI) layer. With increasing temperature, the evolution in film properties was shown to involve two counterbalancing influences: an increase in overall film thickness, which would be expected to improve passivity, and a decrease in Cr/Mo content, which would be expected to degrade passivity.…”

Section: Characterization Techniquesmentioning

confidence: 99%

The Role of Copper on the Crevice Corrosion Behavior of Nickel-Chromium-Molybdenum Alloys in Aggressive Solutions

2016

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The effect of Cu on the localized corrosion of Ni-Cr-Mo alloys has been investigated in hot saline solutions by comparing the behavior of N06059 and N06200 alloys, using electrochemical and surface analytical techniques. No measurable effect of copper on anodic film growth kinetics and passive film properties was detected and the breakdown and repassivation potentials of the alloys were very similar. Angle-resolved x-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectroscopy demonstrated that the copper segregated to the oxide/solution interface during anodic film growth and that this process was enhanced as the pH decreased, as would occur in a crevice prior to initiation. Galvanostatically controlled crevice corrosion experiments demonstrated that this surface accumulation suppressed the metastable breakdown events that preceded initiation on the Cu-free alloy. Dynamic secondary ion mass spectrometry showed that copper accumulated with molybdates in crevice corroded locations but could not confirm any influence of copper on crevice propagation.

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“…The composition of the passive films formed on the Ni-Cr-Mo alloys has been characterized by using different methods such as atomic force microscopy (AFM), time of flight secondary ion mass spectrometry (ToF-SIMS), and X-ray photoemission spectroscopy (XPS). These studies indicated that the composition of the passive films depends on many variables such as anodic potential, presence of aggressive anions, pH and aerating conditions [5,[11][12][13].…”

Section: Introductionmentioning

confidence: 98%

Modified Point Defect Model for the Electrochemical Behavior of the Passive Films Formed on Alloy C (UNS N10002) in Borax Solutions

Fattah‐alhosseini

2014

Arab J Sci Eng

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Utilizing potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS), the passive films properties of alloy C in borax solutions under open circuit potential condition were evaluated. The potentiodynamic polarization curves suggested that alloy C showed excellent passive behavior in borax solutions. The capacitance versus potential curves revealed that the passive films displayed p-type semiconductive characteristics, where the Ni(II) vacancies preponderated over the oxygen vacancies and interstitials. The EIS data showed that the equivalent circuit R s [(R fs Q fs )(R f Q f )(R mf Q mf )] by three time constants is applicable. These results also revealed that the measured value of polarization resistance increases with decreasing concentration of borax solutions.

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Characterization of surface composition on Alloy 22 in neutral chloride solutions

Cited by 34 publications

References 50 publications

The Kinetics of Nucleation of Metastable Pits on Metal Surfaces: The Point Defect Model and Its Optimization on Data Obtained on Stainless Steel, Carbon Steel, Iron, Aluminum and Alloy-22

The Kinetics of Nucleation of Metastable Pits on Metal Surfaces: The Point Defect Model and Its Optimization on Data Obtained on Stainless Steel, Carbon Steel, Iron, Aluminum and Alloy-22

The Role of Copper on the Crevice Corrosion Behavior of Nickel-Chromium-Molybdenum Alloys in Aggressive Solutions

Modified Point Defect Model for the Electrochemical Behavior of the Passive Films Formed on Alloy C (UNS N10002) in Borax Solutions

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