Wavelet Analysis of Electrochemical Noise Data

Smith, Morgan; Macdonald, Digby D.

doi:10.5006/1.3319148

Cited by 32 publications

(10 citation statements)

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“…12 Burstein and Mattin, 6 suggest that passivity breakdown gives rise to current pulses that are of the pA order in magnitude. However, in the light of much work on the origin of electrochemical noise, [13][14][15] it is evident that there are many processes, other than passivity breakdown, that give rise to noise at a passive metal interface, such as bubble detachment, the "flickering" of anodic and cathodic sites across the surface, as in general corrosion, and possibly the existence of intermittently active, low impedance paths along emergent grain boundaries in the nano-crystalline passive film. These paths are intermittent, because the barrier layer continuously forms at the metal/film interface and dissolves at the film/solution interface, so that the grain boundaries between the nano-crystallites are continuously redistributed with time.…”

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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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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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“…Wavelet transform is a procedure used in data analyses without the precondition of stationarity or linearity and with a high distinguishing capacity in frequency domain simultaneously …”

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confidence: 99%

Corrosion mechanism and behavior of high‐velocity arc‐sprayed Al–Ti–Si–RE coating in a simulated deep sea

Tong

Wei

Wang

et al. 2019

Materials & Corrosion

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The corrosion protection of deep-sea equipment using the economical method of thermal spraying has become a research hotspot. This study investigated the corrosion behavior of high-velocity arc-sprayed Al-Ti-Si-RE coating in a simulated deep sea with regard to microstructures, compositions, and electrochemical measurements. Results showed that the Al-Ti-Si-RE coating has excellent corrosion resistance at high hydrostatic pressure (HP). HP plays an important role in the anodic reaction of the coating, whereas dissolved oxygen (DO) mainly affects the cathodic reaction. HP accelerates the dissolution of the coating's passive film, which results in steady corrosion. The amount of corrosion products depends on DO. The corrosion of the self-sealing coating is inhibited in low DO when steady corrosion is achieved. K E Y W O R D S deep sea corrosion, dissolved oxygen, electrochemical noise, high-velocity arc-sprayed coating, hydrostatic pressure

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“…[35][36][37][38][39] An advantage of wavelet analysis is that the time domain information is preserved and non-stationary time records can be analyzed without detrending and windowing. [40] In the present investigation, the orthogonal wavelet transform, (OWT), was used to analyze the detrended potential noise-time record. [38,39] In this method, as well reported in literature, [35][36][37][38][39][40] an EN time record, x(t) = X n (n = 1. .…”

Section: Wavelet Analysismentioning

confidence: 99%

Monitoring localized corrosion of Inconel 82 weld overlay on 304L SS weld by electrochemical noise

Suresh

Kumar

2019

Mater Eng Res

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The manuscript presents the results from the electrochemical noise (EN) monitoring of Inconel 82 weld overlay on Type 304L stainless steel (SS) weld in 0.01M FeCl 3. The microstructure of the weld overlay obtained from optical and scanning electron microscopy (SEM) showed an austenite structure, containing equiaxed dendrites and secondary phases at the interdendritic region. Energy dispersive spectroscopy (EDS) attached to SEM revealed the secondary phases to be Nb rich Laves phase. The electrochemical potential noise was monitored using a three identical electrode configuration. The acquired signals were detrended, and wavelet analysis was employed to encode useful information from the noise transients. Visual examination of the potential noise-time record contained distinct high amplitude transients typical of localized corrosion attack. The energy distribution plots (EDP) of the potential noise derived from wavelet analysis depicted maximum relative energy on D6-D8 crystals, which represent large time scale events such as those occurring from localized attacks. Also, repassivation events too could be divulged from the potential EDP. The micrographs of the post electrochemical noise experimented specimens revealed the occurrence of localized attacks along the interdendritic region and none inside the dendritic cores. The presence of secondary phases along the interdendritic regions was found to be detrimental in chloride medium, imparting inferior localized corrosion resistance to the weld overlay.

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Wavelet Analysis of Electrochemical Noise Data

Cited by 32 publications

References 1 publication

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

Corrosion mechanism and behavior of high‐velocity arc‐sprayed Al–Ti–Si–RE coating in a simulated deep sea

Monitoring localized corrosion of Inconel 82 weld overlay on 304L SS weld by electrochemical noise

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