Reflective microscopy for mechanistic insights in corrosion research

Shkirskiy, Viacheslav; Kanoufi, Frédéric

doi:10.1016/j.coelec.2023.101259

Cited by 9 publications

(14 citation statements)

References 58 publications

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“…Recently, optical models utilizing light interference at oxidized metal interfaces have shown that variations in optical intensities can quantitatively relate to the thickness (to nanometer precision) and composition of surface films. 23,25,26,37 These parameters are central to our understanding of metal passivation and corrosion protection. When augmented with machine vision methodologies, 38,39 RM evolves into an automated, robust, and flexible approach.…”

Section: ■ Introductionmentioning

confidence: 99%

“…This is due to the cooperative interplay between metal heterogeneities resulting from the formation of extensive galvanic couplings, , the diffusive exchange of dissolved species, − among other factors . As a result, conducting a comprehensive analysis of metal oxidation reactions necessitates the formulation and implementation of methodologiesones that balance both highly precise quantitative measurements, capable of delving into nanometer-scale intricacies, and wide-field measurements that can cover expanses up to the millimeter range . To tackle this challenge and demonstrate the merits of dual-pronged, precision-focused, quantitative, and wide-field in situ measurements in the realm of metal oxidation, we utilized reflective microscopy (RM).…”

Section: Introductionmentioning

confidence: 99%

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Deciphering the Interplay between Local and Global Dynamics of Anodic Metal Oxidation

Makogon,

Noël,

Kanoufi

et al. 2024

Anal. Chem.

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The stark difference between global and local metal oxidation dynamics underscores the need for methodologies capable of performing precise sub-μm-scale and wide-field measurements. In this study, we present reflective microscopy as a tool developed to address this challenge, illustrated by the example of chronoamperometric Fe oxidation in a NaCl solution. Analysis at a local scale of 10 s of μm has revealed three distinct periods of Fe oxidation: the initial covering of the metal interface with a surface film, followed by the electrochemical conversion of the formed surface film, and finally, the in-depth oxidation of Fe. In addition, thermodynamic calculations and the quantitative analysis of changes in optical signal (light intensity), correlated with variations in refractive indexes, suggest the initial formation of maghemite, followed by its subsequent conversion to magnetite. The reactivity maps for all three periods are heterogeneous, which can be attributed to the preferential oxidation of certain crystallographic grains. Notably, at the global scale of 100 s of μm, reactivity initiates at the electrode border and progresses toward its center, demonstrating a unique pattern that is independent of the local metal structure. This finding underscores the significance of simultaneously employing subμm-precise, quantitative, and wide-field measurements for a comprehensive description of metal oxidation processes.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Deciphering the Interplay between Local and Global Dynamics of Anodic Metal Oxidation

Makogon,

Noël,

Kanoufi

et al. 2024

Anal. Chem.

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“…[13] RM is a label-free optical imaging technique that utilizes the local changes in the refractive index of the imaged interface to reveal various (electro-)chemical phase conversions. [14][15][16][17][18][19][20][21][22] This technique is particularly useful for detecting bubble formation, changes in surface film thickness and roughness, and ion intercalations. [16,18,[23][24][25][26][27] RM is widely employed in the field of surface science, both as a standalone method and in combination with other local techniques such as nanopipet approaches.…”

Section: Introductionmentioning

confidence: 99%

“…[28][29][30] RM has high temporal and spatial resolution, allowing for measurements with a resolution of ≈200 nm and acquisition rates up to kHz in a wide field (mm) range. [14,25] However, the generation of large optical datasets also poses significant challenges in processing feature-rich optical images. One common approach is the use of machine vision procedures that employ computer algorithms.…”

Section: Introductionmentioning

confidence: 99%

Unsupervised Analysis of Optical Imaging Data for the Discovery of Reactivity Patterns in Metal Alloy

Makogon

Galochkina

et al. 2023

Small Methods

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Operando wide‐field optical microscopy imaging yields a wealth of information about the reactivity of metal interfaces, yet the data are often unstructured and challenging to process. In this study, the power of unsupervised machine learning (ML) algorithms is harnessed to analyze chemical reactivity images obtained dynamically by reflectivity microscopy in combination with ex situ scanning electron microscopy to identify and cluster the chemical reactivity of particles in Al alloy. The ML analysis uncovers three distinct clusters of reactivity from unlabeled datasets. A detailed examination of representative reactivity patterns confirms the chemical communication of generated OH− fluxes within particles, as supported by statistical analysis of size distribution and finite element modelling (FEM). The ML procedures also reveal statistically significant patterns of reactivity under dynamic conditions, such as pH acidification. The results align well with a numerical model of chemical communication, underscoring the synergy between data‐driven ML and physics‐driven FEM approaches.

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“…This work studies the passive film breakdown in a 1 M NaCl electrolyte and the subsequent formation of corrosion scales, formed by the redeposited corrosion products from a corroding Ni–Cr–Mo alloy (alloy 59). We use an emerging optical technique termed 2-Dimensional surface optical reflectance (2D-SOR) microscopy − (also known as reflectance microscopy), to follow the corrosion initiation and progression in operando conditions with high temporal and spatial resolution. 2D-SOR has previously been used to study the corrosion of duplex stainless steel, the anodization of aluminum, the local corrosion of aluminum alloys, − the electrooxidation of gold, ,, and corrosion inhibition. , Here we demonstrate the additional capabilities of this affordable and straightforward technique.…”

Section: Introductionmentioning

confidence: 99%

Operando Surface Optical Reflectance Microscopy Study of Corrosion Film Growth on a Ni–Cr–Mo Alloy During Anodic Polarization

Larsson,

Vorobyova,

Pfaff

et al. 2023

J. Phys. Chem. C

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The solid–liquid interface, where corrosion reactions occur, is notoriously difficult to study in operando conditions. Few experimental techniques can provide surface sensitivity and spatial and temporal resolution and are compatible with liquid environments. 2-Dimensional surface optical reflectance (2D-SOR) is an emerging optical technique providing microscopic information with high temporal resolution. It complements methods such as ambient pressure X-ray photoelectron spectroscopy or inductively coupled plasma-mass spectrometry, which provides valuable chemical information from the surface and the dissolving species but lacks spatial resolution. Here, we show how 2D-SOR can be used to measure the formation and growth of corrosion products in operando through oscillations in the reflected signal caused by constructive and destructive interference of the light in the film of growing corrosion products. The total thickness of the corrosion product film obtained with 2D-SOR agrees well with that measured using scanning electron microscopy ex situ. 2D-SOR has proved to be an excellent and valuable tool for monitoring the corrosion process with spatial resolution in operating conditions.

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Reflective microscopy for mechanistic insights in corrosion research

Cited by 9 publications

References 58 publications

Deciphering the Interplay between Local and Global Dynamics of Anodic Metal Oxidation

Deciphering the Interplay between Local and Global Dynamics of Anodic Metal Oxidation

Unsupervised Analysis of Optical Imaging Data for the Discovery of Reactivity Patterns in Metal Alloy

Operando Surface Optical Reflectance Microscopy Study of Corrosion Film Growth on a Ni–Cr–Mo Alloy During Anodic Polarization

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