Potentiometric scanning electrochemical microscopy for the local characterization of the electrochemical behaviour of magnesium-based materials

Izquierdo, Javier; Nagy, Lı́via; Bitter, István; Souto, Ricardo M.; Nagy, Géza

doi:10.1016/j.electacta.2012.09.029

Cited by 56 publications

(52 citation statements)

References 62 publications

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“…One of the broad and controversially discussed questions is the change of pH during the degradation of Mg, as well as increases and the fact of no changes of pH during the corrosion of Mg and Mg-alloys. [46] have shown over a Mg strip in 10 mM NaCl solution,that the pH measured with a UME (diameter of 175 μm) in a constant height mode at a distance of 80 μm away from the interface and moved along a distance of 1 mm diversifies between 8.5 and 5.5. The shift to lower pH was detected at surface areas where hydrogen evolution took place.…”

Section: Scanning Electro-chemical Microscopy (Secm)mentioning

confidence: 99%

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Electrochemical techniques for assessment of corrosion behaviour of Mg and Mg-alloys

Müeller

2015

BioNanoMaterials

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During the recent years different reviews have been published focusing on several aspects: the challenge of application of Mg-alloys as biomaterials, manufacturing procedure and its influence on the corrosion stability, application of different techniques to produce protection layers, coatings onto the surface of Mg-bulk devices, the influence of various elements applied as alloying part for Mg in order to change the mechanical as well as the electrochemical properties. The aim of this paper is to review and to comment electrochemical techniques applied to assess the corrosion/degradation behaviour of Mg and Mg-alloys for biomedical application.

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Section: Scanning Electro-chemical Microscopy (Secm)mentioning

confidence: 99%

“…Usually Pt or Ir wires are used for this purpose. They are fixed in glass tubes with a diameter of < 1 mm [19,46]. Depending on the problem in focus, various techniques have been developed.…”

Section: Scanning Electro-chemical Microscopy (Secm)mentioning

confidence: 99%

Electrochemical techniques for assessment of corrosion behaviour of Mg and Mg-alloys

Müeller

2015

BioNanoMaterials

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“…Such techniques have been applied to study the corrosion of Mg alloys including localized electrochemical impedance spectroscopy (LEIS) [4,5], scanning Kelvin probe force microscopy (SKPFM) [6,7], the scanning vibrating electrode (SVET) technique [8][9][10][11][12], and different modes of scanning electrochemical microscopy (SECM) [13][14][15][16][17]. Monitoring corrosion processes above Mg alloys in an aqueous environment with these techniques is challenging because of large H 2 fluxes evolving as corrosion progresses which can interfere with mediator detection at the microelectrode tip and create a convective medium at the corroding surface [18].…”

Section: Introductionmentioning

confidence: 99%

Reducing the corrosion rate of magnesium alloys using ethylene glycol for advanced electrochemical imaging

et al. 2015

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“…15,17 The potentiometric mode of SECM has also been extensively employed to characterize both pHs and Mg 2+ flux during corrosion of Mg alloys. 16,18,[33][34][35] The Mg 2+ is generated by anodic oxidation of the matrix phase (Equation 1) while the reduction of water occurs predominantly on the more noble alloy constituents (secondary phases) producing dissolved molecular H 2 and OH − species (Equation 2). Generation of OH − in the cathodic reaction leads to localized pH changes and the deposition of Mg(OH) 2 (Equation 3) on the alloy surface (K sp, Mg(OH) 2 = 5.61 × 10 −12 ).…”

mentioning

confidence: 99%

“…15,17 The potentiometric mode of SECM has also been extensively employed to characterize both pHs and Mg 2+ flux during corrosion of Mg alloys. 16,18,[33][34][35] …”

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confidence: 99%

Local Hydrogen Fluxes Correlated to Microstructural Features of a Corroding Sand Cast AM50 Magnesium Alloy

Dauphin‐Ducharme

Asmussen

Tefashe

et al. 2014

J. Electrochem. Soc.

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Successful in situ spatiotemporal tracking of corrosion processes occurring at heterogeneous Mg alloy microstructures was achieved through tandem analyses involving electron and electrochemical microscopies. Through cross-correlation of scanning electron microscopy and scanning electrochemical microscopy images and subsequent analytical transmission electron microscopy, the morphology and chemical composition of microstructural components on the surface of a sand-cast AM50 Mg alloy were related to their respective local evolution of H 2 with micron scale resolution prior to, during and post corrosion. The results confirm that the preferential water reduction sites in the initial stages of corrosion are the Al 8 Mn 5 intermetallics while a β-Mg 17 Al 12 precipitate contaminated with Ni becomes cathodically active at a later stage of corrosion. This approach demonstrates the power of correlative approaches to probe and understand local electrochemical phenomena. Owing to their light weight, high strength-to-weight ratio, good castability and high damping capacity, Mg alloys are ideal candidates for automotive structural components.1-5 The compromise of formability, room temperature ductility and price represent major challenges in commercializing these materials. Importantly, Mg alloys also suffer from poor corrosion resistance in aqueous environments 6-8 and due to their positions in the electrochemical activity series, are highly susceptible to accelerated corrosion rates when in galvanic contact with a more noble material.9 At open circuit, the overall galvanic current is null due to a balance between the anodic and cathodic current densities, while on a microscopic scale, a difference in electrochemical potential is obtained. In Mg alloys, galvanic coupling between microstructural components of the alloy (commonly referred to as microgalvanic coupling) stems from an inherent electrochemical potential difference between the Mg matrix and its secondary phases, [10][11][12] and can be tracked using local scanning probe methods.Local scanning probe techniques such as several modes of scanning electrochemical microscopy (SECM), [13][14][15][16][17][18][19] scanning Kelvin probe force microscopy (SKPFM), 20-22 the scanning vibrating electrode technique (SVET) [23][24][25] and local electrochemical impedance spectroscopy (LEIS) 26 have been used to probe the heterogeneous surfaces of Mg alloys and to assess the electrochemical behavior of the different microstructural constituents responsible for microgalvanic corrosion. Among these techniques, SECM has the ability to quantify electrochemical fluxes in situ with high lateral resolution using a microelectrode (ME). 27 This technique has been successfully applied in corrosion research to provide in situ analyses of pitting corrosion at oxide films, [28][29][30] to assess lateral variations in corrosion kinetics, 31 and to detect defects within coated metal samples. 32The feedback mode of SECM has been employed to probe corroding AM60 15 and AZ31 17 Mg alloys. The incre...

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Potentiometric scanning electrochemical microscopy for the local characterization of the electrochemical behaviour of magnesium-based materials

Cited by 56 publications

References 62 publications

Electrochemical techniques for assessment of corrosion behaviour of Mg and Mg-alloys

Electrochemical techniques for assessment of corrosion behaviour of Mg and Mg-alloys

Reducing the corrosion rate of magnesium alloys using ethylene glycol for advanced electrochemical imaging

Local Hydrogen Fluxes Correlated to Microstructural Features of a Corroding Sand Cast AM50 Magnesium Alloy

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