Insight into physical interpretation of high frequency time constant in electrochemical impedance spectra of Mg

Wang, Linqian; Snihirova, Darya; Deng, Min; Wang, Cheng; Vaghefinazari, Bahram; Wiese, Gert; Langridge, Mark; Höche, Daniel; Lamaka, Sviatlana V.; Zheludkevich, Mikhail L.

doi:10.1016/j.corsci.2021.109501

Cited by 87 publications

(29 citation statements)

References 55 publications

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“…7(a, c, e, g)) are composed of two capacitive loops followed by a low frequency (LF) inductive loop. This EIS diagrams shape is often reported for Mg alloys in different electrolytes [75,[82][83][84][85], and the origin of the different time constants will be discussed later. Even though similar, a closer examination of the phase angle plots (Fig.…”

Section: Eis Testssupporting

confidence: 66%

“…8; initially, due to the small number of experimental points for its definition in most of the experimental diagrams, and secondly, due to the difficulties in associating the values extracted from the EEC fitting procedure to the physical-chemical phenomenon it represents. Following EIS diagrams interpretation for other metals [88,89], this LF inductive loop has been more frequently associated with relaxation of reaction intermediates [84], even though phenomena related to the breakdown of protective films have also been claimed to produce this inductive response [84,90,91]. Fig.…”

Section: Eis Testsmentioning

confidence: 91%

“…For further comprehension of the corrosion behavior of the different samples, the impedance data were fitted using EEC. As mentioned and documented by Wang et al [84], different EEC has been proposed in the literature to interpret the EIS responses of Mg and its alloys in several media. Besides differences in the arrangement of the EEC passive elements (parallel or series), different physical processes have been associated with each time constant (TC) of the EIS diagrams, even though most of them present similar shapes to those found in the present investigation.…”

Section: Eis Testsmentioning

confidence: 99%

“…Hence, a normal distribution of time constants within the coating thickness can be associated, as suggested by Hirschorn et al [93], an argument that has been recently used by Prada-Ramirez et al [55][56][57] to explain the impedance response of anodized Al as sealing occurs within the pores. It is important to emphasize that, as extensively discussed in the literature, the oxide layer on top of the Mg surface exposed to different electrolytes is composed of a porous, non-protective layer, mainly Mg(OH) 2 , on top of a thin MgO compact and protective layer [75,83,84]. The percolation of the hybrid solution within the structure of the porous layer followed by its drying during the curing step must explain the relatively low "n" values for the Hyb sample; moreover, as shown in Table 3," n" becomes even lower for the CeP-Hyb sample, in this case, the hybrid layer must also percolate through the dry mud structure of the Ce conversion layer, leading to an even more complex behavior.…”

Section: Eis Testsmentioning

confidence: 99%

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Cerium conversion coating and sol-gel coating for corrosion protection of the WE43 Mg alloy

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Section: Eis Testssupporting

confidence: 66%

Section: Eis Testsmentioning

confidence: 91%

Section: Eis Testsmentioning

confidence: 99%

Section: Eis Testsmentioning

confidence: 99%

See 2 more Smart Citations

Cerium conversion coating and sol-gel coating for corrosion protection of the WE43 Mg alloy

et al. 2022

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“…48 ) In addition, R t describes the charge transfer resistance, which also was the resistance of surface oxide film (MgO). 49 R f and C f represent the resistance and capacitance of the Mg(OH) 2 surface film on the anode surface, respectively. And L and R L reflect the inductive loop in the fourth quadrant.…”

Section: Electrochemical Behavior and Corrosion Resistancementioning

confidence: 99%

Influence of Ba micro‐alloying on electrochemical and discharge behaviors of Mg‐Al anodes for mg‐air primary battery

Zou

Jia

et al. 2022

Intl J of Energy Research

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Herein, we report a new strategy of Ba micro-alloying to enhance the anode properties of the Mg-air primary battery anode materials. The influence of Ba micro-alloying on electrochemical behavior, corrosion resistance, and discharge properties of Mg-6Al anodes in Mg-air batteries was specifically investigated. Ba micro-alloying markedly improved the corrosion resistance of Mg-6Al alloys, which was due to the grain refinement and the inhibition of the cathodic hydrogen evolution reaction. However, when Ba content reached 0.7 wt.%, the coarse Al 13 Ba 7 phase accelerated the galvanic corrosion and increased the corrosion rate. Moreover, the Mg-6Al-0.4Ba anode had the optimal discharge capacity and anode efficiency at 20 mA cm À2 with 893.66 mAh g À1 and 39.36%, respectively, which was 22.1% and 22.4% higher than that of the Mg-6Al anode. The enrichment of discharge properties was attributed to the refinement of grains and the improvement of the self-corrosion resistance. In addition, Ba micro-alloying improved the absorption capacity of the anode, which was conducive to the selfexfoliation of the discharge products. The Novelty StatementThis paper prepared the Mg-6Al-xBa anodes by Ba micro-alloying to enhance the discharge properties. The generation of Al 13 Ba 7 phase and the refinement of grains caused by Ba addition reduced the corrosion rate and increased the discharge capacity and anodic efficiency of Mg-6Al alloy. Thus, Ba micro-alloying can improve the corrosion resistance and discharge performance of Mg-6Al alloy.

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Corrosion mechanisms of AZ31 magnesium alloy: Importance of starting pH and its evolution

Prince

Noirfalise

Paint

et al. 2022

Materials & Corrosion

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This article aims at improving the understanding of the corrosion mechanism of AZ31 magnesium alloys during a long period of immersion in an aqueous electrolyte. In particular, the influence of the starting pH of the electrolyte on the oxidation of AZ31 alloy and its evolution due to corrosion phenomena were investigated. Several electrolytes with different pH values containing or not chlorides were used. The electrochemical properties of the metal substrate in these electrolytes were studied as a function of immersion time by electrochemical impedance spectroscopy. The kinetics of the reactions were determined by potentiodynamic polarization as well as dihydrogen evolution measurements by eudiometry. All these tests were carried out while the sample surface and electrolyte volume remained constant. The corrosion products generated on the alloy surface were analyzed by X‐ray photoelectrons spectrometry. This study has shown that the evolution of the corrosion rate and the corrosion products depends greatly on the initial pH and the nature of the used electrolyte. Alkaline electrolyte leads to a passive protective layer that can be locally destroyed by chloride ions. For a neutral chloride electrolyte, the strong increase of the pH due to the magnesium corrosion is not able to form a protective layer by precipitation of corrosion products. The kinetic and the corrosion extent are affected by the pH changes.

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Insight into physical interpretation of high frequency time constant in electrochemical impedance spectra of Mg

Cited by 87 publications

References 55 publications

Cerium conversion coating and sol-gel coating for corrosion protection of the WE43 Mg alloy

Cerium conversion coating and sol-gel coating for corrosion protection of the WE43 Mg alloy

Influence of Ba micro‐alloying on electrochemical and discharge behaviors of Mg‐Al anodes for mg‐air primary battery

Corrosion mechanisms of AZ31 magnesium alloy: Importance of starting pH and its evolution

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