Discussion of “Uncommon Valency Ions and the Difference Effect” [M. E. Straumanis (pp. 284–286, Vol. 105)]

Brouillet, Ph.; Epelboin, I.; Froment, Marie-Thérèse

doi:10.1149/1.2427413

Cited by 7 publications

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Section: 2mentioning

confidence: 99%

“…This phenomenon called "the negative difference effect" (NDE) 9-16 and more recently "the anodic hydrogen evolution" process 17,18 has been also observed for other metals than Mg such as Al, Li. [19][20][21][22] Despite the abundant literature on Mg corrosion and many models of Mg corrosion (such as: the formation of Mg(I) as an intermediate product, 23,24 the formation and breakdown of the partially protective film, 11,[25][26][27] the formation of hydride intermediates, [28][29][30][31][32] formation of dark filiform patterns 13,16 and increase the hydrogen production in aqueous chloride solutions.12,15 Even a very low content of impurities (usually < 150 ppm in "pure" Mg) 41 can lead to formation of such surface film and the morphology of this film depends on electrolyte composition and Cl − concentration. 45,46 The effects of different alloy precipitates and alloy microstructure were widely studied in the case of Mg alloys [47][48][49][50][51][52][53][54][55] but not pure Mg.…”

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“…Data acquisition and post processing analyses were performed using Ion-Spec software (version 4.1). 24 Mg + ions characteristic of metallic and/or oxidized magnesium, 40 MgO + and 41 MgOH + characteristic of magnesium oxide and hydroxides, respectively, and 13 Al + , 25 Mn + and 26 Fe + characteristic of metallic (and/or oxidized) impurities (Al, Mn and Fe, respectively), were chosen for ion depth profiling and imaging.…”

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Role of Segregated Iron at Grain Boundaries on Mg Corrosion

Mercier

Światowska

Zanna

et al. 2018

J. Electrochem. Soc.

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To elucidate the role of noble metal impurities on corrosion of Mg, 3D time-of-flight secondary ion mass spectrometry (ToF-SIMS) imaging in combination with X-ray photoelectron spectroscopy and optical microscopy measurements were carried out on Mg samples (99.9%) before and after Mg polarization at E OCP +0.5 V in 0.1 M NaCl. A significant segregation of Fe (and of Mn and Al) metallic impurities at grain boundaries (GBs) was observed on the Mg surface by 3D ToF-SIMS. A 3-step mechanism of Mg corrosion was proposed, including a catalytic effect of Fe segregated at the GBs on the hydrogen evolution reaction (HER). In the 1 st stage, the initiation of Mg corrosion is accompanied by the HER occurring over Fe impurities segregated at GBs leading to formation of small circular defects, and propagation with occurrence of dark filiform-like pattern corrosion enriched in Cl − . Magnesium and its alloys exhibiting interesting physico-chemical properties such as excellent wide range of mechanical properties at room temperature and low weight (1.7 g.cm −3 ), become good alternatives to aluminum and iron-based alloys in many industrial applications such as automobile, aerospace, energy storage or biomedicine. 1,2Mg and its alloys are spontaneously covered by an oxide/hydroxide layer.3 When exposed to aqueous solution, the oxide layer has a duplex structure consisting of an inner magnesium oxide and an outer porous hydroxide layer 4,5 with a possible presence of magnesium hydride (MgH 2 ).6 At ambient temperature, this oxide layer formed on the Mg (or Mg alloys) surfaces is protective. 1,7 In most aqueous environments (or high humidity) and in a large range of pH, (0-10) as inferred from the potential-pH diagram, this oxide/hydroxide layer is not stable and Mg undergoes dissolution.8 Thus, this is one of the most important limiting factors for applications of Mg and its alloys. Mg dissolution is accompanied by the hydrogen evolution reaction (HER), as the major cathodic reaction. The well-known increase of the HER rate under anodic polarization of Mg seems to be in contradiction with the kinetic models of charge transfer electrochemical reactions (Butler-Volmer equation), predicting that the cathodic current should decrease exponentially with increasing anodic potential. This phenomenon called "the negative difference effect" (NDE) 9-16 and more recently "the anodic hydrogen evolution" process 17,18 has been also observed for other metals than Mg such as Al, Li. [19][20][21][22] Despite the abundant literature on Mg corrosion and many models of Mg corrosion (such as: the formation of Mg(I) as an intermediate product, 23,24 the formation and breakdown of the partially protective film, 11,[25][26][27] the formation of hydride intermediates, [28][29][30][31][32] formation of dark filiform patterns 13,16 and increase the hydrogen production in aqueous chloride solutions.12,15 Even a very low content of impurities (usually < 150 ppm in "pure" Mg) 41 can lead to formation of such surface film and the morphology of this film depen...

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Section: 2mentioning

confidence: 99%

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Role of Segregated Iron at Grain Boundaries on Mg Corrosion

Mercier

Światowska

Zanna

et al. 2018

J. Electrochem. Soc.

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“…1). -Resonances at = 5.47 (CS2 solution) or = 5.46 (CHCb solution) (double doublet), = 6.08 (CSz solution) or r = 6.05 (CHCls solution) (doubled double doublet), r = 7.35 (C& solution) or = 7.29 (CHCls solution) (apparent sextet), = 7.96 (CSs solution) or 7.97 (CHCls solution) (apparent sextet), and at = 8.47 (CSs solution) or r = 8.50 (CHCls solution) (complex quintet) of relative intensities 2:2:2:2:2.…”

Section: Methodsmentioning

confidence: 99%

Organometallic Chemistry of the Transition Metals. V. New Iron Carbonyl Complexes of Cycloöctatriene Derivatives

King¹

1963

Inorg. Chem.

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Reaction of Fed( C0)lz or Fez( (20)s with cyclooctatrienone yields a mixture of yellow C&OFe( Fez( CO)6. and cyclooctatriene.[C&Fez(CO)e]+ may be isolated. and orange C8H80-A red-orange compound CsHl0Fez( CO)6 has been isolated from the reaction between triiron dodecacarbonyl From the reaction between CsH1bFe2(CO)e and salts of (C&,)aC+, salts of an orange cation apparently A. Cyclooctatrienone ComplexesRecently several interesting complexes have been isolated from the reaction between cyclooctatriene and various metal carbonyl derivatives. Thus the hexacarbonyls of chromium, molybdenum, and tungsten react with a mixture of 1,3,5-cyclooctatriene and 1,3,6cyclooctatriene t o give the red complexes 1,3,5-C8H10-M(CO)3 (M = Cr and M o )~,~ and the yellow complexes 1,3,6-(CgHlo)zM(CO)2 (M = Mo and W).z From the reaction between the various iron carbonyls and a mixture of the two isomeric cyclooctatrienes the following three compounds have been isolated : yellow-orange bicyclo [4,2,0]octadieneiron tricarbonyl, 2,4,5 yellow 1,3,5cyclooctatrieneiron tricarbonyl,6 and a red-orange compound of apparent composition CgH&e2(CO)e. The cobalt compounds [ C~H I O C O ( C O )~]~~and C5H5CoCsHlo7"a have also been isolated.The existence of these metal complexes of cyclooctatriene made of interest an investigation of the reaction between 1,3,5-cycl~octatrienone~ and various metal carbonyl derivatives in order to determine the effect on the nature of the complexes formed of the electronegative ketonic oxygen atom bonded to one of the carbon atoms of the eight-membered ring. ExperimentalIn general infrared spectra were taken in potassium bromide pellets and recorded on a Perkin-Elmer Model 21 double-beam machine with NaCl optics. In addition, the metal carbonyl regions of the infrared spectra were taken in Halocarbon oil mulls and recorded on a Perkin-Elmer Model 112 single-beam machine with CaF2 optics. Proton n.m.r. spectra were taken on a Varian Associates Model A-60 machine. Hexamethyldisiloxane was used as an internal standard. Microanalyses and molecular weight determinations (Mechrolab vapor pressure osmometer in benzene solution) were performed by Dr. A. Bernhardt, Mikroanalytisches Laboratorium, Max-Planck-Institut far Kohlen-(1) For part I V of this series, see R.

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“…The reducing power of the anolyte, which was thought to be due to the presence of Al+, was investigated by many authors (3,(11)(12)(13)(14)(15)(16)(17). However, the possibility that the A1 particles themselves could act as reducers, was not considered until recently (2).…”

Section: Problem and Literature Reviewmentioning

confidence: 99%

The Valency of Aluminum Ions and the Anodic Disintegration of the Metal

Straumanis¹,

Poush²

1965

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Discussion of “Uncommon Valency Ions and the Difference Effect” [M. E. Straumanis (pp. 284–286, Vol. 105)]

Cited by 7 publications

References 0 publications

Role of Segregated Iron at Grain Boundaries on Mg Corrosion

Role of Segregated Iron at Grain Boundaries on Mg Corrosion

Organometallic Chemistry of the Transition Metals. V. New Iron Carbonyl Complexes of Cycloöctatriene Derivatives

The Valency of Aluminum Ions and the Anodic Disintegration of the Metal

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