An XPS investigation of the oxidation/corrosion of melt-spun Mg

Yao, Hongyan; Li, Y.; Wee, Andrew Thye Shen

doi:10.1016/s0169-4332(99)00593-0

Cited by 294 publications

(141 citation statements)

References 16 publications

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“…These effects have been linked to enhanced dissolution and increased aqueous solubility by formation of MgCl 2 and/or Mg hydroxychloride complexes, 9,12,13,15,21,51 as well as possible cracking and rupture of the inner film regions [e.g. 17,22]. In the present work, Cl was detected in the inner MgO-base layer, and extending to the metal-film interface (Figs.…”

Section: Discussionsupporting

confidence: 52%

Film Breakdown and Nano-Porous Mg(OH)₂Formation from Corrosion of Magnesium Alloys in Salt Solutions

Brady

Rother

Anovitz

et al. 2015

J. Electrochem. Soc.

138

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Small angle neutron scattering (SANS) and scanning transmission electron microscopy (STEM) were used to study film formation by magnesium alloys AZ31B (Mg-3Al-1Zn base) and ZE10A (Elektron 717, E717: Mg-1Zn + Nd, Zr) in H 2 O and D 2 O with and without 1 or 5 wt% NaCl. No SANS scattering changes were observed after 24 h D 2 O or H 2 O exposures compared with as-received (unreacted) alloy, consistent with relatively dense MgO-base film formation. However, exposure to 5 wt% NaCl resulted in accelerated corrosion, with resultant SANS scattering changes detected. The SANS data indicated both particle and rough surface (internal and external) scattering, but with no preferential size features. The films formed in 5 wt% NaCl consisted of a thin, inner MgO-base layer, and a nano-porous and filamentous Mg(OH) 2 outer region tens of microns thick. Chlorine was detected extending to the inner MgO-base film region, with segregation of select alloying elements also observed in the inner MgO, but not the outer Mg(OH) 2 . Modeling of the SANS data suggested that the outer Mg(OH) 2 films had very high surface areas, consistent with loss of film protectiveness. Implications for the NaCl corrosion mechanism, and the potential utility of SANS for Mg corrosion, are discussed. Magnesium and its alloys are of great interest for a wide range of structural and functional applications, including lightweight automotive and aircraft structural materials, biomedical implants, fuel cells and hydrogen storage, batteries, etc.1-7 However, the high reactivity and rapid corrosion of Mg in many aqueous and humid environments is a key issue. [8][9][10][11] Of particular challenge and interest is the acceleration of Mg corrosion in the presence of salt species. Mechanisms of accelerated attack in salt solutions include enhanced local micro-galvanic coupling at alloy second phases and/or impurities (e.g. Fe, Ni, Cu etc.) and disruption of the MgO and/or Mg(OH) 2 base surface films by Cl-. 3,9,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26] Film formation by Mg alloys under aqueous conditions can be quite complex, involving MgO, Mg(OH) 2 , and MgCO 3 base phases, as well as complexes of those phases when alloy additions (e.g. Al) or environmental species (e.g. Cl-) become incorporated into parts or all of the film structure. [15][16][17]21,[27][28][29][30][31][32][33][34] In some cases, porous and even filiform-like corrosion films have been reported on bare or surface-modified Mg alloys. 11,14,16,18,24,[35][36][37][38] Small angle neutron scattering (SANS) has emerged as a powerful technique to assess structural and morphological features in the ∼1 to up to ∼200-300 nm feature size range (specific range accessed depends on the instrument capabilities and settings, as well as the nature of neutron scattering from the test samples). 39,40 Information can be obtained regarding size, morphology, and number density of scatterers (e.g. 2 nd phase precipitates, phase separation, grain structure, voids, pores, etc.), as well as surface area a...

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Section: Discussionsupporting

confidence: 52%

Film Breakdown and Nano-Porous Mg(OH)₂Formation from Corrosion of Magnesium Alloys in Salt Solutions

Brady

Rother

Anovitz

et al. 2015

J. Electrochem. Soc.

138

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“…The high resolution O 1s spectra of Ce oxide nanofibers were deconvoluted into four peaks: two oxygen species on the surface region (O-Surf. ), 30,31 oxygen moieties bound with Ce 3+ (O-Ce…”

Section: Resultsmentioning

confidence: 99%

Structural and Spectroscopic Investigation of Ceria Nanofibers Fabricated by Electrospinning Process

Hwang¹,

Park²,

Kang³

2011

Bulletin of the Korean Chemical Society

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We fabricated ceria (CeO 2 ) nanofibers by applying a mixed solution of polyvinylpyrrolidone (PVP) and various concentrations of cerium nitrate hydrate (Ce(NO 3 ) 3 ) ranging from 15.0 to 26.0 wt % by the electrospinning process. Ceria nanofibers were obtained after calcining PVP/Ce(NO 3 ) 3 nanofiber composites at 873 and 1173 K. The SEM images indicated that the diameters of CeO 2 nanofibers calcined at 873 and 1173 K were smaller than those of nanofibers obtained at RT. As the amount of cerium increased, the diameter of CeO 2 nanofibers increased. XRD analysis revealed that the ceria nanofibers were in cubic form. TEM results revealed that the ceria nanofibers were formed by the interconnection of Ce oxide nanoparticles. The ceria nanofibers obtained at low concentrations of Ce (CeL) showed spotty ring patterns indicated that the ceria nanofibers were polycrystalline structure. And the ceria nanofibers obtained at high concentration of Ce (CeH) showed fcc (001) diffraction pattern. XPS study indicated that the oxidation of Ce shifted from Ce 3+ to Ce 4+ as the calcination temperature increased.

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“…At room temperature the surface of any metal, irrespective of its composition, in contact with the atmosphere instantaneously becomes coated with a thin film of C-C/C-H groups (less than 3 nm thickness). A second less intense component appears at 286.5 eV, which may be associated with the presence of C-O groups, and at higher binding energies, 289.0 eV, a third component appears which may be associated with the presence of CO 3 2- [51]. After 10 minutes of AIB (Fig.…”

Section: Xps Analysis Of the Spontaneously Formed Native Oxide Film Omentioning

confidence: 92%

“…3c) shows the most intense component at 532.2 eV. This component may be associated principally with the presence of oxygen in the form of magnesium hydroxide (Mg(OH) 2 ) [51]. Two less intense components appear at binding energies of 530.2 eV and 534.2 eV which may be associated with the presence of oxygen in the form of calcium oxide [52] and water or C-O groups.…”

Section: Xps Analysis Of the Spontaneously Formed Native Oxide Film Omentioning

confidence: 99%

Native Air-Formed Oxide Film and its Effect on Magnesium Alloys Corrosion

Galván¹

2010

TOCORRJ

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Abstract:The present work uses X-ray photoelectron spectroscopy (XPS) analysis to compare the chemical composition of native oxide films formed spontaneously on commercial pure magnesium and AZ31, AZ80 and AZ91D magnesium alloys. The study considers both the outer surface and inner regions of the films with the assistance of argon ion bombardment. Possible relationships are established between the alloy Al content and the native oxide film characteristics. The Al content is very similar in the oxide films on all three studied alloys. XPS identifies a much greater film thickness on AZ80 and AZ91D specimens than on AZ31 and pure Mg specimens, which seems to be related with the presence of phase (Mg 17 Al 12 ) on the AZ91D alloy surface and of the eutectic -Mg/ on the AZ80 alloy surface. Considerable Ca segregation is observed (directly related with the calcium impurities content in the bulk material) towards the outer surface of the metal, where it appears in the form of calcium oxide. Direct correspondence is found between the thickness of the native oxide film formed spontaneously on the surface of magnesium and its alloys and their subsequent corrosion resistance in exposure to a 3.5 wt% NaCl solution.

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An XPS investigation of the oxidation/corrosion of melt-spun Mg

Cited by 294 publications

References 16 publications

Film Breakdown and Nano-Porous Mg(OH)₂Formation from Corrosion of Magnesium Alloys in Salt Solutions

Film Breakdown and Nano-Porous Mg(OH)₂Formation from Corrosion of Magnesium Alloys in Salt Solutions

Structural and Spectroscopic Investigation of Ceria Nanofibers Fabricated by Electrospinning Process

Native Air-Formed Oxide Film and its Effect on Magnesium Alloys Corrosion

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An XPS investigation of the oxidation/corrosion of melt-spun Mg

Cited by 294 publications

References 16 publications

Film Breakdown and Nano-Porous Mg(OH)2Formation from Corrosion of Magnesium Alloys in Salt Solutions

Film Breakdown and Nano-Porous Mg(OH)2Formation from Corrosion of Magnesium Alloys in Salt Solutions

Structural and Spectroscopic Investigation of Ceria Nanofibers Fabricated by Electrospinning Process

Native Air-Formed Oxide Film and its Effect on Magnesium Alloys Corrosion

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Film Breakdown and Nano-Porous Mg(OH)₂Formation from Corrosion of Magnesium Alloys in Salt Solutions

Film Breakdown and Nano-Porous Mg(OH)₂Formation from Corrosion of Magnesium Alloys in Salt Solutions