Electron microscopic studies of anodic oxide films on the AZ91HP alloy

Barbosa, D. Peixoto; Knörnschild, Gerhard Hans; Strunk, H. P.

doi:10.1590/s1516-14392003000100018

Cited by 11 publications

(5 citation statements)

References 7 publications

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“…The anodized layers were slightly porous (Fig. 4a), which is typical of coatings on Mg alloys [2][3][4][5][6]21]. Taking the density of the anodized coating to be 80% of the average density of 2.9 g/cm 3 (based on the densities and mole fractions of the four main constituents), the average thickness of an anodized layer was estimated to be 12 m, which is consistent with previous studies [6,7] and cross-sectional SEM (Fig.…”

Section: Resultssupporting

confidence: 88%

“…Dose-dependent depths ranged from 6 to 68 m. Examination of the data in Table 2 suggests that erosion rates will be within experimental error identical for depths of removal greater than ≈80 m. Chemical-profile data for Mg alloys anodized near room temperature suggests that the depth of internal oxidation from anodizing should be small [21], which is consistent with the data reported here.…”

Section: Resultssupporting

confidence: 81%

“…5).) Such hardening would be consistent with occurrence of appreciable internal oxidation during the anodizing process of the surface regions of the underlying alloy [21]. This apparent hardening near the surface may have exerted a significant effect of the erosion response of the anodized alloy, as will be discussed below.…”

Section: Resultsmentioning

confidence: 60%

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Solid-particle erosion of an anodized Mg alloy

Goretta

Cunningham

Chen

et al. 2007

Wear

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Section: Resultssupporting

confidence: 88%

Section: Resultssupporting

confidence: 81%

See 1 more Smart Citation

Solid-particle erosion of an anodized Mg alloy

Goretta

Cunningham

Chen

et al. 2007

Wear

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“…In the latter case the solubility of Mg 2+ is reduced by ethanol. In the case of fluoride and stannate anodic films showed enrichment of fluorine [6] and tin [7], respectively, close to the metal-film interface. With the addition of Al(OH) 3 neither the critical current density nor the potential for secondary passivation was lowered (Table 1).…”

Section: Ecs Transactions 43 (1) 29-33 (2012)mentioning

confidence: 99%

Influence of Electrolyte Composition on the Behavior of Magnesium at High Anodic Potentials

Borba¹,

Poznyak²,

Knörnschild³

2012

ECS Trans.

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Potentiodynamic curves were measured in electrolytes of 0.2Mol/L NaOH with the addition of compounds used in conventional and in recently developed anodizing baths. The curves showed as a characteristic behavior passivity breakdown at about +3V, high current densities of magnesium dissolution, followed by secondary passivation and breakdown of the anodic film at high potentials. The compounds were characterized according to their influence on the potential and the critical current density for secondary passivation, the passive current density and the breakdown potential of the anodic film. Compared with 0.2Mol/L NaOH, the addition of fluoride, phosphate, stannate and ethanol lowered the critical current density for secondary passivation. Al(OH) 3 and silicate showed no effect on the critical current density. No secondary passivation occurred in the presence of permanganate, while in the presence of silicate no sharp active-passive transition was found.

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“…They claimed that aluminate combined with magnesium oxide was beneficial to the corrosion resistance of the anodized coatings on Mg-Al alloy (30)(31)(32). Barbosa studied anodic oxide films on the AZ91HP alloy in the type HAE-electrolyte and found that fluorine and phosphorus were prevailing at the metal/oxide interface (33). Oho and Osami prepared the films formed on magnesium in acidic, fluoride-containing electrolyte (type DOW17).…”

Section: Introductionmentioning

confidence: 99%

Microstructural Evaluations of Oxide Films During Spark Anodizing of Mg-Al Alloy in Alkaline Fluoride Electrolytes

et al. 2008

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Spark anodizing (SA) has been developed as a novel technique for corrosion protection by forming a ceramic layer on magnesium alloys, in which the fluoride in the electrolyte recipes plays a key role during coating. In the present work, the SA ceramic layer produced on AZ91D magnesium alloy was characterized by using SEM, TEM and EDS. The results showed that: 1) there was a fluoride enriched zone around 1-2µm in thickness at the coating/substrate interface, which was composed of the amorphous substrate, nanocrystal MgO particles sized in 20-60nm and sealed cavities; 2) the oxygen content in the inner layer was higher than that in the outer layer, while the fluorine content was relative even in both layers, which suggested that the barrier layer was included in this fluoride zone, and that the fluorine may be only a retained marker during the formation of new coating materials.

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Electron microscopic studies of anodic oxide films on the AZ91HP alloy

Cited by 11 publications

References 7 publications

Solid-particle erosion of an anodized Mg alloy

Solid-particle erosion of an anodized Mg alloy

Influence of Electrolyte Composition on the Behavior of Magnesium at High Anodic Potentials

Microstructural Evaluations of Oxide Films During Spark Anodizing of Mg-Al Alloy in Alkaline Fluoride Electrolytes

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