Oxidation of Molten High-purity Aluminum in Dry Oxygen

Sleppy, W. C.

doi:10.1149/1.2427963

Cited by 51 publications

(18 citation statements)

References 2 publications

(3 reference statements)

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“…Oxygen consumption rates reported in the literature are shown in Table I. [8][9][10] These were measured in an environment with an unlimited supply of oxygen, i.e., a constant fraction of oxygen equal to 0.2. The measurement of the initial oxygen consumption rate (when f O = 0.2) in the experiment was not possible due to the small delay in operating the equipment, [3] but extrapolation of Eq.…”

Section: B Boundary Conditionsmentioning

confidence: 99%

A Semi-empirical Mathematical Model to Estimate the Duration of the Atmosphere within a Double Oxide Film Defect in Pure Aluminum Alloy

Raiszadeh

Griffiths

2008

Metall Mater Trans B

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It has been shown that the oxygen and nitrogen within the atmosphere of a double oxide film defect can be consumed by the surrounding Al melt. Experimentally determined reaction rates were used to construct a semi-empirical model to predict the change in volume with time of a bubble of air trapped in an Al melt, with the model including the diffusion of H from the metal into the bubble. Comparison with experimental results showed that the model predicted the change in volume well. The model was then used to estimate the duration of the internal atmosphere within double oxide film defects, which suggested that these would be consumed in a time of up to 3 minutes, depending upon assumptions made about the initial defect size.

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Section: B Boundary Conditionsmentioning

confidence: 99%

A Semi-empirical Mathematical Model to Estimate the Duration of the Atmosphere within a Double Oxide Film Defect in Pure Aluminum Alloy

Raiszadeh

Griffiths

2008

Metall Mater Trans B

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“…12 The data points in Fig. 2 are the values published by Sleppy 22 for molten aluminum; the molten condition of the substrate practically eliminates the influence on the kinetics from epitaxial and other structural effects at the metal-oxide interface. 12 A single value (2.75 eV) for the metal-oxide work function x 0 was deduced from the illustrated fit to the curves; this value is in reasonable agreement with published values 23 ranging from 1.5 to 2.5 eV.…”

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confidence: 99%

Schottky Emission as a Rate-Limiting Factor in Thermal Oxidation of Metals

Fromhold

Cook

1966

Phys. Rev. Lett.

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Wagner 1 based a theory for the formation of coherent oxide (and other tarnish) layers on metals on the hypothesis that particle transport through the layer occurs by the separate diffusion of ions and electrons by lattice-defect mechanisms, the driving force being the electrochemical potential gradient in the layer. The formation rate was considered to be limited by either ions or electrons, depending upon which had the smaller partial conductivity since equal magnitude charge currents were assumed. This model has been verified for a number of tarnishing processes, 1 one example apparently being very thick copper-oxide films (1.25 xl0~2 cm) formed during the high-temperature oxidation of copper. 2 Equal charge concentra-p. 109. 10 G. Dolling and R. A. Cowley, Proc. Phys. Soc. (London) ^8, 463 (1966); G. Dolling, private communication. u The Ge frequency-distribution function given in Ref. 10 is for 90°K. Following a suggestion of Dolling (private communication) based on the work of B. N. Brockhouse and B. A. Dasannacharya [Solid State Commun. 1. , 205 (1963)], the distribution at 300°K was obtained from the one at 90°K by multiplying all vibrational frequencies by 0.983. 12

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“…Under equilibrium conditions, [O 2Ϫ ] is a function of oxygen pressure (P) and the thickness of the oxide layer (X). With a very short time of adsorption and relatively low oxygen pressure that are characteristics during RAD process, the following equation can be obtained: [50][51][52][53] [A3]…”

Section: Growth Rate Of the Very Thin Oxidesmentioning

confidence: 99%

A numerical study of oxidation behavior during reactive atomization and deposition

Lin

Zhou

Lavernia

2004

Metall Mater Trans B

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The oxidation behavior of droplets during reactive atomization and deposition (RAD) is analyzed on the basis of a numerical framework proposed here. Commercial 5083 Al is chosen as a model material; moreover, in the numerical model, nonspherical droplets are approximated as cylinders with a length/diameter ratio of 3. An equation that represents the growth rate of the oxide phases, together with models that describe the dynamic and thermal behavior of droplets, is implemented in an effort to elucidate the oxidation behavior of individual droplets. The numerical results reveal that the oxidation rate of a droplet is extremely high and that the oxide phase grows very rapidly initially, eventually attaining a steady state of limited oxide growth. The overall volume fraction of oxide phases in the RAD material increases with increasing atomization pressure, superheat temperature, and O 2 concentration, whereas it decreases with increasing melt flow rate. The oxygen concentrations in the RAD powders and deposited materials predicted on the basis of numerical analysis are in good agreement with the results from chemical analysis when O 2 concentration is lower than 16 vol pct.

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Oxidation of Molten High-purity Aluminum in Dry Oxygen

Cited by 51 publications

References 2 publications

A Semi-empirical Mathematical Model to Estimate the Duration of the Atmosphere within a Double Oxide Film Defect in Pure Aluminum Alloy

A Semi-empirical Mathematical Model to Estimate the Duration of the Atmosphere within a Double Oxide Film Defect in Pure Aluminum Alloy

Schottky Emission as a Rate-Limiting Factor in Thermal Oxidation of Metals

A numerical study of oxidation behavior during reactive atomization and deposition

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