Internal Oxidation of a Ag-l.3 at.% Se Alloy. Part I: Composition and Appearance of Oxidation Products

Roth, J.; Kosec, Ladislav; Skraba, P.; Bizjak, M.; Medved, Jožef; Dobnikar, Meta; Anžel, Ivan

doi:10.1007/s11085-004-7811-y

Cited by 2 publications

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“…From the XRD and EDS characterization of the oxidized alloy presented in the previous artic1e, 3 it is evident that the internal oxide formed is silver selenite, Ag 2 SeO 3 , with a stoichiometric ratio v = 3. As seen from the kinetics results in Table II, the Ag-1.3 Se alloy oxidizes 2-3 times faster than it would if all the selenium would be oxidized at the inner internal-oxidation front, with v eff ranging from 1.167 to 1.916.…”

Section: Interpretation Of the Kinetics Of Internal Oxidationmentioning

confidence: 94%

“…3 For thermogravimetric (TG) experiments the alloy was cut into pieces having a surface area of approx. 1 cm 2 (−5 × 4 × 3 mm) using a diamond-wheel saw.…”

Section: Methodsmentioning

confidence: 99%

“…However, a closer look reveals that local deviations and irregularities can be significant. 3 These irregularities make it difficult to determine the exact location of the internal-oxidation front which can, therefore, be given only as an average of multiple measurements.…”

Section: Kinetics In Terms Of Depth Of Internal Oxidationmentioning

confidence: 99%

“…For the present system, c is calculated assuming that the density and atomic weight of the alloy are the sum of the densities and atomic weights of silver and selenium in their atomic fractions, respectively (c = 0.0973 mol/cm 3 Table II.…”

Section: Analysis Of the Experimental Data For The Kinetics Of Internmentioning

confidence: 99%

“…3 The internal oxidation of a two-phase Ag-l.3 at.% Se alloy proceeds through in-situ or diffusionless and classical or diffusive mode simultaneously, so called primary and secondary internal oxidation. 2 In the present article, the results of the kinetics of internal oxidation are reported and discussed in the context of the mechanisms of the internal oxidation of two-phase alloys.…”

Section: Introductionmentioning

confidence: 99%

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Internal Oxidation of a Ag-1.3 at.% Se Alloy. Part II: Kinetics of Internal Oxidation

Roth

Kosec

Anžel

2004

Oxidation of Metals

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The kinetics of internal oxidation of a two-phase Ag-1.3 at.% Se alloy were studied at 750, 800 and 830 • C in pure oxygen. The parabolic rate law was followed to a reasonable extent for the first 2 hr of oxidation. The rate of internal oxidation was much faster than expected from the classical Wagner model. Three major factors affected this: (i) the non-uniform distribution of Ag 2 Se particles in the as-cast alloy caused non-uniform internal oxidation of the alloy; (ii) the formation of a liquid phase during in-situ oxidation of Ag 2 Se particles accelerated the diffusional processes and lowered the activation energy of the oxidation reactions (a sort of "catastrophic" internal oxidation); (iii) gradual oxidation of the alloying element in the form of second-phase particles caused the extension of the single internal-oxidation front (IOF) to the internal-oxidation volume (IOV) between the inner and outer IOFs. The IOV requires a much lower oxygen quantity for its advancement than the (single) IOF thereby enabling much faster internal oxidation of two-phase alloys that oxidize in the in situ (diffusionless) mode. The kinetics are, also discussed according to the treatment which was proposed for internal oxidation of two-phase alloys by Gesmundo. 7 KEY WORDS: silver-selenium alloy; Ag 2 Se in-situ oxidation; liquid-oxidation product; catastrophic internal oxidation; internal oxidation of two-phase alloys.

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Section: Interpretation Of the Kinetics Of Internal Oxidationmentioning

confidence: 94%

“…3 For thermogravimetric (TG) experiments the alloy was cut into pieces having a surface area of approx. 1 cm 2 (−5 × 4 × 3 mm) using a diamond-wheel saw.…”

Section: Methodsmentioning

confidence: 99%

Section: Kinetics In Terms Of Depth Of Internal Oxidationmentioning

confidence: 99%

Section: Analysis Of the Experimental Data For The Kinetics Of Internmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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