Die Temperaturabhängigkeit der Verzunderung von reinem Eisen in Sauerstoff

Schmahl, Norbert G.; Baumann, H.-J.; Schenck, Hermann

doi:10.1002/srin.195802678

Cited by 29 publications

(14 citation statements)

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“…It was thought that this was because the chemical potential of oxygen was insufficient for magnetite formation. The parabolic rate constants obtained were only 10 to 20 pct smaller than those obtained by Davies et al [27] and Schmahl et al [28] for iron oxidation in oxygen. The reduced oxidation rates were thought to be the result of absence of magnetite.…”

Section: Possible Mechanisms Responsible For the Parabolic Growthcontrasting

confidence: 58%

Oxidation of Low-Carbon Steel in 17H2O-N2 at 900 °C

Chen¹,

Yuen²

2009

Metall Mater Trans A

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The oxidation kinetics of two low-carbon steels in a flowing 17H 2 O-N 2 gas mixture at 900°C and the scale structures developed are examined. Similar linear and parabolic oxidation kinetics are observed for the two steels, although some differences are observed within the first 5 minutes of oxidation and in the linear-to-parabolic transition period. The oxidation behaviors observed in the linear kinetics stage are more consistent with published results, exhibiting typical surfacereaction-controlled patterns. However, the observed parabolic oxidation rates are two orders of magnitude smaller than those of iron and steel oxidation in air and oxygen as well as that predicted using Wagner's parabolic oxidation theory. Similar oxide scale structures are observed on the two steels for the samples oxidized for more than 15 minutes. The surfaces of the scales exhibit pyramidal, faceted grain structures with growth ledges developed on some crystal faces and growth pits at the peaks of the pyramidal grains. In their cross sections, the scales have a columnar structure and appear two layered, with a thin, outer magnetite layer and an inner, growing wustite layer. The wustite grains coarsen with increased oxidation time and develop a growth texture with preferred (111) and (110) orientations in parallel to the sample surface after oxidation for longer than 60 minutes. Conventional oxidation theories cannot provide a satisfactory explanation of the apparently conflicting results observed during the parabolic oxidation stage.

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Section: Possible Mechanisms Responsible For the Parabolic Growthcontrasting

confidence: 58%

Oxidation of Low-Carbon Steel in 17H2O-N2 at 900 °C

Chen¹,

Yuen²

2009

Metall Mater Trans A

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“…On the contrary, Hussey et al < 5 J<sJ reported that unusual kinetic behavior was observed up to 50 h in the oxygen pressure from 10-o. 9 to 10 4 • 1 Pa between 723 and 823 K due to the separation of oxide film from the metal surface under the reduced pressure.…”

Section: Introductionmentioning

confidence: 99%

Oxidation of Iron at Oxygen Partial Pressures of 1, 10^4.3and 10⁵Pa in Temperature Range from 523 to 673 K

Sakai

Tsuji

Naito

1989

Journal of Nuclear Science and Technology

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The oxidation of iron was studied by means of Rutherford backscattering spectroscopy in the temperature range from 523 to 673 K under the oxygen partial pressures of 1, 104.3 and 10 5Pa for up to 7 d. It was found that the ionic diffusion in oxides is the rate-determining step of oxidation, since the oxidation of iron obeyed the parabolic rate law in the temperature and oxygen partial pressure ranges studied. As was observed at 573 K<'', two-stage oxidations were observed at temperatures lower than around 650 K, and one-stage oxidations at higher temperatures. The activation energies for the oxidation in the second stage were obtained to be 133± 10, 149± 17 and 144±6 kJ ·mol-1 at 1, 10 4 • 3 and 10 5 Pa, respectively. The activation energies for oxidation obtained are nearly constant regardless of the oxygen partial pressure, but the absolute values of the parabolic rate constants are determined by the fraction of the coverage on magnetite with hematite. The changes in the temperature dependence of the parabolic rate constants were found around 670 K at 10 4 • 3 Pa and around 523 K at 10 5 Pa, where the oxidation mechanism may change from the simultaneous growth of magnetite and hematite at higher temperatures to the dense hematite formation at lower temperatures. Comparing the temperature dependence of the corrosion rate in water with that of the oxidation rate in gas phase, the corrosion rate in water becomes considerably larger than the oxidation rate in gas phase below 523 K, where the metal dissolution may be dominant in the corrosion process in water.

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“…These alloys exist at 1000 "C as austenite up to 1 . The silicon concentration at the alloy internal oxidation zone front in specimens exposed for various times to a 50 vol.…”

Section: Resultsmentioning

confidence: 99%

“…Nodules composed of iron oxides are formed in the silica film on Fe-Si alloys in atmospheres of low oxygen pressures at high temperatures (1,2 ) . These nodules develop into a superficial scale consisting of inner and outer layers of a wustite-fayalite conglomerate and wustite, respectively, in the case of alloys containing up to 2 wt.O/o silicon upon their exposure to atmospheres containing carbon dioxide (3-7).…”

Section: Introductionmentioning

confidence: 99%

The Oxidation Properties of an Iron‐1.5 wt.% Silicon Alloy in Carbon Dioxide‐Carbon Monoxide Atmospheres at 1000°C

Logani

Smeltzer

1970

Materials & Corrosion

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An investigation is reported on the growth and structure of the scale formed on a ferritic Fe‐1.5 wt.% Si alloy exposed to carbon‐dioxide‐carbon monooxide atmospheres at 1000°C. The amorphous silica film on the metallographically polished specimens crystallized to β‐cristobalite. Wustite and fayalite developed within nodules which grew laterally to cover the alloy surface. Oxygen diffusion into the underlying alloy led to precipitation of silica as α‐tridymite. This internal oxidation zone was sufficiently depleted of silicon for its transformation to an austenitic phase. A fully developed scale was composed of an external wustite layer and an inner wustite‐fayalite conglomerate layer, interspersed with discontinuous fayalite bands. A model and a reaction sequence are advanced to account for the form of the oxidation curves and the reaction rate constants in terms of surface reaction steps similar to those for wustite formation on pure iron in these atmospheres.

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Die Temperaturabhängigkeit der Verzunderung von reinem Eisen in Sauerstoff

Cited by 29 publications

References 0 publications

Oxidation of Low-Carbon Steel in 17H2O-N2 at 900 °C

Oxidation of Low-Carbon Steel in 17H2O-N2 at 900 °C

Oxidation of Iron at Oxygen Partial Pressures of 1, 10^4.3and 10⁵Pa in Temperature Range from 523 to 673 K

The Oxidation Properties of an Iron‐1.5 wt.% Silicon Alloy in Carbon Dioxide‐Carbon Monoxide Atmospheres at 1000°C

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Die Temperaturabhängigkeit der Verzunderung von reinem Eisen in Sauerstoff

Cited by 29 publications

References 0 publications

Oxidation of Low-Carbon Steel in 17H2O-N2 at 900 °C

Oxidation of Low-Carbon Steel in 17H2O-N2 at 900 °C

Oxidation of Iron at Oxygen Partial Pressures of 1, 104.3and 105Pa in Temperature Range from 523 to 673 K

The Oxidation Properties of an Iron‐1.5 wt.% Silicon Alloy in Carbon Dioxide‐Carbon Monoxide Atmospheres at 1000°C

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Oxidation of Iron at Oxygen Partial Pressures of 1, 10^4.3and 10⁵Pa in Temperature Range from 523 to 673 K