Einfluß von Wasserdampf und Kohlendioxyd auf die Oxydation von Eisen‐Silicium‐Legierungen in Sauerstoff bei Temperaturen von 750 bis 1050°C

Rahmel, A.; Tobolski, J.

doi:10.1002/maco.19650160806

Cited by 47 publications

(7 citation statements)

References 12 publications

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“…10. Apparently, in agreement with previous investigations (4,5), the growth of the wustite layer was associated with outward iron migration, while the growth of the conglomerate layer was associated with inward oxygen migration.…”

Section: Resultssupporting

confidence: 93%

“…As demonstrated by the marker measurements, wustite dissociated at its inner surface and oxygen was able to migrate rapidly through the conglomerate. Possibly this reactant was transported along oxide crystal boundaries and/or as carbon dioxide through pores resulting from the reaction of oxygen with carbon dissolved in the alloy or wustite (4,IS,19). The oxygen gradient in this conglomerate layer, nevertheless, must be small since the atmospheric oxidizing potential did not influence its parabolic growth kinetics.…”

Section: Discussionmentioning

confidence: 99%

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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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Section: Resultssupporting

confidence: 93%

Section: Discussionmentioning

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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“…Voids within iron oxide scales and the iron-rich oxides formed on dilute Fe-Cr and Fe-Al alloys developed far more faster in the presence of water vapor. Rahmel et al [2,3] have reported that presence of H 2 O(g) caused the scale to develop porosity. Ehlers et.…”

Section: Introductionmentioning

confidence: 99%

Observation On Void Formed In Oxide Scale Of Fe-Cr-Ni Alloy At 1073k In Dry And Humid Environments

Kaderi¹,

Zainal

Ani³

et al. 2012

IIUMEJ

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Void formation in oxide scale during high temperature oxidation is a common phenomenon. Over a long period of time voids will affect the mechanical property of scales by influencing the cracking and spalling. Voids formed in dry environment are different than that of formed in humid environment. With the presence of water vapor in humid environment the formation of void will increase, thus greater number of void compared to that in dry environment. Fe-Cr-Ni alloy samples were exposed isothermally at 1073 K in air (P_(O_2 )= 0.21atm = 2.1×?10?^(5 )Pa) and humid (air + steam) environments. XRD analysis done to all samples confirms that Fe2O3, Fe3O4, NiCr2O4, FeCr2O4, Cr2O3 and NiO phases exist in the scale. EDX analysis done shows varying compositions of Fe,Cr,Ni and O in outer and inner oxide scale, oxide scale/metal interface and metal. Field emission scanning electron microscope (FE-SEM) was used to investigate voids formed in the cross sections of the oxidized samples. Volume fraction of voids in the oxide scale was calculated in accordance to the cross sectional area fraction of voids in the scale. It shows that Fe-Cr-Ni alloy samples exposed in humid environment has as high as 71% more voids than that exposed in dry environment. It is concluded that the humid environment increased the number of void formed in the oxide scale, thus facilitates the exfoliation of protective scale during the high temperature oxidation. ABSTRAK: Pembentukan gelembung udara di dalam lapisan oksida ketika proses pengoksidaan di suhu tinggi merupakan satu fenomena biasa. Pada satu jangka masa yang panjang gelembung-gelembung ini akan memberi kesan kepada sifat mekanikal oksida dengan mempengaruhi pembentukan keretakan dan pengelupasan oksida. Gelembung udara yang terbentuk di dalam persekitaran kering berbeza daripada yang terbentuk di dalam persekitaran lembap. Dengan adanya wap air, pembentukan gelembung akan bertambah berbanding yang terbentuk di dalam persekitaran kering. Sampel aloi Fe-Cr-Ni telah dioksidakan secara isoterma pada suhu 1073 K di dalam udara (P_(O_2 )= 0.21atm = 2.1×?10?^(5 )Pa) dan lembap (udara + wap air). Analisis Pembelauan Sinar – X (XRD) kepada semua sampel menunjukkan oksida yang terbentuk ialah Fe2O3, Fe3O4, NiCr2O4, FeCr2O4, Cr2O3 dan NiO. Analisis Penyebaran Tenaga Sinar – X (EDX) menunjukkan komposisi Fe, Cr, Ni dan O yang berubah - ubah di lapisan oksida luar dan dalam, oksida/ antara muka logam dan logam. Mikroskop Imbasan Elektron-Pancaran Medan (FE-SEM) digunakan untuk meneliti gelembung di dalam oksida pada keratan rentas sampel. Pecahan isi padu gelembung yang terbentuk pada oksida dikira dengan merujuk kepada pecahan luas keratan rentas pada oksida tersebut. Sampel aloi Fe-Cr-Ni yang dioksidakan di dalam persekitaran lembap mempunyai kandungan gelembung udara 71% lebih banyak berbanding dengan yang dioksidakan di dalam persekitaran kering. Kesimpulannya persekitaran lembap meningkatkan bilangan gelembung yang terbentuk di dalam lapisan oksida, sekaligus memudahkan pengelupasan oksida semasa pengoksidaan suhu tinggi.KEYWORDS: high temperature oxidatio;, Fe-Cr-Ni alloy; void formation; quantitative analysis of voi;, dry environment; humid environment

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“…It is well known, however, that oxidation in water vapor produces oxides that are compact, adherent, and relatively pore-free. 29) In addition, the presence of water vapor has been theorized to increase the plasticity of oxides, again causing the oxide layer to better adhere to the metal. 30) It could be possible that the lack of pores and gaps in the oxide changes the stress state at the oxide/metal interface.…”

Section: Discussionmentioning

confidence: 99%

Evolution and Distribution of the Copper-rich Phase during Oxidation of an Iron–0.3wt%Copper Alloy at 1150°C

Webler

Sridhar

2008

ISIJ Int.

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Residual copper contents in low carbon steels lead to a cracking phenomenon known as surface hot shortness. This phenomenon is caused by a copper-rich liquid layer that forms due to copper enrichment as iron oxidizes during casting, reheating and/or hot rolling. Evolution of the copper-rich liquid layer is dependent on the competing processes of enrichment due to iron oxidation and diffusion of copper back into the metal. This paper presents comparisons between experiments and calculations of a fixed grid finite difference model that predicts the evolution of the copper-rich region. Experiments involved oxidizing an iron-0.3wt%copper alloy in a gold-image furnace equipped with thermogravimetric balance. Samples were oxidized at 1 150°C in three atmospheres, dry air, wet air (15 vol% H 2 O), and argon-15vol%H 2 O. Model predictions agree with measured data for dry air oxidation at 1 150°C for 60, 300, 420, 600, 900, and 1 200 s. Agreement was also obtained for iron oxidized for 1 800 and 2 700 s in argon-15vol%water vapor. However, model predictions deviated for samples oxidized 3 600 s in dry air, 3 600 s in water vapor, and 600 s in wet air. The deviations arise due to grain boundary penetration and diffusion of copper. Results suggest a critical amount of separated copper is necessary for substantial grain boundary penetration to occur and the required amount decreases when the gas contains H 2 O. The model was also used to estimate the evolution behavior of the liquid copper phase under industrially relevant conditions.

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Einfluß von Wasserdampf und Kohlendioxyd auf die Oxydation von Eisen‐Silicium‐Legierungen in Sauerstoff bei Temperaturen von 750 bis 1050°C

Cited by 47 publications

References 12 publications

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

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

Observation On Void Formed In Oxide Scale Of Fe-Cr-Ni Alloy At 1073k In Dry And Humid Environments

Evolution and Distribution of the Copper-rich Phase during Oxidation of an Iron–0.3wt%Copper Alloy at 1150°C

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