Behavior of Selected Commercial Alloys during High Temperature Oxychloridation

Elliott, Peter; Ansari, A.; Prescott, R.; Rothman, M. F.

doi:10.5006/1.3583974

Cited by 22 publications

(19 citation statements)

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“…Two types of specimens were preoxidized, where one had a vapor deposited aluminium surface while the other specimens were untreated. A similar behavior was found by Eliott et al [25]. The results showed that at 2.6% chlorine in nitrogen aluminum oxide cannot offer any protection.…”

Section: 1 Aluminiumsupporting

confidence: 86%

“…At a temperature of 900 8C and an Ar-20%O 2 -2%Cl 2 gas mixture it was found that materials with high molybdenum content (Hastelloy X, S and C276) suffered from the evaporation of molybdenum oxychlorides. After increasing the temperature up to 1000 8C a complete disappearance of molybdenum and other refractory metals from the near surface regions could be found (even at molybdenum contents > 10%) [25]. After increasing the temperature up to 1000 8C a complete disappearance of molybdenum and other refractory metals from the near surface regions could be found (even at molybdenum contents > 10%) [25].…”

Section: Molybdenummentioning

confidence: 98%

“…Several authors observed that with increasing content of nickel and decreasing content of iron the resistance of the alloys in chlorine containing atmospheres increases [25,28,29,33,70,71]. Several authors observed that with increasing content of nickel and decreasing content of iron the resistance of the alloys in chlorine containing atmospheres increases [25,28,29,33,70,71].…”

Section: Nickelmentioning

confidence: 99%

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The role of alloying elements in commercial alloys for corrosion resistance in oxidizing‐chloridizing atmospheres. Part I: Literature evaluation and thermodynamic calculations on phase stabilities

Bender

Schütze

2003

Materials & Corrosion

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In several high temperature processing environments the presence of chlorine may significantly reduce the life-time of the components. Although metallic materials have been widely used under such conditions there is still a need for data on the role of the different alloying elements in commercial alloys. In the present work this role was investigated in detail at temperatures between 650 and 1000 8C in synthetic air containing up to 2 vol.% Cl 2 . Before starting the experimental investigation a detailed literature evaluation on chlorine high temperature corrosion was performed followed by a thermodynamic assessment of the stability and the partial pressures of the phases formed by the reaction between alloy and environment. The results of this "theoretical approach" are presented in the following first part of the publication while the experimental work will be reported in the second part appearing in a later issue of this journal. Already the results of the "theoretical approach" yield a clear picture of which alloying elements play a detrimental role and which elements are beneficial. These results can be used as a tool for a general assessment of metallic alloys with regard to their performance in oxidizing/chloridizing high temperature environments. In the second part of this work the results from this "theoretical approach" will be compared with the behavior of 14 commercial materials, where the content of the major alloying elements was varied in a systematic manner.In einer Reihe von Hochtemperatur-Prozeßumgebungen führt die Anwesenheit von chlorhaltigen Verbindungen zu einer deutlichen Verkürzung der Lebensdauer der Anlagenbauteile. Obwohl in diesen Anlagen metallische Legierungen bereits in großem Umfang eingesetzt werden, besteht immer noch ein ausgeprägter Bedarf an Daten zur Rolle des Verhaltens der verschiedenen Legierungselemente unter diesen Bedingungen. In der vorliegenden Arbeit wurde diese Rolle im Detail bei Temperaturen von 650 bis 1000 8C in Luft mit Chlorgehalten bis zu 2% vol. untersucht. Vor der Durchführung des experimentellen Teils der Untersuchungen wurde eine umfangreiche Literaturauswertung vorgenommen, gefolgt von thermodynamischen Rechnungen zur Stabilität und zum Partialdruck der Phasen, die durch die Reaktion der Legierungen mit der Prozeßumgebung gebildet werden können. Die Ergebnisse dieses "theoretischen Ansatzes" werden im ersten Teil einer zweiteiligen Veröffentlichung vorgestellt, während über die Ergebnisse der experimentellen Untersuchungen im zweiten Teil berichtet wird, der in einer späteren Ausgabe dieser Zeitschrift erscheint. Bereits die Ergebnisse des "theoretischen Ansatzes" erlauben eine klare Einschätzung, welche Legierungselemente eine positive und welche eine negative Rolle bezüglich der Korrosionsbeständigkeit von metallischen Legierungen in diesen Umgebungen spielen. Diese Ergebnisse können als Werkzeug für die Bewertung des Verhaltens kommerzieller Werkstoffe in oxidierend/chlorierend wirkenden Atmosphären eingesetzt werden. Im zweiten Teil dieser Arbeit we...

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Section: 1 Aluminiumsupporting

confidence: 86%

Section: Molybdenummentioning

confidence: 98%

Section: Nickelmentioning

confidence: 99%

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The role of alloying elements in commercial alloys for corrosion resistance in oxidizing‐chloridizing atmospheres. Part I: Literature evaluation and thermodynamic calculations on phase stabilities

Bender

Schütze

2003

Materials & Corrosion

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“…Scanning electron micrograph showing microstructure of oxide scale farmed on iron specimen exposed to Ar-15%O2-O.5%CI2 at 1100 K.of oxide f o r m a t i o n from a parabolic rate e q u a t i o n a n d to c h a n g e s in t h e relative t h i c k n e s s e s of t h e different layers of oxide in t h e scale with time(23)(24)(25)(26)(27).W h e n reaction[5] proceedsfrom left to right, t h e result is t h e f o r m a t i o n of a layer of metal oxide by chemical v a p o r deposition. Chemical v a p o r deposition processes can be characterized by t h e use of a d i m e n s i o n l e s s n u m b e r (the CVD n u m b e r ) , w h i c h e x p r e s s e s the ratio of t h e resistance to t h e deposition process due to diffusional t r a n s p o r t in t h e gas p h a s e to t h e resistance to t h e deposition process d u e to the kinetics of the chemical reaction at the surface of t h e deposit.…”

mentioning

confidence: 98%

Inhibition of Oxidation of Iron in Environments Containing Chlorine at 1100 and 1200 K

Lee

McNallan

1990

J. Electrochem. Soc.

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The oxidation of iron in gas mixtures consisting of Ar, O2, and C12 at 1100 and 1200 K has been investigated by thermogravimetric analysis and examination of the corrosion products of the process by scanning electron microscopy and x-ray diffraction analysis. The results of the experiments have been compared with theoretical corrosion rates calculated from a model which accounts for the formation of an iron oxide scale according to a parabolic rate equation and the formation of volatile chloride reaction products according to a linear rate equation. The results indicate that the rate of oxidation of iron in this temperature range is significantly inhibited by the presence of chlorine in the environment. This effect is attributed to the formation of a dense layer of Fe203 on the outside of the oxide scale which is formed in the presence of chlorine.The rates of oxidation of many metals at high temperatures are limited by the diffusion-controlled growth of protective oxide scales which form on the surfaces of the metals. Because the resistance to diffusional transport increases with time as the scale thickens, if the driving force for oxidation is constant, then parabolic kinetics are observed (1). The scale may grow via the outward transport of metal species or the inward transport of oxidizing species or a combination of the two. The transport coefficients for oxygen anions or metal cations in the oxide are the most important parameters affecting the rate constant for parabolic growth, with the scales growing rapidly when the transport coefficients are high.Iron and a few other transition metals can form oxides with more than one stoichiometry depending on the chemical potential of oxygen in the environment. The oxide scales formed on these metals are multilayered, with the oxides which require the highest oxygen potentials to be stable forming near the gas-scale interface, and those which are stable at lower oxygen potentials forming nearer the scale-metal interface. Ifinterfacial reaction rates do not influence the rates of growth of the layers, then the relative thicknesses of the layers will be proportional to the transport coefficients for oxidizing species within the layers. Iron forms three oxides: FeO "(wustite), Fe304 (magnetite), and Fe203 (hematite) in order of increasing oxygen to iron ratio. The order of the diffusion coefficients for oxidizing species in the oxides is the reverse of this, with the relative thicknesses of FeO, Fe304, and Fe203 in a growing oxide scale on iron at 1200 K being approximately 95:4:1 (2).Mixed oxidation refers to the oxidation of materials in the presence of more than one oxidizing species. Several transition metals have been shown to oxidize at accelerated rates in the presence of second oxidizing species (3). This implies that the presence of second oxidizing species can speed up the transport of species in the growing scale.

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“…When 5%H 2 O was introduced, the formation of internal Cr-rich oxides is probably related to the internal penetration of fluorine and oxygen. This internal penetration could also involve the fluorine-carbide reactions, leading to the formation of some new carbides in some places [18].…”

Section: Discussionmentioning

confidence: 99%

Electrochemical study of the corrosion of a Ni-based alloy GH3535 in molten (Li,Na,K)F at 700°C

Wang

Liu

et al. 2015

Journal of Fluorine Chemistry

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Behavior of Selected Commercial Alloys during High Temperature Oxychloridation

Cited by 22 publications

References 0 publications

The role of alloying elements in commercial alloys for corrosion resistance in oxidizing‐chloridizing atmospheres. Part I: Literature evaluation and thermodynamic calculations on phase stabilities

The role of alloying elements in commercial alloys for corrosion resistance in oxidizing‐chloridizing atmospheres. Part I: Literature evaluation and thermodynamic calculations on phase stabilities

Inhibition of Oxidation of Iron in Environments Containing Chlorine at 1100 and 1200 K

Electrochemical study of the corrosion of a Ni-based alloy GH3535 in molten (Li,Na,K)F at 700°C

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