The Effect of Water-Vapor Content and Gas Flow Rate on the Oxidation Mechanism of a 10%Cr-Ferritic Steel in Ar-H2O Mixtures

Żurek, J.; Michalík, Marek; Schmitz, F.; Kern, Torsten-Ulf; Singheiser, L.; Quadakkers, W. J.

doi:10.1007/s11085-005-4394-1

Cited by 67 publications

(44 citation statements)

References 9 publications

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“…This effect is frequently observed in case of oxide scales exhibiting very high growth rates (see e.g. [20]). -As result of the reaction of the water vapor with the metal, minor amounts of H 2 are formed.…”

Section: O 4 From Incorporation Of Internal Oxidesmentioning

confidence: 60%

“…-As result of the reaction of the water vapor with the metal, minor amounts of H 2 are formed. It is easy to derive [20] that at the prevailing temperature this effect leads to a substantial decrease in the equilibrium oxygen partial pressure of the gas if the amount of hydrogen exceeds about 10 ppm. Which of these mechanisms is responsible for the FeO formation in contact with the gas cannot be derived with certainty from the present results.…”

Section: O 4 From Incorporation Of Internal Oxidesmentioning

confidence: 99%

“…20,21]. Several authors attributed the loss of protection of chromia-base surface scales to the enhanced formation of volatile Cr oxy-hydroxide, CrO 2 (OH) 2 via the reaction:…”

Section: Mechanism Of Breakaway Oxidationmentioning

confidence: 99%

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The Effect of Water Vapor on Selective Oxidation of Fe–Cr Alloys

et al. 2008

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Binary Fe-Cr alloys containing 10 and 20 mass% Cr were studied with respect to isothermal oxidation behavior at 900 and 1,050°C in Ar-20%O 2 , Ar-7%H 2 O and Ar-4%H 2 -7%H 2 O. Thermogravimetric analyses in combination with analytical studies using SEM/EDX and Raman Spectroscopy revealed, that in atmospheres in which water vapor is the source of oxygen, Cr exhibits a higher tendency to become internally oxidized than in the Ar-O 2 gas. Contrary to previous studies which showed the presence of water vapor to affect transport processes in the scale, the present results thus reveal that the presence of water vapor also affects the transport processes in the alloy. This mechanism is an ''easy'' explanation of the frequently observed effect that Fe-Cr alloys with intermediate Cr contents (e.g. 10-20%, depending on temperature) exhibit protective chromia-rich scale formation in dry gases but breakaway type Fe-rich oxides in wet gases, provided the oxygen partial pressure is sufficiently high for Fe to become oxidized.

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Section: O 4 From Incorporation Of Internal Oxidesmentioning

confidence: 60%

Section: O 4 From Incorporation Of Internal Oxidesmentioning

confidence: 99%

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The Effect of Water Vapor on Selective Oxidation of Fe–Cr Alloys

et al. 2008

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“…The real oxygen concentration at the magnetite/atmosphere interface is not the oxygen concentration in air or water. Zurek et al [20], who studied oxidation of 10% Cr ferritic steel in Ar-H 2 O mixture, showed that the oxide scale thickness does not depend on the H 2 O content in the gas mixture (Ar-4% H 2 O or Ar-50% H 2 O) if the oxygen activity is sufficient to allow the thin hematite layer formation. The estimated oxygen partial pressure using Henry's constant of SCW is lower than that of steam.…”

Section: Determination Of Iron Diffusion Coefficient Inmentioning

confidence: 99%

Estimation of Oxidation Kinetics and Oxide Scale Void Position of Ferritic-Martensitic Steels in Supercritical Water

Sun

Yan

2017

Advances in Materials Science and Engineering

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Exfoliation of oxide scales from high-temperature heating surfaces of power boilers threatened the safety of supercritical power generating units. According to available space model, the oxidation kinetics of two ferritic-martensitic steels are developed to predict in supercritical water at 400 ∘ C, 500 ∘ C, and 600 ∘ C. The iron diffusion coefficients in magnetite and Fe-Cr spinel are extrapolated from studies of Backhaus and Töpfer. According to Fe-Cr-O ternary phase diagram, oxygen partial pressure at the steel/Fe-Cr spinel oxide interface is determined. The oxygen partial pressure at the magnetite/supercritical water interface meets the equivalent oxygen partial pressure when system equilibrium has been attained. The relative error between calculated values and experimental values is analyzed and the reasons of error are suggested. The research results show that the results of simulation at 600 ∘ C are approximately close to experimental results. The iron diffusion coefficient is discontinuous in the duplex scale of two ferritic-martensitic steels. The simulation results of thicknesses of the oxide scale on tubes (T91) of final superheater of a 600 MW supercritical boiler are compared with field measurement data and calculation results by Adrian's method. The calculated void positions of oxide scales are in good agreement with a cross-sectional SEM image of the oxide layers.

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“…Many studies have shown that oxidation rates in humid environment are relatively higher than in dry environment. [2][3][4][5][6] A possible mechanism is that water vapor retards the formation of protective scale. Extensive works have been done to understand the role of water vapor in impeding the formation of protective Cr 2 O 3 scale, but the explanations remain in qualitative manner.…”

Section: Introductionmentioning

confidence: 99%