Chromium volatilization rates from Cr2O3 scales into flowing gases containing water vapor

D. J. Young; B. A. Pint

doi:10.1007/s11085-006-9030-1

Chromium volatilization rates from Cr₂O₃ scales into flowing gases containing water vapor

D. J. Young, B. A. Pint

Materials Science and Technology Div

University of New South Wales

Research output: Contribution to journal › Article › peer-review

282 Scopus citations

Abstract

The mass-transfer coefficient for CrO₂(OH)₂ volatilization into flowing air-10% H₂O or steam was evaluated using classical gas transport theory in the viscous-flow regime. The resulting values were applied to new thermodynamic data for the reaction: 1/2 Cr ₂O₃ + 3/4 O₂(g) + H₂O(g) = CrO ₂(OH)₂(g) to predict Cr-evaporation fluxes in the temperature range 650-800°C. The calculation was found to predict correctly the Cr-loss rate measured from foil specimens of Fe-20Cr-25Ni+Nb (alloy 709) exposed for up to 10,000 hr under these conditions. In 240 atm (24 MPa) high-purity steam, the calculations suggest that the Cr-evaporation rates will be much lower than in humid air.

Original language	English
Pages (from-to)	137-153
Number of pages	17
Journal	Oxidation of Metals
Volume	66
Issue number	3-4
DOIs	https://doi.org/10.1007/s11085-006-9030-1
State	Published - Oct 2006

Keywords

Chromium oxy-hydroxide
Convection
Gas diffusion
Mass-transfer coefficient
Water vapor

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10.1007/s11085-006-9030-1

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title = "Chromium volatilization rates from Cr2O3 scales into flowing gases containing water vapor",

abstract = "The mass-transfer coefficient for CrO2(OH)2 volatilization into flowing air-10% H2O or steam was evaluated using classical gas transport theory in the viscous-flow regime. The resulting values were applied to new thermodynamic data for the reaction: 1/2 Cr 2O3 + 3/4 O2(g) + H2O(g) = CrO 2(OH)2(g) to predict Cr-evaporation fluxes in the temperature range 650-800°C. The calculation was found to predict correctly the Cr-loss rate measured from foil specimens of Fe-20Cr-25Ni+Nb (alloy 709) exposed for up to 10,000 hr under these conditions. In 240 atm (24 MPa) high-purity steam, the calculations suggest that the Cr-evaporation rates will be much lower than in humid air.",

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journal = "Oxidation of Metals",

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T1 - Chromium volatilization rates from Cr2O3 scales into flowing gases containing water vapor

AU - Young, D. J.

AU - Pint, B. A.

PY - 2006/10

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N2 - The mass-transfer coefficient for CrO2(OH)2 volatilization into flowing air-10% H2O or steam was evaluated using classical gas transport theory in the viscous-flow regime. The resulting values were applied to new thermodynamic data for the reaction: 1/2 Cr 2O3 + 3/4 O2(g) + H2O(g) = CrO 2(OH)2(g) to predict Cr-evaporation fluxes in the temperature range 650-800°C. The calculation was found to predict correctly the Cr-loss rate measured from foil specimens of Fe-20Cr-25Ni+Nb (alloy 709) exposed for up to 10,000 hr under these conditions. In 240 atm (24 MPa) high-purity steam, the calculations suggest that the Cr-evaporation rates will be much lower than in humid air.

AB - The mass-transfer coefficient for CrO2(OH)2 volatilization into flowing air-10% H2O or steam was evaluated using classical gas transport theory in the viscous-flow regime. The resulting values were applied to new thermodynamic data for the reaction: 1/2 Cr 2O3 + 3/4 O2(g) + H2O(g) = CrO 2(OH)2(g) to predict Cr-evaporation fluxes in the temperature range 650-800°C. The calculation was found to predict correctly the Cr-loss rate measured from foil specimens of Fe-20Cr-25Ni+Nb (alloy 709) exposed for up to 10,000 hr under these conditions. In 240 atm (24 MPa) high-purity steam, the calculations suggest that the Cr-evaporation rates will be much lower than in humid air.

KW - Chromium oxy-hydroxide

KW - Convection

KW - Gas diffusion

KW - Mass-transfer coefficient

KW - Water vapor

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SP - 137

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JO - Oxidation of Metals

JF - Oxidation of Metals

IS - 3-4

ER -

Chromium volatilization rates from Cr₂O₃ scales into flowing gases containing water vapor

Abstract

Keywords

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