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

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

301 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

Funding

The authors would like to thank L. D. Chitwood, G. Garner, J. Moser, L. Walker and H. Longmire at ORNL for assistance with the experimental work and S. Dryepondt, I. G. Wright and P. F. Tortorelli for comments on the manuscript. This research was sponsored by the U.S. Department of Energy, Distributed Energy Program, under contract DE-AC05-00OR22725 with UT-Battelle, LLC.

Keywords

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

Access to Document

10.1007/s11085-006-9030-1

Cite this

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

AU - Young, D. J.

AU - Pint, B. A.

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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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