This title appears in the Scientific Report :
2010
Please use the identifier:
http://dx.doi.org/10.1002/maco.200905432 in citations.
Oxidation Kinetics of Y-doped FeCrAl-Alloys in Low and High pO2 Gases
Oxidation Kinetics of Y-doped FeCrAl-Alloys in Low and High pO2 Gases
A model Fe-20Cr-5Al-0.05Y alloy was oxidized in Ar-20%O-2 and Ar-4%H-2-7%H2O at 1200-1300 degrees C. Two-stage oxidation experiments using oxygen isotope tracers showed that inward oxygen diffusion was predominant in both gases, but more isotope exchange was observed in the H-2/H2O gas reaction. The...
Saved in:
Personal Name(s): | Young, D.J. |
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Naumenko, D. / Niewolak, L. / Wessel, E. / Singheiser, L. / Quadakkers, W. J. | |
Contributing Institute: |
Werkstoffstruktur und -eigenschaften; IEK-2 JARA-ENERGY; JARA-ENERGY |
Published in: | Materials and corrosion, 61 (2010) S. 838 -844 |
Imprint: |
Weinheim [u.a.]
Wiley-VCH
2010
|
Physical Description: |
838 -844 |
DOI: |
10.1002/maco.200905432 |
Document Type: |
Journal Article |
Research Program: |
Rationelle Energieumwandlung |
Series Title: |
Materials and Corrosion
61 |
Subject (ZB): | |
Publikationsportal JuSER |
A model Fe-20Cr-5Al-0.05Y alloy was oxidized in Ar-20%O-2 and Ar-4%H-2-7%H2O at 1200-1300 degrees C. Two-stage oxidation experiments using oxygen isotope tracers showed that inward oxygen diffusion was predominant in both gases, but more isotope exchange was observed in the H-2/H2O gas reaction. The alumina scales formed in both gases were composed of columnar grains, the lateral size of which increased linearly with depth beneath the scale surface. Thermogravimetric measurement of oxygen uptake revealed kinetics which were intermediate to parabolic and cubic kinetic rate laws. A model based on grain boundary diffusion control coupled with competitive oxide grain growth accounts satisfactorily for the results when the requirement for a divergence-free flux within the scale is imposed. This treatment shows that the oxide grain boundary diffusion coefficient is lower when H2O is the oxidant. It is concluded that hydrogen slows the grain boundary diffusion process by altering the nature of the diffusing species. |