Growth Rates of Alumina Scales on Fe–Cr–Al Alloys
- Cite this article as:
- Quadakkers, W.J., Naumenko, D., Wessel, E. et al. Oxidation of Metals (2004) 61: 17. doi:10.1023/B:OXID.0000016274.78642.ae
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The growth rates of alumina scales formed on high-temperature alloys often show a strong deviation from classical parabolic kinetics, and frequently scale growth rates near to a cubic time dependence are observed. This is e.g. the case for most RE doped Fe–Cr–Al-alloys oxidized at temperatures in the range of 1000 to 1300°C. For a number of components made of Fe–Cr–Al alloys, which e.g. prevail in car catalyst carriers, gas burners or hot-gas filters, the detailed knowledge of the rate law governing scaling kinetics is an absolutely necessary requirement for a reliable prediction of the component lifetime and/or the materials application limits. It seems that for ideally gas-tight α-Al2O3 scales a near-cubic time dependence is more a rule than an exception, although the frequently used methods for evaluating measured oxidation data might lead to the erroneous conclusion that the scale growth is governed by a transient-oxidation stage followed by parabolic oxidation. Deviations from an ideal, near-cubic time dependence of the oxidation kinetics of the Fe–Cr–Al alloys are caused by scale cracking during thermal cycling and/or local inhomogenities in the alloy and/or the scale.