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Stability and oxidation properties of RE–α-Sialon ceramics (RE = Y, Nd, Sm, Yb)
Stockholm University.
Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
Dept. Physical, Inorganic and Structural Chemistry, Stockholm University.
Dept. Physical, Inorganic and Structural Chemistry, Stockholm University.
1998 (English)In: Journal of The American Ceramic Society, ISSN 0002-7820, Vol. 81, no 6, 1461-1470 p.Article in journal (Refereed) Published
##### Abstract [en]

Oxidation studies of hot-pressed RE–α-sialons, REx-Si12−4.5xAl4.5xO1.5xN16−1.5x (with x = 0.40 for RE = Nd, Sm,Yb; and x = 0.48 for RE = Y) were carried out in oxygen in a TG apparatus for ca. 20 h. Very good oxidation resistance was found for the Yb-doped samples, with parabolic rateconstants Kp ≈ 0.09 × 10−6–3 × 10−6 mg2 cm−4 s−1 in the temperature range 1250–1350°C. The promising performance of this material was corroborated by long-term oxidation experiments (5 days) in air at 1350°C. Although the oxidation kinetics can be described by simple equations related to the parabolic rate law (e.g., the arctan equation, ΔW/Ao = α·arctan$\sqrt[]{}$(bt)½+ct½), the oxidation process in these materials is likely to be complex. The significantly lower oxidation resistance of the RE = Nd, Sm doped α-sialons, especially at higher temperatures, is related to the formation of melilite, RE2Si3−yAlyO3+yN4−y (y ≈$\approx$$\approx$ 1), in these systems. The melilite phase is also responsible for the thermal instability of the Nd– and Sm–α-sialons.

##### Place, publisher, year, edition, pages
1998. Vol. 81, no 6, 1461-1470 p.
Natural Sciences
##### Identifiers
OAI: oai:DiVA.org:liu-54191DiVA: diva2:300901
Available from: 2010-03-01 Created: 2010-03-01 Last updated: 2010-03-17

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Käll, Per-Olov
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Department of Physics, Chemistry and BiologyThe Institute of Technology
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Journal of The American Ceramic Society
Natural Sciences