Thermodynamic Analysis of ZrB2-SiC Oxidation: Formation of a SiC-Depleted Region

A thermodynamic model was developed to explain the formation of a SiC‐depleted layer during ZrB2–SiC oxidation in air at 1500°C. The proposed model suggests that a structure consisting of (1) a silica‐rich layer, (2) a Zr‐rich oxidized layer, and (3) a SiC‐depleted zirconium diboride layer is thermo...

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Bibliographic Details
Published in:Journal of the American Ceramic Society 2007-01, Vol.90 (1), p.143-148
Main Author: Fahrenholtz, William G.
Format: Article
Language:English
Subjects:
Applied sciences
Building materials. Ceramics. Glasses
Ceramic industries
Cermets, ceramic and refractory composites
Chemical industry and chemicals
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Materials science
Miscellaneous
Other materials
Physics
Specific materials
Technical ceramics
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Summary:A thermodynamic model was developed to explain the formation of a SiC‐depleted layer during ZrB2–SiC oxidation in air at 1500°C. The proposed model suggests that a structure consisting of (1) a silica‐rich layer, (2) a Zr‐rich oxidized layer, and (3) a SiC‐depleted zirconium diboride layer is thermodynamically stable. The SiC‐depleted layer developed due to active oxidation of SiC. The oxygen partial pressure in the SiC‐depleted layer was calculated to lie between 4.0 × 10−14 and 1.8 × 10−11 Pa. Even though SiC underwent active oxidation, the overall process was consistent with passive oxidation and the formation of a protective surface layer.
ISSN:0002-7820
1551-2916
DOI:10.1111/j.1551-2916.2006.01329.x