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Thermodynamic Analysis of ZrB 2 –SiC Oxidation: Formation of a SiC‐Depleted Region
Author(s) -
Fahrenholtz William G.
Publication year - 2007
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2006.01329.x
Subject(s) - layer (electronics) , materials science , zirconium diboride , zirconium , oxygen , chemical engineering , silicon carbide , composite material , metallurgy , chemistry , organic chemistry , engineering
A thermodynamic model was developed to explain the formation of a SiC‐depleted layer during ZrB 2 –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.