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Effect of Zirconia Content on the Oxidation Behavior of Silicon Carbide/Zirconia/Mullite Composites
Author(s) -
Tsai ChengYuan,
Lin ChienCheng,
Zangvil Avigdor,
Li AiKang
Publication year - 1998
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.1151-2916.1998.tb02637.x
Subject(s) - mullite , materials science , cubic zirconia , silicon carbide , composite material , isothermal process , percolation threshold , composite number , oxide , ceramic , metallurgy , physics , engineering , electrical engineering , thermodynamics , electrical resistivity and conductivity
The oxidation of hot‐pressed SiC‐particle (SiC p )/zirconia (ZrO 2 )/mullite composites with various ZrO 2 contents, exposed in air isothermally at 1000° and 1200°C for up to 500 h, was investigated; an emphasis was placed on the effects of the ZrO 2 content on the oxidation behavior. A clear critical volume fraction of ZrO 2 existed for exposures at either 1000° or 1200°C: the oxidation rate increased dramatically at ZrO 2 contents of >20 vol%. The sharp transition in the oxidation rate due to the variation of ZrO 2 content could be explained by the percolation theory, when applied to the oxygen diffusivity in a randomly distributed two‐phase medium. Morphologically, the composites with ZrO 2 contents greater than the critical value showed a large oxidation zone, whereas the composites with ZrO 2 contents less than the critical value revealed a much‐thinner oxidation zone. The results also indicated that the formation of zircon (ZrSiO 4 ) at 1200°C, through the reaction between ZrO 2 and the oxide product, could reduce the oxidation rate of the composite.