A composite consisting of 30 wt% SiC whiskers and a mullite-based matrix (mullite-32.4 wt% ZrO2-2.2 wt% MgO) was isothermally exposed in air at 1000°-1350°C, for up to 1000 h. Microstructural evolution in the oxidized samples was investigated using X-ray diffractometry and analytical transmission electron microscopy. Amorphous SiO2, formed through the oxidation of SiC whiskers, was devitrified into cristobalite at T ≥ 1200°C and into quartz at 1000°C. At T ≥ 1200°C, the reaction between ZrO2 and SiO2 resulted in zircon, and prismatic secondary mullite grains were formed via a solution-reprecipitation mechanism in severely oxidized regions. Ternary compounds, such as sapphirine and cordierite, also were found after long-term exposure at T ≥ 1200°C.
|頁（從 - 到）||1797-1803|
|期刊||Journal of the American Ceramic Society|
|出版狀態||Published - 1 七月 2000|