Decomposition of Mullite by Silica Volatilization |
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| Authors: | SHIN-ICHI IWAI,TAKASHI WATANABE,ICHIRO MINATO,KIYOSHI OKADA&dagger ,HIDEKI MORIKAWA |
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| Affiliation: | Research Laboratory of Engineering Materials, Tokyo Institute of Technology, Nagatsuda, Midori-ku, Yokohama, Japan |
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| Abstract: | Thermal decomposition of mullite into corundum was investigated using a high-temperature X-ray single-crystal camera equipped with a gas-flame furnace and by scanning electron microscopy and electron probe microanalysis (EPMA). When heated to ∼1750°C, mullite decomposed to corundum by the liberation of the SiO2 component with topotaxial relations of: - (1)
(310)mull∥(001)cor; [001]mull∥[110]cor - (2)
(130)mull∥(001)cor; [001]mull∥[110]cor - (3)
(110)mull∥(001)cor; [001]mull∥[110]cor
Thus, it was considered that, when mullite decomposed into corundum, their oxygen close-packed planes were almost preserved. The SEM photographs showed that the crystals of the developed corundum are prismatic and ∼5 μm wide. The EPMA showed that the phase boundary between mullite and developed corundum is discontinuous. |
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