Phase Diagram for Mullite‐SiF₄

Abstract

At 1 atm of SiF4, mullite and SiF4 react below 660° 7°C to form A1F3 and SiO2. From 660° to 1056°± 5°C, the product is fluorotopaz. Mullite is stable in the presence of 1 atm of SiF4 above 1056°C. The transition temperatures at other pressures of SiF4 can be calculated from log p(atm) = 11.587 – 10811/T(K) and log p(atm) = 9.9609 – 13238/T(K). The phase diagram shows only gas–solid equilibria, but there is evidence for a metastable melt from which acicular mullite and fluorotopaz grow.

New Design of a Ceramic Filter for Diesel Emission Control Applications

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