Synthesis of Porous Mullite by Vapor Phase Reaction

摘要

The porous microstructure with acicular mullites was fabricated using Al(OH)_3, Al_2O_3, and amorphous SiO_2 as starting materials by reaction sintering. Several molar ratios of Al_2O_3/SiO_2 and Al(OH)_3/SiO_2 were selected and AlF_3 of 0, 4, 7, 10wt% was added to each composition to examine the effects of composition and the additives for the mullite formation. Fluorotopaz was produced at a temperature around 900℃ under a constant SiF_4 atmosphere and it was decomposed to produce the mullite at a relatively low sintering temperature around 1200℃. The acicular mullite was more easily fabricated in the case of the Al(OH)_3/SiO_2 mixture with a larger amount of AlF_3.