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Synthesis and 980°C Phase Development of Some Mullite Gels
Author(s) -
CHAKRAVORTY AKSHOY KUMAR,
GHOSH DILIP KUMAR
Publication year - 1988
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.1151-2916.1988.tb07568.x
Subject(s) - mullite , orthorhombic crystal system , aluminosilicate , kaolinite , differential thermal analysis , phase (matter) , materials science , chemical engineering , mineralogy , sol gel , chemistry , crystallography , nanotechnology , metallurgy , catalysis , crystal structure , organic chemistry , diffraction , optics , ceramic , physics , engineering
Earlier works of mullitization through the gel route have been reviewed and the results show 980°C DTA and crystalline phases. Some Al 2 O 3 ‐SiO 2 gels have been synthesized by using different precursors and by varying pH and water content during the gelification process. Thermal changes of these coherent gels were studied by DTA and X‐ray powder diffractometry. The results demonstrate that two types of aluminosilicate gels form. The first type produces orthorhombic mullite directly on heating at 980°C, whereas the second type forms cubic mullite first at 980°C and then transforms to the orthorhombic variety on further heating. Lastly, the cause of the 980°C exotherm is explained with reference to kaolinite.