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Reactions in Silica‐Alumina Mixtures
Author(s) -
WEST RICHARD R.,
GRAY THOMAS J.
Publication year - 1958
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.1151-2916.1958.tb13526.x
Subject(s) - mullite , spinel , stoichiometry , exothermic reaction , reactivity (psychology) , crystallization , differential thermal analysis , materials science , hydrogen , aluminium , chemical engineering , aluminium silicate , aluminium oxides , amorphous silica alumina , mineralogy , inorganic chemistry , chemistry , catalysis , composite material , organic chemistry , ceramic , metallurgy , medicine , alternative medicine , physics , pathology , optics , diffraction , engineering
Examination of mixtures of extremely pure silica and alumina shows that the greatest reactivity is not encountered with stoichiometric ratios to form mullite with the formula 3Al 2 O 3 . 2SiO 2 but rather with the formula 2A1 2 O 3 ‐SiO 2 , and that reactivity also depends on the crystalline modification of alumina. A sharp exothermic differential thermal peak at 980°C. is attributed to three simultaneous reactions dependent on the silica‐alumina ratio of the mixture: (1) the crystallization of gamma alumina, (2) the crystallization of a hydrogen aluminum spinel (HAl 5 O 5 ), and (3) the reaction of silica with the hydrogen aluminum spinel to form mullite.