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Development of Noncrystalline Material in Subsolidus Reactions Between Silica and Alumina
Author(s) -
STALEY W. G.,
BRINDLEY G. W.
Publication year - 1969
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.1151-2916.1969.tb15852.x
Subject(s) - corundum , cristobalite , electron microprobe , microprobe , mullite , phase (matter) , mineralogy , materials science , tridymite , scanning electron microscope , chemical engineering , chemistry , analytical chemistry (journal) , quartz , metallurgy , composite material , chromatography , ceramic , organic chemistry , engineering
Reactions between corundum and cristobalite in mixed powders and at interfaces between sintered pellets at 1500°C and in various forms of reaction couples at 1550°C were studied by quantitative X‐ray diffraction, electron microprobe analysis, and optical microscopy. The results indicate that a noncrystalline product is an important transitional phase in reactions under subsolidus conditions. When corundum is used as a coarse powder (particle size 20 to 30 μm), the amount of noncrystalline material produced can be as much as 30 to 40% of the total reactants, and the amount of mullite is correspondingly small. When corundum is used as a single crystal, the development of a noncrystalline phase is notably increased. Microprobe analyses of coarse powders reacted at 1500°C show a noncrystalline phase of the approximate composition Al 2 O 3 ·12SiO 2 . Calculations based on the X‐ray analyses indicate a higher proportion of alumina in the noncrystalline material, and it is suggested that alumina‐rich zones may form adjacent the corundum surfaces where they are not resolved in the microprobe analysis.