Mullite Crystallization from SiO/sub 2/--Al/sub 2/O/sub 3/ melts

Journal Article · Sun Jan 01 04:00:00 EST 1978 · J. Am. Ceram. Soc.; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1978.tb09232.x· OSTI ID:6343742

Risbud, S H; Pask, J A

SiO/sub 2/--Al/sub 2/O/sub 3/ melts containing 42 and 60 wt% Al/sub 2/O/sub 3/ were homogenized at 2090/sup 0/C(+-10/sup 0/) and crystallized by various heat treatment schedules in sealed molybdenum crucibles. Mullite containing approx. = 78 wt% Al/sub 2/O/sub 3/ precipitated from the 60 wt% Al/sub 2/O/sub 3/ melts at approx. = 1325/sup 0/ +- 20/sup 0/C, which is the boundary of a previously calculated liquid miscibility gap. When the homogenized melts were heat-treated within this gap, the Al/sub 2/O/sub 3/ in the mullite decreased with a corresponding increase in the Al/sub 2/O/sub 3/ content of the glass. A similar decrease of Al/sub 2/O/sub 3/ in mullite was observed when crystallized melts were reheated at 1725/sup 0/ +- 10/sup 0/C; the lowest Al/sub 2/O/sub 3/ content (approx. =73.5 wt% was in melts that were reheated for 110 h. All melts indicated that the composition of the precipitating mullite was sensitive to the heat treatment of the melts.

• Research Organization: Univ. of California, Berkeley
• OSTI ID: 6343742
• Journal Information: J. Am. Ceram. Soc.; (United States), Journal Name: J. Am. Ceram. Soc.; (United States) Vol. 61:1-2; ISSN JACTA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CHEMICAL COMPOSITION
COOLING
CRYSTAL STRUCTURE
CRYSTALLIZATION
ENTHALPY
FUSION HEAT
MELTING
MICROSTRUCTURE
MINERALS
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SILICA
SILICON COMPOUNDS
SILICON OXIDES
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TIME DEPENDENCE
TRANSITION HEAT