Premium
Infrared‐Transparent Mullite Ceramic
Author(s) -
PROCHAZKA S.,
KLUG F. J.
Publication year - 1983
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.1151-2916.1983.tb11004.x
Subject(s) - mullite , materials science , ceramic , annealing (glass) , microstructure , hot pressing , grain growth , mineralogy , transmittance , grain size , grain boundary , composite material , phase (matter) , metallurgy , analytical chemistry (journal) , chemistry , optoelectronics , chromatography , organic chemistry
Mullite ceramic, transparent in the infrared, was prepared by hot‐pressing and hot‐isostatically pressing starting materials derived from alkyloxides. A composition with 72.3 wt% Al 2 O 3 yielded transparent, submicrometer grain size bodies at 1630°C, whereas higher temperatures produced glass‐containing microstructures. A composition with 76 wt% A1 2 O 3 formed precipitates of α‐Al 2 O 3 at the consolidation temperature, which could be removed by subsequent annealing between 1800° and 1850°C. Spectral transmittance and absorption coefficients of the bodies are reported. The formation of the second phases was linked to phase equilibria and grain growth that promoted compositional equilibration of the mullite phase. The results suggest adjustments to phase boundaries in the high‐temperature segment of the SiO 2 ‐Al 2 O 3 phase diagram.