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Processing and Properties of Cellular Silica Synthesized by Foaming Sol‐Gels
Author(s) -
Fujiu Takamitsu,
Messing Gary L.,
Huebner Wayne
Publication year - 1990
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.1151-2916.1990.tb05095.x
Subject(s) - materials science , dielectric , composite material , viscosity , flexural strength , ceramic , cell size , spheres , sol gel , foaming agent , chemical engineering , porosity , nanotechnology , physics , optoelectronics , astronomy , engineering , biology , microbiology and biotechnology
A novel process for fabricating lightweight, cellular ceramics from sols is presented. The process utilizes the rapid viscosity change during gelation to stabilize the structure of a foamed silica sol. Manipulation of gel viscosity and foaming agent concentration resulted in a minimum cell size of 90 μm at 31% density and minimum density of 17% with average cell size of 400 μm. The flexural strength compared favorably with space shuttle tiles and sintered hollow glass spheres. From −50° to 150°C, the dielectric constant ranged from 1.51 to 1.55 for a 20% dense foam and was slightly dispersive, whereas the dielectric loss was comparable with fused silica.