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Silsesquioxanes as precursors to ceramic compositesSilsesquioxanes having the general structure RSiO(1.5), where R = methyl, propyl, or phenyl, melt flow at 70 to 100 C. Above 100 C, free OH groups condense. At 225 C further crosslinking occurs, and the materials form thermosets. Pyrolysis, with accompanying loss of volatiles, takes place at nominally 525 C. At higher temperatures, the R group serves as an internal carbon source for carbo-thermal reduction to SiC accompanied by the evolution of CO. By blending silsesquioxanes with varying R groups, both the melt rheology and composition of the fired ceramic can be controlled. Fibers can be spun from the melt which are stable in argon in 1400 C. The silsesquioxanes also were used as matrix precursors for Nicalon and alpha-SiC platelet reinforced composites.
Document ID
19880025372
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Hurwitz, F. I.
(NASA Lewis Research Center Cleveland, OH, United States)
Hyatt, L.
(NASA Lewis Research Center Cleveland, OH, United States)
Gorecki, J.
(NASA Lewis Research Center Cleveland, OH, United States)
D'Amore, L.
(NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
August 13, 2013
Publication Date
August 1, 1987
Publication Information
Publication: Ceramic Engineering and Science Proceedings
Volume: 8
ISSN: 0196-6219
Subject Category
Composite Materials
Accession Number
88A12599
Distribution Limits
Public
Copyright
Other

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