Silicon nitride ceramic fibers from preceramic polymers. Technical report
The program objectives are to develop: (1) Transition metal catalyzed synthetic routes to designed, tractable silicon nitride (Si/sub 3/N/sub 4/) preceramic polymers (polysilazanes) based on SRI developed technology; (2) Methods of spinning the resultant polysilazanes into continuous preceramic fibers; and, (3) Pyrolysis techniques for transforming the preceramic fibers into high strength Si/sub 3/N/sub 4/ and silicon carbide nitride (SiCN) fibers. In the past year, polysilazanes driven from precursors of the type-H/sub 2/SiNMe were prepared, whose viscoelastic properties can be carefully controlled by type of catalyst and/or reaction conditions. This control permitted drawing preceramic fibers of diameters as small as 10 um. Furthermore, pyrolysis methodology was developed from which ceramic yields of 50-70% were obtained with Si/sub 3/N/sub 4/ purities ranging from 80-99%. It was discovered that polymer molecular weight greatly influences the ceramic yield, but only monomer design or pyrolysis under a reactive atmosphere seems to influence selectivity to specific ceramic products.
- Research Organization:
- SRI International, Menlo Park, CA (USA)
- OSTI ID:
- 6017303
- Report Number(s):
- AD-A-183442/3/XAB; TR-8
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360601 -- Other Materials-- Preparation & Manufacture
CARBIDES
CARBON COMPOUNDS
CATALYSTS
CERAMICS
CHEMICAL REACTIONS
DECOMPOSITION
FIBERS
MOLECULAR WEIGHT
MONOMERS
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
POLYMERS
PROCESSING
PRODUCTION
PYROLYSIS
SILICON CARBIDES
SILICON COMPOUNDS
SILICON NITRIDES
SYNTHESIS
THERMOCHEMICAL PROCESSES