Synthesis and characterization of SiC whiskers and their application in Si sub 3 N sub 4 matrix composites
Tailored SiC whiskers were synthesized by a low cost method: carbothermal reduction of silica with the addition of a halide as an auxiliary bath. The formation of the SiC whiskers was through SiO(g) as a medium. The morphologies of three distinctive whiskers were related to the differences in their microstructures. Type A whiskers contained a high density of basal plane stacking faults along their entire length; Type B whiskers showed periodic changes between stacking faults and well defined single crystals; Type C whiskers had stacking faults mainly on the three non-basal {l brace}111{r brace} planes instead of the basal (111) plane, and the density of the stacking faults was much lower than that of Type A and B whiskers. The SiC whiskers were likely grown through a two-dimensional vapor-solid nucleation mechanisms. A two-step sintering process, pressureless sintering followed by N{sub 2} gas-pressure sintering was effective in densifying SiC{sub w}/Si{sub 3}N{sub 4} composites, as well as monolithic Si{sub 3}N{sub 4}. The Type C SiC whiskers showed a more obvious toughening effect for Si{sub 3}N{sub 4} ceramics than the commercial Tokamax SiC whiskers.
- Research Organization:
- Michigan Univ., Ann Arbor, MI (United States)
- OSTI ID:
- 7292811
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
360601* -- Other Materials-- Preparation & Manufacture
360602 -- Other Materials-- Structure & Phase Studies
CARBIDES
CARBON COMPOUNDS
COMPOSITE MATERIALS
CRYSTAL STRUCTURE
CRYSTALS
FABRICATION
MATERIALS
MATRIX MATERIALS
MICROSTRUCTURE
MONOCRYSTALS
MORPHOLOGY
NITRIDES
NITROGEN COMPOUNDS
PNICTIDES
SILICON CARBIDES
SILICON COMPOUNDS
SILICON NITRIDES
SYNTHESIS
WHISKERS