The evolutionary process during pyrolytic transformation of poly(N-methylsilazane) from a preceramic polymer into an amorphous silicon nitride/carbon composite
- Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Materials Science and Engineering
- Univ. Pierre et Marie Curie, Paris (France). Lab. de la Matiere Condensee
- Univ. of Washington, Seattle, WA (United States). Dept. of Materials Science and Engineering
- Battelle Pacific Northwest Labs., Richland, WA (United States)
The pyrolytic evolution of poly(N-methylsilazane), -[H{sub 2}SiN-Me]{sub x}-, from preceramic polymer to ceramic product is followed by heating samples of the partially cross-linked polymer, in 200 C increments, from ambient temperature to 1,400 C. The intermediate products are characterized by chemical analysis, diffuse reflectance Fourier transform IR spectroscopy (DRIFTS), Raman spectroscopy, and {sup 29}Si and {sup 13}C magic-angle spinning (MAS) solid-state NMR. Spectroscopic characterization indicates that the 1,400 C pyrolysis products are amorphous silicon nitride mixed with amorphous and graphitic carbon (as determined by Raman spectroscopy), rather than silicon carbide nitride, as expected based on the presence of up to 20 mol% retained carbon. Efforts to crystallize the silicon nitride through heat treatments up to 1,400 C do not lead to any crystalline phases, as established by transmission electron microscopy (TEM) and small-area electron diffraction (SAD). It appears that the presence of free carbon, along with the absence of oxygen, strongly inhibits crystallization of amorphous silicon nitride. These results contrast with the isostructural poly(Si-methylsilazane), -[MeHSiNH]{sub x}-, which is reported to form silicon carbide nitride on pyrolysis.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 182654
- Journal Information:
- Journal of the American Ceramic Society, Vol. 78, Issue 1; Other Information: PBD: Jan 1995
- Country of Publication:
- United States
- Language:
- English
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