Galusek, D. ; Reschke, S. ; Riedel, R. (1999):
In-situ carbon content adjustment in polymer-derived Si/C/N ceramics by reactive heat treatment. Calculations of the pyrolysis product composition.
In: Silicate industriels, 64 (1-2), pp. 3-7. ISSN 0037-5225,
[Article]
Abstract
A simplified mechanistic approach has been developed to estimate the range of compositional changes during the reactive heat treatment of different preceramic organosilicon precursors resulting in their conversion to amorphous Si/C/N ceramics. The calculations use the compositions of the respective crosslinked polyilazanes as starting values and combine the conversion degrees of chemical reactions with the highest thermodynamical probability taking part during heat treatment. This approach allows to estimate a processing-dependend stoichiometry of the Si/C/N ceramics, assuming the reactions yield thermodynamically stable equilibrium products. Calculated data are consistent with experimental results and indicate, that the stoichiometry of the product is determined by structure and chemical composition of the polymer rather than by the conditions applied during heat treatment. However, within the restrictions through the chemistry of the polymer, the stoichiometry of the productcan be controlled by proper adjustment of the experimental conditions.
| Item Type: | Article |
|---|---|
| Erschienen: | 1999 |
| Creators: | Galusek, D. ; Reschke, S. ; Riedel, R. |
| Title: | In-situ carbon content adjustment in polymer-derived Si/C/N ceramics by reactive heat treatment. Calculations of the pyrolysis product composition |
| Language: | English |
| Abstract: | A simplified mechanistic approach has been developed to estimate the range of compositional changes during the reactive heat treatment of different preceramic organosilicon precursors resulting in their conversion to amorphous Si/C/N ceramics. The calculations use the compositions of the respective crosslinked polyilazanes as starting values and combine the conversion degrees of chemical reactions with the highest thermodynamical probability taking part during heat treatment. This approach allows to estimate a processing-dependend stoichiometry of the Si/C/N ceramics, assuming the reactions yield thermodynamically stable equilibrium products. Calculated data are consistent with experimental results and indicate, that the stoichiometry of the product is determined by structure and chemical composition of the polymer rather than by the conditions applied during heat treatment. However, within the restrictions through the chemistry of the polymer, the stoichiometry of the productcan be controlled by proper adjustment of the experimental conditions. |
| Journal or Publication Title: | Silicate industriels |
| Volume of the journal: | 64 |
| Issue Number: | 1-2 |
| Uncontrolled Keywords: | precursor, polymer pyrolysis, NH3, Si/N(/C), amorphous ceramics, calculations, poly(hydridomethyl)silazanes, polyvinylsilazanes, polymethyldisilazanes |
| Divisions: | 11 Department of Materials and Earth Sciences 11 Department of Materials and Earth Sciences > Material Science 11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids |
| Date Deposited: | 19 Nov 2008 15:58 |
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