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Dense silicon carbonitride ceramics by pyrolysis of cross-linked and warm pressed polysilazane powders

Konetschny, Christoph ; Galusek, D. ; Reschke, S. ; Fasel, C. ; Riedel, R. :
Dense silicon carbonitride ceramics by pyrolysis of cross-linked and warm pressed polysilazane powders.
In: Journal of the European Ceramic Society, 19 (16) pp. 2789-2796.
[Artikel], (1999)

Kurzbeschreibung (Abstract)

This study reports on the pyrolysis and densifaction behavior of cross-linked poly(hydridomethylsilazane) powders. The influence of the cross-linking procedure such as temperature and annealing time of the polymer powders on the compaction behavior under cold and warm pressing conditions is discussed. The degree of cross-linking is determined by thermal mechanical analysis (TMA). In addition to particle sliding which is assumed to be the compaction mechanism obtained by cold-pressing, the polymer powder consolidates by plastic deformation applying warm-pressing. A continuous 3-dimensional polysilazane network is formed after a dwelling time under these conditions. Pyrolysis of the cross-linked and compacted polysilazane powder in argon at 1100°C gives crack-free amorphous silicon carbonitride Si3+xCx+yN4 with compositions ranging from x=1·47 and y=0·88 for cold pressed samples to x=1·47 and y=1·86 for warm pressed materials. The residual open porosity is significantly reduced from 10–15 vol% in the cold pressed specimens to 1·3–5 vol% by the warm pressing procedure. The weight loss during pyrolysis between room temperature and 1300°C is about 5 wt% lower than that for cold pressed specimens. This result is explained by a reduced methane evolution during the polymer-to-ceramic conversion and is in accordance with the enhanced carbon content of the warm pressed material.

Typ des Eintrags: Artikel
Erschienen: 1999
Autor(en): Konetschny, Christoph ; Galusek, D. ; Reschke, S. ; Fasel, C. ; Riedel, R.
Titel: Dense silicon carbonitride ceramics by pyrolysis of cross-linked and warm pressed polysilazane powders
Sprache: Englisch
Kurzbeschreibung (Abstract):

This study reports on the pyrolysis and densifaction behavior of cross-linked poly(hydridomethylsilazane) powders. The influence of the cross-linking procedure such as temperature and annealing time of the polymer powders on the compaction behavior under cold and warm pressing conditions is discussed. The degree of cross-linking is determined by thermal mechanical analysis (TMA). In addition to particle sliding which is assumed to be the compaction mechanism obtained by cold-pressing, the polymer powder consolidates by plastic deformation applying warm-pressing. A continuous 3-dimensional polysilazane network is formed after a dwelling time under these conditions. Pyrolysis of the cross-linked and compacted polysilazane powder in argon at 1100°C gives crack-free amorphous silicon carbonitride Si3+xCx+yN4 with compositions ranging from x=1·47 and y=0·88 for cold pressed samples to x=1·47 and y=1·86 for warm pressed materials. The residual open porosity is significantly reduced from 10–15 vol% in the cold pressed specimens to 1·3–5 vol% by the warm pressing procedure. The weight loss during pyrolysis between room temperature and 1300°C is about 5 wt% lower than that for cold pressed specimens. This result is explained by a reduced methane evolution during the polymer-to-ceramic conversion and is in accordance with the enhanced carbon content of the warm pressed material.

Titel der Zeitschrift, Zeitung oder Schriftenreihe: Journal of the European Ceramic Society
Band: 19
(Heft-)Nummer: 16
Verlag: Elsevier
Freie Schlagworte: silicon carbonitride, precursors-organics, pressing, SiC, Si3N4.
Fachbereich(e)/-gebiet(e): Fachbereich Material- und Geowissenschaften > Materialwissenschaften > Disperse Feststoffe, Dispersive Solids
Fachbereich Material- und Geowissenschaften > Materialwissenschaften
Fachbereich Material- und Geowissenschaften
Hinterlegungsdatum: 19 Nov 2008 16:22
Sponsoren: The work was financially supported by the DAAD, Bonn, Germany, the NEDO (New Energy and Industrial Technology Development Organization), Tokyo, Japan, the BMBF (WTZ project X262.11),, and by the Slovak Grant Agency Project No2/1169/96 and the Fonds der Chemischen Industrie, Frankfurt, Germany.
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