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

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

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.

Item Type: Article
Erschienen: 1999
Creators: Konetschny, Christoph and Galusek, D. and Reschke, S. and Fasel, C. and Riedel, R.
Title: Dense silicon carbonitride ceramics by pyrolysis of cross-linked and warm pressed polysilazane powders
Language: English
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.

Journal or Publication Title: Journal of the European Ceramic Society
Volume: 19
Number: 16
Publisher: Elsevier
Uncontrolled Keywords: silicon carbonitride, precursors-organics, pressing, SiC, Si3N4.
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 16:22
Funders: 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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