TU Darmstadt / ULB / TUbiblio

In-situ carbon content adjustment in polysilazane derived amorphous SiCN bulk ceramics

Galusek, Dusan and Reschke, Stefan and Riedel, Ralf and Dreßler, Wolfgang and Sajgalik, Pavol and Lences, Zoltan and Majling, Jan (1999):
In-situ carbon content adjustment in polysilazane derived amorphous SiCN bulk ceramics.
In: Journal of the European Ceramic Society, Elsevier, pp. 1911-1921, 19, (10), [Article]

Abstract

The present paper is concerned with the in-situ carbon content adjustment in amorphous bulk silicon carbonitride (SiCN) ceramic matrices prepared by the polymer to ceramic transformation of cross-linked and compacted poly(hydridomethyl)silazane powders. Heat treatment in inert (Ar) or reactive atmosphere (ammonia, or mixed Ar/NH3 with different volume ratio of ammonia) was used for carbon content adjustment. Isothermal annealing steps in Ar and/or mixed atmospheres at various intermediate temperatures were also included into the pyrolysis schedule (i) to adjust the final carbon content, (ii) to control outgassing of low molecular reaction products like methane or hydrogen from the matrix during polysilazane decomposition and thus (iii) to avoid cracking of the pressed polymer powders. Optimal annealing temperature for carbon content adjustment was found to be in the range between 500 and 550°C. Increasing NH3 contents from 10 to 50 vol% in the pyrolysis atmosphere as well as enhanced transient annealing temperature and time promote carbon reduction. In contrast intermediate isothermal annealing in Ar at 500 up to 600°C results in pronounced formation of Si–C bonds and in increased carbon contents after the final pyrolysis process. Depending on the pyrolysis conditions, flawless bulk specimens with carbon contents ranging from 0·3 up to 16·2 wt% were obtained. Different possible chemical reactions are considered to explain the generation of the particular Si(C)N compositions found.

Item Type: Article
Erschienen: 1999
Creators: Galusek, Dusan and Reschke, Stefan and Riedel, Ralf and Dreßler, Wolfgang and Sajgalik, Pavol and Lences, Zoltan and Majling, Jan
Title: In-situ carbon content adjustment in polysilazane derived amorphous SiCN bulk ceramics
Language: English
Abstract:

The present paper is concerned with the in-situ carbon content adjustment in amorphous bulk silicon carbonitride (SiCN) ceramic matrices prepared by the polymer to ceramic transformation of cross-linked and compacted poly(hydridomethyl)silazane powders. Heat treatment in inert (Ar) or reactive atmosphere (ammonia, or mixed Ar/NH3 with different volume ratio of ammonia) was used for carbon content adjustment. Isothermal annealing steps in Ar and/or mixed atmospheres at various intermediate temperatures were also included into the pyrolysis schedule (i) to adjust the final carbon content, (ii) to control outgassing of low molecular reaction products like methane or hydrogen from the matrix during polysilazane decomposition and thus (iii) to avoid cracking of the pressed polymer powders. Optimal annealing temperature for carbon content adjustment was found to be in the range between 500 and 550°C. Increasing NH3 contents from 10 to 50 vol% in the pyrolysis atmosphere as well as enhanced transient annealing temperature and time promote carbon reduction. In contrast intermediate isothermal annealing in Ar at 500 up to 600°C results in pronounced formation of Si–C bonds and in increased carbon contents after the final pyrolysis process. Depending on the pyrolysis conditions, flawless bulk specimens with carbon contents ranging from 0·3 up to 16·2 wt% were obtained. Different possible chemical reactions are considered to explain the generation of the particular Si(C)N compositions found.

Journal or Publication Title: Journal of the European Ceramic Society
Volume: 19
Number: 10
Publisher: Elsevier
Uncontrolled Keywords: amorphous ceramics, precursors, organic, carbon, Si3N4, SiC.
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 19 Nov 2008 15:54
Funders: The work was financially supported by the DAAD, Bonn, Germany, NEDO (New Energy and Industrial Technology Development Organisation), Tokyo, Japan, the BMBF (WTZ project X262.11), Bonn, Germany, the Slovak Grant Agency (Project no. 2/1169/96),, Bratislava, Slovak Republic and the Fonds der Chemsichen Industrie, Frankfurt, Germany.
Export:
Suche nach Titel in: TUfind oder in Google

Optionen (nur für Redakteure)

View Item View Item