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Polymer-derived mullite–SiC-based nanocomposites

Riedel, Ralf and Toma, Liviu and Fasel, Claudia and Miehe, Gerhard (2009):
Polymer-derived mullite–SiC-based nanocomposites.
In: Journal of the European Ceramic Society, SciVerse, pp. 3079-3090, 29, (14), ISSN 09552219,
[Online-Edition: http://dx.doi.org/10.1016/j.jeurceramsoc.2009.05.016],
[Article]

Abstract

Ceramic mullite–SiC nanocomposites were successfully produced at temperatures below 1500 °C by the polymer pyrolysis technique. An alumina-filled poly(methylsilsesquioxane) compound was prepared by mechanically mixing and cross-linking via a catalyst prior to pyrolysis. Heat treatment of warm pressed alumina/polymer bulk samples under the exclusion of oxygen (inert argon atmosphere) up to 1500 °C initiated crystallization of mullite even at pyrolysis temperatures as low as 1300 °C. The influence of the filler and of the pyrolysis temperature on the crystallization behavior of the materials has been investigated. Based on thermal analysis in combination with elemental analysis and X-ray powder diffraction studies four polymer mixtures differing in type and content of nano-alumina powders were examined. Nano-sized γ-Al2O3 powders functionalized at the surface by octylsilane groups proved to be more reactive towards the preceramic polymer leading to the formation of a larger weight fraction of mullite crystals at lower processing temperatures (1300 °C) as compared to native nano-γ-Al2O3 filler. Moreover, the functionalized nano-alumina particles offer an enhanced homogeneity of the distribution of alumina nano-particles in the starting polysiloxane system. In consequence, the received ceramic samples exhibited a nano-microstructure consisting of crystals of mullite with an average dimension in the range of 60–160 nm and silicon carbide crystals in the range of 1–8 nm.

Item Type: Article
Erschienen: 2009
Creators: Riedel, Ralf and Toma, Liviu and Fasel, Claudia and Miehe, Gerhard
Title: Polymer-derived mullite–SiC-based nanocomposites
Language: English
Abstract:

Ceramic mullite–SiC nanocomposites were successfully produced at temperatures below 1500 °C by the polymer pyrolysis technique. An alumina-filled poly(methylsilsesquioxane) compound was prepared by mechanically mixing and cross-linking via a catalyst prior to pyrolysis. Heat treatment of warm pressed alumina/polymer bulk samples under the exclusion of oxygen (inert argon atmosphere) up to 1500 °C initiated crystallization of mullite even at pyrolysis temperatures as low as 1300 °C. The influence of the filler and of the pyrolysis temperature on the crystallization behavior of the materials has been investigated. Based on thermal analysis in combination with elemental analysis and X-ray powder diffraction studies four polymer mixtures differing in type and content of nano-alumina powders were examined. Nano-sized γ-Al2O3 powders functionalized at the surface by octylsilane groups proved to be more reactive towards the preceramic polymer leading to the formation of a larger weight fraction of mullite crystals at lower processing temperatures (1300 °C) as compared to native nano-γ-Al2O3 filler. Moreover, the functionalized nano-alumina particles offer an enhanced homogeneity of the distribution of alumina nano-particles in the starting polysiloxane system. In consequence, the received ceramic samples exhibited a nano-microstructure consisting of crystals of mullite with an average dimension in the range of 60–160 nm and silicon carbide crystals in the range of 1–8 nm.

Journal or Publication Title: Journal of the European Ceramic Society
Volume: 29
Number: 14
Publisher: SciVerse
Uncontrolled Keywords: Polymer-derived ceramics, Mullite, Silicon carbide (SiC), Ceramic nanocomposites
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: 13 Apr 2012 09:01
Official URL: http://dx.doi.org/10.1016/j.jeurceramsoc.2009.05.016
Identification Number: doi:10.1016/j.jeurceramsoc.2009.05.016
Funders: The work reported here is part of the Priority Program “Nanoscaled Inorganic Materials by Molecular Design: New Materials for Advanced Technologies” (DFG-SPP 1181) funded by the Deutsche Forschungsgemeinschaft, Bonn, Germany., R.R. also thanks the Fonds der Chemischen Industrie, Frankfurt, Germany, for financial support.
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