Pressureless synthesis of fully dense and crack-free SiOC bulk ceramics via photo-crosslinking and pyrolysis of a polysiloxane
| Autor: | Emanuel Ionescu, Ralf Riedel, Sandra Martínez-Crespiera, Hans-Joachim Kleebe |
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| Rok vydání: | 2011 |
| Předmět: |
Materials science
Prepared Material chemistry.chemical_element Amorphous solid symbols.namesake chemistry.chemical_compound Chemical engineering chemistry visual_art Vickers hardness test Materials Chemistry Ceramics and Composites visual_art.visual_art_medium symbols Silicon carbide Ceramic Composite material Raman spectroscopy Pyrolysis Carbon |
| Zdroj: | Journal of the European Ceramic Society. 31:913-919 |
| ISSN: | 0955-2219 |
| DOI: | 10.1016/j.jeurceramsoc.2010.11.019 |
| Popis: | This paper presents the pressureless preparation of fully dense and crack-free SiOC ceramics via direct photo-crosslinking and pyrolysis of a polysiloxane. Elemental analysis revealed the presence of high levels of carbon in the SiOC ceramics. Thus, the samples showed the highest content (78–86 mol%) of segregated “free” carbon reported so far. XRD investigations indicated that the materials prepared at 1100 °C were X-ray amorphous, whereas the sample prepared at 1400 °C contained a turbostratic graphite-like phase and silicon carbide as crystalline phases, as additionally confirmed by TEM and Raman spectroscopy. Vickers hardness was measured to be 5.5–8.6 GPa. The dc resistivity of the prepared material at 1100 °C was 0.35 Ω m, whereas the ceramic pyrolyzed at 1400 °C showed a value of 0.14 Ω m; both values are much lower than those of other known SiOC materials. This latter feature was attributed to the presence of a percolating carbon network in the ceramic. |
| Databáze: | OpenAIRE |
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