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Polymer-derived SiCO/HfO2 and SiCN/HfO2 Ceramic Nanocomposites for
Ultra-high Temperature Applications
Dr. Emanuel Ionescu
Technische Universität Darmstadt
Fachbereich 11 - Material- und Geowissenschaften
Darmstadt
In collaboration with:
Professor Dr. Dr. h.c. Ralf Riedel
Technische Universität Darmstadt
Fachbereich 11 - Material- und Geowissenschaften
Darmstadt
Professor Dr. Hans-Joachim Kleebe
Technische Universität Darmstadt
Fachbereich 11 Material- und Geowissenschaften
Institut für Angewandte Geowissenschaften
Darmstadt
The research project involves the synthesis of novel polymer-derived, HfO2 modified SiCO and SiCN nanocomposites exhibiting a high potential as thermal barrier coatings (TBC) or environmental barrier coatings (EBC). These materials will be produced by cross-linking and ceramisation (pyrolisis) of commercially available polysiloxanes and polysilazanes modified by hafnium oxides. Furthermore, silyl- substituted Di- and tramin-based polycarbosilazanes will be synthesised and processed to create SiCN/HfO2 nanocompoites (bulk materials and coatings) at Darmstadt University. The preceramic precursors and the ceramic nanocomposites will be examined by means of NMR, IR and Raman spectroscopy as well as X-ray diffraction and electron microscopy (REM, REM/HRTEM) in terms of their chemical composition and structure in order to determine the influence of HfO2 additive on the microstrctural and nanostructural development as well as on the high-temperature properties. In addition, annealing experiments will be conducted in order to examine the thermal stability on the nanocomposites in terms of crystallisation and oxidation resistance. Furthermore, the deformation behaviour will be investigated at high temperatures (max. 1600 °C) by carrying out pressure creep experiments. The variation of the HfO2 content is intended to provide information about the correlation between the high-temperature behaviour and the composite micro/nanostructure. The main aim of the project is to carry out detailed examinations on the relationship between the molecular assembly of the precursors (hafnium oxide modified polysiloxanes, polysilazanes and polycarbosilazanes) as well as the nanostructure and microstructure of their derived nanocomposites and their properties.
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