Thor, Nathalie ; Bernauer, Jan ; Petry, Nils-Christian ; Ionescu, Emanuel ; Riedel, Ralf ; Pundt, Astrid ; Kleebe, Hans-Joachim (2023):
Microstructural evolution of Si(HfxTa1−x)(C)N polymer-derived ceramics upon high-temperature anneal.
In: Journal of the European Ceramic Society, 43 (4), pp. 1417-1431. Elsevier, ISSN 0955-2219, e-ISSN 1873-619X,
DOI: 10.1016/j.jeurceramsoc.2022.11.060,
[Article]
Abstract
Ultra-high temperature ceramic nanocomposites (UHTC-NC) within the Si(HfxTa1_x)(C)N system were synthe-sized via the polymer-derived ceramics (PDC) synthesis route. The microstructure evolution of the materials was investigated upon pyrolysis and subsequent heat treatment. The crystallization behavior and phase composition were studied utilizing X-ray diffraction, scanning-and transmission electron microscopy. Single-source -precursors were converted into amorphous single-phase ceramics, with the exception of surface crystallization effects, at 1000 degrees C in NH3. Annealing in N2 at 1600 degrees C resulted in fully crystalline UHTCs. The powder samples revealed microstructures consisting of two characteristic regions, bulk and surface; displaying intrinsic micro-structure and phase composition differences. Instead of the expected nitrides, transition metal carbides (TMC) were detected upon high-temperature anneal. The residual carbon available in the system triggered a decom-position reaction, resulting in the formation of TMCs plus gaseous nitrogen and SiC. Experimental data underline that N-containing PDCs are prone to phase separation accompanied by thermal decomposition and diffusion -controlled coarsening.
| Item Type: | Article |
|---|---|
| Erschienen: | 2023 |
| Creators: | Thor, Nathalie ; Bernauer, Jan ; Petry, Nils-Christian ; Ionescu, Emanuel ; Riedel, Ralf ; Pundt, Astrid ; Kleebe, Hans-Joachim |
| Title: | Microstructural evolution of Si(HfxTa1−x)(C)N polymer-derived ceramics upon high-temperature anneal |
| Language: | English |
| Abstract: | Ultra-high temperature ceramic nanocomposites (UHTC-NC) within the Si(HfxTa1_x)(C)N system were synthe-sized via the polymer-derived ceramics (PDC) synthesis route. The microstructure evolution of the materials was investigated upon pyrolysis and subsequent heat treatment. The crystallization behavior and phase composition were studied utilizing X-ray diffraction, scanning-and transmission electron microscopy. Single-source -precursors were converted into amorphous single-phase ceramics, with the exception of surface crystallization effects, at 1000 degrees C in NH3. Annealing in N2 at 1600 degrees C resulted in fully crystalline UHTCs. The powder samples revealed microstructures consisting of two characteristic regions, bulk and surface; displaying intrinsic micro-structure and phase composition differences. Instead of the expected nitrides, transition metal carbides (TMC) were detected upon high-temperature anneal. The residual carbon available in the system triggered a decom-position reaction, resulting in the formation of TMCs plus gaseous nitrogen and SiC. Experimental data underline that N-containing PDCs are prone to phase separation accompanied by thermal decomposition and diffusion -controlled coarsening. |
| Journal or Publication Title: | Journal of the European Ceramic Society |
| Volume of the journal: | 43 |
| Issue Number: | 4 |
| Publisher: | Elsevier |
| Uncontrolled Keywords: | polymer-derived ceramic, electron microscopy thermal decomposition, UHTC, transition metal carbide, source-precusor synthesis, oxidation behavior, nanocomposites, decomposition, Hafnium, TAC, polysilzane, composites, resistance, reduction |
| Divisions: | 11 Department of Materials and Earth Sciences 11 Department of Materials and Earth Sciences > Earth Science 11 Department of Materials and Earth Sciences > Earth Science > Geo-Material-Science 11 Department of Materials and Earth Sciences > Material Science 11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids |
| Date Deposited: | 26 Jan 2023 06:32 |
| DOI: | 10.1016/j.jeurceramsoc.2022.11.060 |
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