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Microstructural evolution of Si(HfxTa1−x)(C)N polymer-derived ceramics upon high-temperature anneal

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)
doi: 10.1016/j.jeurceramsoc.2022.11.060
Article, Bibliographie

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
Type of entry: Bibliographie
Title: Microstructural evolution of Si(HfxTa1−x)(C)N polymer-derived ceramics upon high-temperature anneal
Language: English
Date: April 2023
Publisher: Elsevier
Journal or Publication Title: Journal of the European Ceramic Society
Volume of the journal: 43
Issue Number: 4
DOI: 10.1016/j.jeurceramsoc.2022.11.060
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.

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
Last Modified: 26 Jan 2023 06:32
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