New class of funCtionAl silicon caRBOnitride-based ceramic FIBErs from oRganometal compound-modified polySilazanes

• Applicant: Dr. Günter Motz
• Subject Area: Glass, Ceramics and Derived Composites ; Synthesis and Properties of Functional Materials ; Mechanical Properties of Metallic Materials and their Microstructural Origins
• Term: from 2015 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 284004736

Non-oxide ceramic fibers have been widely used for the reinforcement of ceramic matrix composites (CMCs). Despite considerable efforts to develop new non-oxide ceramic fibers in the last few years, their use at industrial level exclusively concern silicon carbide (SiC) fibers. But SiC fibers are very expensive (from 1.5 to 10 kEuro/kg) depending on the quality of the fibers, mainly because the production is dominated by companies from Japan with no alternative products from other countries. To reduce the costs of the fibers and to be competitive on this topic, a mobilization of activities and resources of the academic European researchers, especially from France and Germany, is proposed in the present project. This project concerns the design, processing and investigation of the properties of a new class of cost-effective polymer derived non-oxide ceramic fibers with additional functional properties. The proposed materials are expected to be used as reinforcement for thermostructural applications with electrical and magnetic properties. To meet the requirements for the applications mentioned above the obtained fibers need to combine durability in aggressive and harsh environments while achieving functional properties, such as electrical conductivity and magnetic properties. These properties can be achieved through the modification of (Si-(B/Al)-C-N) polymers with metal-organic compounds, leading to the in-situ growth of the functional nanophase simultaneously with the formation of the respective ceramic SiCN(B/Al) matrix during pyrolysis. To reach our objectives, the project is divided into five interconnected scientific tasks. The first task (Ta1) is focused on the synthesis and characterization (through NMR, FTIR, molecular weight measurements and elemental analyses) of the metal-modified preceramic polymers. The second task (Ta2) deals with the melt-spinning and curing of the polymer fibers, as the optimization of the spinning process by means of rheological investigation of the synthesized preceramic polymers. Task 3 (Ta3) is focused on the conversion of the cured polymer fibers prepared in Ta2 into the desired metal containing functionalized ceramic fibers. Detailed investigation of the polymer-to-ceramic conversion will be achieved through FTIR, TG-GC/MS and solid-state NMR. Task 4 (Ta4) is dedicated to the characterization of ceramic fibers, concerning the mechanical and (nano)structural properties and the functionalities of the metal-containing SiCN(B/Al) fibers, in particular their electrical and magnetic properties. Ta5 deals with the process modeling of the ceramic fiber transformation.

• DFG Programme: Research Grants
• International Connection: France
• Partner Organisation: Agence Nationale de la Recherche / The French National Research Agency
• Cooperation Partner: Dr. Samuel Bernard