Processing and characterization of large diameter ceramic SiCN monofilaments from commercial oligosilazanes
| Autor: | Samuel Bernard, Walter Krenkel, Günter Motz, Rajendra K. Bordia, Octavio Flores, T. Uhlemann |
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| Přispěvatelé: | Centro de Estudios Superiores de Energia y Minas, Universidad de San Carlos de Guatemala, University of Washington [Seattle], Institut Européen des membranes (IEM), Université de Montpellier (UM)-Université Montpellier 2 - Sciences et Techniques (UM2)-Ecole Nationale Supérieure de Chimie de Montpellier (ENSCM)-Centre National de la Recherche Scientifique (CNRS) |
| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
chemistry.chemical_classification
Materials science General Chemical Engineering General Chemistry Chemical vapor deposition Polymer Polysilazane chemistry.chemical_compound chemistry visual_art Ultimate tensile strength visual_art.visual_art_medium Stress relaxation [CHIM]Chemical Sciences Ceramic Composite material Pyrolysis Curing (chemistry) ComputingMilieux_MISCELLANEOUS |
| Zdroj: | RSC Advances RSC Advances, Royal Society of Chemistry, 2015, 5 (129), pp.107001-107011. ⟨10.1039/c5ra17300k⟩ |
| ISSN: | 2046-2069 |
| DOI: | 10.1039/c5ra17300k⟩ |
| Popis: | This work reports the processing of large diameter ceramic SiCN monofilaments via the precursor route using two chemically different polysilazanes ML33S and HTTS self-synthesized from respective commercially available oligosilazanes. The melt-spinning of continuous polymer fibers with controllable diameters from 35 to 150 μm and their pyrolysis to ceramic SiCN fibers is not influenced by differences in the chemical structure of the polysilazanes. In contrast, the necessary e-beam curing dose is reduced by Si-vinyl groups from 600 kGy for ML33S (vinyl free) to 200 kGy for HTTS derived polymer fibers. The curing step leads to an enhanced handleability important for further pyrolysis at 1100 °C in nitrogen and to an increase in ceramic yield. The resulting ceramic SiCN fibers from both systems have similar mechanical and thermal behavior, indicating quite a low influence of the polysilazane type on these properties. For the first time a comprehensive investigation of the effect of fiber diameter on the tensile strength is reported for SiCN fibers. The average strength increases from ∼800 MPa for 90 μm diameter fibers to ∼1600 MPa for the 30 μm diameter fibers. Bend Stress Relaxation (BSR) tests demonstrated that no stress relaxation occurs up to 1000 °C for SiCN monofilaments and the creep resistance is equal to or better than commercially available SiC monofilaments produced by chemical vapour deposition (CVD). The oxidation resistance is also comparable to commercially available oxygen free CVD SiC fibers (SCS-6). The ceramic fibers in this study were pyrolyzed at low temperature (1100 °C) and have high oxygen content (13 to 29 wt%). The high temperature creep resistance and oxidation resistance is expected to improve if the oxygen content is reduced and the pyrolysis temperature increased. |
| Databáze: | OpenAIRE |
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