Pressureless fabrication of dense monolithic SiC ceramics from a polycarbosilane |
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| Affiliation: | 1. Empa, Laboratory for High Performance Ceramics, Swiss Federal Laboratories for Materials Science and Technology, Ueberlandstrasse 129, Duebendorf, Switzerland;2. Laboratory for Multifunctional Materials, Department of Materials, ETH Zürich, Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland;3. Microsystems Laboratory, EPFL, Station 17, CH-1015 Lausanne, Switzerland;4. Clinic for Cardiovascular Surgery, Inselspital Berne, Berne University Hospital and University of Berne, Berne, Switzerland;1. Engineering Laboratory of Advanced Energy Materials, Ningbo Institute of Material Technology and Engineering, Chinese Academy of Sciences, Ningbo, Zhejiang, China;2. School of Material Science and Engineering, Shanghai University, Shanghai, 200444, China;1. College of Materials, Key Laboratory of High Performance Ceramic Fibers (Xiamen University), Ministry of Education, Xiamen 361005, China;2. College of Materials, Fujian Key Laboratory of Advanced Materials, Xiamen University, Xiamen 361005, China;3. Institut für Materialwissenschaft, Technische Universität Darmstadt, D-64287 Darmstadt, Germany;1. Technische Universität Darmstadt, Institut für Materialwissenschaft, Fachgebiet Disperse Feststoffe, Jovanka-Bontschits-Strasse 2, D-64287 Darmstadt, Germany;2. Technische Universität Darmstadt, Institut für Materialwissenschaft, Fachgebiet Oberflächenforschung, Jovanka-Bontschits-Strasse 2, D-64287 Darmstadt, Germany;3. Technische Universität Darmstadt, Institut für Angewandte Geowissenschaften, Fachgebiet Geomaterialwissenschaft, Schnittspahnstrasse 9, D-64287 Darmstadt, Germany;1. Technische Universität Darmstadt, Fachbereich Material–und Geowissenschaften, Jovanka-Bontschits-Straße 2, 64287 Darmstadt, Germany;2. Department of Materials and Environmental Chemistry, Arrhenius Laboratory, Stockholm University, 106 91, Stockholm, Sweden;3. Technische Universität Berlin, Fakultät III Prozesswissenschaften, Institut für Werkstoffwissenschaften und –technologien, Fachgebiet Keramische Werkstoffe, Hardenbergstraße 40, 10623 Berlin, Germany |
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| Abstract: | This paper presents the pressureless preparation of dense and crack-free near stoichiometric SiC monoliths via cross-linking and pyrolysis of a polycarbosilane, followed by polymer-infiltration-pyrolysis cycles. The composition and the porosity of the samples strongly depend on the processing temperature. Thus, at 1050–1100 °C, the SiC monoliths are X-ray amorphous and exhibit low amounts of oxygen and excess carbon; their porosity was rather high (>10%). Higher processing temperatures induced the crystallization of β-SiC. The removal of oxygen and excess carbon due to CO release allowed for obtaining near-stoichiometric compositions at 1700 °C. However, the residual porosity of the samples increased. The use of the PIP technique led already after six cycles to dense monoliths (residual porosity ca. 0.5%).The present study emphasizes the potential of the polymer processing technique for the fabrication of near stoichiometric and dense SiC monoliths, which might be used for structural applications in harsh conditions. |
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| Keywords: | Polycarbosilane SiC monoliths Polymer derived ceramics (PDCs) Pressureless processing Polymer infiltration pyrolysis (PIP) |
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