High porosity SiC ceramics prepared via a process involving an SHS stage |
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| Affiliation: | 1. Nanotechnology Department, School of New Technologies, Iran University of Science & Technology (IUST), Narmak, Tehran 16846-13114, Iran;2. Instituto de Ciencia de Materiales de Sevilla (CSIC-US), Americo Vespucio 49, Sevilla 41092, Spain;1. Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, 1206 W. Green St., Urbana, IL 61801, USA;2. Mechanical Engineering Department, Khalifa University, P.O. Box 127788, Abu Dhabi, UAE;3. Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, 1304 W. Green St., Urbana, IL 61801, USA;4. Department of Mechanical Engineering, Texas A&M University, College Station, TX 77843, USA;1. Eskisehir Technical University, Faculty of Engineering, Department of Materials Science & Engineering, Iki Eylul Campus, TR-26480, Eskişehir, Turkey;2. Osmangazi University, Faculty of Engineering and Architecture, Department of Metallurgy& Materials Engineering, Meşelik Campus, 26040, Eskişehir, Turkey |
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| Abstract: | The preparation of porous SiC ceramics from stoechiometric mixtures of silicon and graphite has been studied. Products with very high pore contents (≈80%) were obtained using a process which consisted of heating the reactive pellets in purified argon, at 15 °C min−1, up to 1430 °C and applying a weak d.c. voltage across the sample for 20 s. The resulting electrical current was necessary for the ignition of an SHS reaction simultaneously in the whole sample. The analysis of the sample microstructure evolution all along the process has enabled the identification of the different mechanisms involved in the SiC formation. Before the SHS stage, the formation of silicon carbide, during heating from about 1325 up to 1430 °C, is associated with a large sample expansion, which mainly determined the final pore volume fraction. The pore transfer mechanisms, which occur during the SHS stage at 1430 °C, have a specific influence on the pore development. Since the final pore size distribution is strongly related to silicon grain granulometry, the porosity of the porous SiC ceramic, obtained by this process, can be easily modulated. |
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