Neck formation and role of particle-particle contact area in the thermal conductivity of green and partially sintered alumina ceramics |
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| Affiliation: | 1. School of Materials Science and Engineering, Chang’an University, Xi’an, 710061, China;2. State Key Laboratory of Environment-Friendly Energy Materials, Southwest University of Science and Technology, Mianyang, 621010, China;3. School of Advanced Materials and Nanotechnology, Xidian University, Xi’an, 710126, China;1. School of Materials Science and Engineering, Shanghai University, Shanghai, 200444, China;2. Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing, 100080, China;1. School of Chemistry and Resource Engineering, Honghe University, Yunnan Province, 661199, China;2. Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming, 650093, China;1. Dept. of Material Science and Engineering, Case Western Reserve University, United States;2. Dept. of Materials, Imperial College London, United Kingdom;3. Dept. of Physics, Imperial College London, United Kingdom;1. Dipartimento di Ingegneria Meccanica, Chimica e dei Materiali, Unità di Ricerca del Consorzio Interuniversitario Nazionale Per la Scienza e Tecnologia dei Materiali (INSTM), Università Degli Studi di Cagliari, via Marengo 2, 09123, Cagliari, Italy;2. Dipartimento di Chimica e Farmacia, Università Degli Studi di Sassari, Via Vienna 2, 07100, Sassari, Italy;3. Dipartimento di Ingegneria “Enzo Ferrari”, Università Degli Studi di Modena e Reggio Emilia, Via P. Vivarelli 10, 41125, Modena, Italy;1. School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510641, China;2. School of Materials Science and Engineering, Shenzhen University, Shenzhen, 518055, China |
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| Abstract: | Sintering ceramics involves neck formation, densification and eventually grain growth. A simplified model is developed to describe the effects of pore fraction, average grain size and the contact area between particles due to neck formation on the thermal conductivity of the green or partially sintered ceramic. Laser flash measurements on green bodies of alumina powders with different average particle sizes reveal similar thermal conductivity values close to 0.5 Wm?1K?1, corresponding to thermal resistances for equivalent planes of contacts in the range 10-7 to 2 10-6 m2KW?1. BET specific surface area measurements were then used to estimate the contact area due to neck formation in partially sintered alumina ceramics fired from 400 °C to 1200 °C. As predicted by the model, there is a strong increase in thermal conductivity. Such information is relevant as input data for numerical modelling of the green body behaviour during thermal treatment. |
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| Keywords: | Alumina ceramics Green bodies Thermal conductivity Sintering Neck formation |
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