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Role of microstructure reactivity and surface diffusion in explaining flash (ultra-rapid) sintering kinetics |
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| Affiliation: | 1. KU Leuven, Department of Materials Engineering, Kasteelpark Arenberg 44, B-3001 Leuven, Belgium;2. KU Leuven, Department of Oral Health Sciences, BIOMAT-Biomaterials Research Group & UZ Leuven (University Hospitals Leuven), Dentistry, Kapucijnenvoer 7 Block A, B-3000 Leuven, Belgium;1. School of Materials Science and Engineering, Xiangtan University, Xiangtan, Hunan 411105, China;2. Centre of Excellence for Advanced Materials, Dongguan 523808, China;1. Univ Rennes, CNRS, ISCR - UMR 6226, F-35000 Rennes, France;2. Univ Rennes, CNRS, ScanMAT - UAR 2025, F-35000 Rennes, France;3. Univ Rennes, CNRS, IPR - UMR 6251, F-35000 Rennes, France;1. Dept. of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, 1–1 Yanagido, Gifu 501–1193, Japan;2. National Institute for Materials Science, 1–2-1 Sengen, Tsukuba, Ibaraki 305–0047, Japan;1. Institute of Materials Science and Engineering, School of Materials and Energy, Lanzhou University, Lanzhou 730000, China;2. Institute of Materials Structure and Composition Analysis, School of Materials and Energy, Lanzhou University, Lanzhou 730000, China;3. State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing, 100084, China |
| Abstract: | The competition between sintering and coarsening is cited by numerous authors as one of the potential factors for explaining the ultra-rapid sintering kinetics of flash sintering. In particular, surface diffusion is a mechanism decreasing the driving force of sintering by changing the initial highly reactive microstructures (particle contact) into poorly reactive porous skeleton structures (spherical porosity). We show by finite element simulations that flash SPS experiments high specimen temperatures close to 2000 °C. These high temperatures are not sufficient to explain the ultra-rapid sintering kinetics if typical spherical pore theoretical moduli are employed. On the contrary, reactive experimentally determined moduli succeed in explaining the ultra-rapid sintering kinetics. Mesoscale simulations evidenced that the origin of such reactive experimental moduli is a porous skeleton geometry with a significant delay in surface diffusion and particle rearrangement. This highlights the important role of the surface diffusion negation (favoring higher stress intensification factor) in flash sintering. |
| Keywords: | Flash sintering Coarsening Surface diffusion Mesoscale simulation Spark Plasma Sintering |
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