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2013-01-29 - Colloque/Présentation - poster - Anglais - 1 page(s)

Jean Guillaume , Vanherck Thierry , Sciamanna Valérie , Demuynck Maryse, Cambier Francis, Gonon Maurice , "EFFECT OF THERMAL GRADIENT ON THE DENSITY DISTRIBUTION OF MACROPOROUS CERAMICS OBTAINED BY SPARK PLASMA SINTERING" in Fifth International Conference on Shaping of Advanced Materials, Mons, Belgium, 2013

  • Codes CREF : Matériaux céramiques et poudres (DI2744)
  • Unités de recherche UMONS : Science des Matériaux (F502)
  • Instituts UMONS : Institut de Recherche en Science et Ingénierie des Matériaux (Matériaux)
  • Centres UMONS : Ingénierie des matériaux (CRIM)
Texte intégral :

Abstract(s) :

(Anglais) The method developed in our laboratory to make macroporous ceramics consists to “bridge” together packed alumina granules obtained by spray-drying. The final porosity consists of two levels of scale of void spaces: between granules (intergranular porosity), and open porosity (around 50%) within the granules (intragranular porosity) due to spray-drying process. The “bonding” may be carried out by partially sintering. In order to keep open porosity, the sintering process must promote diffusion at interfaces between granules while the densification is limited. The consolidation of the material was conducted by conventional sintering techniques (free sintering, Hot Pressing) and by Spark Plasma Sintering (SPS). Compared with hot pressing sintering, porous alumina ceramics can be manufactured by SPS at lower heating temperature, high heating and cooling rates and short holding time [1, 2]. Moreover, contrary to samples obtained by conventional sintering technique, the samples produced by SPS have density gradient. This gradient was revealed by X-ray tomography. We assumed that the density gradient is related to the thermal gradient inside the compact. The link between temperature field and density gradients within the sample was studied. Direct evaluation of heat flow and temperature field within the sample is not experimentally possible. So, the temperature field is evaluated by a coupled thermo-electric numerical model of the SPS using the finite elements method. Knowing the electrical and thermal characteristics of materials and the limit conditions, this model allows the determination of the temperature field inside the tools and the compact. We note that the temperature field largely depends on the geometry of tools. We compare the experimental microstructure gradients with numerical model temperature field for different geometries. References (1) Jayaseelan, D.D., Kondo, N., Brito, M.E., Journal of the American Ceramic Society, vol.85, 2002, pp. 267-269 (2) Wang, K., FU, Z., Peng, Y., Wang, Y., Zhang, J., Zhang, Q., Chinese Journal of Aeronautics, vol. 19, 2006, pp. 257-260 points.