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Densification of alumina by SPS and HP: A comparative study
Authors:Maryse Demuynck  Jean-Pierre Erauw  Omer Van der Biest  Francis Delannay  Francis Cambier
Affiliation:2. CEMES, CNRS UPR 8011 and University of Toulouse, Toulouse, France;3. CIRIMAT, University of Toulouse, CNRS, INP-ENSIACET, Toulouse, France;4. Clément Ader Institute (ICA), University of Toulouse, CNRS, Mines Albi, INSA, UPS, ISAE-SUPAERO, Toulouse, France;2. Centre for Materials Research and Sintering Technology, Institute of Advanced Manufacturing Technology, Krakow, Poland
Abstract:In this study, the densification of alumina by spark plasma sintering (SPS) was investigated and compared to conventional hot pressing. It was shown that SPS is very effective in the sintering of alumina leading to higher densities and allows to work at lower temperatures and with shorter sintering cycles. The effect of the heating rate is dependent on the heating mode (SPS or HP). The identification of active sintering mechanisms was attempted by an isothermal and an anisothermal methods, showing that other mechanisms probably related to electrical effects enhance the densification. We suggest the higher contribution of surface diffusion mainly during the initial stage of sintering and an influence of the presence of impurities segregated at the grain boundaries. They could create conductive layers and also introduce ions with a lower valence than Al3+; defects are created in the surface layers and the diffusion of the species is increased.
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