Transparent polycrystalline alumina obtained by SPS: Green bodies processing effect

Lucile Lallemant (1) , Gilbert Fantozzi (1) , Vincent Garnier (2) , Guillaume Bonnefont (1)

1 MATEIS - Matériaux, ingénierie et science [Villeurbanne]
2 O&I - Ondes et Imagerie

Starting from a commercial slurry of high purity α-Al 2O 3, freeze-dried powders, cast, filter-pressed or cold isostatically pressed samples were produced. Resulting powders or green bodies showing different particles packing were densified by spark plasma sintering (SPS) to obtain transparent polycrystalline α-Al 2O 3. Microstructure and real in-line transmittance (RIT) after SPS were dependent on the particles packing quality. Avoiding large agglomerates, narrowing the pore size distribution, reducing the most-frequent pore size (D mode) and avoiding macroscopic heterogeneities within the green bodies enabled high RIT values to be achieved in the visible and near-infrared spectrum. However, a limit was achieved in the preparation of green bodies for which reducing the D mode had no more influence on the optical behaviour of samples sintered by SPS. Finally, pure α-Al 2O 3 samples presenting a high RIT 640nm value of 53% were produced from all the green bodies obtained by the following techniques: filter-pressing, slip casting and cold isostatic pressing.

Mots clés: Cold isostatic pressing; Green body; Large agglomerate; Macroscopic heterogeneity; Optical behaviour; Polycrystalline; Polycrystalline alumina; Processing effects; Slip casting; Visible and near infrared; Optical properties; Spark plasma sintering; Aluminum

Domaines: Matériaux

Lucile Lallemant, Gilbert Fantozzi, Vincent Garnier, Guillaume Bonnefont. Transparent polycrystalline alumina obtained by SPS: Green bodies processing effect. Journal of the European Ceramic Society, 2012, 32 (11), pp.2909-2915. ⟨10.1016/j.jeurceramsoc.2012.02.041⟩. ⟨hal-01834932⟩