Influence of pulse current during Spark Plasma Sintering evidenced on reactive alumina–hematite powders

Julien Gurt Santanach (1) , Claude Estournès (1) , Alicia Weibel (1) , Geoffroy Chevallier (1) , Vincent Bley (2) , Christophe Laurent (1) , Alain Peigney (1)

1 CIRIMAT - Centre interuniversitaire de recherche et d'ingenierie des matériaux
2 LAPLACE-MDCE - Matériaux Diélectriques dans la Conversion d’Energie

Spark Plasma Sintering (SPS) is increasingly used. The temperature and current are not independent parameters, making it difficult to separate the current intrinsic role from Joule heating. There is a debate on whether there are any specific SPS mechanisms. The influence of a key parameter, the (on:off) pulse pattern, is studied on the SPS of reactive α-Al2−2xFe2xO3 (x = 0.02; 0.05; 0.07; 0.10) powders. Changing it modifies the current crest intensity and has a great influence on the materials microstructure. Comparisons with runs where the current is blocked and hot-pressing reveal three competing phenomena: formation of FeAl2O4, dominant in the core and not peculiar to SPS, formation of Fe, producing Fe-Al2O3 composite surface layers, and most notably electrical-field induced diffusion of Fe3+ ions towards the cathode, which could have far-ranging implications for the consolidation of ionic materials and the in situ reactive shaping of composites and multimaterials.

Mots clés: Spark Plasma Sintering; Hot pressing; Nanocomposites; Electron microscopy; Fe-Al2O3

Domaines: Matériaux

Julien Gurt Santanach, Claude Estournès, Alicia Weibel, Geoffroy Chevallier, Vincent Bley, et al.. Influence of pulse current during Spark Plasma Sintering evidenced on reactive alumina–hematite powders. Journal of the European Ceramic Society, 2011, 31 (13), pp.2247-2254. ⟨10.1016/j.jeurceramsoc.2011.06.003⟩. ⟨hal-03542098⟩