Control of the γ-alumina to α-alumina phase transformation for an optimized alumina densification

Samir Lamouri (1) , M. Hamidouche (2) , Noureddine Bouaouadja (1) , H. Belhouchet (1) , Vincent Garnier (3) , Gilbert Fantozzi (3) , Jean-François Trelcat (4)

1 Laboratoire des Matériaux Non Métalliques
2 UFAS1 - Université Ferhat-Abbas Sétif 1 [Sétif]
3 MATEIS - Matériaux, ingénierie et science [Villeurbanne]
4 LMCPA - Laboratoire des Matériaux Céramiques et Procédés Associés - EA 2443

In this work, we studied the aptitude to sintering green bodies using γ-Al2O3 transition alumina as raw powder. We focused on the influence of the heating rate on densification and microstructural evolution. Phase transformations from transition alumina γ → δ → θ → α-Al2O3 were studied by in situ X-rays diffraction from the ambient to 1200 °C. XRD patterns revealed coexistence of various phase transformations during the heating cycle. DTA and dilatometry results showed that low heating rate leads to a significant reduction of the temperature of the α-Al2O3 alumina formation. Around 1190, 1217 and 1240 °C were found when using 5, 10 and 20 °C/min of heating rate, respectively. The activation energy for θ-Al2O3 → α-Al2O3 transformation calculated by Kissinger and JMA equations using dilatometry method were 464.29 and 488.79 kJ/mol, respectively and by DTA method were 450.72 and 475.49 kJ/mol, respectively. In addition, the sintering of the green bodies with low heating rate promotes the rearrangement of the grains during θ-Al2O3 → α-Al2O3 transformation, enhancing the relative density to 95% and preventing the development of a vermicular structure. © 2016 SECV.

Mots clés: Transition alumina; Phase transformation; Densification; Microstructure

Domaines: Matériaux

Samir Lamouri, M. Hamidouche, Noureddine Bouaouadja, H. Belhouchet, Vincent Garnier, et al.. Control of the γ-alumina to α-alumina phase transformation for an optimized alumina densification. Boletín de la Sociedad Española de Cerámica y Vidrio, 2017, 56 (2), pp.47-54. ⟨10.1016/j.bsecv.2016.10.001⟩. ⟨hal-01804220⟩