Particle redistribution and structural defect development during ice templating

Audrey Lasalle (1) , Christian Guizard (1) , Eric Maire (2) , Jérôme Adrien (2) , Sylvain Deville (1)

1 LSFC - Laboratoire de Synthèse et Fonctionnalisation des Céramiques
2 MATEIS - Matériaux, ingénierie et science [Villeurbanne]

The freezing of colloidal suspensions is encountered in many natural and engineering processes. It can be harnessed through a process known as ice templating, to produce porous materials and composites exhibiting unique functional properties. The phenomenon by itself appears simple: a solidification interface propagates through a colloidal suspension. We are nevertheless still far from a complete understanding and control of the phenomenon. Such lack of control is reflected in the very large scattering of mechanical properties reported for ice-templated ceramics, largely due to the formation of structural defects. Through systematic in situ investigations, we demonstrate here the role of the suspension composition and the role of particle-particle electrostatic interactions on defect formation during ice templating. Flocculation can occur in the intercrystal space, leading to a destabilisation of the solid/liquid interface triggering the growth of crystals perpendicular to the main ice growth direction. This mechanism largely contributes to the formation of structural defects and explains, to a large extent, the scattering of compressive strength values reported in the literature.

Keywords: Freeze-casting; ceramic material; cellular solids; mechanical properties; defects

Domains: Material chemistry

Audrey Lasalle, Christian Guizard, Eric Maire, Jérôme Adrien, Sylvain Deville. Particle redistribution and structural defect development during ice templating. Acta Materialia, 2012, 60 (11), pp.4594-4603. ⟨10.1016/j.actamat.2012.02.023⟩. ⟨hal-01133901⟩