Understanding the freezing of colloids

The behaviour of a solidification front in a suspension of particles is of major interest for its implication in a very large number of theoretical and practical issues. If the physical mechanisms controlling the interactions are relatively well understood for single large particles, the solidification behavior of colloidal suspensions is a matter of great interest, but highly challenging. Conclusions derived from single large particles experiments cannot be extrapolated to smaller particles (submicronic) where Brownian motion is dominating and segregation effects are negligible. The analysis is further complicated by the necessity to take into account the various interactions between particles, which could be of different natures: electrostatic, Van der Waals, steric, etc. Additional deviations from the ideal situation such as the distribution of particle size, their surface state, charge, and roughness, could have a major influence over the general behavior and stability of the system but are difficult to take into account.

My approach was based on the observations, mostly using finely controlled and characterized suspensions. We recently joined the happy world of modeling, with very simple approaches to begin with.

Particle concentration around crystals tips, by X-rays radiography

Publications

[1] Bareggi A, Maire E, Lasalle A, Deville S. Dynamics of the freezing front during the solidification of a colloidal alumina aqueous suspension: in situ x-ray radiography, tomography, and modeling. Journal of the American Ceramic Society 2011;early view.

[2] Deville S, Bernard-Granger G. Influence of surface tension, osmotic pressure and pores morphology on the densification of ice-templated ceramics. Journal of the European Ceramic Society 2011.

[3] Lasalle A, Guizard C, Deville S, Rossignol F, Carles P. Investigating the dispersion state of alumina suspensions: contribution of cryo-field-emission gun scanning electron microscopy characterizations. Journal of the American Ceramic Society 2011;94:244-249.

[4] Deville S, Maire E, Lasalle A, Bogner A, Gauthier C, Leloup J, Guizard C. Influence of particle size on ice nucleation and growth during the ice-templating process. Journal of the American Ceramic Society 2010;93:2507-2510.

[5] Deville S, Maire E, Lasalle A, Bogner A, Gauthier C, Leloup J, Guizard C. In situ x-ray radiography and tomography observations of the solidification of aqueous alumina particle suspensions-part i: initial instants. Journal of the American Ceramic Society 2009;92:2489-2496.

[6] Deville S, Maire E, Lasalle A, Bogner A, Gauthier C, Leloup J, Guizard C. In situ x-ray radiography and tomography observations of the solidification of aqueous alumina particles suspensions. part ii: steady state. Journal of the American Ceramic Society 2009;92:2497-2503.

[7] Deville S, Maire E, Bernard-Granger G, Lasalle A, Bogner A, Gauthier C, Leloup J, Guizard C. Metastable and unstable cellular solidification of colloidal suspensions. Nature Materials 2009;8:966-72.

[8]  Lasalle, A., Guizard, C., Maire, E., Adrien, J. & Deville, S. Particle redistribution and structural defect development during ice templating. Acta Materialia (2012).doi:10.1016/j.actamat.2012.02.023

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