Dynamics of the Freezing Front During the Solidification of a Colloidal Alumina Aqueous Suspension: In Situ X-Ray Radiography, Tomography, and Modeling

Ice templating of colloidal suspension is gaining interest in material science because it offers the possibility to shape advanced materials, in particular porous ceramics. Recent investigations on this process show that a correlation between the morphology of the frozen suspension and the velocity of the freezing front do exist. The dynamics of the freezing front of a colloidal suspension of alumina is investigated in this study by experimental tests, finite element analysis, and analytical calculations. The experimental tests are carried out by in situ X-ray radiography (dynamics of the freezing front) and tomography (morphology of the frozen suspension). The finite element model is a continuous properties model; it is used for investigating the dynamics and the shape of the freezing front. The analytical model is based on the two-phase Stefan problem. We propose a solution for the dynamics of the solidification front based on the calculation of the diffusivity as a function of the particle fraction and local temperature.