Multiphase imaging of freezing particle suspensions by confocal microscopy

摘要

Ice-templating is a well-established processing route for porous ceramics.Because of the structure/properties relationships, it is essential to betterunderstand and control the solidification microstructures. Ice-templating isbased on the segregation and concentration of particles by growing icecrystals. What we understand so far of the process is based on eitherobservations by optical or X-ray imaging techniques, or on the characterizationof ice-templated materials. However, in situ observations at particle-scale arestill missing. Here we show that confocal microscopy can provide multiphaseimaging of ice growth and the segregation and organization of particles. Weillustrate the benefits of our approach with the observation of particles andpore ice in the frozen structure, the dynamic evolution of the freeze frontmorphology, and the impact of PVA addition on the solidificationmicrostructures. These results prove in particular the importance ofcontrolling both the temperature gradient and the growth rate duringice-templating.