  Ice-templating is a well-established processing route for porous ceramics.
Because of the structure/properties relationships, it is essential to better
understand and control the solidification microstructures. Ice-templating is
based on the segregation and concentration of particles by growing ice
crystals. What we understand so far of the process is based on either
observations by optical or X-ray imaging techniques, or on the characterization
of ice-templated materials. However, in situ observations at particle-scale are
still missing. Here we show that confocal microscopy can provide multiphase
imaging of ice growth and the segregation and organization of particles. We
illustrate the benefits of our approach with the observation of particles and
pore ice in the frozen structure, the dynamic evolution of the freeze front
morphology, and the impact of PVA addition on the solidification
microstructures. These results prove in particular the importance of
controlling both the temperature gradient and the growth rate during
ice-templating.
