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.

冰模板是用于多孔陶瓷的行之有效的加工方法。由于结构/性质的关系，必须更好地理解和控制凝固的微观结构。冰模板基于通过生长冰晶而产生的颗粒的分离和集中。到目前为止，我们对过程的了解是基于光学或X射线成像技术的观察结果，还是基于以冰为模板的材料的表征。但是，仍然缺少在粒子尺度上的原位观测。在这里，我们显示共聚焦显微镜可以提供冰生长以及颗粒的分离和组织的多相成像。我们通过观察冻结结构中的颗粒和孔隙冰，冻结前沿形态的动态演变来说明我们的方法的好处，以及添加PVA对凝固组织的影响。这些结果特别证明了在冰模板化过程中控制温度梯度和生长速率的重要性。