3D Phase-Field Simulations Explain Experimental Observations of Structure Formation in Ice-Templated Materials

Freeze casting is a promising processing technique that provides a means to mimic natural materials with hierarchical designs over several length-scales with biomedical applications. Directional solidification of ceramic-based suspensions in water. 3D quantitative phase-field simulation with massive parallel computing at the experimentally relevant time and length scales. Objective and Approach: Qualitative comparisons between phase-field simulations and freeze casting experiments to understand top hierarchical levels in the freeze-cast material

Process of casting heavy slips Patent

Freeze casting of metal ceramic and refractory compound powders into plastic slip

Porous Titanium Cylinders Obtained by the Freeze-Casting Technique: Influence of Process Parameters on Porosity and Mechanical Behavior

 The discrepancy between the stiffness of commercially pure titanium and cortical bone  tissue compromises its success as a biomaterial. The use of porous titanium has been widely studied,  however, it is still challenging to obtain materials able to replicate the porous structure of the bones  (content, size, morphology and distribution). In this work, the freeze‐casting technique is used to  manufacture cylinders with elongated porosity, using a home‐made and economical device. The  relationship between the processing parameters (diameter and material of the mold, temperature  gradient), microstructural features and mechanical properties is established and discussed, in terms  of ensuring biomechanical and biofunctional balance. The cylinders have a gradient porosity  suitable for use in dentistry, presenting higher Young’s modulus at the bottom, near the cold spot  and, therefore better mechanical resistance (it would be in contact with a prosthetic crown), while  the opposite side, the hot spot, has bigger, elongated pores and walls.  Ministry of Economy and Competitiveness of Spain  grant  MAT2015‐71284‐P  FEDER‐Junta de Andalucía Research  Project (Modeling and implementation of the freeze casting technique: gradients of porosity with a tribomechanical equilibrium and electro‐stimulated cellular behavior).

Multiphase imaging of freezing particle suspensions by confocal microscopy

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.Comment: 20 pages, 9 figure