Structure/processing relationships and mechanical properties of freeze-cast B4C scaffolds with unidirectional channels

Freeze casting technique has become a promising way to assemble various components into multifunctional nacre-like materials. Surprisingly, although many ceramics materials have been processed by this approach, there are few studies reporting the structure-property-processing relationships of freeze-cast porous B4C ceramics. Here we generate bimodally lamellar porous B4C scaffolds by freeze casting and describe how processing parameters such as solid concentration and freezing front velocity control the architecture. The porosity, pore morphology and lamella thickness of B4C scaffolds can be tailored via altering such two parameters, which makes the scaffolds with excellent mechanical properties suitable as a support for the melt infiltration process. The pore morphology, structural characteristics, compressive mechanical response and fracture mechanism of the scaffolds are explored. Additionally, we have utilized a morphology map to identify the different structures such as lamellar and dendritic, which are formed by varying processing parameters. This study offers the freeze-cast scaffolds with custom-designed structure and mechanical properties for developing bioinspired multifunctional materials represented by B4C/Al composites.