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.