Ice-Templated Porous Tungsten and Tungsten Carbide

The structures of tungsten and tungsten carbide scaffolds play a key role in determining the properties of their infiltrated composites for multifunctional applications. However, the architectural construction of W/WC systems is challenging because of the difficulty of assembly due to their large densities. Here we present the generation of unidirectionally porous architectures, with high porosities exceeding 65%, for W and WC scaffolds using direct ice-templating techniques, which in many respects reproduce the design motif of wood. This was achieved by adjusting the viscosities of suspensions to retard sedimentation during freezing. The processing, structural characteristics and mechanical properties of the resulting scaffolds were investigated and the correlations between them explored. Quantitative relationships were established to describe their strengths based on a simple model taking into account both inter- and intra-lamellar pores. The fracture mechanisms were also identified, especially in light of the porosity. This study extends the effectiveness of ice-templating techniques for systems with large densities or particle sizes. It further provides preforms for developing new nature-inspired multifunctional materials, as represented by W/WC-Cu composites.