Synthesis, structure and mechanical properties of ice-templated tungsten foams

Tungsten foams with directional, controlled porosity were created by directional freeze-casting of aqueous WO 3 powder slurries, subsequent freeze-drying by ice sublimation, followed by reduction and sintering under flowing hydrogen gas to form metallic tungsten. Addition of 0.51 wt% NiO to the WO 3 slurry improved the densification of tungsten cell walls significantly at sintering temperatures above 1250 °C, yielding densely sintered W–0.5 wt% Ni walls with a small fraction of closed porosity (