Structural evolution of directionally freeze-cast iron foams during oxidation/reduction cycles

Cyclical oxidation/reduction behavior of iron-based powders and porous pellets is of great interest for iron-air batteries, steam-iron, and chemical looping processes, but extended cycling is limited by degradation via sintering or pulverization. To address these problems, we use directional freeze casting to fabricate porous iron foams, consisting of colonies of parallel iron lamellae and open channels of sufficient width (20–40 and 20–50 μm,...