Effects of Powder Carrier on the Morphology and Compressive Strength of Iron Foams: Water vs Camphene
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With its well-known popularity in structural applications, considerable attention has recently been paid to iron (Fe) and its oxides for its promising functional applications such as biodegradable implants, water-splitting electrodes, and the anode of lithium-ion batteries. For these applications, iron and its oxides can be even further utilized in the form of porous structures. In order to control the pore size, shape, and amount, we synthesized Fe foams using suspensions of micrometric Fe2O3 powder reduced to Fe via freeze casting in water or liquid camphene as a solvent through sublimation of either ice or camphene under 5 pct H2/Ar gas and sintering. We then compared them and found that the resulting Fe foam using water as a solvent (p = 71.7 pct) showed aligned lamellar macropores replicating ice dendrite colonies, while Fe foam using camphene as a solvent (p = 68.0 pct) exhibited interconnected equiaxed macropores replicating camphene dendrites. For all directions with respect to the loading axis, the compressive behavior of the water-based Fe foam with a directional elongated wall pore structure was anisotropic (11.6 ± 0.9 MPa vs 7.8 ± 0.8 MPa), whereas that of the camphene-based Fe foam with a random round pore structure was nearly isotropic (12.0 ± 1.1 MPa vs 11.6 ± 0.4 MPa).
This work was supported by the NRF-2016-Fostering Core Leaders of the Future Basic Science Program/Global Ph.D. Fellowship Program (2016H1A2A1909161) from the National Research Foundation (NRF) of Korea. This research was also supported by the International Research & Development Program of the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT of Korea (2017K1A3A1A30083363). Nam and Choe acknowledge supports from the National Research Foundation (NRF) of Korea (2009-0093814; 2017R1A2B4012871).
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