Iron and Nickel Cellular Structures by Sintering of 3D-Printed Oxide or Metallic Particle Inks

Inks comprised of metallic Fe or Ni powders, an elastomeric binder, and graded volatility solvents are 3D-printed via syringe extrusion and sintered to form metallic cellular structures. Similar structures are created from Fe₂O₃ and NiO particle-based inks, with an additional hydrogen reduction step before sintering. All sintered structures exhibit 92–98% relative density within their struts, with neither cracking nor visible warping despite extensive volumetric shrinkage (≈70–80%) associated with reduction (for oxide powders) and sintering (for both metal and oxide powders). The cellular architectures, with overall relative densities of 32–49%, exhibit low stiffness (1–6 GPa, due to the particular architecture used), high strength (4–31 MPa), and high ductility, leading to excellent elastic and plastic energy absorption, when subjected to uniaxial compression.