3D Printing Of Metallic Structures From A Green Ink

A green metallic ink is developed for 3D printing of metallic structures featuring high mechanical and electrical performances. The metallic ink consists of steel micro powders and a water-based chitosan/acetic acid polymer solution which replaces the previously used toxic polylactic acid (PLA)/dichloromethane (DCM) polymer solution. The optimized ink is printed at room temperature to build a metal/polymer hybrid structure. While printing, a fan is used to blow air over the ink filament upon extrusion to accelerate the solvent evaporation and shorten the solidification time, which significantly reduces the sagging and deformation. After a drying period at ambient conditions, the as-printed structure is then thermally treated using a furnace. The polymer binder is decomposed and the metal powders are sintered, resulting in a strong metallic structure. Melted copper is infiltrated into the sintered structure to achieve a fully dense metal/metal hybrid structure. The sintered structure exhibits high stiffness (205 GPa), electrical conductivity (9 × 105 S/m) and low filament porosity (7%).