A green extrusion-based 3D printing of hierarchically porous aluminum

Additive manufacturing (AM) of porous Al via laser-assisted techniques is limited by the intrinsic high reflectivity of the laser and high oxidation propensity of Al. Herein, a green extrusion-based three-dimensional (3D) printing method was proposed for the fabrication of Al structures, whereby, hierarchical porosity is generated via solvent evaporation, starch removal, and parameter optimization. The process comprises slurry preparation, 3D printing and thermal post-treatment. The feasibility of the procedure and the effect of starch addition on the porous Al microstructure were investigated. An ethyl alcohol-based slurry exhibiting appropriate shear thinning behavior with sufficient yield stress was utilized for the extrusion-based 3D printing, and slurry filaments could be ex-truded smoothly and unyieldingly deposited by adjusting the nozzle diameter, applied air pressure, and printing speed. Furthermore, hierarchically porous Al structures were obtained following sintering, demonstrating that the proposed extrusion-based 3D printing method is suitable for direct AM of Al structures.(c) 2022 Elsevier B.V. All rights reserved.