Brief Paper: Additive Manufacturing of Hierarchical Porous Structure of Copper

Abstract Hierarchical porous copper (Cu) structures are promising for applications in filtration, catalysis, and lightweight components due to the strength, durability, and permeability of Cu. However, one key challenge in manufacturing is achieving precise control of the pore size distribution within these structures. This study introduces a novel approach that integrates the space-holder technique with binder jetting additive manufacturing to fabricate Cu structures with both meso- and macro-scale porosity. In the initial stage, sodium chloride (NaCl) powder was used as a removable space holder within a Cu powder matrix to fabricate samples. NaCl in the samples was later dissolved by water to create meso-scale pores. The final porosity could be tuned by adjusting the volume percentage of NaCl within the mixed powder. In the second stage, the Cu-NaCl mixture was used to print samples using the binder jetting technique. The meso-scale pores were formed through the removal of the NaCl space holder, while the macro-scale channels were directly printed according to specific design specifications. The porous structures were characterized with optical microscopy and X-ray micro-CT scanning. The pore morphology and distribution were measured. This study demonstrates a versatile and scalable method for producing porous Cu structures with customizable porosity levels and pore size distributions. This method is tailored to cater to various industrial applications. Additionally, it holds the potential for optimization and application to other metal systems, highlighting its broad applicability in manufacturing advanced porous materials with multifunctional capabilities.