Synchrotron µ-CT-based morphological characterization of additively manufactured open porous structures

Abstract

Additive Manufacturing of open porous metallic structures has a high potential for advanced applications such as for cooling or catalysis on small length-scales. For such applications the 3D morphology, and in particular the surface geometry, will strongly determine the performance. Attached spherical particles on the surface of functional structures made by Laser-based Powder Bed Fusion (PBF-LB) have been observed in various studies. This study applies a novel approach to characterize such complex structures made by Additive Manufacturing. In this study, synchrotron µ-CT was applied to analyze the surface morphology of six different open porous PBF-LB-samples at ~ 1.5 µm voxel size. Due to the high level of detail, the reconstructed 3D images allow an impression very close to the original physical sample. In contrast to classic functional design for AM, the open porosities considered in this study are the result of the manufacturing parameters (e.g. hatch spacing) and not of a CAD-design. The work shows that scan strategy and process parameters have a major impact on the resulting surface area and the volume of the open porous structures. In particular, the surface area is driven by the attached particles, while their impact on the volume is considerably lower. This difference between material distribution and material property could be used to determine specific application properties. The presented findings may thus pave the path for adding an additional level of functionality to Additive Manufacturing of porous metallic samples.