Micro and nanolattice fabrication using projection micro litho stereo exposure additive manufacturing techniques and synchrotron X-ray 3D imaging-based defect characterization

Abstract

Synchrotron radiation X-ray micro-computed tomography (SR-µCT) is a 3D imaging technique that is widely employed for the characterization of defects in advanced materials and structures. In this study, we characterize several typical defects in octettruss and re-entrant 3D lattice structures by using SR-µCT. The 3D micro-lattice structures are manufactured using projection micro litho stereo exposure (PµLSE) additive manufacturing technology. The as-fabricated 3D lattice samples are characterized using optical microscopy, and subsequently, by SR-µCT. Further more, a statistical analysis is performed to characterize the surface roughness and internal defects qualitatively, whereby the statistical geometrical parameters of struts along different directions and strut joints are analyzed and classified. Consequently, several typical defects are identified: (1) holes at the joints of the strut and irregular diameter deviations of the strut in the octet-truss lattice structure; (2) irregular diameter variations, bulges, dislocations, grooves, accumulations, and torsion in the re-entrant lattice structure. All of these defects are related to the building direction, the weight of the structure, bubbles, dust, and impurities during the PµLSE additive manufacturing process.