Powder particle size and surface modification effects on aluminum-filled lattice structures in additive manufacturing of energetic materials

The incorporation of metallic fillers into photocurable resins offers a promising route for the fabrication of advanced energetic materials by Digital Light Processing (DLP). This study investigates the printability and compressive performance of triply periodic minimal surface (TPMS) lattice structures manufactured with micron-sized aluminum filled resins with 20 wt% loading (9.9 vol.%). Two micron-sized aluminum powders with distinct particle size distributions were evaluated to assess their influence on suspension stability, curing behavior and mechanical performance. Formulations were characterized through sedimentation over time, working curve analysis and filler content via density measurements and thermogravimetric analysis. Results indicate that suspension homogeneity is significantly improved via powder surface modification and optimized dispersant concentration. Broader particle size distribution promoted enhanced particle packing and reduced light scattering, resulting in increased curing depth with respect to the finer formulation. Compression testing (ASTM D695) revealed significant improvements in mechanical properties across all TPMS configurations. In particular, the Gyroid lattice exhibited a 30% increase in yield strength and a 10% increase in ductility with respect to the unfilled baseline. These findings confirm the suitability of aluminum loaded resins for high resolution DLP printing of functional lattice structures and emphasize the critical role of powder formulation in governing both print fidelity and mechanical response.