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Binder jetting (BJT) has been extensively explored for additive manufacturing of ceramics due to its ability to create complex structures by processing refractory and hard-to-machine materials. However, achieving a uniform powder bed with high packing density while processing ceramics in BJT remains a challenge. This study systematically examines the role of powder size, powder temperature, flow behavior, and powder size distribution on powder bed formation and resulting part properties. Four different alumina powder sizes (1 μm, 5 μm, 10 μm, and 20 μm) were investigated. Flowability characterizations reveal that 1 μm powder remains poorly flowable at both room and elevated temperatures, while 20 μm powder demonstrates excellent flowability at both temperatures. Smaller powders, especially 1 μm, exhibit around 25% loss in moisture, which results in pronounced agglomeration at room temperature. Discrete element method simulations were used to identify the ideal mixing ratio of the bimodal powder using 5 μm and 20 μm powders. For bimodal powder, both the simulation and the experiments exhibited a preferential deposition of smaller powders in the spreading direction. However, the 5 μm and 20 μm powders did not show any preferential deposition in the simulation, but experiments showed preferential deposition behavior. When using bimodal powder, packing density decreases by 7.65% along the spreading direction, which aligns with an 8.19% drop in part relative density. These findings offer valuable insights into the effects of bimodal powder distribution for controlling powder bed packing density and potentially leveraging spatial density variations for functional applications such as biomedical implants, heat exchangers, and gas filtration. 

The ability to manufacture complex design geometries via Additive Manufacturing (AM) has led to a rapid growth in advancing the design methods, fabrication, and application of Triply Periodic Minimal Surface (TPMS) lattices with minimal surface topologies. Due to its zero-mean curvature, TPMS lattices can be additively manufactured without any sacrificial support structures and offer both design and manufacturing engineers, unprecedented control over the local physical properties (surface area, relative density, etc.) and local mechanical properties (flexural strength, Young’s modulus, etc.). TPMS lattices are of high interest for a wide range of applications such as biomedical implants, energy absorption, and surface fluidic applications such as heat exchangers, and energy storage. Recent advancements in functionally graded TPMS lattice design by varying local lattice geometry has shown to result in different mechanical performance. However, there have been limited studies in understanding the functional grading of AM process conditions (e.g., Laser-Powder Bed Fusion in this study) and lattice sheet thickness to better map the design-processing conditions-properties. The goal of this study is to achieve similar mechanical properties in TPMS sheet lattices with two different TPMS sheet thicknesses by varying laser processing conditions (e.g., contour and hatch conditions in this study). Quasi-static tensile testing of solid samples with corresponding AM conditions and 3-point bending tests of TPMS lattices were performed in accordance with ASTM E8 and ASTM E290, respectively. It was observed that the flexural properties of the 0.75 mm and 0.25 mm TPMS lattices are similar and exhibit different properties with different scan strategies and speed variations under contour-only and hatch-only laser scanning strategies. Also, the 0.75 mm TPMS sheet lattices exhibited 79 % higher flexural stiffness than the 0.25 mm sheet lattices. It was also observed that this observed trend was reversed in the case of tensile properties. Findings from this study can provide new directions towards achieving gradient TPMS lattice designs with varying local mechanical performance by grading the laser scanning strategies to achieve desired mechanical properties and surface topologies.