Influence of Particle Size on Laser Beam Melting of Lunar Regolith Simulant

• Powder bed fusion by laser beam of LX-M100 lunar regolith simulant at particle sizes <45 µm, 90-160 µm, and 500-1000 µm. • Sample length and mass decreased as particle size increased. • Ultimate strength in bending and modulus of elasticity of samples increased slightly as particle size increased. • Average sample thickness and porosity decreased as particle size increased. • Chemical composition of samples changed slightly as particle size increased and pore walls were depleted in oxygen, calcium, sodium, and magnesium relative to solid material across all particle sizes. Several space agencies are planning to construct permanent bases on the Moon within the next few decades. Reducing material and transportation costs by using locally available materials, a concept known as “in-situ resource utilization,” is essential. The primary resource available on the Moon is the lunar regolith. A promising method to create construction materials from lunar regolith is powder bed fusion by laser beam (PBF-LB), which uses a guided laser beam to melt lunar regolith, such that it cools and hardens into a desired shape. In this work, PBF-LB is conducted on the LX-M100 lunar regolith simulant in a vacuum chamber at 12-18 mbar using 200 W of laser power scanning over a regolith simulant powder bed at 4 mm/s. The effect of lunar regolith particle size is investigated using three particle size fractions that have been sieved from the bulk LX-M100 regolith simulant powder: <45 µm, 90-160 µm, and 500-1000 µm. The surface appearance, length, mass, ultimate strength in bending, modulus of elasticity, thickness, porosity, and chemistry of the samples produced by PBF-LB at each particle size are determined. As particle size increases: surface smoothness decreases, mass decreases, length decreases, strength slightly increases, elasticity slightly increases, thickness decreases, porosity decreases, and chemical composition changes. These results indicate that the bulk lunar regolith should be separated into particle size fractions and the optimal particle size fraction should be used for PBF-LB, in applications where these physical or mechanical properties are relevant.