In-situ visualization of powder wrapping behavior in millimeter-scale-beam lunar regolith powder bed fusion

Abstract

Future lunar base additive manufacturing is accelerated by ground-based technology. Naturally, loosely packed lunar regolith must be directly treated into a solid surface on the first layer of lunar base construction. Solar powder bed fusion (Solar PBF), with huge spot sizes and low energy densities, is the most efficient energy and material usage method on the moon. However, the powder bed's low heat conductivity hinders energy penetration. This investigation used a millimeter-scale laser beam to recreate the solar PBF spot. The beam was directed at the powder bed without substrate. In-situ observation revealed a wrapping mechanism works for multiple parameters. The wrapping process was primarily observed with lunar regolith simulant CUG-1A, and SS316L was used for comparison under a similar spot and no substrate. The periodic wrapping helps to form deeper melt tracks. The wrapping process has the potential to produce a substrate on a loose powder bed directly.