Improving relative density and mechanical strength of lunar regolith structures via DLP-stereolithography integrated with powder surface modification process

Abstract

Three-dimensional (3D) printing is one of the most promising techniques for on-site manufacturing and is expected to become a key technology for the construction and maintenance of lunar bases. In this study, powder surface modification was integrated with digital light process (DLP)-based 3D printing to improve the mechanical properties of 3D printed lunar regolith simulant (CUG-1A) structures. A silane coupling agent (KH570) was utilised to modify the CUG-1A powder, and the underlying surface modification mechanism was elucidated. In addition, the effects of the silane coupling agent on the rheological properties, wettability, cure depth and dispersity of the slurries were investigated. It was revealed that the introduction of the silane coupling agent improved the wettability between the CUG-1A powder and photocurable resin, which effectively decreased the slurry viscosity. In addition, powder surface modification enhanced the homogeneity of CUG-1A particle distribution, which is beneficial for obtaining a uniformly distributed liquid phase during the sintering process, thus promoting the sintering densification of the printed sample. The relative density and flexural strength of the CUG-1A sample prepared by the modified powder sintered at 1100 °C reached 86.47% and 91.13±5.50 MPa, being 6.5% and 22.5% higher than the values of sample prepared by the unmodified powder, respectively. Finally, complex shaped lunar regolith simulant structures were successfully fabricated via DLP-stereolithography integrated with powder surface modification, which indicating powder surface modification is an effective way to fabricate 3D printed lunar regolith simulant components with high density and mechanical strength.