Optimized sintering strategy for lunar regolith simulant particles bound via vat photopolymerization

In deep space exploration, additive manufacturing (AM) of lunar regolith is extremely attractive by using Moon's in-situ resources with the potential to reduce spacecraft launching costs and alleviate Earth's resource limit. However, previous studies are limited to feasibility investigation by fabricating samples using lunar regolith simulant (LRS) and have not considered real lunar environmental conditions such as space weathering, temperature cycles, and exosphere, leaving a big unknown on how to obtain reliable samples via AM using really lunar regolith on the Moon. Hence, the influence of several environmental conditions on LRS-based vat photopolymerization (VP) is comprehensively studied in this work, to obtain better mechanical properties for practical application. First, the effects of different particle size distributions in the lunar regolith caused by space weathering on VP are examined. An optimal middle D50 of 2.37 μm is proved to be beneficial for great stability, high resolution (30 μm), and mechanical properties. Secondly, the strategy of debinding in the nitrogen followed by sintering in the air is proven to be more beneficial for improving mechanical properties and reducing oxygen consumption, preventing samples from reduced durability caused by the wide temperature cycle. Overall, this study provides an initial step for developing in-situ resource utilization on the Moon using the AM method by considering the lunar environment conditions.