基于SLM的模拟月壤原位成形技术

激光选区熔化（SLM）技术与原位资源利用（ISRU）概念结合，有望解决地外大规模基地建设的工程难题。利用模拟月壤考察了SLM成形技术用于月球原位资源增材制造的可行性。采用高能束激光为热源，对粉床内模拟月壤颗粒进行逐层照射，使颗粒熔融固结。以激光体积能量密度为综合评价指标，开展SLM工艺参数研究，实现模拟月壤的低能耗、高效率、高几何精度成形。研究结果表明:模拟月壤在激光工作波长吸收率高，热稳定性好，利用较低激光能量可实现模拟月壤SLM成形，成形件几何精度高；激光体积能量密度决定了成形件质量，增加激光体积能量密度可以提高成形件力学性能，但过高的激光体积能量密度使成形件发生严重变形；模拟月壤颗粒形态复杂、粒度分布广、流动性差，通过优化颗粒粒径分布范围，可以有效提高粉体的流动性，从而形成致密且均匀的粉床，避免成形件缺陷的产生。 

In-situ forming of lunar regolith simulant via selective laser melting

Selective laser melting (SLM) technique in combination with the in-situ resource utilization (ISRU) concept can be an off-world manufacturing solution to the significant engineering challenge on the large-scale construction for extra-terrestrial bases. The feasibility of SLM process applied to the additive manufacturing of lunar in-situ resource was investigated by utilizing lunar regolith simulant. A laser source was utilized to melt the powder locally in a layer-wise manner. In order to successfully fuse the powder into parts with low laser power, high efficiency and high geometrical accuracy, the SLM process parameters were investigated and evaluated by laser volume energy density. The results show that the simulant can be successfully fused into parts with high geometrical accuracy using SLM process with low laser power due to its high absorbance and low mass loss. The fabricated part quality depends on the laser volume energy density:increase of laser volume energy density input results in better mechanical properties of parts; however, excessive laser volume energy density input leads to high distortion of parts. Poor powder fluidity of the raw simulant is observed due to its complex particulate shape and a wide range of particle size distribution. The powder fluidity of the simulant is improved by optimizing its particle size range, resulting in a denser and more uniform powder bed, which can avoid defects within fabricated parts.