| In-situ resource utilization on the moon is currently a hot topic in the aerospace field,with attention being paid to lunar regolith additive manufacturing technology.However,the development and application of this technology are constrained by various problems,such as the diversity of lunar regolith types,poor raw material durability,low processing accuracy,complex manufacturing processes,and poor mechanical properties of finished products.Moreover,previous research has focused on the feasibility of manufacturing,while neglecting the actual effects of the lunar environment on the manufacturing process,such as space weathering causing a wide range of lunar regolith particle sizes,organic material degradation,and differences in the composition of the lunar exosphere from that of Earth.To address these issues,this study combines the actual lunar environment to propose a high-precision vat photopolymerization for in-situ low-titanium lunar regolith.The main research contents and findings are as follows:1.To overcome the limitations of commercial photosensitive materials’ poor durability and the need for ball grinding of lunar regolith before slurry preparation for vat photopolymerization,this study investigates the effect of solid content on the rheological properties and settling behavior of slurry during the slurry preparation,based on raw low-titanium lunar regolith and easily storable resins.The results show that high solid content(50 vol%)and low settling slurry can be prepared from the un-ball-ground low-titanium lunar regolith.Besides,the interplay between particle size,solid content,and rheological properties is studied,revealing that the slurry prepared with medium-sized(D50=2.37 μm)lunar regolith simultaneously possess high solid content,low viscosity,and good stability.2.To improve the accuracy of lunar regolith samples,the effect of photoinitiator concentration and exposure strategy on cure depth and interlayer bonding are studied,revealing that the Jacobs formula is not applicable to lunar regolith slurry due to measurement errors in cure depth.Increasing the exposure time can improve the success rate of printing and interlayer bonding.Furthermore,the interplay between particle size,cure depth,and layer thickness is investigated,demonstrating that the slurry prepared from fine lunar regolith particles(D50=1.94 μm)achieves the best printing accuracy(15 μm).3.To address the problem of sample degradation in the lunar environment,considering the difference between the oxygen-rich Earth environment and the oxygen-deficient lunar surface environment,the effect of protective gases and particle sizes on the sintering process is studied.The results show that sintered bodies obtained in air exhibit superior mechanical properties to those obtained in nitrogen.The sintered body prepared from medium-sized lunar regolith has the best mechanical performance after heat treatment,ultimately achieving the highest compressive strength(386 MPa)of low-titanium lunar regolith sample to date.Considering the oxygen-deficient lunar environment,a "two-step sintering method"(degreasing in nitrogen and subsequent sintering in the air)is proposed and validated to achieve higher sintered body mechanical properties(302 MPa)with less oxygen consumption,achieving the lowest porosity(less than 2%)in the field. |
