Laser additive manufacturing of lunar regolith simulant: New insights from in situ synchrotron X-ray imaging

Abstract

The establishment of on-site autonomous manufacturing capabilities for a sustainable long term lunar base can benefit from additive manufacturing. While previous studies have demonstrated that laser powder bed fusion (LPBF) can manufacture lunar Regolith parts, significant challenges remain in fabricating large structural parts with consistent properties due to the complexities of LPBF process and the variability in the mineralogical composition of Regolith. This study examines process instabilities, melt flow dynamics and defect evolution during LPBF of lunar Mare Regolith simulant LMS-1, using in situ and operando synchrotron X-ray imaging and ex situ characterisation techniques across a range of processing parameters. Five processing regimes for LPBF of LMS-1 were identified: (i) no deposition, (ii) balling, (iii) sintering, (iv) vitrification, and (v) vaporization. The optimal LPBF parameters are 145 W laser power, 390 mm/s scan speed, and 0.25 mm hatch spacing. A laser re-scan strategy is used to further improve sample consolidation and minimise thermal stress accumulation in LMS-1 parts. Essential materials data and in situ X-rays images of melt pool geometry evolution for validating multiphysics numerical models of lunar Regolith laser melting are provided.