Vacuum sintering of lunar regolith simulant into homogeneous blocks: Outgassing behavior and optimized heating strategy

The lunar south pole is believed to contain abundant water ice, making it a strategically important location for future missions to explore space. Plans are underway to establish a base in this region, as its water resources would be useful to long-term human exploration and habitation. Numerous studies have considered the sintering of lunar regolith to produce materials for the construction of lunar infrastructure. This study addresses the challenges posed by outgassing, particularly the release of water vapor, during the sintering of lunar regolith simulant under vacuum conditions. The experiments revealed that the outgassing of water vapor can explosively eject soil particles, which in turn can weaken or damage the resulting sintered bodies. After assessing the effects of outgassing under different heating profiles, optimal pretreatment conditions were identified to minimize the impact of outgassing on the sintered bodies. Sintering under vacuum (∼10 −2 mbar) was tested using various heating rates and dwell times to produce homogeneous sintered bodies without internal cracks or pores. Blocks produced under the optimized conditions at a range of sintering temperatures were assessed in terms of their physical, microstructural, and mechanical properties. The results provide valuable insights into the vacuum sintering processes and offer practical guidance regarding the fabrication of construction materials from lunar regolith. Thus, this work contributes to the advancement of future lunar infrastructure, particularly at the south pole.