Physical, mechanical, and microstructural characterization of NUW-LHT-5M lunar highland simulant through spark plasma sintering

For achieving permanent habitation of mankind on the Moon, the development of in-situ resource utilization (ISRU) construction materials is imperative, and the spark plasma sintering (SPS) method has been regarded as a promising option due to its accelerated densification process, enhanced microstructural evolution and mechanical properties. This study investigates the effects of sintering temperature (800 °C, 900 °C, and 1000 °C) on the physical, mechanical, and microstructural characteristics of a new NASA lunar highland simulant (NUW-LHT-5M) targeting potential landing sites near the lunar south pole region. Laboratory tests were conducted to investigate the fundamental characteristics of the simulant in its raw powder and SPS sintered at varying temperatures. SPS at 1000 °C produced higher strength up to around 160 MPa, compared to 46 MPa at 900 °C and 12 MPa at 800 °C. Mineralogical and microstructural analysis indicated that elevated sintering temperatures yielded crystalline phases with high values of modulus and hardness and promoted microstructural homogeneity, both contributing to improving mechanical strength. The findings of this study imply the feasibility of using SPS as a promising ISRU method on the lunar south pole region to produce high density-strength construction materials without the need for water and other additives.