The lunar base establishing is crucial for the long-term deep space exploration. Given the high costs associated with Earth-Moon transportation, in-situ resource utilization (ISRU) has become the most viable approach for lunar construction. This study investigates the sintering behavior of BH-1 lunar regolith simulant (LRS) in a vacuum environment across various temperatures. The sintered samples were characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), along with nanoindentation, uniaxial compression, and thermal property tests to evaluate the microstructural, mechanical, and thermal properties. The results show that the sintering temperature significantly affects both the microstructure and mechanical strength of the samples. At a sintering temperature of 1100 degrees C, the compressive strength reached a maximum of 90 MPa. The mineral composition of the sintered samples remains largely unchanged at different sintering temperatures, with the primary differences observed in the XRD peak intensities of the phases. The plagioclase melting first and filling the intergranular pores as a molten liquid phase. The BH-1 LRS exhibited a low coefficient of thermal expansion (CTE) within the temperature range of - 150 degrees C to 150 degrees C, indicating its potential for resisting fatigue damage caused by temperature fluctuations. These findings provide technical support for the in-situ consolidation of lunar regolith and the construction of lunar bases using local resources.

Establishing a base on the Moon is one of the new goals of human lunar exploration in recent years. Sintered lunar regolith is one of the most potential building materials for lunar bases. The physical, mechanical and thermal properties of sintered lunar regolith are vital performance indices for the structural design of a lunar base and analysis of many critical mechanical and thermal issues. In this study, the HUST-1 lunar regolith simulant (HLRS) was sintered at 1030, 1040, 1050, 1060, 1070, and 1080 C. The effect of sintering temperature on the compressive strength was investigated, and the exact value of the optimum vacuum sintering temperature was determined between 1040 and 1060 C. Then, the microstructure and material composition of vacuum sintered HLRS at different temperatures were characterized. It was found that the sintering temperature has no significant effect on the mineral composition in the temperature range of 1030-1080 C. Besides, the heat capacity, thermal conductivity, and coefficient of thermal expansion (CTE) of vacuum sintered HLRS at different temperatures were investigated. Specific heat capacity of sintered samples increases with the increase of test temperature within the temperature range from -75 to 145 C. Besides, the thermal conductivity of the sintered sample is proportional to density. Finally, the two temperatures of 1040 and 1050 degrees C were selected for a more detailed study of mechanical properties. The results showed that compressive strength of sintered sample is much higher than tensile strength. This study reveals the effects of sintering temperature on the physical, mechanical and thermal properties of vacuum sintered HLRS, and these material parameters will provide support for the construction of future lunar bases. (c) 2024 Published by Elsevier B.V. on behalf of China University of Mining & Technology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

The utilization of in-situ lunar resources through the additive manufacturing of lunar regolith (LR) has attracted considerable interest. Sintering of LR is considered a promising method for lunar construction due to its high utilization rate and excellent service stability. However, numerous studies have been carried out on Apollo series LRs with similar chemical compositions in air or inert gas atmospheres. The effects of the lunar ultra-high vacuum conditions and the complex chemical composition of LRs on the sintering process require extensive investigation. In this study, a self-developed Chang'E-5 lunar regolith simulant (LRS) with a high-Fe content was used as the only raw material to investigate its potential applicability for future lunar construction in vacuum environment. The effects of sintering temperature on the microstructure, linear shrinkage, bulk density, weight loss ratio, and mechanical and thermal expansion properties were investigated. The results show that the linear shrinkage and weight loss ratio increase with increasing sintering temperature. However, the bulk density and unconfined compressive strength (USC) initially increase and then decrease, with the sample sintered at 1075 degrees C giving the highest bulk density of 2.10 +/- 0.03 g/cm3 and a USC of 31.19 +/- 1.96 MPa. This is attributed to the transformation of the sample sintered at 1090 degrees C into a semi-porous material with many cracks. Furthermore, the mechanism of pore and crack formation was revealed. The coefficient of thermal expansion (CET) of the sintered samples is approximately 7x10-6 degrees C 1, which maintains a good service stability after cyclic temperature stress from room temperature up to 200 degrees C. Both the USC and CET of the sample sintered at 1075 degrees C are superior to those of common terrestrial concrete materials. This indicates that the vacuum sintering process appears feasible for the production of building materials with sufficient mechanical strength and thermal durability for lunar base construction.