Effect of compaction pressure on the microstructural, mechanical, and thermal properties of microwave-sintered KLS-1 lunar regolith simulant

The effects of compaction on the physical, microstructural, mechanical, and thermal properties of microwave-sintered KLS-1 lunar regolith simulant were assessed. KLS-1 was compacted at 2.5, 5.0, and 7.5 MPa, and then sintered at 1100 °C for 10 min in a microwave furnace. With increasing compaction pressure, the initial powder density increased, leading to higher density and lower porosity in the sintered product. Microstructural analysis using scanning electron microscopy and X-ray computed tomography confirmed that porosity decreased with increasing compaction pressure. The initial compaction had a strong influence on the mechanical strength of the sintered product. Unconfined compressive strength testing demonstrated increasing mechanical strength with increasing compaction pressure, with 7.5 MPa yielding the highest strength of 56 MPa. The coefficient of thermal expansion decreased with increasing compaction pressure, and remained stable even after cyclic thermal stressing between −140 and 200 °C. Pre-compacting lunar regolith before microwave sintering can produce a structurally robust material with high mechanical strength and thermal stability, making it a promising candidate for lunar construction applications.