Characterization of volatiles evolved during vacuum sintering of lunar regolith simulants

This work describes an experimental vacuum setup, designed for sintering of lunar regolith simulant materials, and its application to real-time characterization and identification of volatile species, resulting from in vacuo decomposition of the non-lunar components in the materials. We carried out a thorough experimental system characterization, highlighted critical aspects (temperature, pressure) with respect to regolith sintering, identified the volatile release / sample environment correlations, and postulated the need for high-vacuum capabilities in light of the high gas loads, generated by the simulants. We detailed the identification process of specific released gas species (H2O, NO, H2S, CO2, SO2, SO3, HCl, HF, etc.) using mass spectrometry, and advanced the use of them as markers for thermally activated processes, such as dehydration of hydrates, decomposition of major non-lunar phases (carbonates and sulfates) and lesser-represented components (nitrates, fluorides, chlorites, etc.). Quantification of individual decomposing phases is feasible within reason despite the inherent limitations of mass spectrometry. The methods, detailed in this paper, are intended for use in developing a better understanding of lunar regolith simulants with respect to sintering applications.

Automated summary

This work presents an experimental vacuum setup designed for sintering lunar regolith simulants and characterizing volatile species released from the decomposition of non-lunar components. The study highlights the importance of temperature and pressure in regolith sintering and emphasizes the need for high-vacuum capabilities due to high gas loads generated by the simulants. The use of mass spectrometry allows for the identification of specific released gas species and their potential as markers for thermally activated processes.