Mechanisms of Thermite Reactions during Combustion of Magnesium with Lunar and Martian Regolith Simulants

摘要

Recently, it has been shown that mixtures of JSC-1A lunar regolith simulant with magnesium are combustible [1-4]. Thermite-type reactions in these mixtures could be used for in situ production of construction materials on the Moon. Because of complex composition of lunar regolith, however, the mechanisms of these reactions are not well understood. Also, for Mars mission applications, it is important to explore the possibility of using Martian regolith in such mixtures. In the present work, combustion of two Martian regolith simulants (JSC-Mars-lA and Mojave Mars) with magnesium was studied using thermodynamic calculations and combustion experiments. To understand the reaction mechanisms in these mixtures as well as in the mixtures of JSC-1A lunar regolith simulant with magnesium, thermoanalytical experiments were also conducted. The combustion experiments have shown that the Martian regolith simulants form combustible mixtures with magnesium. The measured temperatures and identified product compositions are in reasonable agreement with thermodynamic predictions. The mixtures of JSC-Mars-1 A with 20-30 wt% Mg exhibit higher temperatures and burn more vigorously than mixtures based on Mojave Mars, which is explained by the higher content of iron oxide in JSC-Mars-1 A. The thermoanalytical studies have confirmed that iron oxide plays a dominant role in the combustion of JSC-Mars-lA simulant with magnesium. However, Mg/SiO_2 mixture ignites at a temperature lower by approximately 100℃ than for Mg/Fe_2O_3. For Mojave Mars and JSC-1A (lunar) materials, which include more silica and less iron oxide, silica exhibits a significant effect on the combustion, promoting reactions at lower temperatures. For more information on the present work, see Ref. [5.]